Nuova ricerca

Massimo MILANI

Professore Ordinario
Dipartimento di Scienze e Metodi dell'Ingegneria

Home | Curriculum(pdf) | Didattica |


Pubblicazioni

- Metallic Fuel Co-Generative Plant [Brevetto]
Franzoni, Federica; Milani, Massimo; Montorsi, Luca
abstract

The patent deals with an innovative power co-generation plant based on the combustion of metallic powders in water.

2023 - A Computation Fluid Dynamics Methodology for the Analysis of the Slipper-Swash Plate Dynamic Interaction in Axial Piston Pumps [Articolo su rivista]
Muzzioli, G; Paltrinieri, F; Montorsi, L; Milani, M
abstract

This paper proposes a CFD methodology for the simulation of the slipper's dynamics of a swash-plate axial piston unit under actual operating conditions. The study considers a typical slipper design, including a vented groove at the swash-plate interface. The dynamic fluid-body interaction (DFBI) model is exploited to find the instantaneous position of the slipper, while the morphing approach is adopted to cope with the corresponding mesh distortion. A modular approach is adopted to ensure high-quality mesh on the entire slipper surface and sliding interfaces provide the fluid dynamic connection between neighboring regions. The external forces acting on the slipper are included by means of user-defined lookup tables with the simulation estimating the lift force induced by fluid compression. Moreover, the force produced by the metal-to-metal contact between the slipper and the swash plate is modeled through a specific tool of the software. The pressure signal over an entire revolution of the pump is taken as an input of the simulation and a variable time step is used to manage the high-pressure gradients occurring in the regions of inner and outer dead points of the piston. The weakly compressible characteristic of the fluid is considered by a specific pressure-dependent density approach, and the two-equation eddy-viscosity k-omega SST (shear stress transport) model is used to assess the turbulent behavior of the flow. Furthermore, the transitional model predicts the onset of transition, thus solving different equations depending on whether the flow enters a laminar or turbulent regime. In conclusion, the proposed methodology investigates the motion of the slipper in response to several external forces acting on the component. The numerical results are discussed in terms of variable clearance height, pressure distribution within the gap, and lift forces acting on the slipper under specific pump operations.

2023 - CFD with FLUID STRUCTURE INTERACTION ANALYSIS of LUNG ALVEOLAR SACS and ITS APPLICATIONS in EMPHYSEMA STUDY [Relazione in Atti di Convegno]
Carotenuto, C.; Orlandi, F.; Montorsi, L.; Milani, M.
abstract

Emphysema, a chronic lung disease characterized by respiratory distress and reduced lung function, poses significant challenges. Computational Fluid Dynamics (CFD) coupled with fluid structure interaction (FSI) is a highly effective simulation technique that offers valuable insights into the mechanics of lung function and the influence of diseases like emphysema. The intricate lung alveolar sacs play a vital role in gas exchange, and CFD with FSI enables the simulation of mechanical forces that shape and impact their functionality. By employing CFD with FSI, we can simulate the fluid dynamics of emphysema and acquire a comprehensive understanding of disease progression. These simulations allow us to explore the contributions of tidal breathing and surface tension forces. This study has demonstrated through FSI that a lung alveolus affected by pulmonary emphysema, and therefore collapsed, causes reduced air intake with each breath. This is due to the significantly compromised deformability of the alveolar wall. Ultimately, this technique plays a critical role in developing therapeutic interventions to improve patient outcomes.

2023 - Cavitation analysis through CFD in industrial pumps: A review [Articolo su rivista]
Orlandi, F.; Montorsi, L.; Milani, M.
abstract

Cavitation is one of the most detrimental fluid-dynamic anomalies that occur to turbomachines. It mainly affects machines characterized by high rotation speeds and clear distinctions between low and high pressure zones, where cavitation first appears. During the years, starting from the well known Rayleigh formulation for the formation of bubbles in a liquid medium, many models have been proposed to analyse the phenomenon. Spanning from higher simplifications to more detailed formulations, the range of applications of these models is wide and led to different quality results, where a clear methodology is not fully established when regarding specific sectors, for example the industrial pumps. Restricting the application field to few, specific kinds of pumps, i.e centrifugal, axial flow pumps, external gear and mixed flow pumps, this article analyses the main literature sources in order to give an overall view to the Computational Fluid Dynamic applications of the different cavitation models and their applications to industrial pumps.

2023 - Combined numerical approach for the evaluation of the energy efficiency and economic investment of building external insulation technologies [Articolo su rivista]
Venturelli, M.; Saponelli, R.; Milani, M.; Montorsi, L.
abstract

2023 - Computational Fluid Dynamics Study of Particle Deposition on Human Lung Dynamic: A Comparison Between the Healthy and Fibrotic Lung [Articolo su rivista]
Carotenuto, Carlo; Scurani, Letizia; Fontanili, Luca; Montorsi, Luca; Milani, Massimo
abstract

2023 - Development of a Numerical Approach for the CFD Simulation of a Gear Pump under Actual Operating Conditions [Articolo su rivista]
Orlandi, F; Muzzioli, G; Milani, M; Paltrinieri, F; Montorsi, L
abstract

The geometric complexity and high-pressure gradients that characterize the design of the flow field of gear pumps make it very difficult to obtain an accurate CFD simulation of the component. Usually, assumptions are made both in terms of geometrical features and physics being included in the analysis. The contact between the teeth, which is a key factor for the correct functioning of these pumps, represents a critical challenge in 3D CFD simulations, mainly due to the intrinsic limits of the dynamic meshing techniques that can hardly effectively manage a zero or close to zero gap point forming during gear rotation. The geometric complexity and high-pressure gradients that characterize the gear pump flow field make a CFD analysis quite difficult, and the contact between the gear teeth is usually avoided, thus being an extremely important feature. In this paper, a gear pump composed of inlet and outlet pipes was considered, and the contact between the gear's teeth was modeled in two different ways, one where it is effectively implemented and one where it is avoided using distancing and a proper casing modification. Herein, a new methodology is proposed for the application of the dynamic mesh method in the Simcenter STAR-CCM+ environment using an adaptive remeshing technique. The proposed methodology is compared with the alternative overset meshing method available in the software. The new meshing method is implemented using a user-routing that reproduces the real geometry of the gears while rotating during the pump operation, with teeth contact included. The routine is optimized in order to limit the additional computation and time needed for the remeshing process. The results that can be obtained using the two meshing approaches for the gear pump are compared in terms of computational effort and the accuracy of the results. The two methods showed opposite results in almost all the reported results, with the overset being more precise in the radial pressure evaluation and the dynamic being more reliable in the cavitation/aeration extension cloud.

2022 - A lumped parameter and CFD combined approach for the lubrication analysis of a helical gear transmission [Relazione in Atti di Convegno]
Muzzioli, G.; Paini, G.; Denti, F.; Paltrinieri, F.; Montorsi, L.; Milani, M.
abstract

2022 - A lumped parameter approach for the filling analysis of V6 engine lubrication systems [Articolo su rivista]
Polastri, M.; Storchi, G.; Battarra, M.; Montorsi, L.; Milani, M.; Mucchi, E.
abstract

The present work describes a lumped parameter approach for the filling analysis of engine lubrication systems. Filling analyses are typically carried out by means of multi-phase 3-D CFD models but, despite allowing detailed and reliable results, they require very demanding computational capabilities. Based on these premises, the authors present a modelling procedure to address the topic by means of a lumped parameter approach. By introducing a detailed modelling technique, the proposed method offers the possibility to reproduce not only the common and simple elements such as pipes and bends, but also permits the discretization of complex three-dimensional fluid domains. The proposed approach has been applied to the lubrication system of a heavy-duty V6 engine: since long stop intervals are planned during the engine lifetime, the filling time of the system plays a fundamental role. The analysis has been run with the obtained 0-D model, simulating at different lubricant temperature. The predictive capabilities of the numerical model are presented in terms of flow pattern and filling time of the circuit branches. The simulation has also been performed by means of a 3-D CFD model, providing the possibility of a result comparison: since this methodology is nowadays considered the state of the art for this kind of analyses, the results are taken as reference to evaluate the capabilities of the proposed 0-D approach. The comparative analysis concerns both the overall distribution of the lubricant over time, and the local phenomena. The differences in terms of computational effort are considered as well, to assess the approximation of the lumped parameter approach with respect to the complex but more accurate three-dimensional models. The results highlight the accuracy of the methodology on the estimation of the filling time. Moreover, the proposed procedure reveals great advantages in terms of computational effort.

2022 - Analysis and characterization of diffusive flows and movement of the human acinar region: An experimentally validated CFD model [Articolo su rivista]
Scurani, L.; Fontanili, L.; Montorsi, L.; Milani, M.
abstract

This paper presents a study of the gas exchanges at the alveolar level to define the respiratory capacity of a subject. A numerical multidimensional approach is proposed for the prediction of the diffusive flows of gases (oxygen and carbon dioxide) in the alveoli accounting for the gas exchange phenomena including the surface variation due to the alveoli motion. The overset mesh technique is used to reproduce a realistic surface variation during inspiration and expiration and simulate the expansion and retraction of the alveolar sac. A gas-exchange model is implemented to predict the gas distribution in the alveolar sac wall by assigning a gas flow function through the membrane. The numerical analysis enables to evaluate the flow field within the single alveoli in terms of total and partial pressure of the considered alveolar gases, as well as the species distribution due to the diffusive flows. The predictive capabilities of the numerical model are addressed by comparing the calculations with the values obtained by means the mobile metabolic system K5 from COSMED. An experimental campaign on a set of healthy subjects is used to evaluate the diffusive flows through the membrane and a good agreement between the numerical results and the experimental measurements is found. These evaluations are suitable for the characterization of the breathing capacity in physiological or pathological conditions; therefore, the proposed model can be used as a valid support for bioengineering studies in terms of respiratory gas exchange prediction.

2022 - CFD Study of the Influence of SARS-CoV-2 Deposition on Human Lung Dynamic: A Comparison Between Healthy and Diseased Condition [Relazione in Atti di Convegno]
Carotenuto, Carlo; Scurani, Letizia; Fontanili, Luca; Montorsi, Luca; Milani, Massimo
abstract

2022 - Detailed CFD transient heat transfer modelling in a brake friction system [Relazione in Atti di Convegno]
Orlandi, F.; Milani, M.; Montorsi, L.
abstract

2022 - Experimental evaluation of the pyrolysis of plastic residues and waste tires [Articolo su rivista]
Venturelli, M.; Falletta, E.; Pirola, C.; Ferrari, F.; Milani, M.; Montorsi, L.
abstract

The paper presents the design of the experimental apparatus developed in order to analyse the performance of a prototype of a pyrolysis system for the exploitation of the plastic residues of industrial processes and the end-of-life tires. The small-scale pilot prototype is specifically designed for carrying out an experimental campaign aimed at determining the influence of different plastic types on the yield and on the quality of the liquid oil, gas and char obtained in the pyrolysis process. The study investigates the effect of different mixtures of various plastic products mainly made of polyethylene, styrene butadiene rubber, nylon, and natural rubber. The prototype is equipped with a control system able to monitor the main operating parameters of the process, such as the pyrogas pressure and temperature as well as the temperature inside the reactor where the pyrolysis takes place. The monitored variables are employed for deriving correlations among the operating conditions and the yield of the pyrolysis process. Moreover, SPME-GC/MS analysis were performed on different gas samples to estimate the main compounds that are contained in the syngas in comparison to the different plastic wastes analysed. Thus, the emissions of the small-scale prototype are evaluated. The results obtained by means of the experimental campaign performed on the test rig were used to carry out the economic assessment of an integrated pyrolysis system for the exploitation of the plastic residues from an industrial plant.

2022 - Prediction Capabilities of a One-dimensional Wall-flow Particulate Filter Model [Articolo su rivista]
Impiombato, A. N.; Biserni, C.; Milani, M.; Montorsi, L.
abstract

This work is focused on the formulation of a numerical model for prediction of flow field inside a particulate filter. More specifically, a one-dimensional mathematical model of the gas flow in a particulate trap-cell is deduced and solved numerically. The results are given in terms of velocity, pressure, and filtration velocity. In addition, the dependence of the pressure drop on the main governing parameters has been investigated. More specifically, the permeability of the porous medium and the hydraulic diameter play a fundamental role in the pressure drop

2021 - A statistical approach for modeling individual vertical walking forces [Articolo su rivista]
Pancaldi, F.; Bassoli, E.; Milani, M.; Vincenzi, L.
abstract

This paper proposes a statistical approach for modeling vertical walking forces induced by single pedestrians. To account for the random nature of human walking, the individual vertical walking force is modeled as a series of steps and the gait parameters are assumed to vary at each step. Walking parameters are statistically calibrated with respect to the results of experimental tests performed with a force plate system. Results showed that the walking parameters change during walking and are correlated with each other. The force model proposed in this paper is a step-by-step model based on the description of the multivariate distribution of the walking features through a Gaussian Mixture model. The performance of the proposed model is compared to that of a simplified load model and of two force models proposed in the literature in a numerical case study. Results demonstrate the importance of an accurate modeling of both the single step force and the variability of the individual walking force.

2021 - About the influence of eco-friendly fluids on the performance of an external gear pump [Articolo su rivista]
Muzzioli, G.; Montorsi, L.; Polito, A.; Lucchi, A.; Sassi, A.; Milani, M.
abstract

This paper wants to investigate the effects of eco-friendly fluids on the thermo-fluid-dynamic performance of external gear pumps in order to provide a first response to the increasingly urgent demands of the green economy. A computational fluid dynamics (CFD) approach based on the overset mesh technique was developed for the simulation of the full 3D geometry of an industrial pump, including all the characteristic leakages between components. A sensibility analysis of the numerical model with respect to different fluid properties was performed on a commonly used mineral oil, showing the key role of the fluid compressibility on the prediction of the pump volumetric efficiency. Moreover, the influence of temperature internal variations on both fluid density and viscosity were included. The BIOHYDRAN TMP 46 eco-friendly industrial oil and olive oil were further considered in this work, and the results of the simulations were compared for the three fluid configurations. A slightly lower volumetric efficiency was derived for the olive oil application against the other two conditions, but suggestive improvements were produced in terms of pressure and temperature distributions. Therefore, based on the obtained results, this paper encourages research activity towards the use of eco-friendly fluids in the hydraulic field.

2021 - CFD analysis and experimental measurements of the liquid aluminum spray formation for an Al–H2O based hydrogen production system [Articolo su rivista]
Milani, M.; Montorsi, L.; Storchi, G.; Venturelli, M.
abstract

The paper proposes a combined approach between numerical modeling and experimental measurements for the analysis of a cogeneration system based on the reaction of liquid aluminum and water steam. Scrap aluminum is used for hydrogen production and the primary one is employed as an energy carrier to transport the energy from the alumina reduction system to the site of the suggested plant. The analysis focuses on the liquid aluminum injection phase immediately downstream the nozzle. High frequency thermo-cameras are employed to qualitatively assess the thermal behaviour the liquid aluminum jet. Fast imaging techniques are used to capture the multiphase flow pattern of the liquid metal jet during the injection phase. The experimental results are used to validate a 2D multi-phase CFD approach. The computational fluid dynamics model of the injection phase is created and used to extend the measurements and deepen the understanding of the thermo-fluid dynamics behaviour of the system. In particular, the influence of different nozzles diameters and different injection pressures on the liquid aluminum jet is investigated. A modular approach is adopted for the domain subdivision in order to represent accurately all the geometrical features, while the volume of fluid approach is used to model the multi-phase flow distribution in the real geometry under actual operating conditions. Finally, a good agreement between the measurements and the calculations is found.

2021 - Comprehensive numerical model for the analysis of potential heat recovery solutions in a ceramic industry [Articolo su rivista]
Venturelli, M.; Brough, D.; Milani, M.; Montorsi, L.; Jouhara, H.
abstract

Heat recovery opportunities and total plant energy efficiency improvements need to be evaluated before manufacturing the real components when addressing the energy and economic effectiveness in industrial applications. Numerical modelling of the complete energy systems can be a key design tool in order to investigate the potential solutions to improve the performance of the considered system. In this study, a 0D/1D numerical analysis and transient system simulation analysis are adopted to investigate the energy efficiency enhancement given by the application of a heat pipe-based heat exchanger in the ceramic industry. The thermal power is recovered from the exhaust gases of the kilns used to fire the tiles. The numerical model includes all the main components of the heat recovery system: the primary side of the exhaust gases, the heat exchanger, the secondary circuit of the heat transfer fluid and the heat sink where the thermal power is exploited. Particular care is devoted to the modelling of the heat pipe-based heat exchanger and the necessary control strategy of the system; a specific model for the simulation of the secondary side pump is also accounted for in the analysis. The numerical results of the primary circuit are validated against experimental measurements carried out on the real ceramic facility. The good agreement between the numerical and experimental results demonstrates that the numerical model is an appropriate tool for investigating the energy efficiency enhancement of an industrial plant and for evaluating different configurations and solutions in order to fulfil the industry requirements.

2021 - Development of an experimental test rig for the pyrolysis of plastic residues and waste tires [Relazione in Atti di Convegno]
Milani, M.; Montorsi, L.; Storchi, G.; Venturelli, M.; Pirola, C.; Falletta, E.
abstract

The paper presents the design of the experimental apparatus developed in order to analyse the performance of a prototype of a pyrolysis system for the exploitation of the plastic residues of industrial processes and the end of life tires. The small scale pilot prototype is specifically designed for carrying out an experimental campaign aimed at determining the influence of different plastic types on the yield and on the quality of the liquid oil, gas and char obtained in the pyrolysis process. The study investigates the effect of different mixture of various plastic products mainly made of polyethylene, styrene butadiene rubber, nylon and natural rubber. The prototype is equipped with a control system able to monitor the main operating parameters of the process, such as the pyrogas pressure and temperature as well as the temperature inside the reactor where the pyrolysis takes place. The monitored variables are employed for deriving correlations among the operating conditions and the yield of the pyrolysis process. Therefore, further analysis concerns experimental measurements in order to estimate the main compounds that are contained in the syngas in comparison to the different plastic wastes analysed. Finally, the emissions of the small-scale prototype are evaluated.

2021 - Evaluation of pressure resonance phenomena in dct actuation circuits [Articolo su rivista]
Terzi, S.; Montorsi, L.; Milani, M.
abstract

The paper investigates hydraulic wave propagation phenomena through hydraulic circuits of power transmission systems by means of numerical approaches. The actuation circuit of a Dual-Clutch Transmission (DCT) power transmission system supplied by a Gerotor pump is analyzed. A steady state approach is adopted to detect resonance phenomena due to Gerotor design parameters and circuit lengths, while one-dimensional numerical models are implemented to predict the pressure oscillations through the hydraulic ducts for the whole pump operating domain. CFD-1D pipelines are adopted to address the pressure oscillation behavior through the hydraulic pipeline, while spectral maps and order tracking techniques are used to evaluate their fluctuation intensity in function of the pump speed rate. The numerical models are validated with experimental tests performed on an ad hoc test rig for power transmission systems and a good match is found between the numerical and the experimental results. Pump design parameters as well as hydraulic accumulators and resonators are numerically investigated to quantitatively evaluate their improvement on the circuits’ hydro-dynamic behavior. Furthermore, simplified numerical models are implemented to investigate the frequency response behavior of the hydraulic circuits by means of linear analysis. This approach resulted to be particularly effective for the prediction of the resonance frequencies location, and it can be adopted as an optimization tool since significant simulation time can be saved. Finally, the performance of the circuits operating with an eco-friendly fluid is evaluated numerically and the results are compared with the ones obtained with a traditional petroleum-based oil.

2021 - Investigation on a full-scale heat pipe heat exchanger in the ceramics industry for waste heat recovery [Articolo su rivista]
Jouhara, H.; Bertrand, D.; Axcell, B.; Montorsi, L.; Venturelli, M.; Almahmoud, S.; Milani, M.; Ahmad, L.; Chauhan, A.
abstract

The ceramics industry is the second largest energy consuming sector in Europe. The main energy used in the ceramics industry is heat generated through burners using natural gas. The main area can be identified in three stages, the drying stage and the firing stage, and the cooling stage. The firing stage represents about 75% of the total energy cost. The roller hearth kiln technology is considered to be the most cost-effective solution for ceramic tile manufacturing. The kiln is separated into two sections, the firing stage and the cooling stage. The cooling stage generates large amounts of waste heat as the exhaust of the kiln is composed of a challenging flue gas for heat recovery. The recovery of this heat in an efficient way with no cross contamination has been achieved with a heat pipe heat exchanger (HPHE) system, which was designed, manufactured and installed on a roller hearth kiln and is presented in this paper. The heat pipe heat exchanger located next to the cooling section exhaust stack managed to recover up to 100 kW at steady state without cross contamination or excess fouling. The return on investment of the system has been evaluated at 16 months with a saving of £30,000 per year. This paper will present a deep row by row theoretical analysis of the heat pipe heat exchanger. The Computational Fluids Dynamics will also be presented to investigate the fluid dynamics within the evaporator and condenser section. Both investigations have then been validated by the experimental investigation carried out on a full-scale industrial system. The design approach used in this paper will highlight the benefits of this type of technology and provide a guideline for the design of novel heat pipe heat exchangers.

2021 - Multiphase Flow Simulation of the Oil Splashing during the Actuated Stage of an Innovative Axle Dry Braking System [Relazione in Atti di Convegno]
Muzzioli, G.; Milani, M.; Rinaldi, P. P.; Stefani, M.; Storchi, G.; Montorsi, L.
abstract

This paper proposes the CFD simulation of the oil splashing within the discs' chamber of a novel concept for axle dry braking system in off-highway vehicles. The system completely removes the lubricating oil from the discs' chamber during the not-engaged configuration of the friction plates and it quickly restore it at the beginning of the braking stage when the discs' cooling becomes crucial, thus ensuring a significant reduction of the power losses. The CFD analysis of the real component is performed to predict the efficiency of the system in terms of both the time needed to replenish the discs' chamber when brake is actuated, and the hydraulic torque exerted by the splashing of the oil. The entire three-dimensional geometry of the domain is accurately discretized, and the multi-phase flow nature is addressed by means of the volume of fluid approach. Moreover, the two-equation realizable k-epsilon model is adopted to describe the turbulent characteristic of the flow under actual operating conditions. The results highlight the prompt response of the system at brake actuation in terms of discs' lubrication and cooling and the amount of viscous energy losses produced by the rotating discs in the engaged configuration.

2021 - Numerical Modeling of the Critical Operating Conditions for a Hydraulic Lubrication System in a Heavy-Duty Tractor Driveline [Relazione in Atti di Convegno]
Polito, A.; Montorsi, L.; Muzzioli, G.; Storchi, G.; Milani, M.
abstract

This paper analyzes the lubrication system of a heavy-duty tractor driveline in different working conditions by means of a lumped parameter approach. The study highlights the critical areas of the hydraulic circuit that are not sufficiently lubricated and a new system setup is proposed to guarantee an adequate flow rates distribution. The numerical model of the lubrication system combines lumped elements with more complex user-defined components in order to address both the pressure losses due to the geometrical features of the circuit and the specific flow characteristics of the hydraulic components. The model considers several configurations of the system accounting for the rotation rate of the engine and the clutches engagement. The results are validated through experimental comparisons. Several critical issues are identified in terms of insufficient lubricant supplied to the utilities. Consequently, an optimized version of the system is proposed to reach any area of the driveline, thus ensuring the required flow rate at each component and preventing their early damaging. Therefore, this paper highlights the potential of the lumped parameter approach in evaluating the performance of an entire lubrication system and in addressing potential failures.

2020 - A CFD approach for the simulation of an entire swash-plate axial piston pump under dynamic operating conditions [Relazione in Atti di Convegno]
Milani, M.; Montorsi, L.; Muzzioli, G.; Lucchi, A.
abstract

The paper proposes a CFD approach for the simulation of a swash-plate axial piston pump including the full 3D geometry of the real component. Different meshing techniques are integrated in order to reproduce all the internal motions of the pump. The overset mesh procedure is used to simulate the dynamic evolution in regions' shape and the variable orientation between parts in the pistonslipper ball joints while the alternating motion of the piston is accounted for by sliding interfaces with the neighboring regions. The multiple dynamics of the different moving elements are implemented in terms of superposing motions in order to reproduce the real position time histories as a function of the rotational speed and the swash plate inclination angle. The proposed numerical model includes all the leakages that characterize the coupling of the many components of the pump and nominal values are assumed (i.e. 10μm) throughout the entire simulation. A pressure-dependent fluid density approach is adopted to improve the performance prediction of the pump under real operating conditions. Moreover, the turbulent behavior of the flow is addressed by means of the two equation k-omega SST model. Therefore the proposed modeling approach highlights the capabilities to address any type of swash-plate axial piston pump in order to simulate the entire machine under dynamic operations; the numerical results are discussed in terms of flow ripple, pressure distribution and fluid-dynamic forces.

2020 - A combined numerical approach for the thermal analysis of a piston water pump [Articolo su rivista]
Milani, M.; Montorsi, L.; Venturelli, M.
abstract

The paper proposes a numerical model for the investigation of a piston water pump under different operating conditions. In particular, the lubricating system is analysed and modelled. The study accounts for the lubrication and friction phenomena, heat transfer, multiphase fluid approach and motion simulation. A computational thermo fluid dynamics approach has been adopted to develop a numerical tool able to simulate the behaviour of the oil during the machine working phases. The CFD approach simulates the moving metal components by means of moving meshes techniques; the friction phenomenon is estimated on the basis of formulations available in literature. The numerical model evaluates the heat transfer between moving metal parts and oil during the operating phases of the system. Furthermore, the heat transfer between oil and environment is calculated, accounting for conduction through the metal crankcase walls. A multiphase fluid approach is used for the simulation of the oil and air mixing during the crank rotation. The heat transfer coefficient predicted by the CFD approach are employed in a lumped and distributed numerical model; the reliability and accuracy of the proposed numerical approach is addressed and validated against experimental results. Experimental data have been collected by means of a thermographic camera and thermocouples. Finally, the tool's predictive capabilities are addressed by simulating different working conditions.

2020 - An engineering approach to model blood cells electrical characteristics: From biological to digital-twin [Relazione in Atti di Convegno]
Fontanili, L.; Milani, M.; Montorsi, L.; Scurani, L.; Fabbri, F.
abstract

Some of the most effective methods to separate circulating tumor cells (CTCs) from normal blood cells can be implemented using ultra-filtration, and/or electro-magnetic fields. As well known, each biological cell presents, on both sides of its membrane, different concentrations of ionic species that produce an electric charge concentration with respect to the lipid double layer (impermeable to ions). In this way, the bio-cell can be seen as an electric capacitor, which has the lipid double layer acting as an insulator inserted between two conductive plates, concentrated on the lipid double layer inner and outer surfaces. In this paper, firstly, the electrical capacitor equivalent system is used to treat different types of bio-cells normally flowing in blood vessels (red blood cells, lymphocytes and various types of CTCs-like), and to transform their biological characteristics into digital twin information useful for engineering applications. After, the preliminary 3D geometric analysis of the bio-cells shapes allowed to associate each bio-cell to a different capacitor model, and to predict the electric-equivalent dimensions characterizing its electric behavior. Finally, the equivalent capacitor model is used to study the influence of bio-cells characteristics variation on human blood cells, with particular attention devoted to liver and lung CTCs-like ones.

2020 - An innovative approach to CTCs' liquid surgery [Relazione in Atti di Convegno]
Fontanili, L.; Milani, M.; Montorsi, L.; Scurani, L.; Venturelli, M.; Fabbri, F.
abstract

Circulating Tumor Cells (CTCs) can be defined as cancerous cells, which detach from a tumor and flow through the vascular or lymphatic systems. The blood flow can carry the tumor cells in another region of human body where they can become the starting point for the growth of additional metastases. Because of this behavior, in the CTCs study it is paramount to acquire new data and knowledge to understand the mechanisms that lead to the separation of the cell from the tumor as well as the major characteristics of these cells. The aim of this work is the development of an innovative therapeutic and diagnostic approach able to lead to a new medical device for removing CTCs from the peripheral blood of a patient. The main target of the approach is to detect the CTCs and separate them during a conventional extracorporeal circulation procedure, similar to that used for renal failure. In this work, the CTCs physical properties are investigated in order to explore the possible characteristics that can be exploited in an ad-hoc developed medical device to remove them from the blood flow. The CTCs physical properties are analyzed numerically, and their behavior is studied by means of CFD simulations. The preliminary numerical tests have been carried out on simple geometries in order to assess the influence of magnetic and electric fields on tumor cells' trajectory. These results are the baseline information to develop more complicated geometries and prototypes for real operations.

2020 - Biomechanical analyses of professional ultramarathon athletes: The effect of repeated long distances on the gait kinematic and kinetics [Relazione in Atti di Convegno]
Fontanili, L.; Milani, M.; Montorsi, L.; Citarella, R.
abstract

Constant monitoring of an athlete allows to foresee any injuries by acting on the dynamics of the movements. For runners, the conduct of a correct athletic gesture according to the athlete's specific body biomechanics guarantees the minimization of non-accidental injury factors. For athletes who are engaged in endurance sports such as marathon runners, the long distances to which they are subjected increases the importance of this type of monitoring. This work reports the results of a study carried out on three IUTA (Italian Ultramarathon and Trail Association) athletes during a routine check carried out at a reference healthcare facility that takes care of their care. These athletes are all specialized in the 24-hour race in which they try to reach the most distance in this time. This type of effort can be made if the athlete undergoes an adequate training regime over long distances. The execution of the running pattern in such a repeated way can lead to the accentuation of postural and joint problems. It is therefore necessary to monitor the biomechanics parameters. In this work, therefore, various gestures are analyzed to show potential movement deficits in order to act in advance on the running technique.

2020 - Early assessment of posture disorders through pre-adolescent monitoring: The case of volley academy modena [Relazione in Atti di Convegno]
Fontanili, L.; Milani, M.; Montorsi, L.; Citarella, R.
abstract

The pre-adolescent age is basic in the beginning of the development of body kinematics. During this age the body structure needs to continuously search for stabilization due to the modification in body segment lengths. This behavior can evolve into incorrect postural attitudes that, if not properly treated, can lead to behaviors that are difficult to recover with advancing age. These incorrect attitudes require an accurate and early diagnosis that can be put in place by expert doctors and clinicians. As well known, sporting activity in this age can help the development of proprioceptive apparatus and the musculoskeletal one. Volleyball is considered a complete sport thanks to the wide range of actions necessary for a match. Following this evaluation, it was decided to carry out a monitoring study of young volleyball players in what is one of the capitals of Italian volleyball, i.e. Modena. To achieve this objective, in this work, 97 female volleyball players have been analyzed during their adolescent and pre-adolescent age. The study has the objective to collect data and design an exercise routine for the training to prevent postural problems. Finally, the data have been analyzed and the most representative ones have been reported in this paper.

2020 - Effects of humidified enriched air on combustion and emissions of a diesel engine [Articolo su rivista]
Pirola, C.; Galli, F.; Rinaldini, C. A.; Manenti, F.; Milani, M.; Montorsi, L.
abstract

The potential of Humidified Enriched Air (HEA) on Diesel engine combustion is investigated, by means of 3D CFD combustion simulations, on a current production 4-cylinder turbocharged Diesel engine. HEA is supposed to be obtained by water degassing operation, exploiting the different vapor-liquid equilibria of it main constituents, nitrogen and oxygen. Simulations are carried out using a customized version of the KIVA 3V code, featuring a detailed chemistry combustion mechanism. The model of the engine is previously validated through comparison with experimental data and then it is used to analyse combustion and emissions of HEA combustion in combination with late injection strategies. Numerical results demonstrate that oxygen-enriched air enhances the thermal efficiency of the engine (up to 13%) and reduces significantly soot emissions; on the other hand, in-cylinder peak pressure and NOx emissions increase. The latter can be significantly reduced by using humidified air maintaining the advantage in terms of thermal efficiency and in soot reduction, nevertheless the baseline case NOx emissions cannot be restored.

2020 - Experimental and numerical analysis of a liquid aluminium injector for an Al-H2O based hydrogen production system [Articolo su rivista]
Milani, M.; Montorsi, L.; Storchi, G.; Venturelli, M.; Angeli, D.; Leonforte, A.; Castagnetti, D.; Sorrentino, A.
abstract

This paper investigates pressurised injection system for liquid aluminium for a cogeneration system based on the Al–H2O reaction. The reaction produces hydrogen and heat which is used for super-heating vapour for a steam cycle. The aluminium combustion with water generates also alumina as a byproduct; the aluminium oxide can be recycled and transformed back to aluminium. Thus, aluminium can be exploited as energy carrier in order to transport energy from the alumina recycling plant to the place where the cogeneration system is located. The water is also used in a closed loop; indeed, the amount of water produced employing the hydrogen obtained by the proposed system corresponds to the oxidizing water for the Al/H2O reaction. The development of a specific test rig designed for investigating the liquid aluminium injection is presented in this research study. The injector nozzle is investigated by means of numerical thermal and structural analysis. The calculations are compared and validated against the experimental measurements carried out on ad-hoc developed test rig. A good agreement between the numerical results and the experimental values is found and the new design of the nozzle is devised.

2020 - Fuel consumption reduction of off-road vehicles by improving the efficiency of the hydromechanical variable transmission's lubrication and actuation systems [Relazione in Atti di Convegno]
Milani, M.; Montorsi, L.; Terzi, S.; Mario, G.; Panizzolo, F.; Profumo, G.
abstract

The paper investigates the efficiency of a hydro-mechanical variable transmission combining experimental and numerical approaches in order to develop operating strategies for power transmission losses reduction due to hydraulic circuits design. Two operating regions, characterized by high working time, have been detected analyzing the telescopic boom handler load spectral map of a real off-road vehicle transmission; the first one characterized by high output speed and the second one by low speed and torque transmission. The efficiency of the former region has been increased by improving the fluid dynamic behavior of the lubrication system, which is greatly affected by the high flow rate generated by the fixed displacement pump operating at high speed, while the latter has been improved regulating the flow pressure of the actuation system with a controlled relief valve. The power losses of the system are experimentally determined testing an instrumented transmission on an ad-hoc test rig. CFD dynamic models are adopted for the lubrication circuit optimization, addressing its real geometrical features as well as the actual operating conditions. Furthermore, the influence of the hydrodynamic resistance of the reverse and first wet clutches on the transmission power losses is investigated regulating the lubrication flow through an on/off valve. Tests demonstrated that up to 6.5 kW can be saved at high transmission ratios. Finally, the effect of the two regulating strategies have been estimated in terms of energy saving and C02 emission reduction on the total vehicle life. Results proved that 5600 kWh and 7250 kWh saved energy can be achieved for the two strategies corresponding to 3.7 tons and 4.6 tons of avoided CO2 respectively.

2020 - Life cycle assessment of an innovative cogeneration system based on the aluminum combustion with water [Articolo su rivista]
Pini, M.; Breglia, G.; Venturelli, M.; Montorsi, L.; Milani, M.; Neri, P.; Ferrari, A. M.
abstract

The continuous increase in primary energy demand and the decrease in the availability of fossil fuels were led to a condition of energy security concerns. In this context, hydrogen can be seen as a promising energy carriers. This paper investigated the environmental performance, through Life Cycle Assessment (LCA) methodology, of a combined production system of hydrogen and power based on aluminum combustion with water. This system is potentially able to produce the integrated generation of four energy sources: hydrogen, high temperature steam, heat and work at the turbine shaft. The LCA results indicated that the life-cycle phases that determine the main environmental impact are: liquid aluminum production, transports of liquid aluminum and electricity consumption. In addition, the major release of carbon dioxide emissions is due to the use of natural gas in the aluminum production phase. In order to determine the “greener” alternative and support the system design choices, according to the eco-design perspective, different system configurations were investigated. In particular, the reaction mechanism between first primary aluminum powder and water steam and then secondary aluminum at liquid state and water steam. The environmental comparison highlighted that the former layout increases by more than 78% compared to latter one.

2020 - Mechanical fatigue evaluation by image recognition [Relazione in Atti di Convegno]
Milani, M.; Montorsi, L.; Fontanili, L.; Storchi, G.; Muzzioli, G.
abstract

The mechanical fatigue is an important contributor to the failure of mechanical components. In order to avoid this condition, the phenomenon has to be predicted and controlled during the design and the implementation of a mechanical component. The mechanical fatigue can lead to maintenance, to parts replacement, to extra-needs for lubricants and ancillary labor, and it is one of the main factors of economic loss. Every mechanical component intended for the force transmission is subject to mechanical fatigue. The analysis of the system status during time enables the evaluation and characterization of the fatigue influence on its behavior. In mechanical devices performing a work-cycle with moving parts, the cyclic movements have to be “the same” during time. The main target of this paper is to verify the mechanical behavior of two different gripping blocks during long periods of high cyclic fatigue work. Both blocks have moving parts and all the acquisitions are concentrated to capture fatigue sign on devices work-cycle, mainly in terms of moving parts positioning. To perform the kinematic analysis of both devices under test, and to verify and quantify the degradation in their mechanical performance, a Motion Capture System (VICON) has been combined with an intelligent tool for imaging analysis (KINOVEA). In this way, the precision and the reliability of a free imaging analysis software applied to cyclic working conditions have been compared, on a bi dimensional plane, with data captured by a stereophotogrammetric system.

2020 - Numerical and experimental analysis of a novel concept for axels dry braking system in off-road vehicles [Relazione in Atti di Convegno]
Milani, M.; Montorsi, L.; Muzzioli, G.; Storchi, G.; Terzi, S.; Rinaldi, P. P.; Stefani, M.
abstract

The paper proposes a novel concept for axels dry braking system in off-road vehicles by implementing an oil recovery system in the friction plates chamber. The new system is able to remove the oil in the discs' chamber when they are not engaged and to replenish it when the braking system is activated and the heat generated has to be dissipated. Thus, the energy losses due to the oil splashing will be significantly reduced with remarkable effects on the fuel consumption of the vehicle. Since experimental measurements are very difficult to carry out on a real system, a simplified geometry is designed and an ad-hoc test rig realized. Fast imaging techniques are used to capture the multiphase flow pattern within the friction plates chamber at different rotational speeds of the axel. The experimental results are used to validate a full 3D multi-phase CFD approach. A good agreement between the measurements and the calculations is found. The numerical modeling is therefore employed to predict the flow distribution in the real geometry and under actual operating conditions. A modular approach is adopted for the domain subdivision in order to represent accurately the three dimensional geometrical features, while the volume of fluid approach is used to model the multi-phase flow that characterizes the component. A conjugate heat transfer model is also adopted to predict the heat transferred from the discs to the working fluid and how the fluid is dissipating the heat within the component. By means of the numerical analysis the geometry of the real system is designed in order to improve the performance of the dry braking systems both in terms of energy saving and oil cooling.

2020 - On the 0d - 3d modelling procedure for the filling analysis of the lubrication system of internal combustion engines [Relazione in Atti di Convegno]
Polastri, M.; Battarra, M.; Milani, M.; Storchi, G.; Montorsi, L.; Mucchi, E.
abstract

The paper focuses on the development of a predictive numerical tool for the assessment of the filling performance of engine lubrication systems. Filling analyzes are typically carried out by means of multi-phase 3-D CFD models but, despite allowing detailed and reliable results, they require very demanding computational requirements. On this basis, a procedure for the lumped parameter modelling of the fluid domain is proposed, allowing the discretization of complex systems that cannot be straightforwardly attributable to elementary submodels. The presented criteria are then applied to the lubrication system of a heavy-duty engine, for which the filling of the circuit plays a fundamental role. Different temperature conditions are simulated, and the predictive capabilities of the numerical model are presented in terms of flow pattern and filling time of the circuit branches. The same simulations are also carried out by means of a 3-D CFD model, permitting a result comparison. The comparative analysis concerns both the overall distribution of the lubricant over time, and the local phenomena within the oil domain, in order to assess the approximation of the lumped parameter approach with respect to the more accurate three-dimensional models.

2020 - Tuning a new ECG and breath monitoring system through cardiopulmonary exercise test comparison: The case of IUTA athletes [Relazione in Atti di Convegno]
Fontanili, L.; Milani, M.; Montorsi, L.; Scurani, L.; Citarella, R.
abstract

Heart Rate (HR) and Breath Rate (BR) are important parameters that define the physiological state of the athlete and evaluate his training the performances during a race or a match. In particular for runners, these are two indexes that can be easily monitored during the performance for the athlete to understand their physical state as well as for the trainer or the coach to improve the athlete deep knowledge and better design the subject specific training. The HR can be typically acquired by lots of different technologies. In this paper, a simple and fast fitting new device for ECG and BR acquisition is presented. This device is a first optimized prototype that use a reduced number of electrodes on the torso to acquire both the ECG waveform and a BR signal. In order to evaluate the reliability and precision of this device we have defined an experimental campaign. Two IUTA athletes (a man and a woman) have been selected to wear the device during a Cardio Pulmonary Exercise Test (CPET). The BR track and ECG waveform acquired by the CPET are compared to the ones acquired with the new device to confirm the reliability and precision of the system.

2019 - A novel Carbon Capture and Utilisation concept applied to the ceramic industry [Relazione in Atti di Convegno]
Saponelli, R.; Milani, M.; Montorsi, L.; Rimini, B.; Venturelli, M.; Stendardo, S.; Barbarossa, V.
abstract

This paper investigates a new concept for the CO2 emission mitigation in the ceramic industry based on carbon reduction and methane formation. The concept is analysed as a retrofit to the natural gas fuelled ceramic kiln that represents the main responsible of this industry in terms of energy consumption and exhaust emissions. The carbon dioxide conversion to methane is obtained by reduction with hydrogen on a Ni catalyst and thus methane is used to fuel the standard burners that equip the kiln. The paper addresses different sources for the hydrogen used as a feedstock for the proposed concept as well as alternative catalysts are explored and compared in terms of reduction efficiency and costs. A lumped and distributed parameter simulation of the entire ceramic kiln is combined to the CFD simulation of the reactor to estimate the efficiency of the CO2 reduction and the corresponding methane production for a reference ceramic kiln. The results of the numerical simulations are then employed to discuss the potential benefits of the proposed concept in terms of carbon dioxide emission reduction for the ceramic production. An economic assessment of the system analysed is also carried out concept to determine the investment necessary to implement the technology in an existing ceramic kiln. The potential replicability for other industrial sector is also addressed.

2019 - A numerical approach for the combined analysis of the dynamic thermal behaviour of an entire ceramic roller kiln and the stress formation in the tiles [Articolo su rivista]
Milani, M.; Montorsi, L.; Venturelli, M.; Tiscar, J. M.; Garcia-Ten, J.
abstract

The numerical analysis of thermal and fluid dynamics behaviour of an industrial roller kiln used for manufacturing ceramic tiles is carried out and combined with the analysis of the mechanical stresses formed in the final ceramics product. The developed numerical approach is able to address the energy efficiency, the fuel consumption as well as the pollutant emissions and the quality of the final product. The model of the ceramic kiln is based on a lumped and distributed parameter model and accounts for the heat and mass transfer phenomena that take place in the real components under actual operating conditions of the systems. Models for the simulation of the different components that are used for the kiln functioning are included in the modelling, such as the burners, the fan, the valves and the control system. The numerical approach demonstrates to predict accurately the temperature distribution of both the tiles and the hot gases along the kiln length. Numerical results are validated against experimental measurements carried out on a real kiln during regular production operations. Additionally, the calculated temperature profile of the tiles is employed to predict the mechanical stresses that form in the ceramic product within the kiln. A thermomechanical model is adopted to determine the curvature and residual stresses in the tiles and particular care is devoted to the final stresses that remain at the end of the kiln since they affect the quality of product. The developed numerical approach demonstrates to be an efficient tool for investigating different control strategies to optimize the kiln thermal behaviour as well as the tile quality. On the basis of the fluid-dynamics and thermomechanical numerical approaches, a modified operating strategy for the kiln's cooling section is proposed to minimize the tiles’ residual stresses and the modified cooling profile resulted to be in the operating range of the real kiln.

2019 - A numerical approach for the evaluation of the energy efficiency in ventilated façade [Relazione in Atti di Convegno]
Milani, M.; Montorsi, L.; Venturelli, M.
abstract

The paper studies the ventilated façade as a potential alternative to conventional coating technologies for the thermal insulation of building’s external walls. The ventilated façade is modeled by means of a CFD approach that accounts for the full 3D-geometry of the building, the walls thickness and materials’ thermal properties. The effects of the windows on the heat losses and in the performance of the ventilated façade are modeled in order to accurately characterize the thermal behavior of the system. The solar radiative heat transfer during two representative days of the year is considered in the analysis and a multiband thermal radiation is adopted to capture the different nature of radiative heat exchange according to the light wavelengths. The numerical approach enables to estimate the thermo-fluid dynamic behavior of the system and the temperature distribution and the velocity flow field within the air gap between the walls are addressed and their influence on the heat transfer through the building’s external walls is determined. The CFD analysis is employed to compare different configurations of the ventilated façade for improving the thermal insulation of the building; the performance of each scenario is determined in terms of electric energy and fuel consumption for the air conditioning and the heating system. Thus, the potential saving of the energy cost for ambient thermal conditioning is evaluated. The analysis investigates the effects on the energy efficiency of different geometrical features of the system such as the height of the building and the air gap thickness and theoretical correlations are derived in order to estimate the best tradeoff between the energy efficiency of the building and the investment of the ventilated façade configuration.

2019 - Analysis of a double inlet gerotor pump: A dynamic multi-phase CFD approach accounting for the fluid compressibility and temperature dependent properties [Relazione in Atti di Convegno]
Milani, M.; Montorsi, L.; Terzi, S.; Storchi, G.; Lucchi, A.
abstract

The paper analyzes the fluid dynamic performance of a double inlet Gerotor pump by means of a multi-phase and multi-component CFD approach. The numerical simulation includes the full 3D geometry of the pump as well as the real physics of the compressible hydraulic fluid and the rotating dynamic motion. The aeration and cavitation phenomena are included in the analysis adopting the Rayleight-Plesset equation and inertia controlled growth model for bubble formation. Cavitation and aeration phenomena are detected, especially when intake pressure is lower than atmospheric pressure. The influence of the fluid temperature variation on the component performance is also numerically predicted. The accuracy of a detailed modelling of the fluid properties variation with respect to the temperature and pressure is addressed and the effects on the numerical results is investigated. The rotational speeds of the internal and the external gears of the pump and the engagement between the teeth are addressed by means of an overset mesh approach. Constant leak height is considered between the gears and the case, while the overset mesh approach is adopted in order to accurately predict the leakage due to the teeth engagement. This numerical approach enables to investigate the dynamic performance of Gerotor gear pumps in terms of flow rate and pressure ripples and volumetric efficiency under standard and critical (actual) operating conditions. Good agreement between numerical and experimental results was found for specific operating conditions.

2019 - Combustion analysis of a light duty diesel engine using oxygen-enriched and humidified combustion air [Relazione in Atti di Convegno]
Pirola, C.; Rinaldini, C. A.; Galli, F.; Manenti, F.; Milani, M.; Montorsi, L.
abstract

The present work presents the results of 3D CFD combustion simulations of a current production 4-cylinder turbocharged Diesel engine using oxygen-enriched and humidified combustion air. Enriched Air (EA) is supposed to be produced by desorption from water, exploiting the different Henry constants of N2 and O2. Simulation results show that EA permits to increase the engine thermal efficiency (up to 10%) and drastically reduces soot emissions but increases in-cylinder peak pressure and NOx emissions. Combustion air humidification helps to reduce NOx increment, without losing the advantage in terms of thermal efficiency and in soot reduction, even if NOx emissions cannot be reported to the base case values.

2019 - Energy efficiency in industry: EU and national policies in Italy and the UK [Articolo su rivista]
Malinauskaite, J.; Jouhara, H.; Ahmad, L.; Milani, M.; Montorsi, L.; Venturelli, M.
abstract

Energy efficiency, which is one of the pillars of the EU's Energy Union strategy, has been proposed as a solution, namely as a highly effective pathway to improve economic competitiveness and sustainability of the European economy, lower emissions, reduce energy dependency and increase security of supply, and job creation. The paper reviews the EU strategies and policies on energy efficiency and argues that further focus should be placed on industrial energy efficiency. Despite a decline in energy consumption in recent years in industry, this sector is one of the largest users of energy in the EU. Therefore, the paper reviews the extent to which the European and national policies in the selected jurisdictions, such as Italy and the UK address energy efficiency in industry and whether there are any measures in place to promote it.

2019 - Integration protocol of different measurement methods for the analysis of the physiological and biomechanical efficiency of a professional athlete [Relazione in Atti di Convegno]
Milani, M.; Montorsi, L.; Fontanili, L.; Rossini, S.; Citarella, R.
abstract

The paper focuses on the methodology for the analysis of the physiological and biomechanical efficiency of a professional athlete for integrating the standard preparation routine. The proposed methodology combines an in-house developed prototype of multiple uniaxial force plates for the measurement of the vertical component of ground reaction forces during movement and an infrared motion capture technique is adopted for measuring accurately the body motion. The procedure is applied on a top level professional volley player and integrates the working routines used for the training over an entire season. The dynamic performance of the athlete is measured in terms of fatigue threshold and the aerobic workload. The proposed methodology demonstrates to be an accurate and reliable instrument for quantifying, for both slow and fast movements, the efficiency with which the athlete reaches the defined training targets and the precision achieved in developing an exercises’ routine. Furthermore, the dynamic response of the athlete is also measured by evaluating the position of the body during the workload as well as the speed of the movements and the corresponding interaction with the ground. This analysis verifies if an asymmetrical loading of the lower limbs and the power exerted during the impulsive contact phase with the ground. The measurements carried out during the analysis provide a map of the athlete performances during an entire season training and the mono- and bi-podalic movements could be associated with the time evolution of the athletic results, such as jumping length and height, speed, precision. Therefore, inefficiencies in the postural and technical aspects during the training can be measured and thus corrected leading to an improvement of the performance and to a reduction of the possibility for injuries onset.

2019 - Testing the performance of an innovative high speed external gear pump as a reliable hydraulic power unit for automotive robotized transmissions [Relazione in Atti di Convegno]
Paltrinieri, F.; Milani, M.; Montorsi, L.
abstract

In this paper the performance of an innovative, high speed, external gear pump have been measured and verified in order to evaluate its potential application as a reliable and efficient power unit for automotive, electro-hydraulic actuated, robotized transmissions. More in detail, this particular type of volumetric machine is built with two suction and two delivery ports and is specifically designed for extremely challenging operating conditions, mainly in terms of both rotational speed and delivery pressure. First of all, the most important hydraulic and mechanical performance parameters have been measured and analyzed, over a wide range of rotational speeds, spanning between 400 and 7000 rpm, and for two different operating temperatures, respectively equal to 40 and 60 °C. In this case, with the aim to increase the consistency of the experimental measurements, two external gear pumps, with exactly the same design geometry and features, have been tested and compared, also with available data coming from the pump manufacturer. All the experimental measurements have been performed with the help of a test bench, equipped with a double Cardan joint and an overdrive, specifically tailored for running the pump at high rotational speed and applying a delivery pressure of about 45 bar, very near to a typical actuation value of a high-performance automotive robotized transmission. At the end of this experimental work, it is possible to conclude that the high speed external gear pump here tested and analyzed can be considered a reliable and effective alternative hydraulic power unit for high-performance, automotive, robotized transmissions.

2019 - Thermo-mechanical behaviour of an injection nozzle for a cogeneration system based on the aluminum/water reaction [Relazione in Atti di Convegno]
Angeli, Diego; Castagnetti, Davide; Cingi, Pietro; Leonforte, ADRIANO DAVIDE SERAFINO; Melchionda, Filippo; Milani, Massimo; Montorsi, Luca; Sorrentino, Andrea; Zanni, Davide
abstract

The thermal behaviour of an injection nozzle for a prototype combustion chamber of a cogeneration system based on the reaction of liquid aluminum and water steam, is analyzed. The heat released by the oxidation of aluminum with water is exploited for super-heating the vapor of a steam cycle and simultaneously producing hydrogen. The only by-product is alumina, which can be transformed again into aluminum. From a thermo-mechanical point of view, the most critical part of the system is the injection nozzle, located at the end of a graphite pneumatic needle valve. The head of the injector is made by titanium and includes a Titalox ceramic nozzle characterized by a 0.5 mm calibrated hole. After a warm up cycle, the injector reaches temperatures of the order of 1000°C. During the subsequent cool-down phase, the different strain rates of the two materials could lead to mechanical failure. In this work, the heating and cooling transients of the injection zone are simulated by a Finite Volume approach. Temperature distributions are then transferred to a Finite Element structural solver in order to verify the resulting stresses. Temperature measurements taken during preliminary experimental tests provide a qualitative assessment of the reliability of the numerical predictions.

2018 - CFD analysis of compensator for meter out sensing system [Relazione in Atti di Convegno]
Marani, P.; Ferrari, C.; Milani, M.
abstract

The Meter Out Sensing (abbreviated to MOS) system is a new hydraulic architecture for multi actuators systems based on meter out control and featuring regeneration. The main benefits of the system are the energy saving obtained by regeneration and the simplicity of operation for the absence of electronic controls and sensors. The regeneration and compensation are obtained through a new component called Three Way Compensator. This component compensates the pressure drop across the meter out edge of the hydraulic block, thus the flow rate is independent of the load. Moreover, regeneration is automatically enabled under proper operating conditions. The paper deals with the Computational Fluid Dynamic analysis for studying the control characteristics of the prototype of three way compensator. Since the system is fully hydraulic, the condition for regeneration depends from the load conditions primarily, but also from the pressure drops across the components generated by the fluid flow. Thus the amount of regeneration flow in a working cycle not only depends on the load but also on the flow rate. Moreover, the compensator, like all hydraulic valves, is affected by flow forces phenomenon. This can deviate the control characteristics from the expected behavior in particular by changing the force balance on the valve, thus its position. The knowledge of flow resistance characteristics and flow forces are crucial to understanding the control characteristics and the energy behavior of this new system. The results will enhance the design and will stimulate the further optimization this critical component. The numerical method is validated by comparison with experimental results obtained on the test bench.

2018 - Economic assessment of an integrated waste to energy system for an urban sewage treatment plant: A numerical approach [Articolo su rivista]
Montorsi, L.; Milani, M.; Venturelli, Matteo
abstract

The economic assessment of an integrated anaerobic digestion and gasification system for the exploitation of the residues from an urban sewage treatment plant is carried out. The obtained bio-fuels are used in a cogeneration unit to produce both electric and thermal energy. The analysis focuses on the water treatment plant of a touristic town, characterized by a highly variable number of inhabitants. Therefore, the amount of input biomass for the integrated plant results remarkably time dependent and the design accounts for the transient nature of the input. The performance of the integrated system is modelled by developing an ad-hoc dynamic library for the simulation of the energy conversion systems under the OpenModelica open source platform. The system's performance and economic assessment are modelled by means of equations and correlations that calculate the components' behaviour on a time dependent basis. The simulation demonstrates that the final wastes to landfill decrease by a 73% improving significantly the environmental impact of the plant. Furthermore, the proposed integrated system is able to produce the 25% of the electric energy required for the plant operation. Thus, the payback period of the integrated plant results to be lower than 3 years.

2018 - Energy efficiency analysis of an entire ceramic kiln: A numerical approach [Articolo su rivista]
Cantore, Giuseppe; Milani, Massimo; Montorsi, Luca; Paltrinieri, Fabrizio
abstract

The paper focuses on the numerical analysis of an industrial ceramic kiln to improve the energy efficiency and the fuel consumption as well as the pollutant emissions. The entire ceramic kiln is modelled by means of a lumped and distributed parameter model; particular care is devoted to the modelling of the heat transfer phenomena occurring within the system under actual operating conditions. Models for the simulation of the different components that are used for the kiln functioning are included in the modelling, such as the burners, the fan, the valves and the control system. The numerical approach demonstrates to predict accurately the temperature distribution of both the tiles and the hot gases along the kiln length. Numerical results are validated against experimental measurements carried out on a real ceramic kiln during regular production operations. The developed numerical approach demonstrates to be an efficient tool for investigating different design solutions for the kiln's components as well as for developing new control strategies. The kiln numerical model is employed to compare different configurations of heat recovery and solutions for improving the tiles' heat transfer. The considered designs are simulated and the performance in terms of energy efficiency and fuel consumption is determined.

2018 - Energy efficiency enhancement and waste heat recovery in industrial processes by means of the heat pipe technology: Case of the ceramic industry [Articolo su rivista]
Delpech, Bertrand; Milani, Massimo; Montorsi, Luca; Boscardin, Davide; Chauhan, Amisha; Almahmoud, Sulaiman; Axcell, Brian; Jouhara, Hussam
abstract

This paper investigates the application of heat-pipe based heat exchanger for improving the energy efficiency of industrial processes. In particular, the case of the ceramic industry is addressed and the potential heat recovery and reduction of fuel consumption is determined. A theoretical model is constructed based on the established, proven performance characteristics of heat-pipe technologies and the performance of the ceramic process are calculated using numerical simulation. The results of the kiln numerical model are then combined to the theoretical model of the heat-pipe based heat exchanger and the heat recovery potential is evaluated as well as the reduction of fuel consumption. The combined theoretical and numerical approach demonstrates that the application of the heat pipes based heat exchanger to the cooling stack of the ceramic kiln enables to recover more than 863 MWh of thermal energy that can be used for heating up the hot air stream of the pre-kiln dryer. Thus, approximately 110,600 Sm3per year of natural gas can be saved from the burners powering the dryer and the emission of 164 tonnes per year of carbon dioxide can be avoided. Additionally, the avoided cost due to the fuel consumption reduction amounts to more than 22,000 Euro per year. These figures support the application of the heat pipes based heat recovery to the ceramic process from the viewpoint of the improvement the energy efficiency and environmental impact and also of the economic investment.

2018 - Energy recovery of the biomass from livestock farms in italy: The case of Modena province [Articolo su rivista]
Milani, Massimo; Montorsi, Luca
abstract

The overall energy conversion efficiency of the waste-to-energy technologies is strongly affected by the distance of the biomass supply and the rate available during the year. Therefore, a simulation tool for the evaluation of the main outputs of a power plant for the wastes exploitation is a useful instrument for investigating the best trade-off between the plant size and the biomass supply. Nevertheless, it usually involves a large number of data and an extensive training and expertise. This paper focuses on the development of a numerical tool for the comparison of different waste-to-energy technologies and thus supporting the selection of the best exploitation strategy based on the data usually accessible to administrations. The numerical approach employs validated numerical models for the considered biomass exploitation technologies and its capabilities are demonstrated by simulating a reference case: the energy recovery from manure of different livestock farms in the province of Modena (Italy). The electric and thermal power production from the manure available in the considered territory is estimated and the produced electric energy is balanced with the energy requirements of the local animal farms. The remaining amount of wastes that has to be disposed is also calculated and compared with the initial input to the systems. Finally, different strategies for distributed and centralized exploitation of the manure are investigated and the related plant size and production of electric and thermal energy are evaluated. The proposed approach and the developed numerical tool prove to be useful instruments for decision makers and can help the efficient exploitation of the biomasses available in a region.

2018 - Experimental and numerical analysis of the multiphase flow distribution in multi plate wetclutches for HVT transmissions under actual operating conditions [Relazione in Atti di Convegno]
Terzi, Stefano; Milani, Massimo; Montorsi, Luca; Manhartsgruber, Bernhard
abstract

The paper investigates the multiphase flow through the plates of multi plate wet-clutches for hydro- mechanical variable transmission in order to address the performance of the lubricating systems and its influence on the thermo-mechanical stresses on the plates. The lubricating oil distribution is very difficult to measure experimentally on a real geometry, therefore, a numerical model for the prediction of the flow distribution within the clutch plates is proposed. The volume of fluid approach is used to model the multi-phase flow that characterizes the component and a modular approach is defined to reproduce accurately the real geometry. Furthermore, the numerical modeling is validated against measurements carried out on an ad-hoc designed test rig. The testing facility replicates both the geometry of a real clutch and the actual operating conditions. Transparent PMMA components and fast imaging techniques are used to capture the multiphase flow pattern within the gear distributor chamber, while a 3D printed component and a specific collector system have been designed in order to reproduce the disks position and measure the oil distribution through the plates' clearances by varying the working conditions. A good agreement between the numerical and the experimental results was found and the analysis highlighted the importance of modeling the multi-phase nature of the lubrication process for the accurate prediction of the oil distribution within multi plate wet-clutches.)

2018 - Fluid - Structure interaction of blood flow in human aorta under dynamic conditions: A numerical approach [Relazione in Atti di Convegno]
Martelli, Francesca; Milani, Massimo; Montorsi, Luca; Ligabue, Guido; Torricelli, Pietro
abstract

The paper proposes a numerical approach for the analysis of the blood flow in human aorta under real operating conditions. An ad-hoc procedure is developed for importing the aorta geometry from magnetic resonance imaging in order to have a patient based analysis. The aortic flow is simulated accounting for the dynamic behavior of the flow resulting from the heart pulse and for the non-Newtonian properties of blood. Fluid - structure analysis is carried out to address the mutual influence of the flow transient nature and the aorta walls' deformation on the pressure flow field and tissue's stresses. Finite element method approach is used for the structural analysis of the aorta walls which are assumed as a linear elastic isotropic material; nevertheless, different regions are introduced to account for the Young modulus variation from the ascending aorta to the common iliac arteries. Mesh morphing techniques are adopted to simulate the wall deformation and a two equation turbulence model is adopted to include the turbulence effects. The proposed numerical approach is validated against the measurements carried out on magnetic resonance imaging scanner and a good agreement is found in terms of aorta wall maximum and minimum deformation during the cardiac cycle. Therefore, the fluid-structure analysis can provide an important tool to extend the insight of the aortic system from magnetic resonance imaging techniques and improve the understanding of arteriosclerosis and the related phenomena as well as their dependence on flow structure and tissue stresses.

2018 - Gait analysis for muscular forces evaluation in human movement: Integration protocol of typical measurement methods [Relazione in Atti di Convegno]
Fontanili, Luca; Milani, Massimo; Montorsi, Luca; Valente, Giordano
abstract

The paper focuses on the gait analysis for the investigation of the typical events occurring in human movements and validate its use as a method for musculoskeletal disease evaluation and for the improvement of athletic training. In the present research the motion capture system is combined with an in-house developed prototype of uniaxial force plates for the measurement of the vertical component of ground reaction forces during movement. While similar techniques are implemented for gait, this equipment can be employed to investigate running, thus, covering a larger number of possible applications and providing a deeper insight either of the athlete performance or the disease analysis. For the prevention and the treatment of those events occurring during running, a thorough understanding of its mechanisms is critical; therefore, a method for evaluating both the kinematic behavior of the human body and the ground reaction forces combined to a model for determining the muscle forces is proposed. An infrared motion capture technique is adopted for measuring accurately the body motion and a multiple force-plate system is used to calculate the force exerted by the ground and sub-divided in the three components by an ad-hoc developed routine. Moreover, the data are used as input parameters for the OpenSim software to derive muscles forces. Finally, the potential of the proposed protocol is determined by an experimental campaign on healthy subjects and a significant database of muscle forces is constructed for different running speeds.

2018 - Influence of non-Newtonian fluid on transient operation of a liquid packaging machine: a combined 1D-3D approach [Relazione in Atti di Convegno]
Venturelli, Matteo; Milani, Massimo; Montorsi, Luca; Torelli, Carlo
abstract

This paper investigates the predictive capabilities of numerical simulation for addressing the actual operation of the hydraulic system of a filling machine for beverage packaging processes. The lumped and distributed parameter approach is compared to the full CFD simulation of the filling system and the accuracy of the results obtained is assessed in case of Newtonian and non-Newtonian fluids. First, the 0D-1D model of the complete hydraulic system of the machine filling process is constructed and validated against experimental measurements carried out using water as an operating fluid. Afterward, a combined 1D/3D simulation is carried out in order to simulate the real control strategy of the machine as well as to accurately determine the flow dynamic within the piping. Finally, the two approaches are confronted when using a non-Newtonian fluid and their advantages and limitations are outlined.

2018 - Modelling and Testing an Innovative Combined Hydraulic Valve for High-Pressure Washing [Relazione in Atti di Convegno]
Paltrinieri, Fabrizio; Milani, Massimo; Montorsi, Luca; Terzi, Stefano
abstract

In this paper the main design features of an innovative combined hydraulic valve for high-pressure washing applications have been investigated by means of numerical modelling and experimental testing. This particular type of hydraulic component is obtained joining together a relief and a bypass valve. When the washing system is activated, the relief valve limits the maximum admitted working pressure while, when the washing system is switched off, the bypass valve unloads the hydraulic circuit and a direct connection with the drain ambient is quickly established. First of all, a very detailed lumped and distributed numerical model of the combined valve has been developed, with particular care devoted to the coupling between all the mechanical internal components (piston with holes, bushing and related springs) and to the valve body inner hydraulic connections. Then, the predictive capability of this lumped and distributed numerical model has been verified by means of a numerical versus experimental comparison, performed for a wide range of operating conditions (inlet pressure and volumetric flow rate) and geometrical parameters (sealing gaps, springs' stiffness and nozzle size). Finally, the previously validated numerical model has been applied in order to identify reliable design solutions for typical washing conditions, characterized by fluid pressure values spanning in the range between 50 to 280 bar and inlet volumetric flow rates comprised between 10 and 40 l/min.

2018 - Numerical analysis of the exhaust gases recovery from a turbine CHP unit to improve the energy efficiency of a ceramic kiln [Articolo su rivista]
Montorsi, L.; Milani, M.; Stefani, M.; Terzi, S.
abstract

The paper focuses on the analysis of an industrial ceramic kiln in order to improve the energy efficiency and thus the fuel consumption as well as the pollutant emissions. A lumped and distributed parameter model of the entire system is constructed to simulate the performance of the kiln under actual operating conditions. The model is able to predict accurately the temperature distribution along the different modules of the kiln and the operation of the many natural gas burners employed to provide the required thermal power. Furthermore, the temperature of the tiles is also simulated so that the quality of the final product can be addressed by the modelling. CFD simulation is also employed to determine the heat transfer coefficients between the tiles and the different components of the system. The numerical approach is used for analysing the effects of the exhaust gases recovery from a CHP turbine unit on the overall efficiency of the kiln. In particular, the CFD approach is adopted for investigating the best location for the hot gases injection within the pre-heating zone of the kiln. The influence of the exhaust gases on the heat exchange between the tiles and the air flow is addressed and the improvement on the convection heat transfer is determined. By means of the 0D/1D the behaviour of the entire kiln is evaluated with particular attention to the fuel consumption. The employment of the CHP exhausts recovery demonstrates to be beneficial both in terms of a reduction of the electric energy requirement of the system for powering the many blowers adopted and in terms of increased efficiency of the kiln.

2018 - Optimization of the Lubrication Distribution in Multi Plate Wet-Clutches for HVT Transmissions: An Experimental - Numerical Approach [Relazione in Atti di Convegno]
Terzi, Stefano; Manhartsgruber, Bernhard; Milani, Massimo; Montorsi, Luca
abstract

The paper investigates the lubrication flow within multi plate wet-clutches for hydro-mechanical variable transmissions in order to optimize the oil distribution and to reduce the thermo-mechanical stresses on the plates. Since experimental measurements are very difficult to carry out on a real system, CFD numerical tools are used for predicting the flow distribution in a real geometry under actual operating conditions. A modular approach is adopted for the domain subdivision in order to represent accurately the three dimensional geometrical features, while the volume of fluid approach is used to model the multi-phase flow that characterizes the component. Poor lubrication is predicted where high thermal stresses were observed during tests. Furthermore, the numerical modeling is validated against measurements carried out on an ad-hoc designed test rig, which adopts transparent PMMA and 3D-printed inserts for the flow investigation. Fast imaging techniques are used to capture the multiphase flow pattern within the clutch gear chamber. The testing facility replicates both the geometry of a real clutch and the actual operating conditions. A good agreement between the numerical and the experimental results is found and the analysis highlights the importance of modeling the multi-phase nature of the lubrication process for the accurate prediction of the oil distribution within multi plate wet-clutches. By means of the numerical analysis modifications to the inlet flow configuration and to the leakages' height are developed, leading to a better oil distribution within the clutch and to a more uniform lubrication through the plates clearances.

2018 - Performance and Exhaust Emissions Analysis of a Diesel Engine Using Oxygen-Enriched Air [Relazione in Atti di Convegno]
Manenti, Flavio; Milani, Massimo; Montorsi, Luca; Paltrinieri, Fabrizio; Pirola, Carlo; Rinaldini, Carlo Alberto
abstract

Oxygen enriched air (EA) is a well known industrial mixture in which the content of oxygen is higher respect the atmospheric one, in the range 22-35%. Oxygen EA can be obtained by desorption from water, taking advantage of the higher oxygen solubility in water compared to the nitrogen one, since the Henry constants of this two gases are different. The production of EA by this new approach was already studied by experimental runs and theoretical considerations. New results using salt water are reported. EA promoted combustion is considered as one of the most interesting technologies to improve the performance in diesel engines and to simultaneously control and reduce pollution. This paper explores, by means of 3-dimensional computational fluid dynamics simulations, the effects of EA on the performance and exhaust emissions of a high-speed direct-injection diesel engine. For the analysis, a customized version of the KIVA 3 V code, including a detailed combustion chemistry approach, coupled with a comprehensive oxidation mechanism as a diesel oil surrogate, is used. A current-production 1.3-liter, four-cylinder engine is selected, and available experimental test data are used for validation of the engine model. Using the validated engine model, the effects of enriched air are investigated, along with the influence of injection strategies, under different operating conditions. It is found that oxygen-enriched combustion reduces soot emissions and improves engine thermal efficiency, but also increases in-cylinder peak pressure and nitrogen oxide (NOx) emissions. By changing the start of injection, it is possible to limit in-cylinder pressure to standard values and so reduce the NOx increment.

2017 - A combined 0D-3D numerical approach for the performance prediction of vehicles? heat exchangers under actual operating conditions [Relazione in Atti di Convegno]
Montorsi, Luca; Gessi, Silvia; Martelli, Massimo; Milani, Massimo
abstract

The paper focuses on the development of a predictive numerical tool for the performance assessment of air-cooled cross-flow heat exchangers for vehicle application. First, a CFD approach for the simulation of vehicles’ radiators under actual operating conditions is proposed. The numerical analysis accounts both for the thermo-fluid dynamics behavior of each section of the heat exchanger and for the flow characteristics of the adopted fan. The full-scale geometry of the fan is included in the simulation as well as the casing and the real rotational speed. The CFD results are used to correlate the flow distribution across the different radiator’s sections and the actual working conditions of both the heat exchanger and the fan operation. Following this methodology, a generic radiator was divided in two different sub-domain types (internal/boundary), and for each one the Wall Heat Transfer Coefficient and the pressure drop 2D maps are determined on the basis of preliminary CFD simulations as functions of fluid velocity and temperature. These elements became the elementary blocks to be used by a custom-made algorithm to characterize exchangers of any size. The algorithm was extended to develop a fully featured PC software to calculate the performance of multiple sections exchangers.

2017 - CFD Analysis of a Full-Scale Ceramic Kiln Module Under Actual Operating Conditions [Relazione in Atti di Convegno]
Milani, Massimo; Montorsi, Luca; Stefani, Matteo; Venturelli, Matteo
abstract

The paper focuses on the CFD analysis of a full-scale module of an industrial ceramic kiln under actual operating conditions. The multi-dimensional analysis includes the real geometry of a ceramic kiln module employed in the preheating and firing sections and investigates the heat transfer between the tiles and the burners’ flame as well as the many components that comprise the module. Particular attention is devoted to the simulation of the convective flow field in the upper and lower chambers and to the effects of radiation on the different materials is addressed. The assessment of the radiation contribution to the tiles temperature is paramount to the improvement of the performance of the kiln in terms of energy efficiency and fuel consumption. The CFD analysis is combined to a lumped and distributed parameter model of the entire kiln in order to simulate the module behaviour at the boundaries under actual operating conditions. Finally, the CFD simulation is employed to address the effects of the module operating conditions on the tiles’ temperature distribution in order to improve the temperature uniformity as well as to enhance the energy efficiency of the system and thus to reduce the fuel consumption.

2017 - Effects of a CHP turbine unit exhaust gases recovery on the energy efficiency of a ceramic kiln [Relazione in Atti di Convegno]
Montorsi, L.; Milani, M.; Stefani, M.; Terzi, S.
abstract

The paper focuses on the analysis of an industrial ceramic kiln in order to improve the energy efficiency and thus the fuel consumption as well as the pollutant emissions. A lumped and distributed parameter model of the entire system is constructed to simulate the performance of the kiln under actual operating conditions. The model is able to predict accurately the temperature distribution along the different modules of the kiln and the operation of the many natural gas burners employed to provide the required thermal power. Furthermore, the temperature of the tiles is also simulated so that the quality of the final product can be addressed by the modelling. CFD simulation is also employed to determine the heat transfer coefficients between the tiles and the different components of the system. The numerical approach is used for analysing the effects of the exhaust gases recovery from a CHP turbine unit on the overall efficiency of the kiln. In particular, the CFD approach is adopted for investigating the best location for the hot gases injection within the pre-heating zone of the kiln. The influence of the exhaust gases on the heat exchange between the tiles and the air flow is addressed and the improvement on the convection heat transfer is determined. By means of the 0D/1D the behaviour of the entire kiln is evaluated with particular attention to the fuel consumption. The employment of the CHP exhausts recovery demonstrates to be beneficial both in terms of a reduction of the electric energy requirement of the system for powering the many blowers adopted and in terms of increased efficiency of the kiln.

2017 - Numerical analysis of an entire ceramic kiln under actual operating conditions for the energy efficiency improvement [Articolo su rivista]
Milani, Massimo; Montorsi, Luca; Stefani, Matteo; Saponelli, Roberto; Lizzano, Maurizio
abstract

The paper focuses on the analysis of an industrial ceramic kiln in order to improve the energy efficiency and thus the fuel consumption and the corresponding carbon dioxide emissions. A lumped and distributed parameter model of the entire system is constructed to simulate the performance of the kiln under actual operating conditions. The model is able to predict accurately the temperature distribution along the different modules of the kiln and the operation of the many natural gas burners employed to provide the required thermal power. Furthermore, the temperature of the tiles is also simulated so that the quality of the final product can be addressed by the modelling. Numerical results are validated against experimental measurements carried out on a real ceramic kiln during regular production operations. The developed numerical model demonstrates to be an efficient tool for the investigation of different design solutions for the kiln's components. In addition, a number of control strategies for the system working conditions can be simulated and compared in order to define the best trade off in terms of fuel consumption and product quality. In particular, the paper analyzes the effect of a new burner type characterized by internal heat recovery capability aimed at improving the energy efficiency of the ceramic kiln. The fuel saving and the relating reduction of carbon dioxide emissions resulted in the order of 10% when compared to the standard burner.

2017 - Numerical analysis of centrifugal pumps running in turbine mode under dynamic operating conditions [Relazione in Atti di Convegno]
De Rose, Vincenzo; Martelli, Francesca; Milani, Massimo; Montorsi, Luca
abstract

The use of pumps as turbines (PAT) has gained importance in the recent years as a possible alternative to specifically developed turbine for mini/micro hydropower plants. The use of production pump for hydropower generation reduces the capital cost of the plant but the energy conversion efficiency can be remarkably lower. The paper analyses the performance of a production centrifugal pump running both in direct and reverse mode. The analysis calculates theoretically the behavior of the PAT under the best efficiency point and extends the investigation to other operating points using both a combined theoretical approach and CFD simulation under dynamic conditions. The effects of possible modifications to the initial design of the pump are investigated when running in turbine mode and their influence on the standard pump operation is also determined. Numerical simulation demonstrates that the impeller trimming leads to improvement in the PAT efficiency in some operating conditions. Conversely, the rotational speeds close to the values typical for the electric generator reduce the PAT performance. Finally, the modification of the impeller geometry at the turbine inlet increases the PAT efficiency but lowers the performance of the machine when running in pump mode.

2017 - Numerical analysis of the heat recovery efficiency for the post-combustion flue gas treatment in a coffee roaster plant [Articolo su rivista]
Milani, Massimo; Montorsi, Luca; Terzi, Stefano
abstract

The heat recovery system for the post-combustion flue gas treatment in a coffee roaster plant is investigated using both a lumped and distributed parameter numerical modelling and a transient CFD approach. The combined analysis of the two numerical approaches enables to estimate the thermo-pneumatic behaviour of the entire plant as well as the optimal design of the heat exchanger. The effects of the heat recovery are evaluated in terms of improved energy efficiency and reduction of the fuel consumption. The counter-flow shell and tube and cross-flow plate fin heat exchangers are designed in order to have similar performance in terms of recovered heat and their performance on the real plant is predicted under actual plant operations. The overall volume of the plate fin device results to be approximately one tenth of the shell and tube architecture's volume, while the pressure drop of the two systems is comparable. Finally, the heat recovery from the flue gas enables to save up to 27% of the fuel necessary to power the post-combustor adopted for the exhausts’ treatment and up to 13% of the total fuel consumption of the plant.

2017 - Optimization of a small size chp system by means of a fully transient numerical approach [Relazione in Atti di Convegno]
Chiantera, Luigi; Milani, Massimo; Montorsi, Luca; Stefani, Matteo
abstract

The paper investigates the performance of a combined heat and power system by means of a fully dynamic numerical approach. An ad-hoc library for the simulation of energy conversion systems is developed under the OpenModelica open source platform; the library includes the main components that usually equip a Combined Heat and Power (CHP) system and they can be connected as they are logically connected in the real plant. Each component is modelled by means of equations and correlations that calculate their performance on a time dependent basis. Therefore, many configurations can be evaluated not only in terms of cumulative annual results or average performance, but the instantaneous behavior can be investigated. The numerical library is constructed using the lumped and distributed parameter approach and it is validated by comparing the numerical results with the measured values over a one-year time period. The prediction capabilities of the proposed numerical approach are evaluated by simulating a case study of a health spa. This case study is selected since it is characterized by significant requirements of both thermal and electric energy. The comparison demonstrated that the calculated results are in good agreement with the measurements in terms of both annual values and distribution over the reference period. Furthermore, an optimization algorithm is adopted and linked to the developed library in order to estimate the best size of different components of the CHP system according to a number of constraints. This feature is particularly important when addressing the energy efficiency of a complete system that is depending on a number of interdependent variables. Therefore, the case study is investigated by accounting also for additional technologies that can be further enhance the performance of the system both in terms of energy consumption and economic investment. In particular, the numerical model is used to optimized the CHP energy efficiency by estimating the best trade-off between the reduction of the energy purchased and the overall cost of the system. The application of PV panels and electric energy accumulators is also investigated and the simulation demonstrates that the size of the cogeneration unit equal to 48 kW, the number of PV panels of 299 and the battery capacity of 45 kWh provide the lowest amount of energy purchased, while the best return of investment is obtained by the CHP unit of 40 kW along with 109 PV panels and a battery of 40 kWh.

2016 - An Innovative Approach to Kinematic Analysis of Multibody Hydraulic Actuation Systems [Articolo su rivista]
Francia, Marco; Milani, Massimo; Montorsi, Luca
abstract

The paper focuses on the development of an innovative methodology for the direct measurement of the main kinematic variables in multi-body hydraulic actuation systems. The analysis investigates how the motion capture technique has been applied to the experimental determination of position, velocity and acceleration of hydraulically controlled actuation systems for off-highway machineries. A number of earth-moving machines has been taken into account, in particular a mini-excavator articulated harm has been equipped with both a standard mechanical system for position and acceleration measurement (including different accelerometers, linear and angular transducers), and a set of IR markers for motion capture application. First, the hydraulically controlled boom-arm-bucket system has been operated using a control routine reproducing a reference operating condition, in order to define the accuracy of the motion capture system in detecting the kinematic quantities’ variations. At the same time, the hydraulic variables have been also acquired to monitor the behavior during the machine working routine. Thus, the results obtained by the different experimental techniques have been compared, in order to state the reliability of the motion capture technique to predict the fast dynamics of pressure variations through the accurate measurement of mechanical devices’ oscillation. Finally, the paper reports the main results obtained using the data from the motion capture characterization of the dynamic performance of the mini-excavator, with particular attention devoted to the dynamic analysis through lumped and distributed parameter numerical co-simulation.

2016 - Dynamic Analysis of the Lubrication in a Wet Clutch of a Hydromechanical Variable Transmission [Articolo su rivista]
Bassi, Andrea; Milani, Massimo; Montorsi, Luca; Terzi, Stefano
abstract

The paper investigates the oil flow through a multi plate clutch for a hydro-mechanical variable transmission under actual operating conditions. The analysis focuses on the numerical approach for the accurate prediction of the transient behavior of the lubrication in the gear region: the trade-off between prediction capabilities of the numerical model and computational effort is addressed. The numerical simulation includes the full 3D geometry of the clutch and the VOF multi-phase approach is used to calculate the oil distribution in the clutch region under different relative rotating velocities. Furthermore, the lubrication of the friction disks is calculated for different clutch actuation conditions, i.e. not-engaged and engaged positions. The influence of different geometrical features of the clutch lubricating circuit on the oil distribution is also determined. The results show the areas where poor lubrication occurs and extend the experiments where measurements are difficult to carry out. The simulation highlights the regions where high thermal stresses are observed during tests.

2016 - Energy recovery of the biomass from livestock farms in Italy: the case of Modena Province [Relazione in Atti di Convegno]
Montorsi, Luca; Bassi, Andrea; Francia, Marco; Milani, Massimo; Stefani, Matteo; Terzi, Stefano
abstract

The energy recovery from manure of different Italian livestock farms is analysed by means of numerical simulation using an in-house developed code. In particular, the animal farming in the province of Modena is taken into account and biomass is exploited in an integrated system including different waste to energy technologies. In the considered system, the manure of a number of types of animals is fed into an anaerobic digester, while the digested sludge is separated into the solid and liquid fractions. The former is employed as a fuel in a downdraft gasifier, while the latter is purified by means of both forward and inverse osmosis. Finally, the obtained bio-gas and syngas are used in a cogeneration system based on a spark ignition internal combustion engine to produce electric and thermal power. The potential power production of the considered territory is estimated and compared with the energy requirements of the animal farms. Different strategies for the distributed exploitation of the manure versus a centralized solution are investigated and the relating plant size and production of electric energy and thermal energy are evaluated.

2016 - Nonlinear vibrations and energy exchange of single-walled carbon nanotubes. Circumferential flexural modes [Articolo su rivista]
Strozzi, Matteo; Smirnov, Valeri V.; Manevitch, Leonid I.; Milani, Massimo; Pellicano, Francesco
abstract

In this paper, the nonlinear vibrations and energy exchange of single-walled carbon nanotubes (SWNTs) are studied. The Sanders–Koiter theory is applied to model the nonlinear dynamics of the system in the case of finite amplitude of vibration. The SWNT deformation is described in terms of longitudinal, circumferential and radial displacement fields. Simply supported, clamped and free boundary conditions are considered. The circumferential flexural modes (CFMs) are investigated. Two different approaches based on numerical and analytical models are compared. In the numerical model, an energy method based on the Lagrange equations is used to reduce the nonlinear partial differential equations of motion to a set of nonlinear ordinary differential equations, which is solved by using the implicit Runge–Kutta numerical method. In the analytical model, a reduced form of the Sanders–Koiter theory assuming small circumferential and tangential shear deformations is used to get the nonlinear ordinary differential equations of motion, which are solved by using the multiple scales analytical method. The transition from energy beating to energy localization in the nonlinear field is studied. The effect of the aspect ratio on the analytical and numerical values of the nonlinear energy localization threshold for different boundary conditions is investigated.

2016 - Numerical analysis of an entire ceramic kiln under actual operating conditions for the energy efficiency improvement [Relazione in Atti di Convegno]
Montorsi, Luca; Milani, Massimo; Stefani, Matteo; Saponelli, Roberto; Lizzano, Maurizio
abstract

The paper focuses on the analysis of an industrial ceramic kiln in order to improve the energy efficiency and thus the fuel consumption as well as the pollutant emissions. A lumped and distributed parameter model of the entire system is constructed to simulate the performance of the kiln under actual operating conditions. The model is able to predict accurately the temperature distribution along the different modules of the kiln and the operation of the many natural gas burners employed to provide the required thermal power. Furthermore, the temperature of the tiles is also simulated so that the quality of the final product can be addressed by the modelling. Numerical results are validated against experimental measurements carried out on a real ceramic kiln during regular production operations. The developed numerical model demonstrates to be an efficient tool for the investigation of different design solutions for the kiln’s components. In addition, a number of control strategies for the system working conditions can be simulated and compared in order to define the best trade off in terms of fuel consumption, emissions and product quality. In particular, the paper analyzes the effect of a new burner type characterized by internal heat recovery capability aimed at improving the energy efficiency of the ceramic kiln. The fuel saving and the relating reduction of carbon dioxide emissions resulted in the order of 10% when compared to the standard burner.

2016 - Numerical analysis of the interaction between high-pressure resin spray and wood chips in a vapour stream [Articolo su rivista]
Milani, Massimo; Montorsi, Luca; Lai, Daniele; Zoffoli, Lauro
abstract

This article investigates the interaction between the resin spray and the wood chips in a vapour stream using a multi-phase multi-component computational fluid dynamics approach. The interaction between the spray and the chips is one of the main issues in the industrial process for manufacturing medium density fibre boards. Thus, the optimization of this process can lead to important benefits, such as the reduction in the emission of formaldehyde-based toxic chemicals, the reduction in energy consumption in the blending process and energy saving in the fibreboard drying process. First step of the study is the numerical analysis of the resin injector in order to extend the experimental measurements carried out with water to the resin spray. The effects of the injector's geometrical features on the spray formation are highlighted under different injection pressure values and needle displacements. Afterwards, the results obtained in the analysis of the single injector are used for the complete simulation of multi-injector rail where the mixing of the resin spray and wood chips takes place. The influence of the main operating conditions, such as the vapour and the wood chip flow rates, on the resin distribution is addressed in order to optimize the resination process.

2015 - A Combined Methodology for Studying the Axial Balancing Mechanism of Orbit Annular Hydraulic Machines [Relazione in Atti di Convegno]
Bigliardi, Elisa; Francia, Marco; Milani, Massimo; Montorsi, Luca; Paltrinieri, Fabrizio; Stefani, Matteo
abstract

A customized combined methodology, based on both 2D CFD and lumped parameters numerical modeling, useful for simulating the hydraulic behavior of orbit annular machines, has been developed and here presented. More in details, the predictive capabilities of this CAE tool can be applied for the study of both roller and gerotor architectures and considering both pumping and motoring operating mode. First of all, a in-house developed 2D CFD methodology, based on the integration of the stationary form of the Reynolds equation for the determination of the pressure distribution inside the lateral clearances bounded by the sides of the stator-rotor group and the valve plate, as well as the internal manifold surface, is firstly presented and applied. The same computational procedure has been also involved for the investigation of the leakages through the clearance between the valve plate and the balancing ring. After that, a lumped and distributed parameters numerical model has been involved for the simulation of a typical orbit roller motor operation. In this case, particular care has been devoted to the modeling of the axial leakage clearances, adopting analytical interpolation functions deducted from the numerical results calculated applying the previously described 2D CFD methodology. Finally, the whole CAE approach has been validated by means of a comprehensive numerical vs. experimental comparison, obtaining a general good accordance for the overall operating field of this particular type of hydraulic unit.

2015 - Multi-phase and Multi-component CFD Analysis of a Load - Sensing Proportional Control Valve [Relazione in Atti di Convegno]
Bigliardi, Elisa; Francia, Marco; Milani, Massimo; Montorsi, Luca; Paltrinieri, Fabrizio; Stefani, Matteo
abstract

The paper analyzes the flow through a directional control valve for load –sensing application by means of a multi-phase and multi-component CFD approach. Numerical modeling includes both cavitation and aeration; in particular, the Rayleigh-Plesset equation and the inertia controlled growth model for bubble formation are adopted. The effects of gas release and vapor formation as well as turbulence on the main valve metering characteristics are investigated. The results show a remarkable influence of the aeration phenomena on the recirculating zones downstream of the metering area and thus on the cavitation onset region.

2014 - An integrated approach to energy recovery from biomass and waste: Anaerobic digestion-gasification-water treatment [Articolo su rivista]
Milani, Massimo; Montorsi, Luca; Stefani, Matteo
abstract

The paper investigates the performance of an integrated system for the energy recovery from biomass and waste based on anaerobic digestion, gasification and water treatment. In the proposed system, the organic fraction of waste of the digestible biomass is fed into an anaerobic digester, while a part of the combustible fraction of the Municipal Solid Waste is gasified. Thus, the obtained bio-gas and syngas are used as a fuel for running a cogeneration system based on an internal combustion engine to produce electric and thermal power. The waste water produced by the integrated plant is recovered by means of both forward and inverse osmosis. The different processes as well as the main components of the system are modelled by means of a lumped and distributed parameter approach and the main outputs of the integrated plant such as the electric and thermal power and the amount of purified water are calculated. Finally, the implementation of the proposed system is evaluated for urban areas with different number of inhabitants and the relating performance is estimated in terms of the main outputs of the system.

2014 - Experimental and numerical analysis of the combustor for a cogeneration system based on the aluminum/water reaction [Articolo su rivista]
Montorsi, Luca; Paltrinieri, Fabrizio; Milani, Massimo; Stefani, M.
abstract

The paper focuses on the design of the experimental apparatus aimed at analyzing the performance of the combustion chamber of a cogeneration system based on the reaction of liquid aluminum and water steam. The cogeneration system exploits the heat released by the oxidation of aluminum with water for super-heating the vapor of a steam cycle and simultaneously producing hydrogen. The only by-product is alumina, which in a closed loop can be recycled back and transformed again into aluminum. Therefore, aluminum is used as an energy carrier to transport the energy from the alumina reduction plant to the location of the proposed system. The water is also used in a closed loop since the amount of water produced employing the hydrogen obtained by the proposed system corresponds to the oxidizing water for the Al/H2O reaction. This study investigates the combustor where the liquid aluminum – steam reaction takes place; the design and the performance of the combustion chamber are evaluated using a numerical and an experimental approach. The test rig is specifically designed for the analysis of the liquid aluminum injection in a slightly super-heated steam stream. The first experiments are carried out to verify the correct behavior of the test rig. Thermography is employed to qualitatively assess the steam entrainment of the liquid aluminum jet. Finally, the experimental measurements are compared with the multi-dimension multi-phase flow simulations in order to estimate the influence of varying operating conditions on the combustion behavior. Further analysis will concern experiments aimed at investigating the reaction efficiency for different aluminum and water steam mass flow rates as well as the effects of the relative fuel/oxidizer speeds.

2013 - ANALISI DI IMPATTO AMBIENTALE DI SISTEMI PER LA RACCOLTA E IL TRATTAMENTO DI RIFIUTI SOLIDI URBANI (RSU) [Relazione in Atti di Convegno]
Marinelli, Simona; Gamberini, Rita; Rimini, Bianca; Ferrari, Anna Maria; Neri, P.; Montorsi, Luca; Milani, Massimo
abstract

L'obiettivo dello studio è la valutazione di impatto ambientale di porzioni incrementali di raccolta differenziata, provenienti dal circuito dei Rifiuti Solidi Urbani (RSU) prodotti all'interno di aree dedicate a parco naturale. Mediante l'approccio LCA (LIfe Cycle Assessment) sono stati confrontati diversi sistemi di gestione e trattamento. Si è comparata la tradizionale gestione mediante incenermento con i risultati ottenuti da un innovativo sistema integrato, in grado di fornire energia. I primi risultati dimostrano che l'impatto ambientale è migliorato e che esso diminuisce in maniera considerevole all'aumentare dell'ammontare di rifiuti differenziati trattati.

2013 - An integrated approach to energy recovery from biomass and waste: anaerobic digestion - gasification - water treatment [Relazione in Atti di Convegno]
Milani, Massimo; Montorsi, Luca; M., Muglia; M., Silvestri; M., Stefani
abstract

The paper investigates the performance of an integrated system for the energy recovery from biomass and waste based on anaerobic digestion, gasification and water treatment. In the proposed system, the organic fraction of waste of the digestible biomass is fed into an anaerobic digester, while a part of the combustible fraction of the Municipal Solid Waste is gasified. Thus, the obtained bio-gas and syngas are used as a fuel for running a cogeneration system based on an internal combustion engine to produce electric and thermal power. The waste water produced by the integrated plant is recovered by means of both forward and inverse osmosis. The different processes as well as the main components of the system are modelled by means of a lumped and distributed parameter approach and the main outputs of the integrated plant such as the electric and thermal power and the amount of purified water are calculated. Finally, the implementation of the proposed system is evaluated for urban areas with different number of inhabitants and the relating performance is estimated in terms of the main outputs of the system.

2013 - Combustion of Fine Aluminum and Magnesium Powders in Water [Articolo su rivista]
A., Corcoran; Mercati, Stefano; H., Nie; Milani, Massimo; Montorsi, Luca; E. L., Dreizin
abstract

Micron-sized metal powders carried by a nitrogen flow were fed along the axis of a cylindrical hydrogen/oxygen diffusion flame. The particles ignited and burned in the water vapor at approximately 2500 K. Experiments were performed at atmospheric pressure. The environment in which particles burned was characterized in detail using computational fluid dynamics. The computations confirmed that the metal powders burned in water while the effect of oxygen and other oxidizing species could be neglected. Combustion was characterized experimentally for micron-sized powders of both aluminum and magnesium. Particle size distributions were measured using low-angle laser light scattering. Optical emission of the burning particles was recorded using filtered photomultiplier tubes. Measured durations of individual particle emission pulses were assumed to represent their burn times; these data were classified into logarithmically spaced time bins. The distribution of the particle burn times was correlated with their size distributions assuming that larger size particles burned longer. It was observed that correlation between the burn times, t, and particle diameters, D, can be approximately described as t~D^0.64 and t~D^0.68 for aluminum and magnesium powders, respectively. The results were compared to previous reports and possible reasons for discrepancies between the present and earlier results were discussed.

2013 - IL PROGETTO RELS, PARCHI E AREE PROTETTE: STUDIO DELLA APPLICAZIONE DEI RISULTATI OTTENUTI NEI COMUNI DISLOCATI ALL'INTERNO DELL'AREA DEL PARCO DELLE FORESTE CASENTINESI E NELLE ZONE LIMITROFE [Capitolo/Saggio]
Marinelli, Simona; Gamberini, Rita; Rimini, Bianca; Ferrari, Anna Maria; Neri, P.; Milani, Massimo; Montorsi, Luca
abstract

All’interno del progetto RELS è stata valutata l’applicabilità di un impianto integrato che accoppia un processo di digestione anaerobica e di gassificazione, unitamente a un processo per il recupero delle acque reflue in modo da valorizzare energeticamente la frazione organica dei rifiuti solidi urbani, così come la parte non riciclabile della raccolta differenziata. L’energia elettrica prodotta viene immessa in rete, mentre la parte di energia termica rimanente rispetto ai bisogni interni dell’impianto stesso può essere messa a disposizione in funzione delle necessità del territorio. La presenza come partner del Parco delle Foreste Casentinesi ha permesso di raccogliere informazioni e dati sulla raccolta di rifiuti nell’area del parco e nei comuni che afferiscono al parco stesso. Nel progetto RELS sono stati analizzati diversi scenari e configurazioni d’impianto in modo da identificare quale soluzione progettuale meglio si adatta alle esigenze del territorio.

2013 - Improving the Performance of an Electro-Hydraulic Load-Sensing Proportional Control Valve [Articolo su rivista]
Babbone, Raffaele; Milani, Massimo; Montorsi, Luca; Paltrinieri, Fabrizio
abstract

The paper deals with the simulation and the experimental verification of the hydraulic behavior of an electro-hydraulic load-sensing proportional control valve. An innovative CAE (computer aided engineering) methodology, developed combining CFD (computational fluid dynamics) simulations with lumped and distributed numerical modeling, is firstly introduced and tailored by comparing the numerical results with measurements coming from an experimental campaign performed for a wide range of pressure loads and metered flow rates. Then, both the reliability and the limits of the numerical approach are highlighted through a detailed numerical vs. experimental comparison, involving the pressure of the main hydraulic lines, the flow rate through the first section and the local compensator displacement. Finally, the CAE methodology has been applied for assessing the internal ducts hydraulic permeability and the local compensator spring pre-load influence on the control valve metering curves. At the end of this analysis, an optimized design configuration, featuring a maximum controlled volumetric flow rate increased of more than 25%, has been proposed.

2013 - Modeling the Axial Balancing Mechanism of Orbit Annular Hydraulic Machines [Articolo su rivista]
Grasselli, Fabrizio; Milani, Massimo; Montorsi, Luca; Paltrinieri, Fabrizio
abstract

A customized combined methodology based on both 2D CFD (computational fluid dynamics) and lumped parameters numerical modeling, useful for simulating the hydraulic behavior of orbit annular machines, has been developed and here presented. More in details, the predictive capabilities of this CAE (computer-aided engineering) tool can be applied for the study of both roller and gerotor architectures and considering both pumping and motoring operating mode. First of all, an in-house developed 2D CFD methodology, based on the integration of the stationary form of the Reynolds equation for the determination of the pressure distribution inside the lateral clearances bounded by the sides of the stator-rotor group and the valve plate, as well as the internal manifold surface, is firstly presented and applied. The same computational procedure has been also involved for the investigation of the leakages through the clearance between the valve plate and the balancing ring. After that, a lumped and distributed parameters numerical model has been involved for the simulation of a typical orbit roller motor operation. In this case, particular care has been devoted to the modeling of the axial leakage clearances, adopting analytical interpolation functions deducted from the numerical results calculated applying the previously described 2D CFD methodology. Finally, the whole CAE approach has been validated by means of a comprehensive numerical versus experimental comparison, obtaining a general good accordance for the overall operating field of this particular type of hydraulic unit.

2013 - Optimization of the working cycle for a hydrogen production and power generation plant based on aluminum combustion with water [Articolo su rivista]
Mercati, Stefano; Milani, Massimo; Montorsi, Luca; Paltrinieri, Fabrizio
abstract

The working cycle of a novel hydrogen and power generation system based on aluminum combustion with water is analyzed in order to evaluate the best performance in terms of energy conversion efficiency. The system exploits the exothermic reaction between aluminum and steam and produces thermal power for a super-heated steam cycle and hydrogen as a by-product of the reaction. A lumped and distributed parameter approach is adopted for simulating the whole thermo-dynamics cycle and it includes the main components such as the combustion chamber, the steam generator, the turbine and the heat exchangers. Proper numerical models are created to account for the physical phenomena occurring in each of the considered component and are validated against experimental measurements available in literature or theoretical formulations. In particular several plant configurations corresponding to different working cycles are investigated, and their performance in terms of global efficiency, power output and hydrogen yield is discussed. The adoption of a turbine back pressure working cycle demonstrates to reduce the aluminum consumption and to enhance the electrical power conversion efficiency.

2012 - A NUMERICAL APPROACH FOR THE ANALYSIS OF THE COFFEE ROASTING PROCESS [Articolo su rivista]
Bottazzi, Davide; S., Farina; Milani, Massimo; Montorsi, Luca
abstract

A numerical model of the coffee roasting process under operating conditions is proposed. This numerical tool is able to simulate the behaviour of all the components of a batch roaster as well as the roasting process of the coffee beans within the drum. The model evaluates the heat and mass transfer between a hot air flow and the coffee beans during the roasting process on the basis of the physical properties of the coffee and the operation of the roasting machine. Different submodels are included in the modelling in order to address particular thermo-physical processes, such as the evaporation of coffee moisture and the heat released or absorbed by the beans due to the roasting reactions.The proposed numerical model is thus able to predict the performance of the coffee roaster in terms of pressure, temperature and mass flow rate in the main sections of the system, as well as fuel consumption. In addition, the temperature profile of the coffee beans within the roasting drum is evaluated as a function of the system’s working conditions. Different roasting machine control strategies can therefore be compared and the effects on the coffee roasting profile can be analyzed.Experimental data in the literature on a laboratory roaster are used as a reference to validate the results provided by the numerical model. Finally, the tool’s predictive capabilities are addressed by simulating an industrial coffee roasting machine.

2012 - A Transient Multidimensional CFD Approach to the Analysis of a Control Valve Using Non-Newtonian Fluids [Articolo su rivista]
Grasselli, Fabrizio; Milani, Massimo; Montorsi, Luca; Paltrinieri, Fabrizio
abstract

In this paper the flow through a control directional valve is studied by means of a Computational Fluid-Dynamics analysis under transient operating conditions. The mesh motion is resolved on a time basis as a function of the external actuation system. In the analysis, an open source fluid-dynamics code is used and both cavitation and turbulence are accounted for in the modeling. Moreover, the numerical model of the working fluid is modified in order to account also for the non-Newtonian fluids. The effects of the shear rate on the shear stress are accounted for both by using experimental measurements and correlations available in literature, such as the Herschel-Bulkley model. The analysis determines the performance of the control directional valve under different operating conditions when using either Newtonian or non-Newtonian fluids. In particular, the discharge coefficient, the recirculating regions, the flow acceleration angle and the pressure and velocity fields are investigated.

2012 - Design of a Hydraulic System for Liquid Packaging [Articolo su rivista]
Angeloni, Claudio; Franzoni, Federica; Milani, Massimo; Paltrinieri, Fabrizio
abstract

The paper analyzes the dynamic behaviour of an industrial system devoted to the automated hydraulic packaging of beverages. More in detail, a lumped and distributed numerical approach is used to model both the filling system and the multi-actuators hydraulic circuit needed to shape and separate the packages. The model reliability and accuracy are addressed by means of a numerical vs. experimental comparison of the main hydraulic and mechanical quantities for an actual production rate. Afterwards, the system architecture is redesigned in order to obtain higher production rates, and the effects of the hydraulic behaviour variation on the hydraulic efficiency are highlighted. Finally, a sensitivity analysis with respect to the main design parameters is carried out, in order to determine the circuit layout that maximizes the system efficiency in the whole production-rate range.

2012 - Design of the steam generator in an energy conversion system based on the aluminum combustion with water [Articolo su rivista]
Mercati, Stefano; Milani, Massimo; Montorsi, Luca; Paltrinieri, Fabrizio
abstract

The paper shows the preliminary design of the superheated steam generator to be used in a novel hydrogen production and energy conversion system based on the combustion of aluminum particles with water. The system is aimed at producing hydrogen and pressurized superheated steam, using the heat released by the Al–H2O reaction. The interest on this type of technology arises because of the possibility of obtaining hydrogen with very low pollutant and greenhouse gas emissions, compared to the traditional hydrogen production systems, such as the steam reforming from methane. The analysis of the combustion chamber and the heat recovery system is carried out by means of a lumped and distributed parameter numerical approach. The multi phase and gas mixture theoretical principles are used both to characterize the mass flow rate and the heat release in the combustion chamber and within the heat exchangers in order to relate the steam generator performance to the system operating parameters. Finally, the influence of the steam generator performance on the whole energy conversion system behavior is addressed, with particular care to the evaluation of the total power and efficiency variation with the combustion parameters.

2012 - Multidimensional Design of Hydraulic Components and Systems [Capitolo/Saggio]
Milani, Massimo; Montorsi, Luca; Paltrinieri, Fabrizio
abstract

In this chapter, the above mentioned critical aspects in the application of multidimensional numerical analysis for the design of mechanical devices and components for hydraulic systems are addressed. The objective of the chapter is to provide a roadmap for the multidimensional numerical analysis of the hydraulic components to be used effectively in the design process. In particular, two examples of hydraulic systems are accounted for in the application of the CFD analysis: a proportional control valve and a fuel accumulator for multi-fuel injection systems. These test cases have been selected due to their representativeness in the field of hydraulic applications and to the complexity and variety ofthe physical phenomena involved.

2012 - Proceedings of the 7th FPNI PhD Symposium on Fluid Power [Curatela]
Milani, Massimo; Montorsi, Luca; Paltrinieri, Fabrizio
abstract

All Young Researchers and PhD Students coming from all over the world interested in Fluid Power have been invited to present the results and the directions of their scientific activities, and to establish new contacts for a broader R&D cooperation in fluid power technology and related fields.This Proceedings collect about 50 works from about 200 Authors, coming from more than 15 countries, and they highlight the academic results and the industrial applications shown during the 11 Technical Sessions held during the three days of Symposium.

2011 - A Transient Multidimensional CFD Approach to the Analysis of a Control Valve using Non-Newtonian Fluids [Relazione in Atti di Convegno]
Angeloni, Claudio; Franzoni, Federica; Montorsi, Luca; Milani, Massimo; Paltrinieri, Fabrizio
abstract

--

2011 - CAE Design of Orbit Annular Machines [Relazione in Atti di Convegno]
Babbone, Raffaele; Bottazzi, Davide; Cagni, Gabriele; Grasselli, Fabrizio; Milani, Massimo
abstract

--

2011 - Design of a Hydraulic Systems for Liquid Packaging [Relazione in Atti di Convegno]
Angeloni, Claudio; Castagnetti, Simone; Ernetti, Marina; Franzoni, Federica; Milani, Massimo
abstract

--

2011 - Design of the Steam Generator in an Energy Conversion System Based on the Aluminum Combustion with Water [Relazione in Atti di Convegno]
Babbone, Raffaele; Mercati, Stefano; Milani, Massimo; Montorsi, Luca
abstract

--

2011 - Energy Recovery from Waste by Means of a Gasification System: Numerical Approach [Relazione in Atti di Convegno]
Angeloni, Claudio; Milani, Massimo; Montorsi, Luca; Scolari, Mattia
abstract

--

2011 - Operating maps of a combined hydrogen production and power generation system based on aluminum combustion with water [Articolo su rivista]
Franzoni, Federica; Mercati, Stefano; Milani, Massimo; Montorsi, Luca
abstract

--

2010 - Analysis of Multiphase Multi-Components Internal Flow Fields [Relazione in Atti di Convegno]
Franzoni, Federica; Milani, Massimo; Montorsi, Luca
abstract

--

2010 - Analysis of a Hydraulic Valve by Means of a Transient Multidimensional CFD Approach [Relazione in Atti di Convegno]
Bottazzi, Davide; Franzoni, Federica; Milani, Massimo; Montorsi, Luca
abstract

--

2010 - Combined hydrogen production and power generation from aluminum combustion with water: analysis of the concept [Articolo su rivista]
Franzoni, Federica; Milani, Massimo; Montorsi, Luca; V., Golovitchev
abstract

In this paper the combined production of hydrogen and power based on the aluminum combustion with water is investigated. Furthermore, a concept system is proposed that is potentially able to provide pressurized hydrogen and high temperature steam along with heat and work at the crankshaft. The system demonstrates high energy conversion efficiency, and it fully complies with environment sustainability requirements. The use of aluminum as an energy carrier or a fuel has been already studied in literature, but its application in the field of the energy conversion systems is currently not well explored. Once aluminum oxide layer is removed, the pure aluminum can react with water producing alumina and hydrogen while releasing a significant amount of heat that can be used to produce superheated steam. Both pressurized hydrogen and superheated steam can be used in a turbine power system developing electrical or mechanical power. Moreover, the hydrogen can be either stored for further usage or burned in order to obtaina larger amount of heat for the process. From an environmental viewpoint, an energy conversion system utilizing the combustionof aluminum with water is very interesting since the aluminum oxidation is completely greenhouse gases free and produces only hydrogen and alumina. The high grade alumina obtained by the reaction is harmless and can be employed in other technological processes or recycled back to aluminum; in this case, the closed loop use of aluminum would decrease significantly the need of new bauxite feedstock. Finally, an embodiment of the concept system for the combined production of hydrogen and power based on the aluminum combustion with water is proposed and its possible applications are discussed.

2010 - Design of Hydraulic Systems for Automotive Applications [Relazione in Atti di Convegno]
Ernetti, Marina; Milani, Massimo; Bottazzi, Davide; S., Simonini
abstract

--

2010 - Design of Proportional Anti-Saturative Load-Sensing Control Blocks [Relazione in Atti di Convegno]
Scolari, Mattia; Milani, Massimo; Bottazzi, Davide; Cagni, Gabriele
abstract

--

2010 - Design of a Hydraulic System for Liquid Packaging [Relazione in Atti di Convegno]
Castagnetti, Simone; Milani, Massimo; Franzoni, Federica; Grasselli, Fabrizio
abstract

--

2010 - Design of a Hydrogen Production and Power Generation System based on the Reaction of Aluminium with Water [Relazione in Atti di Convegno]
Mercati, Stefano; Milani, Massimo; Franzoni, Federica; Montorsi, Luca
abstract

--

2010 - Energy Efficiency Analysis in Pneumatic Plants for Food Processing [Relazione in Atti di Convegno]
Bottazzi, Davide; Milani, Massimo; Montorsi, Luca
abstract

--

2010 - Numerical Analysis of a Hydrogen Production and Power Generation System Based on Aluminum-Water Reaction [Relazione in Atti di Convegno]
Bottazzi, Davide; Franzoni, Federica; Milani, Massimo; Montorsi, Luca
abstract

--

2010 - Thermal Fluid Dynamics Analysis of the Pneumatic System for a Food Processing Plant [Relazione in Atti di Convegno]
Bottazzi, Davide; Franzoni, Federica; Milani, Massimo; Montorsi, Luca
abstract

--

2009 - A Novel Concept for Combined Hydrogen Production and Power Generation [Relazione in Atti di Convegno]
Franzoni, Federica; V., Golovitchev; Milani, Massimo; Montorsi, Luca
abstract

A novel concept of combined hydrogen production and power generation system based on the combustion of aluminum in water is explored. The energy conversion system proposed is potentially able to provide four different energy sources, such us pressurized hydrogen, high temperature steam, heat, and work at the crankshaft on demand, as well as to fully comply with the environment sustainability requirements.Once aluminum oxide layer is removed, the pure aluminum can react with water producing alumina and hydrogen while releasing a significant amount of energy. Thus, the hydrogen can be stored for further use and the steam can be employed for energy generation or work production in a supplementary power system. The process is proved to be self-sustained and to provide a remarkable amount of energy available as work or hydrogen. Furthermore, since the aluminum oxidation is completely GHG free and the alumina produced by the reaction can be recycled back to aluminum, the process has a sustainable environmental management.A preliminary design of the combined hydrogen production and power generation unit based on the aluminum combustion in water is proposed and the efficiency of the process is discussed in terms of both hydrogen production and power generation.

2009 - Cavitating Flows in Hydraulic Multidimensional CFD Analysis [Articolo su rivista]
Franzoni, Federica; Milani, Massimo; Montorsi, Luca
abstract

The effect of cavitation plays a fundamental role in the hydraulic components design and the capability of predicting its causes and characteristics is fundamental for the optimization of fluid systems.In this paper, a multidimensional CFD approach is used to analyze the cavitating phenomena typical of hydraulic components using water as operating fluid. An open source fluid-dynamics code is used and the original cavitation model (based on a barotropic equation of state and homogeneous equilibrium assumption) is extended in order to account also for gases dissolved in the liquid medium. The effect of air dissolution into liquid water is modeled by introducing the Henry law for the equilibrium condition, and the time dependence of solubility is calculated on a Bunsen Coefficient basis. Furthermore, a simplified approach to turbulence modelling for compressible flows is coupled to the cavitation model and implemented into the CFD code. The turbulence effects on cavitating regions are addressed for different operating conditions.In the analysis, both basic geometries and water hydraulic poppet valves are addressed, and the numerical results are compared to experimental measurements available in literature. In particular, the reference test case with abrupt section change geometries, such as the forward-facing step, is investigated. The recirculating regions, the vena contracta position, the reattachment point and the pressure and velocity fields are calculated under conditions where cavitation is expected. Furthermore, the diverging and converging flows in hydraulic valves are simulated and the influence of the seat shape on cavitation onset, pressure distribution and discharge coefficient is discussed.

2009 - Design and Optimization of a Variable Displacement Vane Pump for High Performance IC Engine Lubrication - Part 1 - Experimental analysis of the circumferential pressure distribution with dynamic pressure sensors [Relazione in Atti di Convegno]
A., Bianchini; G., Ferrara; L., Ferrari; Milani, Massimo; Paltrinieri, Fabrizio; F., Tosetti
abstract

In the present automotive research, increasing efforts are being directed to improve the overall organic efficiency, which, inter alia, means to improve the operational behavior of the auxiliary organs. This paper reports an experimental approach for the determination and analysis of the pressure distribution in a variable displacement vane pump for high speed internal combustion engine lubrication. More in details, an actual application is presented for a seven-blades variable displacement vane pump equipped with a hydraulic geometry variation system. This unit is characterized by a high performance, in terms of rotational speed, delivery pressure and displacement variation. The experimental layout and some relevant facilities are described. An extended test campaign was performed on the pump to characterize its operational behavior. Rotational speeds from the idling regime to the maximum sustainable regime were tested by varying the hydraulic circuit load: the results of the pressure field are shown together with a detailed description of the oil physical behavior into the pump. Furthermore, several changes in the geometry of the pump, which were suggested by the experimental campaign, are presented and their influence on the performance of the pump is evaluated and discussed with a comparative performance analysis.

2009 - Design and Optimization of a Variable Displacement Vane Pump for High Performance IC Engine Lubrication. Part 2 - Lumped parameters numerical analysis. [Relazione in Atti di Convegno]
A., Bianchini; G., Ferrara; L., Ferrari; Milani, Massimo; Paltrinieri, Fabrizio; F., Tosetti
abstract

In this paper a detailed analysis focused on lumped parameters numerical modeling of a variable displacement vane pump for high speed internal combustion engine lubrication is presented and discussed. This particular volumetric unit is characterized by very extreme performance, both in terms of rotational speed, delivery pressure and displacement variation. First of all, a comprehensive description of the simulation environment properly tailored for the numerical modeling of the vane pump operation is introduced and all its geometric, kinematic and fluid-dynamic characteristics are described in depth. Then, the results coming from an exhaustive experimental campaign have been compared with simulations, finding a general good accordance that demonstrates the reliability of this numerical approach. Finally, the capabilities of the validated model have been applied to investigate the influence exerted by the main geometrical parameters and internal leakages on the pump fluid dynamic behavior.

2009 - Fast Image Processing for Fluid Power Components Characterization [Relazione in Atti di Convegno]
Bottazzi, Davide; Franzoni, Federica; Milani, Massimo; Montorsi, Luca
abstract

This paper focuses on the application of the fast imageprocessing to the internal flow field characterization, andon the set up of the experimental methodology whichenables the use of direct visualization techniques to fluidpower components. More in details, the design of both alow pressure hydraulic power unit and a number ofpolymethyl-methacrylate (PMMA) transparent prototypesare firstly outlined.Afterward, the fast image processing is involved and, tohighlight the usefulness of the fast image processing inthe analysis of multi-phase multi-component effluxes,solid particle injection and air bubble inoculation areused.Finally, some of the results obtained using aprogressive, mid resolution, high frame rate andmonochrome digital camera are shown, and the internalflow evolution is qualitatively analyzed.

2009 - Fast image processing applied to fluid power components [Relazione in Atti di Convegno]
Bottazzi, D.; Franzoni, F.; Milani, M.; Montorsi, L.
abstract

This paper focuses on the application of the fast image processing to the internal flow field characterization, and on the set up of the experimental methodology which enables the use of direct visualization techniques to fluid power components. More in details, the design of both a low pressure hydraulic power unit and a number of polymethyl-methacrylate (PMMA) transparent prototypes are firstly outlined. Afterward, the fast image processing is involved and, to highlight the usefulness of the fast image processing in the analysis of multi-phase multi-component effluxes, solid particle injection and air bubble inoculation are used. Finally, some of the results obtained using a progressive, mid resolution, high frame rate and monochrome digital camera are shown, and the internal flow evolution is qualitatively analyzed. Copyright © 2009 SAE International.

2009 - Influence of gasoline - Ethanol blends on engine torque variation [Relazione in Atti di Convegno]
Bottazzi, Davide; Franzoni, Federica; Milani, Massimo; Montorsi, Luca
abstract

In this paper the possibility to use the instantaneous torque measurement to estimate the injected fuel mixture is explored. The analysis focuses on a four stroke SI engine equipped with a low pressure common rail type multi-fuel injection system. First, the injection system is simulated by means of a comprehensive lumped and distributed parameter numerical model, in order to evaluate the dynamic behavior of the fuel rail in terms of injection pressure profiles, instantaneous mass flow rate delivered to each cylinder and engine heat of combustion power. The accuracy of the model is addressed by comparing the predicted results with the measured data. By using both the experimental in-cylinder pressure profiles as well as the engine total efficiency, and the calculated injection profiles, the instantaneous torque is determined for different engine speeds and ethanol/gasoline blends. In particular the torque variation during the transition from one fuel mixture to a different one is investigated, accounting for the influence of the blend composition rate of change. Finally, the magnitude of instantaneous torque variation is compared with the overall accuracy of a torque sensor currently adopted in production series engines to detect combustion misfires, in order to evidence its capability to monitor the fuel blend transition.

2009 - Metering Characteristics of a Closed Center Load – Sensing Proportional Control Valve [Articolo su rivista]
Bottazzi, Davide; Franzoni, Federica; Milani, Massimo; Montorsi, Luca
abstract

The investigation of the flow through the metering section of hydraulic components plays a fundamental role in the design and optimization processes. In this paper the flow through a closed center directional control valve for load –sensing application is studied by means of a multidimensional CFD approach.In the analysis, an open source fluid-dynamics code is used and both cavitation and turbulence are accounted for in the modeling. A cavitation model based on a barotropic equation of state and homogeneous equilibrium assumption, including gas absorption and dissolution in the liquid medium, is adopted and coupled to a two equation turbulence approach.Both direct and inverse flows through the metering section of the control valve are investigated, and the differences in terms of fluid – dynamics behavior are addressed In particular, the discharge coefficient, the recirculating regions, the flow acceleration angle and the pressure and velocity fields are investigated and compared.

2009 - Metering characteristics of a closed center load - Sensing proportional control valve [Relazione in Atti di Convegno]
Bottazzi, D.; Franzoni, F.; Milani, M.; Montorsi, L.
abstract

The investigation of the flow through the metering section of hydraulic components plays a fundamental role in the design and optimization processes. In this paper the flow through a closed center directional control valve for load -sensing application is studied by means of a multidimensional CFD approach. In the analysis, an open source fluid-dynamics code is used and both cavitation and turbulence are accounted for in the modeling. A cavitation model based on a barotropic equation of state and homogeneous equilibrium assumption, including gas absorption and dissolution in the liquid medium, is adopted and coupled to a two equation turbulence approach. Both direct and inverse flows through the metering section of the control valve are investigated, and the differences in terms of fluid - dynamics behavior are addressed In particular, the discharge coefficient, the recirculating regions, the flow acceleration angle and the pressure and velocity fields are investigated and compared. Copyright © 2009 SAE International.

2008 - A Theoretical Analysis about Multiple Actuation Systems Efficiency [Relazione in Atti di Convegno]
Franzoni, Federica; Milani, Massimo; Montorsi, Luca
abstract

This paper studies the dependency of the total efficiency of a multiple actuation hydraulic system on the operating conditions as well as on the control strategies applicable to control valves. In particular, with respect to the parallel connection among hydraulic actuators managed by proportional control valves, a general structure of the functional relationship correlating the hydraulic power provided by the supply unit and the mechanical power exerted by actuators is proposed and used to determine the operating point and the system overall efficiency. Afterwards, the dependency of the system behavior on external load variations and on valves control is assessed, and the influence of a modification of the operating conditions on the overall efficiency is highlighted. Finally, the validity limits of some compensating corrections are determined.

2008 - Cavitating flows in hydraulic multidimensional CFD analysis [Relazione in Atti di Convegno]
Franzoni, F.; Milani, M.; Montorsi, L.
abstract

The effect of cavitation plays a fundamental role in the hydraulic components design and the capability of predicting its causes and characteristics is fundamental for the optimization of fluid systems. In this paper, a multidimensional CFD approach is used to analyze the cavitating phenomena typical of hydraulic components using water as operating fluid. An open source fluid-dynamics code is used and the original cavitation model (based on a barotropic equation of state and homogeneous equilibrium assumption) is extended in order to account also for gases dissolved in the liquid medium. The effect of air dissolution into liquid water is modeled by introducing the Henry law for the equilibrium condition, and the time dependence of solubility is calculated on a Bunsen Coefficient basis. Furthermore, a simplified approach to turbulence modeling for compressible flows is coupled to the cavitation model and implemented into the CFD code. The turbulence effects on cavitating regions are addressed for different operating conditions. In the analysis, both basic geometries and water hydraulic poppet valves are addressed, and the numerical results are compared to experimental measurements available in literature. In particular, the reference test case with abrupt section change geometries, such as the forward facing step, is investigated. The recirculating regions, the vena contracta position, the reattachment point and the pressure and velocity fields are calculated under conditions where cavitation is expected. Furthermore, the diverging and converging flows in hydraulic valves are simulated and the influence of the seat shape on cavitation onset, pressure distribution and discharge coefficient is discussed. Copyright © 2008 SAE International.

2008 - Combined Hydrogen, Heat, Steam and Power Generation system [Relazione in Atti di Convegno]
Milani, Massimo; Montorsi, Luca; V., Golovitchev
abstract

A novel concept of combined generation of hydrogen, heat, steam and power based on the combustion of aluminum in water is explored. The energy conversion system proposed (patent pending, all rights reserved) is potentially able to provide four different energy sources, such us pressurized hydrogen, high temperature steam, heat, and work at the crankshaft on demand, as well as to fully comply with the environment sustainability requirements.Once aluminum oxide layer is removed, the pure aluminum can react with water producing alumina and hydrogen while releasing a significant amount of energy. Thus, the hydrogen can be stored for further use and the steam can be employed for energy generation in a supplementary power system. The process is proved to be self-sustained and to provide a remarkable energy available as steam, heat or work. Furthermore, since the aluminum oxidation is com-pletely GHG free and the alumina produced by the reaction can be recycled back to aluminum, the process has a sustainable environmental management.A preliminary design of an energy conversion system (patent pending, all rights reserved) based on the aluminum combustion in water is proposed and the efficiency of the process is discussed in terms of both hydrogen production and energy generation.

2008 - Developing and Tailoring a CFD Code for Multiphase Multicomponent Flows [Relazione in Atti di Convegno]
Franzoni, Federica; Milani, Massimo; Montorsi, Luca
abstract

This paper focuses on the development and the tailoring of a open source multidimensional CFD code to the analysis of the internal flow-field in hydraulic components. A preliminary study of two basic geometries is carried out by simulating the efflux of an incompressible fluid through circular pipes and through an abrupt section change determined by a small sharp-edged cylindrical orifice. A qualitative description of the internal flow-field distribution, and a quantitative comparison of pressure and velocity profiles along the pipe axis are used to asses the multidimensional open-source code capabilities. For the circular pipe the results are compared with experiments and with theoretical trends coming from literature fundamentals (Hagen-Poiseuille theory and Nikuradse interpolation), while for the abrupt section change experimental measurements available in literature are taken as a reference for the numerical accuracy determination. Furthermore, the influence of grid resolution and of turbulence models on the vena contracta on the characteristics recirculating regions, on the reattachment point and on the pressure and velocity fields is addressed. Afterwards, to investigate the mixing of different fluids, a preliminary analysis of a reference test case is carried out. The modified VOF approach, used for modeling the fluid-fluid mixing process, is tailored in order to account for turbulence. Different grid resolutions and turbulence models are adopted and results are compared with experiments in order to asses their influence on the interface and on the fluids distribution inside the reference geometrical domain. In particular, two different turbulence models (k-e – SST) are implemented in the original code to address their effect on actual fluids mixing. Finally, the dynamic behavior of a low pressure fuel rail is investigated and the fuels distribution history within the rail is determined for different operating conditions to assess both the fuel mixture at injectors’ inlet, and to highlight the differences among the cylinders in terms of injected fuel blend.

2008 - External Gear Pumps and Motors Bearing Blocks Design: Influence on the Volumetric Efficiency [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; Paltrinieri, Fabrizio; Zardin, Barbara
abstract

External gear pumps and motors, in their typical commercial design, are equipped with hydraulically balanced bearing blocks, which allow to maintain good volumetric efficiencies also when the pressure drop between the ports is high. The aim of this work is to analyze some geometrical aspects characterizing the bearing blocks design, evaluating their influence on the volumetric efficiency of the machine with the aid of a numerical model properly created. External gear pumps and motors operation behavior is strongly influenced by the volumetric efficiency; this parameter takes into account the leakages of fluid which typically affect the hydraulic machine operation and, together with the mechanical efficiency, determines its total efficiency and, consequently, has a great influence on power loss.

2008 - Injection System Control for a Multi-Fuel SI Engine [Relazione in Atti di Convegno]
D., Bottazi; Franzoni, Federica; Milani, Massimo; Montorsi, Luca; M., Luppi; G., Osbat
abstract

In this paper, the dependency on fuel blends of a four-stroke, four-cylinder SI engine equipped with a low-pressure, common-rail-type injection system is analyzed. With reference to an operating condition using E21 (21% ethanol, 79% gasoline) as a fuel, the experimental performance of the engine are firstly introduced, and the brake power, the specific fuel consumption, the total efficiency, the heating combustion power and the injected mass per stroke dependency on shaft speed are introduced.Then, the multi-fuel injection system actual behavior is predicted by means of a properly tailored lumped and distributed numerical model, whose general reliability is defined mainly in terms of injected mass per stroke. Afterward, the engine performance variation with the fuel mixture is determined, and the adaptation of the PWM control applied to injectors is proposed to compensate the engine operating characteristics.Finally, with reference to the engine performance using E100 (100% ethanol, 0% gasoline) as a fuel, the influence of the engine rotational speed on the injected mass per stroke, on the heat of combustion power, on the specific fuel consumption and on the brake power are introduced, and the numerical prediction reliability is assessed with respect to the engine experimental behavior.

2008 - Lumped Parameters Numerical Simulation of a Variable Displacement Vane Pump for High Speed ICE Lubrication [Relazione in Atti di Convegno]
Cantore, Giuseppe; Milani, Massimo; Paltrinieri, Fabrizio; F., Tosetti
abstract

In this paper a detailed analysis focused on lumped parameters numerical modelling of a variable displacement vane pump for high-speed internal combustion engine lubrication is presented and discussed. This particular volumetric unit is characterized by very extreme performance, both in terms of rotational speed, delivery pressure and displacement variation.First of all, a comprehensive description of the simulation environment properly tailored for the numerical modelling of the vane pump operation is introduced and all its geometric, kinematic and fluid-dynamic characteristics are described in depth. Then, the results coming from an exhaustive experimental campaign have been compared with simulations, finding a general good accordance that demonstrates the reliability of this numerical approach. Finally, the capabilities of the validated model have been applied to investigate the influence exerted by the main geometrical parameters and internal leakages on the pump fluid dynamic behavior.

2008 - Numerical Analysis of the Fuel Mixing Process in a Multi-Fuel Injection System [Relazione in Atti di Convegno]
Franzoni, Federica; Milani, Massimo; Montorsi, Luca
abstract

The paper focuses on the mixing process of different fuels in a multi-fuel, low-pressure, common-rail injection system for a four\-stroke SI engine. The study is devoted to the prediction of the fuel mixture delivered by the injectors during a transient in which gasoline is being replaced by ethanol or a gasoline/ethanol blend. An integrated approach of different numerical tools is used to model the rail dynamic behavior under actual operating conditions.First, the 1D model of the injection system is constructed and the time-varying conditions at the accumulator inlet and at the injectors' boundaries are assessed. The second step of the study is centered on the CFD analysis of the mixing process within the rail. The effects of the different engine operations on the fuels mixing are investigated and the injected fuel distribution among the cylinders is calculated. An open source computational fluid dynamics code is used in the simulations. The modified VOF approach, used for modelling the fluid-fluid mixing process, is tailored in order to account for the turbulence effect.

2008 - The Influence of Cavitation and Aeration in a Multi-Fuel Injector [Relazione in Atti di Convegno]
Franzoni, Federica; Milani, Massimo; Montorsi, Luca
abstract

The internal flow field of a low-pressure, common-rail-type, multi-fuel injector is analyzed by means of numerical simulation and particular attention is devoted to the cavitation and aeration phenomena when using different fuel mixtures.The fluid-dynamics open source OpenFOAM code is used; and the original cavitation model (based on a barotropic equation of state and homogeneous equilibrium assumption) is extended in order to account also for gases dissolved in the liquid medium. The effect of air dissolution into liquid is determined by introducing the Henry law for the equilibrium condition and the time dependence of solubility is calculated on a Bunsen Coefficient basis.A preliminary study of test cases available in literature is carried out to address the model predictive capabilities and grid dependency. The calculated pressure distribution and discharge coefficient for different nozzle shapes and operating conditions are compared with the referenced experimental measurements.Finally, the influence of different fuel blends on the injector internal flow field under cavitating conditions is investigated to determine cavitating regions and injected mass flow rates for ethanol and ethanol/gasoline mixtures.

2007 - A CFD Analysis of a Multi-Fuel Injection System Rail [Relazione in Atti di Convegno]
Franzoni, Federica; Milani, Massimo; Montorsi, Luca
abstract

Flexibility in running with different fuel is becoming an important issue in the Internal Combustion Engine design due to the increasingly wider use of alternative fuels. The injection systems must deal with fuels having different properties and effects on engine behavior and take proper adjustments in the control strategy. Particularly the transient during which one fuel is being replaced by the second one is a critical point of the injection system operation, and its capability of recognizing the fuel mixture currently available is a fundamental matter in the engine control development.This paper focuses on the multidimensional CFD analysis of a Common-Rail-type, multi-fuel injection system accumulator during the gasoline-ethanol shift. An open source computational fluid dynamics code was used in the modelling. A preliminary analysis of an experimental test case available in literature was carried out; different grid resolutions were employed in the simulations in order to asses their influence on the interface and distribution of the fluids. Finally the multi-fuel rail dynamic behavior was investigated under limiting operating conditions, and its effects on the engine functioning are discussed.

2007 - A CFD Multidimensional Approach to Hydraulic Component Design [Relazione in Atti di Convegno]
Franzoni, Federica; Milani, Massimo; Montorsi, Luca
abstract

This paper presents a multidimensional approach to the hydraulic components design by means of an open-source fluid dynamics code.A preliminary study of a basic geometry was carried out by simulating the efflux of an incompressible fluid through circular pipes. Both laminar and turbulent conditions were analyzed and the influence of the grid resolution and modelling settings were investigated. A qualitative description of the internal flow-field distribution and a quantitative comparison of pressure and velocity profiles along the pipe axis were used to asses the multidimensional open-source code capabilities.Moreover the results were compared with the experimental measurements available in literature and with the theoretical trends which can be found in well-known literature fundamentals (Hagen-Poiseuille theory and Nikuradse interpolation).Further comparison was performed by using a commercial CFD code. Then, the analysis was focused on the simulation of a reference test case with abrupt section change geometries, such as the forward-facing step. The recirculating regions, the vena contracta position, the reattachment point and the pressure and velocity fields were investigated.The predictive capabilities of three turbulence models were also investigated. The standard k-ge model, including wall functions for the near-wall treatment, was compared with a low-Reynolds number model and the two zonal version of the k-gv model.Finally, the metering section of a hydraulic check valve was modeled, and the capabilities of both CFD codes in describing the component steady-state behavior were analyzed.

2007 - CAE Development of Automotive Hydraulic Applications [Relazione in Atti di Convegno]
Milani, Massimo; Paltrinieri, Fabrizio
abstract

L'articolo illustra i principlai risultati ottenibili mediante l'uso di strumenti numerici a parametri concnetrati e multidimensionali nello sviluppo progettuale e nell'ottimizzazione funzionale di sistemi idraulici per applicazioni automotive.

2007 - Tailoring Simplified Models for the Feeding Performances Prediction of CNG PWM Controlled Single Stage Injectors [Relazione in Atti di Convegno]
Borghi, Massimo; Franzoni, Federica; Milani, Massimo
abstract

In this paper, an orifice-based lumped parametermodel has been developed and tailored to predict thefeeding performances of a single stage, inwardlyopening, PWM controlled gas injector for automotiveapplications.In particular, simplifying the description of injectorrelevant sections, and adopting a “semi-perfect”approach to depict the gas properties dependency onpressure and temperature, the sub-sonic effluxthrough the injector metering section is studiedinvolving both an isentropic and a polytropicexpansion.Then, considering dry air as fluid medium, the injectorfeeding characteristics variations with the duty cycle,with the feeding pressure and with temperature arehighlighted.After, an experimental vs. numerical data comparisonextended to the injector whole operational field is usedto tailor the main corrective parameters of thesimplified numerical model: among others, particularattention is devoted to the efflux coefficient variationwith injector operating conditions.Successively, the parameters setting coming from theadoption of dry air is used to perform computationsinvolving other gases, such as the pure methane andthe Groningen gas (chosen as reference gas forCNG).Finally, through a numerical vs. experimentalcomparison about mass flow-rate, the reliability of thesimplified numerical model, and its design usefulnessto predict the injector feeding performances withdifferent gases of automotive interest, is highlighted.

2007 - The EGR effects on combustion regimes in compression ignited engines [Relazione in Atti di Convegno]
A. T., Calik; V. I., Golovitchev; Milani, Massimo; Montorsi, Luca
abstract

The main purpose of this study is to investigate the effects of exhaust gases on different combustion modes in DI, Direct Injection, compression ignited engines in terms of combustion efficiency and emission formations. The conventional parametric Φ -T (Equivalence Ratio-Temperature) emission map analysis has been extended by constructing the transient maps for different species characterizing the combustion and emission formation processes. The results of the analysis prove the efficiency of different combustion modes when EGR loads and injection scenarios. Copyright © 2007 SAE International Inc.

2007 - The Preliminary Design of a Direct Actuation for CNG Pressure Regulator Low-Pressure Stage Control [Relazione in Atti di Convegno]
Franzoni, F.; Milani, M.; Montorsi, L.; Borghi, M.
abstract

This paper focuses on the preliminary design of aproportional solenoid aimed at controlling the lowpressure stage of a two stage pressure regulator forCNG applications.In particular, the dynamic performance of a two stagepressure regulator is firstly studied in the wholeoperational field of a four stroke, four cylinder sparkignition engine, equipped with a simplified lowpressureCommon Rail type collector serving fourPWM actuated single stage injectors.Then, with the aim of developing an electro-magneticdirect actuation, the dynamic performance of thesecond stage needle is adopted to drive the design ofa spires type, cylindrical coil proportional solenoid. Inparticular, both the steady and the transients stepsneeded to complete the preliminary design arehighlighted, and the influence of some relevant designparameters (such as the coil geometry and the air gap)on the actuation characteristics are evidenced.Finally, the proportional solenoid is introduced into astandard electro-magnetic control circuit, and itsdriving capabilities, its dynamic performance and itslimit of applications are determined for different actualoperating conditions of the second stage needle.

2006 - Numerical Characterization of Pipes And Hoses Dynamic Response [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; Paltrinieri, Fabrizio; Zardin, Barbara
abstract

This paper deals with the study of pipes and hoses dynamic characteristics variation with the fluid-wall equivalent bulkmodulus description, with particular attention devoted to the analysis of the wall thickness, of the mechanical constraintsand of the internal pressure both on the fluid celerity, and on the pipe frequency response. In particular, consideringboth the case of plain stress and of plain strain, the pipe wall compliance and bulk modulus are firstly derived as afunction of the internal pressure and of the wall elastic and geometrical characteristics. Then, the influence of the pipegeometry and of the wall thickness on the pipe wall compliance and bulk modulus are highlighted for some materials ofinterest for industrial, automotive and aerospace applications (steel, aluminium, titanium and wired rubber), and thedependency of the equivalent bulk modulus on these parameters and on fluid physical characteristics is highlighted.Finally, the influence of mechanical constraints, of pipe geometry, of fluid physical properties, of wall material and offluid pressure on the global pipe dynamic response characteristics, and in particular on the fluid celerity, on the Machnumber and on the natural frequency, is evidenced.

2006 - The influence of aeration and cavitation on gear pumps and motors meshing volumes pressures [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; Paltrinieri, Fabrizio; Zardin, Barbara
abstract

The paper describes the influence of the fluid modeling on cavitation and aeration detection in external gear pumps and motors inter-teeth volumes during the gears meshing process, in order to compare the results coming from the use of different physical models of air release/adsorption and cavitation. A simplified cavitation model is firstly involved, and pressure transients are calculated imposing a pressure cut when the fluid vapor pressure (or the dissolved air partial pressure) is reached. After, assuming an equivalent approach able to involve the vapor phase generation, the cavitation phenomena in the meshing volumes are deepened, and the influence of the fluid modeling enhancement on the cavitating machine behavior is highlighted. Then, the equivalent fluid approach is enhanced introducing the air release, and properly coupling the gaseous phases release/adsorption to the Henry's Law for not instantaneous processes. Finally, the influence of the air release/adsorption time constant on meshing volumes pressure transients are detailed, with particular attention devoted to the modification introduced by the cavitation detailing on the gaseous phase void fraction determination and on the angular extension of the cavitation phenomena detection.

2005 - Influence of Notch Shape and Number of Notches on the Metering Characteristics of Hydraulic Spool Valves [Articolo su rivista]
Borghi, Massimo; Milani, Massimo; R., Paoluzzi
abstract

The paper presents theoretical and experimental results of studies on the influence of shape and number of spool notches on the discharge characteristics (discharge coefficient, velocity coefficient and flow angle) of a hydraulic distributor metering edge. The flow rate vs. pressure drop and the steady state axial flow-force vs. pressure drop diagrams are determined for spools with different configurations of multiple notched metering edges. Various combinations of the shape and number of the notches modulating the metering area of the passage between supply and drain ports were investigated and correlated with flow rate, axial flow force and pressure drop, in order to get estimates of discharge coefficient and flow angle. The procedure is applied to all the data collected during the experimental activity, and shows the behaviour of the flow characteristics in both fully turbulent and transitional region of motion. The influence of notch shape and number on the metering edge flow characteristics is evaluated as well.

2005 - Mechanical Cushion Design Influence on Cylinder Dynamics [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; F., Conrad
abstract

The paper deals with the simulation and theexperimental verification of the dynamic behaviour of alinear actuator equipped with different configurations ofmechanical cushion. A numerical model, developedand tailored to describe the influence of differentmodulation of the discharged flow-rate (and of thecorrespondent discharging orifice design) on thecushioning characteristics variation is firstlyintroduced. Then, with respect to the case of thecylindrical cushioning engagement, both the reliabilityand the limits of the numerical approach arehighlighted through a numerical vs. experimentalcomparison, involving the piston velocity and thecylinder chambers pressure. After, with the aim ofhighlighting the effect of mechanical cushions designon a two effect linear actuator dynamic performances,the characteristics modulation of four alternativecushioning systems are determined and deeplyanalyzed. Finally, a sensitivity analysis about theinfluence of the variation of the main geometricalparameters is introduced and, thanks to theintroduction of some dimensional and non-dimensionalparameters of engineering interest, some usefulguidelines in selecting the most effective cushionshape are highlighted.

2005 - Pressure Transients in External Gear Pumps and Motors Meshing Volumes [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; Paltrinieri, Fabrizio; Zardin, Barbara
abstract

In this paper a lumped parameters numerical model isreviewed to study the meshing process of external gearpumps and motors, with the aim of highlighting theinfluence of some geometrical design parameters andoperating conditions on inter-teeth volumes pressures.The inter-teeth space is modeled adopting a two-volumeapproach, properly tailored both for the pump and for themotor units behavior description. In both cases, thecommunications between the interconnected inter-teethvolumes and the high and low pressure ports aresketched as variable equivalent turbulent restrictors; flowareas have been determined as functions of the gearsand of the meshing grooves main design parameters.The inter-teeth pressures, and the leakage flows, arecalculated solving the incompressible and isothermalcontinuity equation, contemporarily applied to bothvolumes and properly combined with the classicalturbulent orifice equation. Successively, for a referenceoperating condition, properly chosen for underlining theinter-teeth meshing cycle and corresponding to a verylow pressure load, the meshing processes of an externalgear pump and of an external gear motor are compared.Among others, the attention is focused on the behaviorof those hydraulic variables more conditioning themeshing cycle, and the differences rising up in interteethpressure peaks and in cavitation interval amplitudeand angular positioning are evidenced. Then, themeshing process analysis is expanded to cover theexternal gear units common operating field, both interms of rotational speed (from 500 to 3000 rpm) and interms of the high pressure port value (from 10 to 250bar). In all cases, the general trend shows that cavitationhas a deeper influence on external gear pumpsoperation, while external gear motors are subjected tomore significant pressure peaks, particularly markedduring the low pressure part of the meshing cycle.Attention is also focused on the influence of gears interaxialdistance and axial width on the meshing processcharacteristics, in order to assess how the volumedimensions could differently affect pressure peaks andcavitation phenomena in pumps and motors.Finally, the role of the balancing plates grooves inconditioning pressure peaks and cavitation is highlightedand, with particular care devoted to external gearmotors, some useful guidelines for their design areoutlined.

2005 - Studying the Axial Balance of External Gear Pumps [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; Paltrinieri, Fabrizio; Zardin, Barbara
abstract

In this paper some design aspects related to externalgear pumps balancing surfaces are studied, and someuseful guidelines for designing bearing blocksbalancing surfaces are suggested. In order to studybearing blocks axial balance, a numerical procedurefor the determination of the pressure distribution insidethe clearance bounded by gears sides and bearingblocks internal surfaces is firstly presented andapplied. After, the influence of bearing blocksgeometry and pump operating conditions on thewidening thrust is highlighted, considering bothconstant and variable lateral clearance heights. Then,the computations are performed to evaluate thewidening thrust variation as a function of bearingblocks relative tilt with respect to gears lateral sides,and both positive and negative bearing blocks tilts areevidenced and discussed. Finally, the numericalprocedure is validated through a comprehensivecomparison of its results with experimental data(coming from some bibliographic sources), and someuseful guidelines in designing external gear pumpsbalancing surfaces are defined.

2005 - Studying the Efficiency of a Compact Excavator Primary Workgroup Hydraulic Control System [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; Paltrinieri, Fabrizio; Zardin, Barbara
abstract

This paper studies the proportional directional controlvalves design influence on the energetic behavior of amid-power compact excavator.In particular, with reference to the hydraulic circuitactuating the primary workgroup, in the paper thehydraulic power metering performed with the boomcylinder proportional control valve is studied, and somedesign solution useful in reducing both the hydraulicpower dissipation, and the power absorption from themachinery prime mover are highlighted.The analysis, experimentally performed for differentoperating conditions, is carried out highlighting theinfluence of a metering configuration both on the supplypressure modulation and on the flow-rate supplied tothe actuator.The hydraulic power metering and the boom actuationhydraulic efficiency are defined for two alternativeproportional control valve metering configurations and,within the limits implicitly implied on the actuation circuitarchitecture, a possible design solution in determiningthe improvement of the boom actuation systemperformances is investigated.

2005 - The Influence of the Notch Shape and Number on Proportional Directional Control Valve Metering Characteristics [Articolo su rivista]
Borghi, Massimo; Milani, Massimo; Paltrinieri, Fabrizio
abstract

The paper investigates, by means of a 3D, steady-state, incompressible and isothermal CFD analysis, the influence of the notch shape and number on proportional directional control valves metering edge characteristics. The numerical activity is firstly performed for a sharp metering edge, considered as reference case.Then, different configurations of notched metering edges are considered, coming from the adoption of two notch geometrical shapes largely used in proportional directional control valves actual design, and from a symmetrical displacement of two, three and four notches on the spool periphery. For all the cases considered, the qualitative analysis of the internal flow field is performed in order to highlight the fluid efflux main characteristics.After, a quantitative analysis of the metering characteristics is introduced, with the aim of determining the influence of the metering configuration, of the spool position and of the operating conditions on the efflux characteristics (the discharge coefficient and the jet angle).

2004 - About the Prediction of Pressure Variation in the Inter-Teeth Volumes of External Gear Pumps [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; Paltrinieri, Fabrizio; Zardin, Barbara
abstract

The paper deals with the analysis of the inter-teeth pressure transients during gears meshing cycle of external gear pumps. A lumped parameter model, tailored for the prediction of pressures in the meshing zone, is firstly presented. The numerical model, based on the integration of the continuity equation, is applied to the inter-teeth volumes, communicating with the neighbouring ambient through geometry dependent orifices. A comparison between numerical results, obtained considering both constant and variable discharge coefficients, is illustrated. Successively, the dependency of pressure transients on gear pump operating conditions, mainly in terms of delivery pressure and rotational speed, is investigated. The effect of some geometric parameters is also discussed, mainly considering different gears widths and interaxial distances, and high-pressure recess positioning. Finally, in order to highlight the influence of the cavitation modelling on low pressure transition, the results coming from the application of two simplified approaches are shown and compared.

2004 - Optimization of the Intake System on Diesel Engines Featuring a High Pressure Injection System [Capitolo/Saggio]
Borghi, Massimo; Cantore, Giuseppe; Mattarelli, Enrico; Milani, Massimo; Fontanesi, Stefano; Montorsi, Luca; D., Balestrazzi
abstract

Combustion in Diesel engines is controlled by the interaction between fuel jet and mean and turbulent flow field. Therefore, the use of novel fuel injection strategies should be always integrated with the optimisation of the mean and turbulent flow field within the cylinder. While in the last years injection system technology has evolved at an impressive rate, establishing new standards, the development of design criteria for intake ports, ducts and plenums is not keeping the same pace. The authors believe that a substantial work should be carried out in this field. For this purpose numerical simulation should play a fundamental role to cut development time, as well as to gain a better understanding of the complex thermo-fluid-dynamics phenomena occurring within the engines.This paper reviews the fundamentals of the experimental and theoretical work carried out at DIMEC-University of Modena and Reggio for supporting the development of more efficient HSDI Diesel engines.

2004 - Stydying the Flow Field Inside Lateral Clearances of External Gear Pumps [Relazione in Atti di Convegno]
Paltrinieri, Fabrizio; Borghi, Massimo; Milani, Massimo
abstract

In this paper the flow field in the clearances bounded by gears lateral sides and bearing blocks internal surfaces of external gear pumps is studied. Firstly, the pressure distribution is determined applying the Laplace equation to the domain limited by two successive teeth profiles, the middle lines of the first and of the last space and the drain circle, and the main leakage paths inside the clearance are evaluated. Then, the leakage flows between the spaces, and between each space and the drain ambient, are calculated considering different boundary conditions and teeth shapes, and the streamlines are highlighted in order to evidence the main leakage paths. The information gathered through this flow field analysis are used to define equivalent conductance for leakage paths, useful to be adopted in simple lumped parameters models, usually applied with the aim to determine the pressure distribution inside pump casing or, for example, gear pumps volumetric efficiency.

2004 - The Effect of Flow Forces Compensating Profile on the Metering Characteristics of a Conical Seat Valve [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; Paltrinieri, Fabrizio
abstract

This paper studies the influence of the discharge chamber geometrical parameters on the steady-state characteristics behavior of a conical seat valve having compensating profile.More in details, starting from the analysis of the experimental behavior of an actual valve showing inefficient characteristic curves, the metering openings leading to the transition from under to over compensation are individuated.Then, a 3D CFD steady-state, incompressible and isothermal analysis is involved, mainly to evidence the valve discharge coefficient and flow-forces variations with operating conditions.After, two alternative valve configurations, presenting a low pressure region designed to optimize the flow-forces compensation, are characterized through the 3D CFD analysis.

2004 - The Influence of the Notch Shape and Number on Proportional Directional Control Valve Metering Characteristics [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; Paltrinieri, Fabrizio
abstract

The paper investigates, by means of a 3D, steady-state, incompressible and isothermal CFD analysis, the influence of the notch shape and number on proportional directional control valves metering edge characteristics. The numerical activity is firstly performed for a sharp metering edge, considered as reference case. Then, different configurations of notched metering edges are considered, coming from the adoption of two notch geometrical shapes largely used in proportional directional control valves actual design, and from asymmetrical displacement of two, three and four notches on the spool periphery. For all the cases considered, the qualitative analysis of the internal flow field is performed in order to highlight the fluid efflux main characteristics. After, a quantitative analysis of the metering characteristics is introduced, with the aim of determining the influence of the metering configuration, of the spool position and of the operating conditions on the efflux characteristics (the discharge coefficient and the jet angle).

2003 - A Conservative High Resolution Scheme for the Study of Gases and Liquids Homentropic Flows [Relazione in Atti di Convegno]
Borghi, Massimo; C., Bussi; Milani, Massimo; Paltrinieri, Fabrizio
abstract

In this paper a high-resolution explicit integration scheme is introduced and adopted to study the one-dimensional homentropic flow of a generic fluid, applicable to gaseous and liquid phase. The generally valid governing equations for one-dimensional homentropic flows are firstly introduced and, without forcing any assumption in relation to the nature of the fluid, an investigation of mathematical properties of the system of equations is given in order to derive the characteristic matrix and the system eigenvalue. Then, the Maxwell differential formulation of the fluid constitutive equations is introduced, with the purpose of providing a general state equation which retains its validity for both gases and liquids, and with the aim of expressing and explicitly calculating pressure, pressure derivative with respect to density and sound speed as functions of fluid bulk modulus. Starting from the differential formulation of the state equation, a high-resolution explicit integration scheme, based on conservative formulation of the governing equations for fluid flows, is then introduced and discussed. Finally, the well-known shock tube test is employed to study both liquid and gaseous flows, and the forthcoming numerical vs. analytical results comparison is used to assess the accuracy and the stability of the integration scheme.

2003 - A Numerical Approach to the Hydraulic Fluid Properties Prediction [Relazione in Atti di Convegno]
Borghi, Massimo; Bussi, Carlo; Milani, Massimo; Paltrinieri, Fabrizio
abstract

This paper presents a numerica! approach tailored for the prediction ofhydraulic fluids physical and thennodynarnic properties, starting from a limited number of information about fluid viscosity and fluid density. Firstly, the review of some experimental based prediction models available in literature for the fluid viscosity variations is presented, and the more accurate ones for the analysis ofindustrial and automotive hydraulic fluids (mineral oils, lubricants and fuels) are selected. Then, the paper highlights the step of a possible procedure able to defme thevariations both of other physical fluid praperties (such as the isothermal or the isentropic bulk modulus, the constant pressure or the constant volume specific heat, the constant pressure, orthe constant volume, volume expansion coefficient), and of the main thermodynamic fluid properties (such as the specific entropy, the specific enthalpy and the specific internal energy).Finally, the resu1ts coming from the numerical approach previously outlined are compared with experimental data, found in literature for different mineral oils, in a range of temperature from O to 160°C and of pressure from O to 600 bar.

2003 - Studio del Campo di Moto nei Meati Laterali di Macchine Volumetriche ad Ingranaggi Esterni [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; Paltrinieri, Fabrizio
abstract

Viene presentato lo studio del campo di moto nel meato, supposto ad altezza costante, esistente tra i fianchi delle ruote dentate e le superfici delle fiancate di bilanciamento di macchine volumetriche ad ingranaggi esterni. A partire dalla determinazione della distribuzione di pressione nel meato vengono determinati, al variare della geometria e delle condizioni al contorno, le portate e le linee di corrente. La valutazione delle portate scambiate dal generico vano con i vani contigui e con l’ambiente di drenaggio viene poi utilizzata per mettere a punto un modello di meato a parametri concentrati che si mostra essere più accurato di quello utilizzato in precedenti lavori per il calcolo della distribuzione di pressione nei vani tra i denti affinando la determinazione delle conduttanze caratteristiche degli strozzatori in esso considerati. I risultati, relativi a diverse geometrie di ruote dentate di corrente impiego, vengono poi confrontati tra loro al fine di evidenziare l’influenza dei parametri geometrici caratteristici delle dentature sulla distribuzione di pressione nel meato, sulla ripartizione delle principali portate di fuga e sulle dimensioni caratteristiche degli strozzatori equivalenti considerati nei modelli a parametri concentrati. I risultati ottenuti mostrano altresì come il modello proposto risulti adeguato per le geometrie di dentatura considerate e pare particolarmente promettente per essere utilizzato nella previsione e calcolo del rendimento volumetrico.

2002 - A Numerical and Experimental Study Towards Possible Improvements of Common Rail Injectors [Articolo su rivista]
G. M., Bianchi; S., Falfari; F., Filicori; Milani, Massimo; P., Pelloni
abstract

The aim of this work is to propose modifications to the managing of the 1st-generation Common-Rail injectors in order to reduce actuation time towards multiple injection strategies. The current Common-Rail injector driven by 1st ECU generation is capable of operating under stable conditions with a minimum dwell between two consecutive injections of 1.8 ms. This limits the possibility in using proper and efficient injection strategies for emission control purposes. A previous numerical study, performed by the electro-fluid-mechanical model built up by Matlab- Simulink environment, highlighted different area where injector may be improved with particular emphasis on electronic driving circuit and components design. Experiments carried out at injector Bosch test-bench showed that a proper control of the solenoid valve allowed reducing drastically the standard deviation during the pilot pulses.

2002 - Analysis of a F1 Car Hydraulic Circuit Dynamic Behaviour [Articolo su rivista]
Borghi, Massimo; Milani, Massimo; M., Piraccini; M., Flandoli
abstract

This paper deals with the study of the dynamic behavior of a F1 car gear selection hydraulic circuit, when involved in different shift transients.In the first part of the paper the actual circuit is described, and the main hypotheses adopted for the numerical modeling of the hydraulic power unit, of the control valves, of hydraulic pipes and of the actuators involved in the gear shift cycles are introduced. Particular attention is devoted to the actuators actual sequences, as applied by the Electronic Control Unit (ECU) to the servo- valves deputed to actuators control. The strategy to define each gear shift cycle in terms of actuators working position in time domain is chosen, using the frequency map of each servo-valve.A numerical versus experimental comparison of the behavior of the actuators involved in the gear selection (during about 50 ms for an up shifting and 100 ms for a down shifting) is performed, with the target to define the validity limits of the numerical model results.Finally, the paper reports the analysis of those hydraulic variables not controlled by the on-board diagnostic, with the aim to analyze the behavior of the power unit and of the pipes when submitted to the sudden hydraulic power request correspondent to a gear shift.

2002 - CFD Analysis of the In-Cylinder Flow in DI Diesel Engines [Capitolo/Saggio]
Borghi, Massimo; Cantore, Giuseppe; Mattarelli, Enrico; Milani, Massimo; Fontanesi, Stefano; Montorsi, Luca
abstract

Non disponibile

2002 - Dynamic Stability of a Pipe Subjected to a Pulsating Flow [Relazione in Atti di Convegno]
Catellani, Giulia; Milani, Massimo; Pellicano, Francesco
abstract

Power transmission pipes are widely present in industrial applications. Moreover, the physical and mathematical model describing the dynamics of a pipe is similar to that of many mechanical systems such as heat exchangers high-speed magnetic tapes, band saw blades, aerial cable threadlines, and sheet production processes. All previous systems are axially moving systems. The dynamic behaviour of an axially moving system is greatly influenced from the presence of the internal flowing fluid, which affects the pipes dynamics and stability. When a critical value of the axial speed is reached, the first linear natural frequency vanishes; the straight equilibrium position loses stability and bifurcates into new equilibrium states. In the sub-critical speed range, all natural frequencies decrease as the axial speed increases and the vibration modes are complex. In actual operating conditions, pipe lines are subjected to many external disturbances, such as external excitations or dynamic disturbances exerted by the flow fluctuations induced by a volumetric pump. Some example of pump-pipes interactions can be found in literature, that highlight the great influence of pump irregularity on lines stability and system noising. When an oscillating external excitation causes a resonance, very dangerous conditions can be met and the axially moving continuum can undergo to catastrophic failures. The presence of an internal flow can cause divergence and flutter type instabilities. The fluid structures interaction analysis requires a deep investigation of the internal velocity field

2002 - Modelling and Simulating Hydraulically Balanced External Gear Pumps [Relazione in Atti di Convegno]
Borghi, Massimo; Paltrinieri, Fabrizio; Milani, Massimo
abstract

The paper presents some developments of a research activity regarding hydraulically balanced external gear pumps.Numerical models are introduced in order to study gears radial equilibrium and axial bearing blocks balance. A numericalapproach useful for determining the eccentric positions assumed by gears inside the pump casing and to assess the radialthrusts acting on gears is proposed. The effect of the running in process on the casing internal surface and on the pressure distribution in sealed spaces between teeth is also shown and discussed. At the end a numerical model useful in designing bearing blocks balancing surfaces is outlined. Comparisons of numerical and experimental results seem to encourage the development of the study.

2001 - Analisi funzionale di un elettro-iniettore per sistema di iniezione common-rail [Relazione in Atti di Convegno]
D., Baccolini; Borghi, Massimo; Milani, Massimo; S., Falfari; A., Mazza
abstract

In questo lavoro vengono presentati alcuni dei risultati ottenuti durante lo studio del comportamento dinamico di un elettro-iniettore per applicazioni Common Rail, facente parte del sistema di iniezione presente a bordo di un motore Diesel 4 cilindri di elevata potenza specifica. Nella sua prima parte, il lavoro presenta il modello numerico adottato per lo studio del comportamento dinamico di un elettro-iniettore di corrente impiego industriale (BOSCH), realizzato utilizzando un codice di calcolo specificatamente sviluppato per lo studio di sistemi idraulici sottoposti a veloci transitori di comando.Successivamente, vengono proposti i risultati ottenuti applicando allo stadio di comando elettroidraulico dell'iniettore alcune delle strategie di comando e controllo disponibili nella mappatura standard della centralina elettronica presente a motore. L'analisi dell'influenza del ciclo di comando sulle caratteristiche di funzionamento dell'elettro-iniettore viene, eseguita con riferimento al comportamento temporale di alcune delle variabili di maggior interesse progettuale, quali gli spostamenti dell'ancora dello stadio di comando e dello spillo di iniezione, la pressione nella camera di controllo e nelpozzetto di iniezione, la portata ela massa iniettate per ciclo.Questa prima parte dello studio viene conclusa da una verifica numerico/sperimentale della massa iniettata per ciclo al variare del regime di rotazione e della pressione media nel rail,con lo scopo di determinare l' affidabilità, la ripetibilità ed i limiti del modello numerico adottato.La generale attendibilità delle previsioni numeriche, soprattutto in termini di massa iniettata per ciclo, permette di utilizzare le informazioni precedentemente introdotte per .determinare le caratteristiche di efflusso del combustibile dai fori di iniezione, quali ad esempio il coefficiente di efflusso, la velocità media del fluido e l'area effettiva nella sezione di uscita dall'iniettore. Nel lavoro vengono presentati e discussi i risultati ottenibili applicando tre modelli di efflusso disponibili in bibliografia.La seconda parte del lavoro è dedicata alla verifica del funzionamento dell'elettro-iniettore una volta inserito nel sistema di iniezione di un motore 4·cilindri. il modello numerico-precedentemente adottato per lo studio del comportamento dell'elettro-iniettore viene inserito in un modello sviluppato persimulare I'intero sistema di iniezione di un motore ad accensione spontanea soggetto a condizioni di funzionamento "reali", coinvolgente sia il ciclo di comando applicato alla valvola di regolazione della pressione nel Rail (presente sulla linea di mandata della pompa di iniezione di alta pressione), siaun'opportuna fasatura dei comandi imposti ai quattro elettro-iniettori coinvolti. Il funzionamento del sistema di iniezione viene poi analizzato con 'lo_scopo di evidenziare come, all'intemodi un ciclo di iniezione, il duty cycle imposto dalla entralina elettronica alla valvola di regolazìone della pressione 'nel rail possa, imporre ai quattro iniettori un comportamento differente, e come la poitatae la massa iniettate per ciclo risultino variabili da iniettore ad iniettore.

2001 - Analysis of a f1 car hydraulic circuit dynamic behavior [Relazione in Atti di Convegno]
Borghi, M.; Milani, M.; Piraccini, M.; Flandoli, M.
abstract

This paper deals with the study of the dynamic behavior of a F1 car gear selection hydraulic circuit, when involved in different shift transients. In the first part of the paper the actual circuit is described, and the main hypotheses adopted for the numerical modeling of the hydraulic power unit, of the control valves, of hydraulic pipes and of the actuators involved in the gear shift cycles are introduced. Particular attention is devoted to the actuators actual sequences, as applied by the Electronic Control Unit (ECU) to the servo-valves deputed to actuators control. The strategy to define each gear shift cycle in terms of actuators working position in time domain is chosen, using the frequency map of each servo-valve. A numerical vs. experimental comparison of the behavior of the actuators involved in the gear selection (during about 50 ms for an up shifting and 100 ms for a down shifting) is performed, with the target to define the validity limits of the numerical model results. Finally, the paper reports the analysis of those hydraulic variables not controlled by the on board diagnostic, with the aim to analyze the behavior of the power unit and of the pipes when submitted to the sudden hydraulic power request correspondent to a gear shift. Copyright © 2001 Society of Automotive Engineers, Inc.

2001 - Designing hydraulic locking balancing grooves [Articolo su rivista]
Milani, Massimo
abstract

The paper deals with the analysis of the influence of the groove axial length, number and position on the total side thrust acting on a spool inserted into a tapered clearance. Adopting a numerical approach based on the Reynolds equation property combined with the continuity equation, the hydraulic locking phenomena are studied for different tapered clearances of practical interest in the presence of different groove configurations. The variation in groove axial length, number and axial position makes it possible to collect important information about the multigrooved spool in a thin film of fluid, including fundamental data for a proper spool design.

2001 - Development of a Dynamic Model for Studying the 1st Generation of Common Rail Injectors for HSDI Diesel Engines [Relazione in Atti di Convegno]
Bianchi, G. M.; Pelloni, S. F. P.; Filicori, F.; Milani, M.
abstract

The aim of this work is to investigate Common Rail injector behavior towards multiple injection strategies. A numerical model has been developed to simulate the electro-fluid-mechanic behavior of a Bosch mass production injector (standard injector) and validation against experiments has been performed. In order make the injector performing multiple injections, a deep investigation has been numerically carried out. The numerical study highlighted different area where injector may be improved with particular emphasis on electronic driving circuit. A new driving circuit concept, previously developed, has been successfully simulated showing promising fast-response capability for injector actuation.

2001 - Development of dynamic model for studying the 1st generation of common-rail injectors for HSDI diesel engines [Relazione in Atti di Convegno]
G. M., Bianchi; S., Falfari; F., Filicori; Milani, Massimo; P., Pelloni
abstract

The aim of this work is to investigate common-rail injector behavior towards multiple injection strategies. A numerical model has been developed to simulate the electro-fluid-mechanic behavior of a Bosch mass production injector (standard injector) and validation against experiments has been performed. In order to make the injector performing multiple injections, a deep investigation has been numerically carried out. The numerical study highlighted different areas where injector may be improved with particular emphasis on electronic driving circuit. A new driving circuit concept, previously developed, has been successfully simulated showing promising fast-response capability for injector actuation.

2001 - Dynamic Analysis of Diesel Engine Common Rail Injection System. Part I: Injector Dynamics [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; Piraccini, Matteo
abstract

The aim of the paper is to analyze the dynamic behavior of an actual electro-hydraulic injector, included into a high-pressure accumulator injection system (Common Rail).Firstly, a brief introduction of the hypotheses adopted for a lumped parameter description of each part of an industrial version of the injector (BOSCH) is outlined, together with the definition of the hypotheses assumed to treat the fuel efflux through the injection holes, through the internal mechanical couplings and the damping orifices, or to descript of the cavitations.Then, the dynamic behavior of the injector is analyzed adopting some of the command signals imposed to the pilot stage by the Electronic Central Unit (ECU), as actually implemented into the standard map of an on board ECU of a industrial diesel engine. Among others, the paper presents the results coming from the injector handling for medium values of the crank-shaft regime (1800 and 2400 rpm), for different pressure levels in the Rail and involving also the pilot injection.The reliability of the numerical results is stated through a wide numerical vs. experimental comparison, made up on the basis of the fuel mass injected for each cycle.Finally, the discharge characteristics characterizing the injection are determined, such as the effective mean velocity and the effective area of the liquid core at the holes exit, or injection holes discharge coefficient.

2001 - Dynamic Analysis of Diesel Engine Common Rail Injection System. Part II: Four-Cylinder Injection System [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; Piraccini, Matteo
abstract

The paper is aimed at studying the overall dynamic behavior of the Common Rail Injection System actually used on a 4 cylinder industrial Diesel engine.Firstly, the paper introduces the main characteristics of a lumped and distributed parameters model of the high pressure branch of an actual Common Rail System, and the main hypotheses assumed to model it using a multi-port approach code for the analysis of the dynamic response of hydraulic systems submitted to fast transients.The model of the Common Rail System is then used to study its dynamic behavior when involved in the handling of the engine injection cycle for medium values of the crankshaft regime and for different pressure levels in the Rail. The analysis is performed applying to the injectors, to the pressure control valve and to the high-pressure pump the control strategies imposed by the Electronic Central Unit (ECU), as actually implemented into an industrial ECU for Diesel engine management.The model reliability and accuracy are evidenced through a numerical vs. experimental data comparison, mainly in term of rail pressure dynamic behavior.The analysis successively outlined in the paper allows to state how the hydraulic behavior of the Common Rail System interact with the electro-hydraulic injectors dynamics, and to determine the influence of this interaction on the total injected mass per cycle.

2001 - Dynamic analysis of diesel engine common rail injection system. Part I: Injector dynamics [Relazione in Atti di Convegno]
Borghi, M.; Milani, M.; Piraccini, M.
abstract

The aim of the paper is to analyze the dynamic behavior of an actual electro-hydraulic injector, included into a high-pressure accumulator injection system (Common Rail). Firstly, a brief introduction of the hypotheses adopted for a lumped parameter description of each part of an industrial version of the injector (BOSCH) is outlined, together with the definition of the hypotheses assumed to treat the fuel efflux through the injection holes, through the internal mechanical couplings and the damping orifices, or to descript of the cavitations. Then, the dynamic behavior of the injector is analyzed adopting some of the command signals imposed to the pilot stage by the Electronic Central Unit (ECU), as actually implemented into the standard map of an on board ECU of a industrial diesel engine. Among others, the paper presents the results coming from the injector handling for medium values of the crank-shaft regime (1800 and 2400 rpm), for different pressure levels in the Rail and involving also the pilot injection. The reliability of the numerical results is stated through a wide numerical vs. experimental comparison, made up on the basis of the fuel mass injected for each cycle. Finally, the discharge characteristics characterizing the injection are determined, such as the effective mean velocity and the effective area of the liquid core at the holes exit, or injection holes discharge coefficient.

2001 - Dynamic analysis of diesel engine common rail injection system. Part II: Four-cylinder injection system [Relazione in Atti di Convegno]
Borghi, M.; Milani, M.; Piraccini, M.
abstract

The paper is aimed at studying the overall dynamic behavior of the Common Rail Injection System actually used on a 4 cylinder industrial Diesel engine.Firstly, the paper introduces the main characteristics of a lumped and distributed parameters model of the high pressure branch of an actual Common Rail System, and the main hypotheses assumed to model it using a multi-port approach code for the analysis of the dynamic response of hydraulic systems submitted to fast transients.The model of the Common Rail System is then used to study its dynamic behavior when involved in the handling of the engine injection cycle for medium values of the crankshaft regime and for different pressure levels in the Rail. The analysis is performed applying to the injectors, to the pressure control valve and to the high-pressure pump the control strategies imposed by the Electronic Central Unit (ECU), as actually implemented into an industrial ECU for Diesel engine management.The model reliability and accuracy are evidenced through a numerical vs. experimental data comparison, mainly in term of rail pressure dynamic behavior.The analysis successively outlined in the paper allows to state how the hydraulic behavior of the Common Rail System interact with the electro-hydraulic injectors dynamics, and to determine the influence of this interaction on the total injected mass per cycle.

2001 - Estimation of Erosion Effects Due to Solid Contaminant in Hydraulic Valves [Relazione in Atti di Convegno]
Milani, Massimo; R., Paoluzzi
abstract

Solid contaminant is one of the major causes of component failures and system brakedowns in fluid power systems.More than 80% of severe damages can be referred back to the effects of fluid contamination. The traditional approach tothe solution of this problem is the introduction of properly designed filtration elements combined with the developmentof filtration strategies tailored for every application need. This approach can be considered substantially passive in nature,since it allows the contaminant to be present in the fluid and provides means for its removal in order to keep eitherdistribution or density of solid particles within prescribed limits. The passive approach, however, does not allow anydynamic estimation of the damages caused to components by fluid contamination, and the knowledge gained on thecorrelation of fluid contamination to component damage is mainly empirical in nature. The work presented in the paper ispart of a comprehensive activity aimed at correlating solid particle erosion effects to hydraulic fluid (usually mineral oil)contamination level, as defined by existing (ISO and NAS) standards. The tool used to predict solid particles erosion is acomputational fluid dynamics (CFD) solution (obtained using a commercial code) of the flow field inside a hydraulic valve,coupled with lagrangian equation of motion solution for solid particles subject to viscous forces.

2001 - Influenza del Rodaggio sulle Condizioni di Funzionamento di Macchine Volumetriche ad Ingranaggi Esterni [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; Paltrinieri, Fabrizio; M., Guidetti
abstract

Si illustrano gli ultimi sviluppi di un modello, descritto in (Bonacini e Borghi, 1990) ed in (Borghi et al., 1997), per il calcolo dell’andamento della pressione nei vani compresi tra due denti consecutivi, le fiancate ed il corpo di macchine volumetriche ad ingranaggi esterni. Nella prima parte del lavoro viene presentato un modello per la determinazione della posizione assunta dalle ruote, durante il funzionamento, all’interno del corpo della macchina. In particolare, la posizione di lavoro delle ruote è determinata valutando separatamente due contributi: il primo dovuto al recupero del gioco esistente tra le fiancate ed il corpo; il secondo legato alla capacità di sostentamento del carico della coppia rotoidale lubrificata costituita dall’albero della ruota e dalle boccole alloggiate nelle fiancate. In questo modo è possibile evidenziare, da un lato le condizioni di funzionamento che portano le ruote ad interferire con la superficie interna del corpo, dall’altro l’entità dell’asportazione di materiale dal corpo stesso. I profili della superficie interna del corpo così ottenibili vengono poi confrontati, per macchine operatrici di corrente produzione industriale di diverse caratteristiche geometriche, con i corrispondenti rilevati al termine di processi di rodaggio appositamente predisposti. I confronti effettuati mostrano la sostanziale validità del modello presentato, la sua generale attendibilità e l’applicabilità industriale.

2001 - Reliability of fluid cavitation analysis by means of an equivalent fluid characteristics modelling [Relazione in Atti di Convegno]
Borghi, Massimo; C., Bussi; Milani, Massimo; R., Paoluzzi
abstract

The modelling of two-phase flows, and in particular the modelling of cavitating flows, represents a remarkable field of interest for fluid power machines and components analysis. Even if the cavitation is a phenomenon physically well known and experimentally well detectable, it is very difficult to introduce its development and effects into numerical models built up for machines and components behaviour analysis. The aim of this paper is to analyse the alternate approach to the two-phase flow description, based on the definition of an “equivalent fluid”, having physical-chemical characteristics defined by a proper combination of a given mixture of different fluids (liquid-gas included). In deeper detail, the correctness of an “equivalent fluid” approach, which is made with the aim to reduce the number of differential equations to be solved in presence of two-phase flows, has to be thoroughly investigated. This is achieved by the simulation of an adiabatic cylinder filled with a water-air mixture, which expand isentropically from atmospheric pressure towards the vapour tension. This simple test case is investigated applying both the “equivalent fluid” model and a homogeneous pressure zero-dimensional two-zone model, which is solved by direct integration. The final scope of the paper is to determine to which extent the “equivalent fluid” approach is able to reproduce the actual behaviour of a cavitating flow, with particular attention paid to the correct representation of heat transfer phenomena. Some of the examples are referred to water, but no major limitation exists to the application of the approach to mineral oil.

2000 - Computational Fluid Dynamics in Solid Particle Estimation in Hydraulic Poppet Valves [Articolo su rivista]
Borghi, Massimo; Milani, Massimo; R., Paoluzzi
abstract

This paper deals with the analysis of the interaction between solid contamination and internal geometry in hydraulic conical and spherical poppet valves, performed through a non-dimensional, axisymmetric CFD analysis of their internal flow.The information coming from the flow field solution is used to identify regions having higher probability to be impacted by particles dragged by the fluid, and to estimate the erosion potential of solid particles having different sizes.The value of the kinetic energy of particles approaching the walls of the geometric domain is used to estimate the amount of material potentially eroded by impacting particles, and to provide a potential correlation between ISO 4406 and NAS 1638 solid contamination level classification. The long-term target is a numerical estimation of service life in hydraulic components.

2000 - Flow-Forces Effect on the Behavior of an Open Center Hydraulic Distributor [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; E., Sedoni
abstract

The effect of steady-state axial flow-forces on the motion of an open center hydraulic distributor notched spool is considered. More in details, the spring driven spool centering is considered, in which undesired axial flow-forces could overcome the spring action. A steady-state analysis of the forces influencing the spool motion is reported, calculating the axial flow-force for different positions of the spool. Different notched shapes of the metering edge are considered, and an optimized solution for the notched edge of the spool is proposed at last.

2000 - Flow-forces effect on the behavior of an open center hydraulic distributor [Relazione in Atti di Convegno]
Borghi, M.; Milani, M.; Sedoni, E.
abstract

The effect of steady-state axial flow-forces on the motion of an open center hydraulic distributor notched spool is considered. More in details, the spring driven spool centering is considered, in which undesired axial flow-forces could overcome the spring action. A steady-state analysis of the forces influencing the spool motion is reported, calculating the axial flow-force for different positions of the spool. Different notched shapes of the metering edge are considered, and an optimized solution for the notched edge of the spool is proposed at last.

2000 - L'adimensionalizzazione per un migliore uso della CFD in oleodinamica [Articolo su rivista]
D., Baccolini; Milani, Massimo; R., Paoluzzi
abstract

La memoria illustra i vantaggi derivanti dall'adozione di strumenti di calcolo fluidodinamico per la progettazione di componenti idraulici di regolazione on-off e proporzionali

2000 - La verifica di un calcolo CFD [Articolo su rivista]
D., Baccolini; Milani, Massimo; R., Paoluzzi
abstract

La memoria mostra l'attendibilità dei risultati ottenibili mediante la progettazione fluidodinamica computazionale applicata al dimensionamento di componenti oleoidraulici di regolazione.

2000 - Stationary Axial Flow Forces Analysis on Compensated Spool Valves [Articolo su rivista]
Borghi, Massimo; Milani, Massimo; R., Paoluzzi
abstract

The paper deals with the application of a simplified numerical analysis, based on Computational Fluid Dynamics (CFD), of the flow field inside the compensated port connections of a reference spool valve. The aim of the study was the evaluation of the proposed analysis procedure, to put in evidence the major effects related to the presence of steady state flow forces affecting the spool equilibrium. Starting from an initial summary of the dimensional analysis proposed by the authors to approach the application of CFD to hydraulic components, the paper presents the results of three commonly used compensating profiles for two reference spool positions. In order to validate the simulation, the curves obtained for one of the three geometries are compared with the experimental data obtained on an equivalent port connection of a commercial distributor.

1999 - CFD as a Design Tool for Fluid Power Components [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; R., Paoluzzi
abstract

The paper collects some examples of CFD application to hydraulic components design, aimed at showing how a complex tool can be used both for the internal flow characterisation and the macroscopic analysis of component behaviour.In its first part, the paper deals with the steady-state characterisation of a commercial 4/3 on Zoff distributor, and focuses the attention on CFD strategies used in order to obtain an accurate description of steady-state axial flow-forces, acting on the spool of the component. The solution of simplified models (axis-symmetric) and the development of an extended and novel non-dimensionalization technique are the key to the use of a limited number of distributor configurations and a minimum number of operational conditions to obtain a full characterisation of the component.The second part of the paper is devoted to hydraulic locking analysis, where CFD is applied to tapered 3D geometry in order to validate the results of specific design assumptions and to verify the results obtained by a simplified, though two-dimensional, approach to radial forces estimation in spool valves. As a final example, the last part of the paper is dedicated to particle tracking analysis and collisioni erosion prediction, using a simplified approach based on the hypothesis of uncoupled motion of fluid and particles. In this last case, the CFD computed flow field, is used in arder to allow the solution of the lagrangian equations of motion for solid particles dragged by the fluid according to a given law. The aim of the examples collected is not the solution of the problems dealt with (to this purpose the reader is referred to the bibliography), but rather the identification of areas and methods where the application of a complex and expensive design toollike CFD analysis can reach the breakeven point of a convenient application in the design phase of a hydrauliccomponent.

1999 - Computational Fluid Dynamics in Solid Particles Effect Estimation in Hydraulic Poppet Valves [Relazione in Atti di Convegno]
R., Paoluzzi; Borghi, Massimo; Milani, Massimo
abstract

This paper deals with the analysis of the interaction between solid contamination and internai geometry in hydraulic conical and spherical poppet valves, performed through a non-dimensional, axis-symmetric CFD analysis of their internal flow. The information coming from the flow field solution is used to identify regions having higher probability to be impacted by particles dragged by the fluid, and to estimate the erosion potential of solid particles having different size.The value of the kinetic energy of particles approaching the walls of the geometric domain is used to estimate the amount of material potentially eroded by impacting particles, and to provide a potential correlation between ISO 4406 and NAS 1638 solid contamination level classification.The long-term target is a numerical estimation of service life in hydraulic components.

1999 - Erosion Estimation in a Pressure Relief Valve by Means of Particles Tracking Analysis [Relazione in Atti di Convegno]
Borghi, Massimo; R., Paoluzzi; Milani, Massimo
abstract

One of the effects of solid contaminant in hydraulic circuits is the erosion of internal parts. This is particularly important when the eroded parts are in the metering edge of valves, because this modifies the area function with unpredictable effects not only on efficiency, but also on functionality of the entire system.The aim of this paper is to investigate a possible alternative to long time-lasting and expensive experiments on erosion, using a lagrangian approach to particle tracking in a flow field whose variables are known. Two gaussian distributions of particles with mass are tracked for two metering edge openings, and are qualitatively compared with the results of an experimental investigation.The final part of the paper describes a first tentative approach to the use of data to estimate the amount of material eroded by impacting particles, presenting some details on flow velocity and angle in different sections of the valve related to data on the yeld characteristic of the impact. The last part is mainly qualitative, and only referable to massless particles. It is however a necessary preliminary step toward the solution of the complete problem, presently under development.

1999 - Le forze Radiali in Valvole a Cassetto [Articolo su rivista]
Borghi, Massimo; Cantore, Giuseppe; Milani, Massimo; R., Paoluzzi
abstract

A partire dal calcolo della spinta radiale agente sulle porzioni di cursore in ricoprimento, la memoria illustra le linee guida principali per un corretto dimensionamento e posizionamento delle scanalature circonferenziali di bilanciamento.

1999 - Pompe a Palette: Sperimentazione e Calcolo [Articolo su rivista]
Borghi, Massimo; Milani, Massimo; A., Valentini
abstract

L'articolo presenta i principali risultati ottenuti, con l'ausilio di modelli numerici a parametri concentrati, nell'ottimizzazione funzionale di macchine volumetriche operatrici a palette, sia a cilindrata fissa che variabile.

1999 - Pompe a Pistoni Assiali a Cilindrata Variabile: Verifica Sperimentale del Rendimento [Articolo su rivista]
Borghi, Massimo; Milani, Massimo; A., Valentini; M., Guidetti
abstract

La memoria illustra i principali risultati ottenuti durante la caratterizzazione sperimentale di macchine volumetriche operatrici a cilindrata variabile, del tipo a pistoni a piastra inclinata (swash plate), dotate di sistemi di regolazione della cilindrata idraulici ed elettro-idraulici.

1999 - Pompe a Pistoni Assiali a Cilindrata Variabile: il Rendimento Volumetrico [Articolo su rivista]
Borghi, Massimo; Milani, Massimo; A., Valentini
abstract

La memoria illustra le potenzialità applicative di strumenti di progettaione assistita da calcolatore a parametri concnetrati nel campo del dimensionamento e dell'ottimizzazione funzionale di pompe a pistoni assiali a piastra inclinata.

1999 - Stationary and Dynamic Analysis of a Water Relief Valve [Relazione in Atti di Convegno]
R., Paoluzzi; Borghi, Massimo; Milani, Massimo
abstract

The use of water as a working fluid in hydraulic circuits is being receiving an increasing attention by both manufacturers and users, due to its environmental characteristics. Although the use of water is neither new nor innovative (more than one hundred years ago it was widely used to transfer power, and many pump and valve manufacturers have commerciai product Iines for water hydraulics) its introduction in the product line of a manufacturers brings many problems to the attention of the designers, from technology adaptation to material compatibility, from erosion to cavitation.The purpose of this paper, based on a joint activity by Cemoter, University of Modena, Aron SpA and Cermet, is to show how the use of a combined approach to valve analysis can provide useful information to shorten the time to market of a valve using tap water as working fluido Starting from an initial reminder of the basic differences between mineraI oil and water in hydraulic circuits, the paper shows the results of some CFD computations on a relief valve, to evaluate the qualitative form of the pressure and velocity field, and to assess the influence of the increased turbulence on the field of motion.In the final part, the results of a comprehensive experimental characterization of the component are presented and considered in view of the indication provided by CFD analysis, both in term of steady state characteristic curves, and dynamic response.

1999 - Variable Displacement Axial Piston Pump Volumetric Efficiency Analysis [Relazione in Atti di Convegno]
Cantore, Giuseppe; Borghi, Massimo; Milani, Massimo
abstract

This paper describes a study of the volumetric efficiency of a variable displacement axial piston pump. A theoretical model, based on the continuity equation and properly combined with a simplified analytical treatment of leakage flows, is first presented and used to characterise the stationary behaviour of a 9 piston pump for different operating conditions and different configurations. In this study attention is focused on pump volumetric efficiency dependency on overall operational conditions as supply pressure, pump speed, leakage clearance heights, swash plate angle and port plate timing. Successively, a numerical vs. experimental comparison of steady-state pump characteristics is presented; this last part of the paper has been developed with the aim of showing the validity limits of the assumptions made to build up the numerical model. Results confirm the applicability of the simplified hypotheses introduced and validates the analysis of volumetric efficiency previously performed.

1998 - Analisi Teorico Sperimentale delle Prestazioni di Macchine e Componenti Oleoidraulici [Monografia/Trattato scientifico]
Milani, Massimo
abstract

Tesi per il conseguimento del Titolo di Dottore di Ricerca in Ingegneria dei Materiali

1998 - Analisi della Risposta Dinamica del Circuito di Comando degli Attuatori di un Escavatore [Relazione in Atti di Convegno]
Borghi, Massimo; Cantore, Giuseppe; Milani, Massimo; A., Valentini
abstract

Vengono presentati i risultati ottenuti dallo studio del comportamento dinamico del circuito idraulico di comando degli attuatori di un escavatore. Più nel dettaglio, utilizzando il codice commerciale AMESim è stato messo a punto un modello di simulazione numerica a parametri concentrati dei circuito idraulico di comando della benna posteriore di un escavatore, per studiare la risposta di uno degli attuatori lineari (il boom cylinder) nella condizione di carico trascinante. L'analisi della risposta dinamica dei sistema idraulico ha permesso di evidenziare come, nella particolare condizione operativa imposta, la discesa dei carico non risulti facilmente controllabile dall'operatore, e venga ad essere completata in un tempo particolarmente breve. L'inserimento di una valvola di bilanciamento (o di overcenter) di corrente produzione industriale, come componente di controllo e di sicurezza, tra il martinetto di comando della benna e il circuito idraulico, ha permesso di verificare come tale componente possa esercitare la sua funzione in presenza di un comando a pressione costante applicato al suo stadio di pilotaggio. Allo scopo è stato previsto l'utilizzo di un accumulatore a precarica sulla linea di pilotaggio della valvola di bilanciamento, in grado, inoltre, di assorbire le eventuali pulsazioni di pressione nella camera lato pistone del boom cylinder, indotte dall'elasticità della struttura meccanica. L'ultima parte del lavoro è dedicata alla scelta della pressione di precarica e dei volume dell'accumulatore, ai fini del raggiungimento della configurazione necessaria ad assicurare il completo controllo della fase di discesa dei carico.

1998 - Analysis of hydraulic components using computational fluid dynamics models [Articolo su rivista]
Borghi, Massimo; Cantore, Giuseppe; Milani, Massimo; R., Paoluzzi
abstract

This paper presents some results obtained during the computational fluid dynamics (CFD) analysis of internal flows inside a hydraulic component, using a scaling technique applied to numerical pre- and post-processing. The main aim of the work is to demonstrate the reduction of computational work needed for a complete analysis of component behaviour over a wide range of operating conditions. This result is achieved through the adoption of a methodology aimed at giving the highest level of generality to a non-dimensional solution, thereby overcoming the two major limitations encountered in the use of CFD in fluid power design: computer resources and time. In the case study, the technique was applied to a hydraulic distributor and computations were performed with a commercial computational fluid dynamics code. The key factor of this technique is the evaluation, for a given distributor opening, of the Reynolds number of the flow in the metering region. Provided that this number is high enough to ensure that the discharge coefficient has reached its asymptotic value, the characterization of the flow by a single non-dimensional numerical run can be shown. The theoretical contents of the analysis of the re-scaling technique, which focuses on the engineering information necessary in component design, are described in detail. The bases for its subsequent application to actual cases are then outlined. Finally, a fairly close correlation between numerical results and experimental data is presented.

1998 - Influenza della Particelle Solide nei Componenti Idraulici con Cicli di Lavoro Affaticanti [Articolo su rivista]
A., Gibertini; Milani, Massimo; A., Valentini
abstract

L'articolo illustra i principali risultati ottenuti durante la verifica sperimentale degli effetti di cicli di lavoro affaticanti sulle prestazioni stazionarie e dinamiche di valvole limitatrici di pressione, in presenza di forti concentrazioni di contaminazione solida.

1998 - NUMERICAL ANALYSIS OF THE LATERAL FORCES ACTING ON SPOOLS OF HYDRAULIC COMPONENTS [Relazione in Atti di Convegno]
Borghi, M.; Cantore, G.; Milani, M.; Paoluzzi, R.
abstract

This paper deals with the analysis of pressure distribution within the fluid film in the clearance between spool and sleeve of hydraulic components, in order to predict the value of the locking force induced by unbalanced pressure acting on tapered geometries. Particular care is devoted to the investigation of the lateral force dependency on clearance and eccentricity of the spool. Some theoretical results are presented, obtained solving (by the finite difference method) the two dimensional Reynolds equation for the fluid film. These results are then compared to those deriving from a generally adopted predictive formula. Results show remarkable differences, up to 70 %, in presence of high values of eccentricity. Moreover, an analogous Reynolds’ based solution is performed for a tapered geometry of the spool with one balancing groove, with particular attention to the influence of its length and position on resulting locking force and leakage flow. Also the locking force reducing effect of a balancing groove is characterized, and a saturated behavior when the groove is placed very close to the high pressure spool side has been found.

1998 - Numerical analysis of the lateral forces acting on spools of hydraulic components. [Relazione in Atti di Convegno]
Borghi, Massimo; Cantore, Giuseppe; Milani, Massimo; Paoluzzi, Roberto
abstract

This paper deals with the analysis of pressure distribution within the fluid film in the clearance between spool and sleeve of hydraulic components, in order to predict the value of the locking force induced by unbalanced pressure acting on tapered geometries. Particular care is devoted to the investigation of the lateral force dependency on clearance and eccentricity of the spool. Some theoretical results are presented, obtained solving (by the finite difference method) the two dimensional Reynolds equation for the fluid film. These results are then compared to those deriving from a generally adopted predictive formula. Results show remarkable differences, up to 70 %, in presence of high values of eccentricity. Moreover, an analogous Reynolds' based solution is performed for a tapered geometry of the spool with one balancing groove, with particular attention to the influence of its length and position on resulting locking force and leakage flow. Also the locking force reducing effect of a balancing groove is characterized, and a saturated behavior when the groove is placed very close to the high pressure spool side has been found.

1998 - Strumenti Numerici per Analisi e Verifica di Valvole Oleodinamiche ad Acqua [Articolo su rivista]
Milani, Massimo; R., Paoluzzi
abstract

La memoria illustra la metodologia utilizzata per applicare gli strumenti propri della fluidodinamica computazionale all'ottimizzazione funzionale di una valvola oleoidraulica funzionante ad acqua industriale.

1998 - TRANSIENT FLOW FORCE ESTIMATION ON THE PILOT STAGE OF A HYDRAULIC VALVE [Relazione in Atti di Convegno]
Borghi, M.; Milani, M.; Paoluzzi, R.
abstract

The effect of flow forces on the spool equilibrium of hydraulic components is well known, and a number of methods have been developed in order to estimate their effect. They span from analytical expression, to experimental evaluation, to CFD analysis. This last approach is usually considered too demanding to the purpose of hydraulic component design, however a careful approach to the problem statement can lead to the collection of a complete set of data, starting from a limited number of numerical runs. A further extension to transient flow is made possible by the acceptance of further approximations on the effect of fluid compressibility, leading to a computational technique able to extend the amount of information extracted from a single model.

1998 - Transient flow force estimation on the pilot stage of a hydraulic valve. [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; Paoluzzi, Roberto
abstract

The effect of flow forces on the spool equilibrium of hydraulic components is well known, and a number of methods have been developed in order to estimate their effect. They span from analytical expression, to experimental evaluation, to CFD analysis. This last approach is usually considered too demanding to the purpose of hydraulic component design, however a careful approach to the problem statement can lead to the collection of a complete set of data, starting from a limited number of numerical runs. A further extension to transient flow is made possible by the acceptance of further approximations on the effect of fluid compressibility, leading to a computational technique able to extend the amount of information extracted from a single model.

1997 - Bilanciamento delle Macchine Oleodinamiche ad Ingranaggi Esterni [Relazione in Atti di Convegno]
Cantore, Giuseppe; Borghi, Massimo; Milani, Massimo
abstract

n.d.

1997 - Distribuzione della pressione nei vani di una pompa a palette [Relazione in Atti di Convegno]
Borghi, Massimo; Cantore, Giuseppe; Milani, Massimo
abstract

In questo lavoro sono presentati e discussi i risultati ottenuti da una serie di rilievi sperimentali volti alla misura della pressione nei vani di una pompa a palette di produzione industriale.Le prove, effettuate in diverse condizioni di funzionamento della macchina, evidenziano alcune singolarita' originate probabilmente dal recupero dei giochi da parte delle palette; tali fenomeni si manifestano in prossimita' delle zone di commutazione, laddove la pressione inizia ad aumentare o a diminuire.Vengono inoltre presentati i risultati di un modello di calcolo semplificato, basato sull'applicazione dell'equazione di continuita' ai vani della macchina.Il confronto fra i risultati forniti dal calcolo e quelli sperimentali si mostra incoraggiante nelle sue linee generali, nonostante la semplicita' del modello. Vengono fornite indicazioni per l'ulteriore miglioramento della modellizzazione.

1997 - Experimental and Numerical Analysis of Forces on a Hydraulic Distributor [Relazione in Atti di Convegno]
Borghi, Massimo; Cantore, Giuseppe; Milani, Massimo; R., Paoluzzi
abstract

The paper relates about experiments and Computational Fluid Dynamics (CFD) analysis on forces acting on a commerci al 4/3 distributor. Experimental results are reported, together with a detailed discussion to asses their reliability. The same results are then used to drive the approach to numerical simulation, in order to minimise the number of runs needed to gather the required informations in term of pressure drop and spool forces.A description of the benefits achievable with an extensive use of dimensional analysis is presented, showing how, within the validity limits of the same set of equations (turbulent or laminar), non-dimensional results of a numerical computation can be consistently extended to various flow conditions. Some final considerations are then reserved to a few indications useful for valve geometry improvement; furthermore a discussion is reported about some controversial numerical and experimental results.

1997 - Pressure balancing in external gear pumps and motors [Articolo su rivista]
Cantore, G.; Milani, M.; Borghi, M.
abstract

The paper relates on a numerical method for designing balancing bearing block areas for external gear pumps and motors. At first, a way is presented for obtaining pressure distribution inside spaces between teeth, bearing blocks and casing; the procedure, based on integration of the continuity equation for sealed spaces, permits also the evaluation of some interesting aspects dealing with the influence of rotational speed, dynamic viscosity and gears eccentricity. Then, a method is presented for calculating pressure distribution in the layer bounded by gears sides and bearing blocks. The method, starting from pressure distribution in spaces, is based on the integration of the laspace equation over the whole layer. Axial thrust on bearing blocks and its point of application are then calculated. Finally, the same problem is analysed with a simplified numerical approach, as well based on the integration of the laplace equation, but on the small portion of the layer corresponding to one tooth, with only one boundary condition. At the end, calculations are made for a commercial pump, obtaining balancing aeras very close to the ones designed by the manufacturer.

1997 - Pressure balancing in external gear pumps and motors[Bilanciamento delle macchine oleodinamiche a ingranaggi esterni] [Articolo su rivista]
Cantore, Giuseppe; Milani, Massimo; Borghi, Massimo
abstract

The paper relates on a numerical method for designing balancing bearing block areas for external gear pumps and motors. At first, a way is presented for obtaining pressure distribution inside spaces between teeth, bearing blocks and casing; the procedure, based on integration of the continuity equation for sealed spaces, permits also the evaluation of some interesting aspects dealing with the influence of rotational speed, dynamic viscosity and gears eccentricity. Then, a method is presented for calculating pressure distribution in the layer bounded by gears sides and bearing blocks. The method, starting from pressure distribution in spaces, is based on the integration of the laspace equation over the whole layer. Axial thrust on bearing blocks and its point of application are then calculated. Finally, the same problem is analysed with a simplified numerical approach, as well based on the integration of the laplace equation, but on the small portion of the layer corresponding to one tooth, with only one boundary condition. At the end, calculations are made for a commercial pump, obtaining balancing aeras very close to the ones designed by the manufacturer.

1997 - Sperimentazione con Fluidodinamica Computazionale di un Distributore Oleodinamico [Articolo su rivista]
Borghi, Massimo; Cantore, Giuseppe; Milani, Massimo; R., Paoluzzi
abstract

La memoria si occupa della riprogettazione di un distributore oleodinamico di tipo on-off mediante l'utilizzo di strumenti di progettazione assistita da calcolatore, sottolineando quali aspetti progettuali debbano essere considerati per ridurre l'effetto delle forze di flusso assiali.

1996 - Fluido contaminato? No grazie! [Articolo su rivista]
Cantore, Giuseppe; Borghi, Massimo; Milani, Massimo; M., Bianchi
abstract

n.d.

1996 - Sul calcolo della spinta sulle fiancate nelle macchine oleodinamiche ad ingranaggi esterni [Relazione in Atti di Convegno]
Borghi, Massimo; Milani, Massimo; G., Toderi
abstract

In un precedente lavoro è stato presentato un metodo approssimato ·per il calcolo delle pressioni sulle fiancate delle ruote dentate di macchine oleodinamìche ad- ingranaggi esterni, calcolo effettuato sulla base delle pressioni agenti nei vani compresi fra i denti. I risultati allora ottenuti integrando l'equazione di Laplace nella porzione di meato delimitato dai piani di mezzeria di due vani adiacenti, vengono ora confrontati con quelli ottenuti dall'integrazione della stessa equazione di Laplace sull'intero meato posto tra la fiancata e la ruota dentata.Quest'ultimo calcolo, a fronte di una minor semplicità, consente di prescindere da qualunque ipotesi sull'andamento della pressione tra il fondo dei vani e la camera di drenaggio; inoltre esso fornisce direttamente i risultati anche per il dente sul quale si ha ilcontatto di ingranamento cui è affidata la tenuta tra gli ambienti di alta e di bassa pressione. TI confronto, effettuato per una famiglia di pompe geometricamente simili, porta ad affermare che, per la maggior parte dei denti, i risultati ottenuti con il procedimento messo a punto in questo lavoro sono in pieno accordo con quelli ottenuti sulla base del procedimento approssimato, le cui ipotesi di base risultano così ben verificate.Vengono poi calcolati, per la famiglia di macchine considerata, la spinta complessiva sulle fiancate ed il relativo punto di applicazione in diverse posizioni angolari delle ruote.