Vincenzo De Bellis - Academia.edu (original) (raw)

Papers by Vincenzo De Bellis

Research paper thumbnail of Assessment of an Adaptive Efficient Thermal/Electric Skipping Control Strategy for the Management of a Parallel Plug-In Hybrid Electric Vehicle

Social Science Research Network, 2022

Research paper thumbnail of Advanced Turbulence Model for SI Combustion in a Heavy-Duty NG Engine

SAE Technical Paper Series

Research paper thumbnail of Experimental and 0D Numerical Investigation of Ultra-Lean Combustion Concept to Improve the Efficiency of SI Engine

SAE Technical Paper Series, 2021

R ecently, the car manufacturers are moving towards innovative Spark Ignition (SI) engine archite... more R ecently, the car manufacturers are moving towards innovative Spark Ignition (SI) engine architectures with unconventional combustion concepts, aiming to comply with the stringent regulation imposed by EU and other legislators. The introduction of burdensome cycles for vehicle homologation, indeed, requires an engine characterized by a high efficiency in the most of its operating conditions, for which a conventional SI engine results to be ineffective. Combustion systems which work with very lean air/fuel mixture have demonstrated to be a promising solution to this concern. Higher specific heat ratio, minor heat losses and increased knock resistance indeed allow improving fuel consumption. Additionally, the lower combustion temperatures enable to reduce NO X production. Since conventional SI engines can work with a limited amount of excess air, alternative solutions are being developed to overcome this constraint and reach the above benefit. Among all these solutions, replacing the spark-plug with a Pre-Chamber (PC) ignition system is gaining increasing interest. For this architecture, the combustion process starts in the PC and propagates in the main-chamber in the form of multiple turbulent jets of hot gas, with high-turbulence level. This ensures stable flame propagation even under extremely lean mixtures. In this research activity, an ultra-lean PC SI engine is numerically and experimentally investigated to assess the potential improvement of the thermal efficiency for ultra-lean operations. To this aim, a research single cylinder engine, fuelled with gasoline, is tested at fixed load and speed, realizing an air / fuel ratio sweep. A 1D/0D model of the examined engine is implemented in a commercial modelling framework (GT-Power™), where "in-house developed" sub-models are embedded, simulating in-cylinder phenomena, such as combustion, turbulence, heat transfer and pollutant emissions. The numerical approach, preliminarily tuned against 3D simulations and experimental outcomes, demonstrated to accurately reproduce the engine behaviour, without requiring any case-dependent tuning of the model constants. Both numerical and experimental results proved that working in ultra-lean condition allows to significantly improve the indicated thermal efficiency, abating the NOx emissions, while penalizing the HC production.

Research paper thumbnail of Potential of hydrogen addition to natural gas or ammonia as a solution towards low- or zero-carbon fuel for the supply of a small turbocharged SI engine

E3S Web of Conferences, 2021

Nowadays there is an increasing interest in carbon-free fuels such as ammonia and hydrogen. Those... more Nowadays there is an increasing interest in carbon-free fuels such as ammonia and hydrogen. Those fuels, on one hand, allow to drastically reduce CO2 emissions, helping to comply with the increasingly stringent emission regulations, and, on the other hand, could lead to possible advantages in performances if blended with conventional fuels. In this regard, this work focuses on the 1D numerical study of an internal combustion engine supplied with different fuels: pure gasoline, and blends of methane-hydrogen and ammonia-hydrogen. The analyses are carried out with reference to a downsized turbocharged two-cylinder engine working in an operating point representative of engine operations along WLTC, namely 1800 rpm and 9.4 bar of BMEP. To evaluate the potential of methane-hydrogen and ammonia-hydrogen blends, a parametric study is performed. The varied parameters are air/fuel proportions (from 1 up to 2) and the hydrogen fraction over the total fuel. Hydrogen volume percentages up to 60...

Research paper thumbnail of Fuel Consumption and Pollutant Emission Optimization at Part and Full Load of a High-Performance V12 SI Engine by a 1D Model

SAE Technical Paper Series, 2019

Research paper thumbnail of Impact of intake valve strategies on fuel consumption and knock tendency of a spark ignition engine

Applied Energy, 2018

Experimental and numerical analyses of a turbocharged VVA SI engine. • 3D in-cylinder turbulence ... more Experimental and numerical analyses of a turbocharged VVA SI engine. • 3D in-cylinder turbulence analyses for various valve strategies and engine speeds. • Validation of a 1D engine model, including sub-models of in-cylinder processes. • Effect of EIVC and LIVC strategies on fuel consumption in two operating points. • A methodology capable to support the virtual calibration of a VVA engine.

Research paper thumbnail of Combined Effects of Valve Strategies, Compression Ratio, Water Injection, and Cooled EGR on the Fuel Consumption of a Small Turbocharged VVA Spark-Ignition Engine

SAE International Journal of Engines, 2018

Research paper thumbnail of Extension and Validation of a 1D Model Applied to the Analysis of a Water Injected Turbocharged Spark Ignited Engine at High Loads and over a WLTP Driving Cycle

SAE International Journal of Engines, 2017

Research paper thumbnail of Experimental and Numerical Study of the Water Injection to Improve the Fuel Economy of a Small Size Turbocharged SI Engine

SAE International Journal of Engines, 2017

Research paper thumbnail of Validation of a 1D Compressor Model for Performance Prediction

SAE International Journal of Engines, 2013

ABSTRACT Export Date: 17 November 2013, Source: Scopus, doi: 10.4271/2013-24-0120, Language of Or... more ABSTRACT Export Date: 17 November 2013, Source: Scopus, doi: 10.4271/2013-24-0120, Language of Original Document: English, Correspondence Address: Universitá di NapoliItaly, References: Winkler, N., Ingström, H., Simulations and Measurements of a Two-Stage Turbocharged Heavy-Duty Diesel Engine Including EGR in Transient Operation (2008) SAE Technical Paper 2008-01-0539, , doi:10.4271/2008-01-0539;

Research paper thumbnail of Hierarchical 1D/3D approach for the development of a turbulent combustion model applied to a VVA turbocharged engine. Part I: Turbulence model

Energy Procedia, 2014

It is widely recognized that air-fuel mixing, combustion and pollutant formation inside internal ... more It is widely recognized that air-fuel mixing, combustion and pollutant formation inside internal combustion engines are strongly influenced by the spatial and temporal evolution of both marco-and micro-turbulent scales. Particularly, in spark ignited engines, the generation of a proper level of turbulence intensity for the correct development of the flame front is traditionally based on the onset, during the intake and compression strokes, of a tumbling macro-structure. Recently, in order to both reduce pumping losses due to throttling and develop advanced and flexible engine control strategies, fully variable valve actuation systems have been introduced, capable of simultaneously governing both valve phasing and lift. Despite the relevant advantages in terms of intake system efficiency, this technology introduces uncertainties on the capability of the intake port/valve assembly to generate, at low loads, sufficiently coherent and stable structures, able therefore to promote adequate turbulence levels towards the end of the compression, with relevant effects on the flame front development. It is a common knowledge that 3D-CFD codes are able to describe the evolution of the in-cylinder flow field and of the subsequent combustion process with good accuracy; however, they require too high computational time to analyze the engine performance for the whole operating domain. On the contrary, this task is easily accomplished by 1D codes, where, however, the combustion process is usually derived from experimental measurements of the in-cylinder pressure trace (Wiebe correlation). This approach is poorly predictive for the simulation of operating conditions relevantly different from the experimental ones. To overcome the above described issues, enhanced physical models for the description of in-cylinder turbulence evolution and combustion to be included in a 1D modeling environment are mandatory. In the present paper (part I), a 0D (i.e. homogeneous and isotropic) phenomenological (i.e. sensitive to the variation of operative parameters such as valve phasing, valve lift, intake and exhaust pressure levels, etc.) turbulence model belonging to the K-k model family is presented in detail. The model is validated against in-cylinder results provided by 3D-CFD analyses carried out

Research paper thumbnail of 1D Simulation and Experimental Analysis of a Turbocharger Compressor for Automotive Engines under Unsteady Flow Conditions

SAE International Journal of Engines, 2011

Turbocharging technique will play a fundamental role in the near future not only to improve autom... more Turbocharging technique will play a fundamental role in the near future not only to improve automotive engine performance, but also to reduce fuel consumption and exhaust emissions both in Spark Ignition and diesel automotive applications. To achieve excellent engine performance for road application, it is necessary to overcome some typical turbocharging drawbacks i.e., low end torque level and transient response. Experimental studies, developed on dedicated test facilities, can supply a lot of information to optimize the engine-turbocharger matching, especially if tests can be extended to the typical engine operating conditions (unsteady flow). Different numerical procedures have been developed at the University of Naples to predict automotive turbocharger compressor performance both under steady and unsteady flow conditions. A classical 1D approach, based on the employment of compressor characteristic maps, was firstly followed. A different and more refined procedure has been recently proposed. The new approach is based on the solution of the 1D unsteady flow within the stationary and rotating channels constituting the compressor device, starting from a reduced set of geometrical data. The refined methodology can be utilized to directly compute the stationary map of the compressor but also to reproduce the unsteady flow behavior of the device. A specialized components test rig (particularly suited to study automotive turbochargers) has been operating since several years at the University of Genoa. The test facility also allows to develop studies under unsteady flow conditions both on single components and subassemblies of engine intake and exhaust circuit. In the paper the results of a preliminary experimental study developed on a turbocharger compressor for gasoline engine application under unsteady flow conditions are presented. Instantaneous inlet and outlet static pressure and mass flow rate are compared with the corresponding numerical data supplied by simulation codes. The numerical results showed a good agreement with experimental data. In addition, the comparison between the classical and the refined procedure results highlighted the potential of the performed unsteady 1D calculation, especially in specific compressor operating conditions. The integration of the experimental activity with the numerical analysis represents a methodology that can be helpfully employed during the design process of internal combustion engine intake systems.

Research paper thumbnail of Fuel Consumption Optimization and Noise Reduction in a Spark-Ignition Turbocharged VVA Engine

SAE International Journal of Engines, 2013

ABSTRACT Cited By (since 1996):3, Export Date: 17 November 2013, Source: Scopus, Language of Orig... more ABSTRACT Cited By (since 1996):3, Export Date: 17 November 2013, Source: Scopus, Language of Original Document: English, Correspondence Address: de Bellis, V.; DII- DiME Section, Università di Napoli 'Federico II', Via Claudio 21, 80125 Napoli, Italy; email: vincenzo.debellis@unina.it, References: Moriya, Y., Watanabe, A., Uda, H., Kawamura, H., A Newly Developed Intelligent Variable Valve Timing System-Continuously Controlled Cam Phasing as Applied to a New 3 Liter Inline 6 Engine (1996) SAE Technical Paper 960579, , doi: 10.4271/960579;

Research paper thumbnail of Analysis and Design of an Intake Filter Box for a Downsized VVA Engine

SAE Technical Paper Series, 2014

ABSTRACT The present paper reports 1D and 3D CFD analyses of the air-filter box of a turbocharged... more ABSTRACT The present paper reports 1D and 3D CFD analyses of the air-filter box of a turbocharged VVA engine, aiming to predict and improve the gas-dynamic noise emissions through a partial re-design of the device. First of all, the gas-dynamic noise at the intake mouth is measured during a dedicated experimental campaign. The developed 1D and 3D models are then validated at full load operation, based on experimental data. In particular, 1D model provides a preliminary evaluation of the radiated noise and simultaneously gives reliable boundary conditions for the unsteady 3D CFD simulations. The latter indeed allow to better take into account the geometrical details of the air-filter and guarantee a more accurate gas-dynamic noise prediction. 3D CFD analyses put in evidence that sound emission mainly occur within a frequency range of 350 to 450 Hz. Starting from the above result, the original air-box design is modified through the installation of a single Helmholtz resonator, taking into account layout constraints and the influence on engine performance, as well. First, the isolated air-box is studied through a 3D FEM approach to compute the Transmission Loss (TL) parameter both for the original and the modified design. This analysis is employed to verify the noise abatement in the frequency range of interest, for a zero-mean flow. Then, the new intake system configuration is investigated under actual engine operation, through unsteady 3D CFD simulations. The resulting reduction in the gas-dynamic noise is verified both in terms of overall radiated SPL and frequency spectrum at full and part load operating conditions, as well. The proposed integrated 1D-3D approach demonstrated to be a useful tool for the design and the analysis of new geometrical intake system configurations, aiming to improve the engine acoustic performance without significant penalties on the delivered power and fuel consumption.

Research paper thumbnail of A Comparison Between External and Internal Resonators Employment to Reduce the Gas-Dynamic Noise of a SI Engine

SAE International Journal of Engines, 2014

ABSTRACT This paper reports 1D and 3D CFD analyses aiming to improve the gas-dynamic noise emissi... more ABSTRACT This paper reports 1D and 3D CFD analyses aiming to improve the gas-dynamic noise emission of a downsized turbocharged VVA engine through the re-design of the intake air-box device, consisting in the introduction of external or internal resonators. Nowadays, modern spark-ignition (SI) engines show more and more complex architectures that, while improving the brake specific fuel consumption (BSFC), may be responsible for the increased noise radiation at the engine intake mouth. In particular VVA systems allow for the actuation of advanced valve strategies that provide a reduction in the BSFC at part load operations thanks to the intake line de-throttling. In these conditions, due to a less effective attenuation of the pressure waves that travel along the intake system, VVA engines produce higher gas-dynamic noise levels. The worsening of the engine gas-dynamic performance can be compensated with a partial re-design of the air-box device, without significantly penalizing the engine power output. In order to find new design configurations of the air-box device capable of improving the noise levels, different numerical models can be successfully employed. In the present work, a detailed 1D engine model is firstly developed and validated against the experimental data at full load operations. 1D model is realized within GT-Power™ software and it utilizes proper user routines for the modeling of the turbulence and combustion process and for the handling of different intake valve strategies. The 1D engine model also includes a refined user model of the turbocharger able to better describe the acoustic behavior of the device. The engine model allows for the prediction of the main overall engine performances and the gas-dynamic noise with good accuracy. It also provides a first estimation of the gas-dynamic noise and gives reliable boundary conditions for the subsequent unsteady 3D CFD analyses, allowing to obtain a more accurate noise prediction. A proper Helmholtz resonator is designed and virtually installed along the inlet pipe of the air-box device. An additional geometrical configuration of the air-filter box, that includes an internal resonator, obtained through the insertion of inner walls, is considered, too. The effectiveness of the redesigned air-box configurations, are firstly tested in terms of Transmission Loss characteristics, and in terms of gasdynamic noise abatement, as well.

Research paper thumbnail of A Multi-Zone Combustion Model Integrated with a Fast Tabulated Chemical Kinetics Applied for the Simulation of HCCI Engines Supplied with Hydrogen or Carbon-Based Fuels

SAE Technical Paper Series

Research paper thumbnail of A phenomenological model for the description of unburned hydrocarbons emission in ultra-lean engines

International Journal of Engine Research

The adoption of lean-burn concepts for internal combustion engines working with a homogenous air/... more The adoption of lean-burn concepts for internal combustion engines working with a homogenous air/fuel charge is under development as a path to simultaneously improve thermal efficiency, fuel consumption, nitric oxides, and carbon monoxide emissions. This technology may lead to a relevant emission of unburned hydrocarbons (uHC) compared to a stoichiometric engine. The uHC sources are various and the relative importance varies according to fuel characteristics, engine operating point, and some geometrical details of the combustion chamber. This concern becomes even more relevant in the case of engines supplied with natural gas since the methane has a global warming potential much greater than the other major pollutant emissions. In this work, a simulation model describing the main mechanisms for uHC formation is proposed. The model describes uHC production from crevices and flame wall quenching, also considering the post-oxidation. The uHC model is implemented in commercial software (...

Research paper thumbnail of Development of an Efficient Thermal Electric Skipping Strategy for the Management of a Series/Parallel Hybrid Powertrain

Energies

In recent years, the development of hybrid powertrain allowed to substantially reduce the CO2 and... more In recent years, the development of hybrid powertrain allowed to substantially reduce the CO2 and pollutant emissions of vehicles. The optimal management of such power units represents a challenging task since more degrees of freedom are available compared to a conventional pure-thermal engine powertrain. The a priori knowledge of the driving mission allows identifying the actual optimal control strategy at the expense of a quite relevant computational effort. This is realized by the off-line optimization strategies, such as Pontryagin minimum principle—PMP—or dynamic programming. On the other hand, for an on-vehicle application, the driving mission is unknown, and a certain performance degradation must be expected, depending on the degree of simplification and the computational burden of the adopted control strategy. This work is focused on the development of a simplified control strategy, labeled as efficient thermal electric skipping strategy—ETESS, which presents performance sim...

Research paper thumbnail of One-dimensional simulations and experimental analysis of a wastegated turbine for automotive engines under unsteady flow conditions

Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering

In this paper, the unsteady-state behaviour of a turbocharger wastegated turbine (IHI-RHF3) is in... more In this paper, the unsteady-state behaviour of a turbocharger wastegated turbine (IHI-RHF3) is investigated using both an experimental approach and a numerical approach. First, an experimental campaign is performed in a specialized test rig operating at the University of Genoa, for different openings of the wastegate valve and under steady flow and unsteady flow operations. An appropriate configuration of the turbine outlet circuit fitted with a separating wall is used to carry out instantaneous measurements downstream of the turbine wheel and the wastegate valve. The above data constitute the basis for the tuning and validation of a one-dimensional turbine model recently developed at the University of Naples. Preliminary model tuning is carried out on the basis of the characteristic map measured for a completely closed wastegate valve under steady flow operations. A refined one-dimensional schematization of the experimental apparatus is implemented within the commercial GT-Power® s...

Research paper thumbnail of CFD 3D Analysis of Charge Motion and Combustion in a Spark-Ignition Internal Combustion Engine under Close-to-Idle Condition

E3S Web of Conferences

The increasingly stringent limitations on noxious missions of transport sector highly affect the ... more The increasingly stringent limitations on noxious missions of transport sector highly affect the development of new engines. The operating conditions of the engine at low-load and idle play a relevant role along the regulatory homologation cycles, contributing to overall emissions. In this work, the effectiveness of some solutions to improve the behaviour under close-to-idle operation of a Spark-Ignition motorcycle engine are compared by 3D CFD analyses. Specifically, the effects of two designs of the intake port and of the opening direction of the throttle valve, either clockwise or counterclockwise, are investigated. Multi-cycle simulations are carried out, under motored and fired conditions, for a single close-to-idle operating point. The various designs are compared in terms of capability to generate a stable tumble vortex during the intake phase and to produce an adequate turbulence level at the beginning of the combustion process. The analyses revealed that a clockwise throttl...

Research paper thumbnail of Assessment of an Adaptive Efficient Thermal/Electric Skipping Control Strategy for the Management of a Parallel Plug-In Hybrid Electric Vehicle

Social Science Research Network, 2022

Research paper thumbnail of Advanced Turbulence Model for SI Combustion in a Heavy-Duty NG Engine

SAE Technical Paper Series

Research paper thumbnail of Experimental and 0D Numerical Investigation of Ultra-Lean Combustion Concept to Improve the Efficiency of SI Engine

SAE Technical Paper Series, 2021

R ecently, the car manufacturers are moving towards innovative Spark Ignition (SI) engine archite... more R ecently, the car manufacturers are moving towards innovative Spark Ignition (SI) engine architectures with unconventional combustion concepts, aiming to comply with the stringent regulation imposed by EU and other legislators. The introduction of burdensome cycles for vehicle homologation, indeed, requires an engine characterized by a high efficiency in the most of its operating conditions, for which a conventional SI engine results to be ineffective. Combustion systems which work with very lean air/fuel mixture have demonstrated to be a promising solution to this concern. Higher specific heat ratio, minor heat losses and increased knock resistance indeed allow improving fuel consumption. Additionally, the lower combustion temperatures enable to reduce NO X production. Since conventional SI engines can work with a limited amount of excess air, alternative solutions are being developed to overcome this constraint and reach the above benefit. Among all these solutions, replacing the spark-plug with a Pre-Chamber (PC) ignition system is gaining increasing interest. For this architecture, the combustion process starts in the PC and propagates in the main-chamber in the form of multiple turbulent jets of hot gas, with high-turbulence level. This ensures stable flame propagation even under extremely lean mixtures. In this research activity, an ultra-lean PC SI engine is numerically and experimentally investigated to assess the potential improvement of the thermal efficiency for ultra-lean operations. To this aim, a research single cylinder engine, fuelled with gasoline, is tested at fixed load and speed, realizing an air / fuel ratio sweep. A 1D/0D model of the examined engine is implemented in a commercial modelling framework (GT-Power™), where "in-house developed" sub-models are embedded, simulating in-cylinder phenomena, such as combustion, turbulence, heat transfer and pollutant emissions. The numerical approach, preliminarily tuned against 3D simulations and experimental outcomes, demonstrated to accurately reproduce the engine behaviour, without requiring any case-dependent tuning of the model constants. Both numerical and experimental results proved that working in ultra-lean condition allows to significantly improve the indicated thermal efficiency, abating the NOx emissions, while penalizing the HC production.

Research paper thumbnail of Potential of hydrogen addition to natural gas or ammonia as a solution towards low- or zero-carbon fuel for the supply of a small turbocharged SI engine

E3S Web of Conferences, 2021

Nowadays there is an increasing interest in carbon-free fuels such as ammonia and hydrogen. Those... more Nowadays there is an increasing interest in carbon-free fuels such as ammonia and hydrogen. Those fuels, on one hand, allow to drastically reduce CO2 emissions, helping to comply with the increasingly stringent emission regulations, and, on the other hand, could lead to possible advantages in performances if blended with conventional fuels. In this regard, this work focuses on the 1D numerical study of an internal combustion engine supplied with different fuels: pure gasoline, and blends of methane-hydrogen and ammonia-hydrogen. The analyses are carried out with reference to a downsized turbocharged two-cylinder engine working in an operating point representative of engine operations along WLTC, namely 1800 rpm and 9.4 bar of BMEP. To evaluate the potential of methane-hydrogen and ammonia-hydrogen blends, a parametric study is performed. The varied parameters are air/fuel proportions (from 1 up to 2) and the hydrogen fraction over the total fuel. Hydrogen volume percentages up to 60...

Research paper thumbnail of Fuel Consumption and Pollutant Emission Optimization at Part and Full Load of a High-Performance V12 SI Engine by a 1D Model

SAE Technical Paper Series, 2019

Research paper thumbnail of Impact of intake valve strategies on fuel consumption and knock tendency of a spark ignition engine

Applied Energy, 2018

Experimental and numerical analyses of a turbocharged VVA SI engine. • 3D in-cylinder turbulence ... more Experimental and numerical analyses of a turbocharged VVA SI engine. • 3D in-cylinder turbulence analyses for various valve strategies and engine speeds. • Validation of a 1D engine model, including sub-models of in-cylinder processes. • Effect of EIVC and LIVC strategies on fuel consumption in two operating points. • A methodology capable to support the virtual calibration of a VVA engine.

Research paper thumbnail of Combined Effects of Valve Strategies, Compression Ratio, Water Injection, and Cooled EGR on the Fuel Consumption of a Small Turbocharged VVA Spark-Ignition Engine

SAE International Journal of Engines, 2018

Research paper thumbnail of Extension and Validation of a 1D Model Applied to the Analysis of a Water Injected Turbocharged Spark Ignited Engine at High Loads and over a WLTP Driving Cycle

SAE International Journal of Engines, 2017

Research paper thumbnail of Experimental and Numerical Study of the Water Injection to Improve the Fuel Economy of a Small Size Turbocharged SI Engine

SAE International Journal of Engines, 2017

Research paper thumbnail of Validation of a 1D Compressor Model for Performance Prediction

SAE International Journal of Engines, 2013

ABSTRACT Export Date: 17 November 2013, Source: Scopus, doi: 10.4271/2013-24-0120, Language of Or... more ABSTRACT Export Date: 17 November 2013, Source: Scopus, doi: 10.4271/2013-24-0120, Language of Original Document: English, Correspondence Address: Universitá di NapoliItaly, References: Winkler, N., Ingström, H., Simulations and Measurements of a Two-Stage Turbocharged Heavy-Duty Diesel Engine Including EGR in Transient Operation (2008) SAE Technical Paper 2008-01-0539, , doi:10.4271/2008-01-0539;

Research paper thumbnail of Hierarchical 1D/3D approach for the development of a turbulent combustion model applied to a VVA turbocharged engine. Part I: Turbulence model

Energy Procedia, 2014

It is widely recognized that air-fuel mixing, combustion and pollutant formation inside internal ... more It is widely recognized that air-fuel mixing, combustion and pollutant formation inside internal combustion engines are strongly influenced by the spatial and temporal evolution of both marco-and micro-turbulent scales. Particularly, in spark ignited engines, the generation of a proper level of turbulence intensity for the correct development of the flame front is traditionally based on the onset, during the intake and compression strokes, of a tumbling macro-structure. Recently, in order to both reduce pumping losses due to throttling and develop advanced and flexible engine control strategies, fully variable valve actuation systems have been introduced, capable of simultaneously governing both valve phasing and lift. Despite the relevant advantages in terms of intake system efficiency, this technology introduces uncertainties on the capability of the intake port/valve assembly to generate, at low loads, sufficiently coherent and stable structures, able therefore to promote adequate turbulence levels towards the end of the compression, with relevant effects on the flame front development. It is a common knowledge that 3D-CFD codes are able to describe the evolution of the in-cylinder flow field and of the subsequent combustion process with good accuracy; however, they require too high computational time to analyze the engine performance for the whole operating domain. On the contrary, this task is easily accomplished by 1D codes, where, however, the combustion process is usually derived from experimental measurements of the in-cylinder pressure trace (Wiebe correlation). This approach is poorly predictive for the simulation of operating conditions relevantly different from the experimental ones. To overcome the above described issues, enhanced physical models for the description of in-cylinder turbulence evolution and combustion to be included in a 1D modeling environment are mandatory. In the present paper (part I), a 0D (i.e. homogeneous and isotropic) phenomenological (i.e. sensitive to the variation of operative parameters such as valve phasing, valve lift, intake and exhaust pressure levels, etc.) turbulence model belonging to the K-k model family is presented in detail. The model is validated against in-cylinder results provided by 3D-CFD analyses carried out

Research paper thumbnail of 1D Simulation and Experimental Analysis of a Turbocharger Compressor for Automotive Engines under Unsteady Flow Conditions

SAE International Journal of Engines, 2011

Turbocharging technique will play a fundamental role in the near future not only to improve autom... more Turbocharging technique will play a fundamental role in the near future not only to improve automotive engine performance, but also to reduce fuel consumption and exhaust emissions both in Spark Ignition and diesel automotive applications. To achieve excellent engine performance for road application, it is necessary to overcome some typical turbocharging drawbacks i.e., low end torque level and transient response. Experimental studies, developed on dedicated test facilities, can supply a lot of information to optimize the engine-turbocharger matching, especially if tests can be extended to the typical engine operating conditions (unsteady flow). Different numerical procedures have been developed at the University of Naples to predict automotive turbocharger compressor performance both under steady and unsteady flow conditions. A classical 1D approach, based on the employment of compressor characteristic maps, was firstly followed. A different and more refined procedure has been recently proposed. The new approach is based on the solution of the 1D unsteady flow within the stationary and rotating channels constituting the compressor device, starting from a reduced set of geometrical data. The refined methodology can be utilized to directly compute the stationary map of the compressor but also to reproduce the unsteady flow behavior of the device. A specialized components test rig (particularly suited to study automotive turbochargers) has been operating since several years at the University of Genoa. The test facility also allows to develop studies under unsteady flow conditions both on single components and subassemblies of engine intake and exhaust circuit. In the paper the results of a preliminary experimental study developed on a turbocharger compressor for gasoline engine application under unsteady flow conditions are presented. Instantaneous inlet and outlet static pressure and mass flow rate are compared with the corresponding numerical data supplied by simulation codes. The numerical results showed a good agreement with experimental data. In addition, the comparison between the classical and the refined procedure results highlighted the potential of the performed unsteady 1D calculation, especially in specific compressor operating conditions. The integration of the experimental activity with the numerical analysis represents a methodology that can be helpfully employed during the design process of internal combustion engine intake systems.

Research paper thumbnail of Fuel Consumption Optimization and Noise Reduction in a Spark-Ignition Turbocharged VVA Engine

SAE International Journal of Engines, 2013

ABSTRACT Cited By (since 1996):3, Export Date: 17 November 2013, Source: Scopus, Language of Orig... more ABSTRACT Cited By (since 1996):3, Export Date: 17 November 2013, Source: Scopus, Language of Original Document: English, Correspondence Address: de Bellis, V.; DII- DiME Section, Università di Napoli 'Federico II', Via Claudio 21, 80125 Napoli, Italy; email: vincenzo.debellis@unina.it, References: Moriya, Y., Watanabe, A., Uda, H., Kawamura, H., A Newly Developed Intelligent Variable Valve Timing System-Continuously Controlled Cam Phasing as Applied to a New 3 Liter Inline 6 Engine (1996) SAE Technical Paper 960579, , doi: 10.4271/960579;

Research paper thumbnail of Analysis and Design of an Intake Filter Box for a Downsized VVA Engine

SAE Technical Paper Series, 2014

ABSTRACT The present paper reports 1D and 3D CFD analyses of the air-filter box of a turbocharged... more ABSTRACT The present paper reports 1D and 3D CFD analyses of the air-filter box of a turbocharged VVA engine, aiming to predict and improve the gas-dynamic noise emissions through a partial re-design of the device. First of all, the gas-dynamic noise at the intake mouth is measured during a dedicated experimental campaign. The developed 1D and 3D models are then validated at full load operation, based on experimental data. In particular, 1D model provides a preliminary evaluation of the radiated noise and simultaneously gives reliable boundary conditions for the unsteady 3D CFD simulations. The latter indeed allow to better take into account the geometrical details of the air-filter and guarantee a more accurate gas-dynamic noise prediction. 3D CFD analyses put in evidence that sound emission mainly occur within a frequency range of 350 to 450 Hz. Starting from the above result, the original air-box design is modified through the installation of a single Helmholtz resonator, taking into account layout constraints and the influence on engine performance, as well. First, the isolated air-box is studied through a 3D FEM approach to compute the Transmission Loss (TL) parameter both for the original and the modified design. This analysis is employed to verify the noise abatement in the frequency range of interest, for a zero-mean flow. Then, the new intake system configuration is investigated under actual engine operation, through unsteady 3D CFD simulations. The resulting reduction in the gas-dynamic noise is verified both in terms of overall radiated SPL and frequency spectrum at full and part load operating conditions, as well. The proposed integrated 1D-3D approach demonstrated to be a useful tool for the design and the analysis of new geometrical intake system configurations, aiming to improve the engine acoustic performance without significant penalties on the delivered power and fuel consumption.

Research paper thumbnail of A Comparison Between External and Internal Resonators Employment to Reduce the Gas-Dynamic Noise of a SI Engine

SAE International Journal of Engines, 2014

ABSTRACT This paper reports 1D and 3D CFD analyses aiming to improve the gas-dynamic noise emissi... more ABSTRACT This paper reports 1D and 3D CFD analyses aiming to improve the gas-dynamic noise emission of a downsized turbocharged VVA engine through the re-design of the intake air-box device, consisting in the introduction of external or internal resonators. Nowadays, modern spark-ignition (SI) engines show more and more complex architectures that, while improving the brake specific fuel consumption (BSFC), may be responsible for the increased noise radiation at the engine intake mouth. In particular VVA systems allow for the actuation of advanced valve strategies that provide a reduction in the BSFC at part load operations thanks to the intake line de-throttling. In these conditions, due to a less effective attenuation of the pressure waves that travel along the intake system, VVA engines produce higher gas-dynamic noise levels. The worsening of the engine gas-dynamic performance can be compensated with a partial re-design of the air-box device, without significantly penalizing the engine power output. In order to find new design configurations of the air-box device capable of improving the noise levels, different numerical models can be successfully employed. In the present work, a detailed 1D engine model is firstly developed and validated against the experimental data at full load operations. 1D model is realized within GT-Power™ software and it utilizes proper user routines for the modeling of the turbulence and combustion process and for the handling of different intake valve strategies. The 1D engine model also includes a refined user model of the turbocharger able to better describe the acoustic behavior of the device. The engine model allows for the prediction of the main overall engine performances and the gas-dynamic noise with good accuracy. It also provides a first estimation of the gas-dynamic noise and gives reliable boundary conditions for the subsequent unsteady 3D CFD analyses, allowing to obtain a more accurate noise prediction. A proper Helmholtz resonator is designed and virtually installed along the inlet pipe of the air-box device. An additional geometrical configuration of the air-filter box, that includes an internal resonator, obtained through the insertion of inner walls, is considered, too. The effectiveness of the redesigned air-box configurations, are firstly tested in terms of Transmission Loss characteristics, and in terms of gasdynamic noise abatement, as well.

Research paper thumbnail of A Multi-Zone Combustion Model Integrated with a Fast Tabulated Chemical Kinetics Applied for the Simulation of HCCI Engines Supplied with Hydrogen or Carbon-Based Fuels

SAE Technical Paper Series

Research paper thumbnail of A phenomenological model for the description of unburned hydrocarbons emission in ultra-lean engines

International Journal of Engine Research

The adoption of lean-burn concepts for internal combustion engines working with a homogenous air/... more The adoption of lean-burn concepts for internal combustion engines working with a homogenous air/fuel charge is under development as a path to simultaneously improve thermal efficiency, fuel consumption, nitric oxides, and carbon monoxide emissions. This technology may lead to a relevant emission of unburned hydrocarbons (uHC) compared to a stoichiometric engine. The uHC sources are various and the relative importance varies according to fuel characteristics, engine operating point, and some geometrical details of the combustion chamber. This concern becomes even more relevant in the case of engines supplied with natural gas since the methane has a global warming potential much greater than the other major pollutant emissions. In this work, a simulation model describing the main mechanisms for uHC formation is proposed. The model describes uHC production from crevices and flame wall quenching, also considering the post-oxidation. The uHC model is implemented in commercial software (...

Research paper thumbnail of Development of an Efficient Thermal Electric Skipping Strategy for the Management of a Series/Parallel Hybrid Powertrain

Energies

In recent years, the development of hybrid powertrain allowed to substantially reduce the CO2 and... more In recent years, the development of hybrid powertrain allowed to substantially reduce the CO2 and pollutant emissions of vehicles. The optimal management of such power units represents a challenging task since more degrees of freedom are available compared to a conventional pure-thermal engine powertrain. The a priori knowledge of the driving mission allows identifying the actual optimal control strategy at the expense of a quite relevant computational effort. This is realized by the off-line optimization strategies, such as Pontryagin minimum principle—PMP—or dynamic programming. On the other hand, for an on-vehicle application, the driving mission is unknown, and a certain performance degradation must be expected, depending on the degree of simplification and the computational burden of the adopted control strategy. This work is focused on the development of a simplified control strategy, labeled as efficient thermal electric skipping strategy—ETESS, which presents performance sim...

Research paper thumbnail of One-dimensional simulations and experimental analysis of a wastegated turbine for automotive engines under unsteady flow conditions

Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering

In this paper, the unsteady-state behaviour of a turbocharger wastegated turbine (IHI-RHF3) is in... more In this paper, the unsteady-state behaviour of a turbocharger wastegated turbine (IHI-RHF3) is investigated using both an experimental approach and a numerical approach. First, an experimental campaign is performed in a specialized test rig operating at the University of Genoa, for different openings of the wastegate valve and under steady flow and unsteady flow operations. An appropriate configuration of the turbine outlet circuit fitted with a separating wall is used to carry out instantaneous measurements downstream of the turbine wheel and the wastegate valve. The above data constitute the basis for the tuning and validation of a one-dimensional turbine model recently developed at the University of Naples. Preliminary model tuning is carried out on the basis of the characteristic map measured for a completely closed wastegate valve under steady flow operations. A refined one-dimensional schematization of the experimental apparatus is implemented within the commercial GT-Power® s...

Research paper thumbnail of CFD 3D Analysis of Charge Motion and Combustion in a Spark-Ignition Internal Combustion Engine under Close-to-Idle Condition

E3S Web of Conferences

The increasingly stringent limitations on noxious missions of transport sector highly affect the ... more The increasingly stringent limitations on noxious missions of transport sector highly affect the development of new engines. The operating conditions of the engine at low-load and idle play a relevant role along the regulatory homologation cycles, contributing to overall emissions. In this work, the effectiveness of some solutions to improve the behaviour under close-to-idle operation of a Spark-Ignition motorcycle engine are compared by 3D CFD analyses. Specifically, the effects of two designs of the intake port and of the opening direction of the throttle valve, either clockwise or counterclockwise, are investigated. Multi-cycle simulations are carried out, under motored and fired conditions, for a single close-to-idle operating point. The various designs are compared in terms of capability to generate a stable tumble vortex during the intake phase and to produce an adequate turbulence level at the beginning of the combustion process. The analyses revealed that a clockwise throttl...