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The paper describes the setup of a 4-cylinder 1.4-liter prototype Spark Ignited (SI)-engine, which is highly boosted, extremely downsized and port fuel injected. During experimental data gathering with the engine it was discovered that the originally mounted fuel injectors were non-optimized an unable to produce an expected low fuel consumption performance at low speed, low load engine working conditions. To solve this problem by finding an optimized alternative solution for the mixture preparation process it was decided to use a high-performance numerical simulation tool. The paper presents the overall layout of the prototype engine as well as the structure of the 3-D dynamic optimization tool used to address the mixture preparation problem. The paper continues with a detailed description of the different steps used to reach the complete optimization of the mixture preparation system (both the fuel injectors and the intake manifold).

Though CFD methods have become very popular and widespread tools in the early as well as more advanced automotive design stages, they are still not so common in the motorcycle industry branch. The present work aims at the development of a comprehensive simulation environment, based on the open-source finite volume toolbox OpenFOAM®, for the aerodynamic and thermal fluxes optimization of a full motorcycle-and-rider geometry. The paper is divided in two parts: in the first one, the OpenFOAM® code is evaluated for a cold flow aerodynamic analysis, using a slightly simplified version of the Aprilia RSV4 motorbike geometry; in the second one, a mixed reduced scale-full scale methodology is proposed for the simultaneous assessment of aerodynamic forces and heat transfer performances of the engine cooling system. Results have been compared against other well established commercial CFD packages and, where available, with experimental measurements.

Computational Fluid Dynamics is nowadays largely employed as an effective optimization tool in the automotive industry, especially for what concerns aerodynamic design driven by critical factors such as the engine cooling system optimization and the reduction of drag forces, both limited by continuously changing stylistic constraints. The Ahmed reference model is a generic car-type bluff body with a slant back, which is frequently used as a benchmark test case by industrial as well as academic researchers, in order to investigate the performances of different turbulence modeling approaches. In spite of its relatively simple geometry, the Ahmed model possesses many of the typical aerodynamic features of a modern passenger car - a bluff body with separated boundary layers, recirculating flows and complex three-dimensional wake structures.

The present paper describes a study, which can enable a small displacement (1.3 liter) turbocharged European CR-diesel engine to tolerate an important increase in EGR-level. The analysis is performed by use of a 3D virtual numerical engine model, which isolates the main parameters that must be optimized within the perimeter of the combustion chamber. The paper gives a short introduction to the physical background for NOx and soot-formation as well as a recall of the main issues related to the simulation models used in the virtual engine simulation. The analysis is performed in a 9 points load/speed test matrix. Several EGR-rates are studied as well as the impact of a precise temperature control of the exhaust gas re-introduced in the intake manifold. The paper concludes by an analysis of the cumulated impact on the EGR-level tolerated by the engine after the introduction of the suggested optimization measures.

The present paper describes a study of the basic parameters, which govern particulate (soot) formation within the combustion chamber of a small displacement (1.3 liter) turbocharged European CR-diesel engine. The main tools used for the study are a real fired engine, a numerical virtual engine and a special high ambient pressure vessel for injector spray visualization. The paper describes an improved soot formation model implemented in the virtual engine setup. A comparison is presented between measured and computed combustion data at 8 different load points. The paper concludes with a discussion of the means, which can be used to minimize the particulate matter formation in the design phase of both the combustion layout and the fuel injector atomizer as well as in the design of the injection control strategies.

The paper presents the today’s power train systems, which largely reflect a one to one mapping of physical units into a dedicated electronic control system. A new approach is suggested for a breakdown strategy with an ECU centered structure linked to a surrounding harness of sensors and actuators. Like body electronics did first, automotive graded combination of semiconductor and packaging technologies are used to develop a network of mechatronic components. This allows an easy and effective separation between the SW development at the vehicle level and an off-line optimization and calibration of components. A development project is shown for a gasoline direct injected engine, where mechatronic components (e.g. cylinder, fuel pump and injectors, valve train) are networked and controlled by a master digital core, which is the application SW restricted area of the car manufacturer.

The main objective of the paper is to describe the optimization work performed to adjust direct injection (DI)-technology to SI-engines running at high (8000 to 10000 rpm.) and extremely high speeds (more than 18000 rpm). In the first category are located a certain number of small and middle displacement two-stroke series produced engines. In the second category are the typical high power racing engines used for competitions like the formula 1. The first part of the paper describes the particular requirements that an in-cylinder fuelling and mixture preparation will have to fulfill with the extremely short period available for introduction and vaporization of the fuel. The paper continues with a description of the different spray shapes, spray penetration velocities and atomization capabilities, which are optimal for the different combustion chamber architectures.

In this paper a numerical analysis is carried out of the flow characteristics in the intake system of a high performance engine. To this aim, the experimental flow bench results - obtained in tests performed on a Ducati Corse 4 valves racing engine head and presented in the parallel work [1] - are compared with the numerical ones. In [1] an experimental analysis was performed to evaluate the influence, on the flow characteristics in the intake system of a high performance 4 stroke - 4 valve internal combustion engine Notwithstanding the macroscopic meaning of the measured global coefficients Cd (Discharge Coefficient) and Nt (Tumble Number), the comparative analysis of their respective trends allowed some hypotheses to be drawn on the flow development internally to intake system ducts. In order to confirm the conclusions drawn in [1] and to reach a deeper insight in the flow characteristics, numerical simulations were performed.

In the future generation of low consumption SI-engine layouts, it has become necessary to reduce costs as well as the complexity level and, increase the system reliability by the latter. To avoid driving the GDI-system in the critical, very lean stratified operation mode without losing the fuel consumption benefit, a solution is suggested, which combines a fully variable valve control system with a low level, robust GDI combustion layout. The first part of the present paper presents the latest development in the field of high precision multi-hole GDI injector spray nozzles. The basic aspects of mixture preparation with multi-hole gasoline atomizers are highlighted and their spray behavior compared to that of the current swirl atomizer nozzle. The second part of the paper presents primary optimization of a largely homogeneous GDI combustion layout combined with a fully variable valve timing control system including complete cylinder de-activation.

The first part of the paper gives an overview of the results obtained with European GDI-powered vehicles launched on the market. Thereafter, a discussion of in-vehicle limitations due to the exhaust gas after-treatment system requirements is given. The paper continues with a description of the current development status of European lean stratified direct injection system layouts. A detailed presentation is made of the mixture preparation system key components, basic control algorithms and the necessary new high-level experimental and analytical development tools. Particularly the topic of the multi-purpose use of 3-D numerical simulation is addressed both in the development and the engine control strategy calibration phases. The development of a small 1.6 liter lean stratified engine project is taken as example to demonstrate the dual application capability of the 3D simulation tool.

Experimental measurements and numerical computations were made to characterize a spray generated by a high-pressure swirl injector. The Phase Doppler technique was applied to get information on droplet sizes (d10) and axial velocities at defined distances from the injector tip. Global spray visualization was also made. Computations were carried out using a modified version of KIVA 3V. In particular, the break-up length of the sheet and its dimension were computed from a semi-empirical correlation related to the wave instability theory suggested by Dombrowski, including the modifications introduced by Han and Reitz. Two different approaches were used to describe the initial spray conditions. According to the first, discrete particles with a characteristic size equal to the thickness of the sheet are injected. The second approach assumes, that the particles having a SMD computed by a semi-empirical correlation are injected according to a statistical distribution.

The recent innovations on automotive Diesel engines require significant research efforts. The new generation of fully electronically controlled injection systems have opened new ways to reduce emissions and improve the efficiency of the engine. The free mapping of injection law together with the enhanced injection pressures favor, in fact, the optimization of mixture formation. In this field, the 3D simulation is playing a substantial role to support the design of combustion chamber. This paper presents a computational model to simulate the multi-injection process, the mixture formation and the combustion of DI diesel engines with high-pressure injection systems. The main code is a modified version of the KIVA 3V and the modifications presented in this work are a high pressure break up model and a multi component evaporation model. The code has been validated through experimental data on a 4-cylinder, 1910 cc, DI turbocharged Diesel engine (Fiat 1.9 JTD).

A computational model and an experimental analysis have been performed to study the atomisation processes of hollow cone fuel sprays from a high pressure swirl injector for gasoline direct injection (GDI) engines. The objective has been to obtain reliable simulations and better understood structure and evolution of the spray and its interaction with air the flow field. The 3D computations are based on the KIVA 3 code in which basic spray sub models have been modified to simulate break-up phenomena and evaporation process. Spray characteristics have been measured using a system, able to gather and to process spray images, including a CCD camera, a frame grabber and a pulsed sheet obtained by the second harmonic of Nd-YAG laser (wavelength 532 nm, width 12 ns, thickness 80 μm). The readout system has been triggered by a TTL signal synchronized with the start of injection. A digital image processing software has been used to analyse the collected pictures.

The new European legislation on two-wheeler pollutant emissions has forced two stroke engine manufacturers to study the direct fuel injection (DI) technology. The Piaggio “ET2 Injection” was the first DI engine in production, using the FAST system (Fully Atomized Stratified Turbulence) applied on a 50 cm3 engine. Within the framework of the DOLCE project (Development Of innovative Low pollutant, noise and fuel Consumption two stroke spark ignition Engines for future vehicles for individual urban mobility) coordinated by Piaggio and supported by the European Commission, a 125 cm3 direct injection 2-stroke engine was developed. This paper presents the engine-related part of this work, which was concluded in March 2000. The engine is equipped with the FAST system and the fuel metering is performed by means of a low-pressure electronic fuel injection system integrated in an Engine Management System (EMS) specially developed for this type of application.

The first part of the paper gives an overview of the environmental conditions with which a future two stroke engine must comply. The reasons for which a direct gasoline injection into the combustion chamber offers one of the most promising solutions are explained. In order to understand the potential of different GDI-layouts to produce very lean stratified combustion behavior two different approaches are studied in detail. The latest version of the fuel/air mixture injection used by the F. A. S. T. engine is confronted with a basically liquid high-pressure layout, similar to the design used in automotive four-stroke passenger car engines. A description is given of the basic fluid dynamics of the 50 cc engine used for the study as well as of the experimental and numerical tools applied. The paper concludes with a detailed presentation of the obtained results as well as of the arguments retained to produce the final rating.

The first part of the paper gives an overview of the current status in fuel consumption gain of the GDI-vehicles previously launched on the European market. In order to increase the potential for a further gain in specific fuel consumption the behaviour of 3 different combustion chamber layouts are studied. The chamber layouts are aimed to adapt as well as possible to the particular requirements for application to a small displacement/small bore engine working in stratified lean conditions. The paper continues with a description of the application that shows the different steps of a structured optimisation methodology for a 1.2 litre, small bore 4-cylinder engine. The applications of an air-motion-guided and a wall-guided layout with a mechanically actuated valve train to the same combustion chamber are discussed. The potential of the air-motion-guided concept is enhanced through the introduction of an electromagnetic fully variable valve train.

The first part of the paper gives an overview of the environmental conditions with which a future two stroke powered vehicle must comply and explains the reasons for which a direct gasoline injection into the combustion chamber offers a potential solution. The paper continues with a description of the fuel/air mixture injection used in the F.A.S.T. concept and gives a detailed overview of the layout of the 125 cc engine to which it is applied. The structure of its electronic engine management system, mandatory for the necessary control precision, is presented. Hereafter is made a short introduction to the visualization and numerical computation tools used for the engine design optimization. The paper concludes with a detailed presentation and discussion of the experimental results obtained with the engine operated, either in steady state and transient conditions on an engine test rig, and mounted in a classic small dimension two-wheel vehicle submitted to road tests.

The first part of the paper gives an overview of the current development status of the GDI system layout for the middle displacement engine, typically 2 liter, using the stoichiometric or weak lean concept. Hereafter are discussed the particular requirements for the transition to a small displacement/small bore engine working in stratified lean conditions. The paper continues with a description of the application of the different steps of the optimization methodology for a 1.2 liter, small bore 4 cylinder engine from its original base line MPI version towards the lean stratified operation mode. The latest changes in the combustion model, used in the numerical simulation software applied to the combustion chamber design, are discussed and comparison made with the previous model. The redesign of the combustion chamber geometry, the proper choice of injector atomizer type and location and the use of two-stage injection and multi-spark strategies are discussed in detail.

The suggestions for upcoming Euro 2000 clean air act puts an increasing legislative pressure for lower specific fuel consumption in order to reduce the emission of CO2 and thereby decrease the impact of the “green house” effect. One of the possible suggestions to meet these requirements for SI-engines is the gasoline direct injected (GDI) power unit. One of the key points of the success of a layout of a GDI system is the optimization of the fuel injector and combustion chamber charge formation parameters. A brief description of the basic GDI-system used during the study is given. Hereafter are outlined the computational and experimental optimization tools which have been used to produce, on a reasonable industrial time scale, the main indications to optimize the design of a given injector/chamber configuration. The paper discusses in detail the results produced by the latest enhancements introduced into the 3D multi-phase computational approach, NCF-3D.

For compliance with future LEV/ULEV emission standards in United States and Euro 2000/Euro 2005 standards in European Community, catalytic converter performance has to be remarkably improved. The development of simulation codes allows to investigate a high range of possible exhaust system configurations and engine operating parameters. In the present study an hybrid Lattice BGK-finite volume technique will be described, able to determine the mass transfer rates of the chemical species to the catalyzed wall of the monolith channels. The BGK code solves the fluid motion governing equations in a reduced form obtained by discretizing the continuum in a fixed number of particles. Each of them will be moved by a set of discrete velocities and collide with the neighbour particles according to a fixed pattern of particle-interaction.