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The spray-guided combustion process offers a high potential for fuel savings in gasoline engines in the part load range. In this connection, the injector and spark plug are arranged in close proximity to one another, as a result of which mixture formation is primarily shaped by the dynamics of the fuel spray. The mixture formation time is very short, so that at the time of ignition the velocity of flow is high and the fuel is still largely present in liquid form. The quality of mixture formation thus constitutes a key aspect of reliable ignition. In this article, the spray characteristics of an outward-opening piezo injector are examined using optical testing methods under pressure chamber conditions and the results obtained are correlated with ignition behaviour in-engine. The global spray formation is examined using high-speed visualisation methods, particularly with regard to cyclical fluctuations.

Presented in this paper is a procedure to develop a high fidelity quasi steady state aerodynamic model for use in race car vehicle dynamic simulations and its application in a race vehicle multi-body full lap simulation. Developed to fit quasi steady state (QSS) wind tunnel data, the aerodynamic model is regressed against three independent variables: front ground clearance, rear ride height, and yaw angle. An initial dual range model is presented and then further refined to reduce the model complexity while maintaining a high level of predictive accuracy. The model complexity reduction decreases the required amount of wind tunnel data thereby reducing wind tunnel testing time and cost. The quasi steady state aerodynamic model for the pitch moment degree of freedom is systematically developed in this paper. This procedure is extended to the other five aerodynamic degrees of freedom to develop a complete, high fidelity, six degree of freedom quasi steady state aerodynamic model.

Engine Start/Stop systems reduce CO₂ emissions by turning off the combustion engine at vehicle standstill. This avoids the injection of fuel that would otherwise be needed simply to overcome internal combustion engine losses. As a next development step, engine losses at higher vehicle speeds are to be addressed. During deceleration, state-of-the-art engine technology turns off fuel injection as soon as the driver releases the gas pedal, thus the combustion engine is motored by the vehicle. The engine's drag torque could be desired by the driver, e.g., as a brake assist during downhill driving. However, quite frequently the driver wishes to coast at almost constant speed. Similar to Start/Stop operation, in such situations fuel is injected to simply overcome the combustion engine's drag torque. An operation mode referred to as "Free-Wheeling" reduces CO₂ emissions under such coasting conditions by disconnecting the combustion engine from the powertrain and by turning it off.

Software-in-the-Loop (SiL) test environments are the ideal virtual platforms for enabling continuous-development, -integration, -testing -delivery or -deployment commonly referred as Continuous-X (CX) of the complex functionalities in the current automotive industry. This trend especially is contributed by several factors such as the industry wide standardization of the model exchange formats, interfaces as well as architecture definitions. The approach of frontloading software testing with SiL test environments is predominantly advocated as well as already adopted by various Automotive OEMs, thereby the demand for innovating applicable methods is increasing. However, prominent usage of the existing monolithic architecture for interaction of various elements in the SiL environment, without regarding the separation between functional and non-functional test scope, is reducing the usability and thus limiting significantly the cost saving potential of CX with SiL.

Filtration of diesel and gasoline fuel in automotive applications is affected by many external and internal parameters, e.g. vibration, temperature, pressure, flow pulsation, and engine start-stop. Current test procedures for automotive fuel filters, proposed by most of the researchers and organizations including Society for Automotive Engineers (SAE) and International Organization for Standardization (ISO), do not apply the previously mentioned real-world-conditions. These operating conditions, which are typical for an automotive fueling system, have a significant effect on fuel filtration and need to be considered for the accurate assessment of the filter. This requires the development of improved testing procedures that will simulate the operating conditions in a fuel system as encountered in the real world.

Cost benefit and teraflop restrictions imposed by racing sanctioning bodies make steady-state RANS CFD simulation a widely accepted first approximation tool for aerodynamics evaluations in motorsports, in spite of its limitations. Research involving generic and simplified vehicle bodies has shown that the veracity of aerodynamic CFD predictions strongly depends on the turbulence model being used. Also, the ability of a turbulence model to accurately predict aerodynamic characteristics can be vehicle shape dependent as well. Modifications to the turbulence model coefficients in some of the models have the potential to improve the predictive capability for a particular vehicle shape. This paper presents a systematic study of turbulence modeling effects on the prediction of aerodynamic characteristics of a NASCAR Gen-6 Cup racecar. Steady-state RANS simulations are completed using a commercial CFD package, STAR-CCM+, from CD-Adapco.

The conventional measurements to describe the photometric quality of headlamps usually only comprise the luminous flux and the illuminance (resp. the luminous intensity) in several measuring points given by Type Approval Legislation. Practically, these photometric measurements do not describe the visual impression of a headlamp light distribution sufficiently, neither in lab nor in real street geometry. With the clear outer lens headlamps introduced recently, filament images are projected directly onto the screens or streets, thus giving new impulses to research. Starting from the established photometric practice, other types of measurements and physiological fundamentals will be discussed. The basic tools to make physical measurement and physiological impression comparable, e.g. in terms of homogeneity, are shown.

Within the scope of this work, the convective mass transfer to the zirconia sensor element of an exhaust oxygen sensor was analyzed experimentally and numerically. For the experimental setup, a heightened model of an oxygen sensor was built from Lucite® considering the similarity theory. Mass transfer is measured based on the absorption of ammonia and subsequent immediate color reaction. For the numerical investigation, a three-dimensional model of the test rig was built. To predict the flow pattern and the species transport inside the protection tubes, the commercial CFD-Code FLUENT® is used. The model for the mass transfer to the surface is implemented through user-defined functions.

In order to prevent injuries due to automatic functions like express- and comfort-opening/closing of power operated window-lift and sunroof systems, mechanisms for detecting obstacles have to be established. The main related regulations are the 74/60/ECC and the FMVSS 118. In this paper we present a unified approach for smart actuators that bases on monitoring the rotational speed of the armature. The advantages have been worked out with the aid of system simulation and proven with tests under realistic and extreme scenarios. The presented results are mainly focused on a sunroof project, which is upcoming for an European car platform in 2001 and is specified to fulfill both regulations simultaneously.

Vehicle inspection in repair shops is often still based on paper forms. Information Technology (IT) does not yet support the entire inspection process. In this paper, we introduce a small wearable IT device that is controlled by speech and enables service technicians to wirelessly access relevant data and to perform on-site communication. Users can carry this device in a pocket and use a small headset to enter speech and receive audio feedback. This system provides a completely speech-enabled functionality and thus offers a hands-free operation. After showing the applicability of wearable computers in this environment, we developed a proprietary hardware system consisting of a thin-client connected via a Digital Enhanced Cordless Telecommunications (DECT) link to a standard Personal Computer (PC) that runs a speech engine and hosts a database. Several field tests in garages helped us during the evolution of our prototypes where service technicians critiqued the prototypes.

Pedestrian protection is an upcoming field for research and development. Active pedestrian protection is described from a system perspective. In this view, the development of an active pedestrian protection system is shown. First an overview on statistics and legal requirements is given and the system requirements are discussed. Sensor concepts and realizations are shown, also different test methods and results are explained. FE-simulations to complete and later replace additional tests are developed, after cross check with the experimental results. In combination with the shown actuator concept this leads to a full functioning active pedestrian protection system.

In view of tight emission standards, injection strategies to reduce raw HC-emissions during the cold starting of port fuel injected engines are evaluated in this study. The relevance of spray targeting and atomization is outlined in the first part of this paper. The foundation and performance of different injector concepts with respect to spray characteristics are discussed. Laboratory experiments demonstrate that concepts relying on auxiliary energy, such as air-assistance, fuel heating and injection at elevated system pressures, are capable of producing spray droplet sizes in the SMD-range of 25μm. For future injection strategies aimed at the compliance of SULEV emission levels, this target value is considered to be essential. In the second part of this paper, emission tests of selected injector concepts are carried out using a V6-3.2I ULEV engine operated both in a vehicle and on a test bench.

Compressed Natural Gas (CNG) is a promising alternative fuel for internal combustion engines as its combustion is fuel-efficient and lean in carbon dioxide compared to gasoline. The high octane number of methane gives rise to significant increase of the thermodynamic efficiency due to higher possible compression ratios. In order to use this potential, new stratified mixture formation concepts for CNG are investigated by means of numerical fluid simulations. For decades RANS methods have been the industry standard to model three-dimensional flows. Indeed, there are well-known deficiencies of the widely used eddy viscosity turbulence models based on the applied Boussinesq hypothesis. Reynolds stress turbulence models as well as scale resolving simulation approaches can be appealing alternative choices since they offer higher accuracy. However, due to their large computing effort, they are still mostly impractical for the daily use in industrial product development processes.

Turbulence modeling and the specific boundary conditions are among the two major simulation physics setup variables that affect the prediction veracity of a CFD simulation. The existing literature is rich with studies investigating the effect of the inlet boundary conditions on the predictability of a CFD simulation, and it is recognized that the turbulence characteristics of the freestream flow, viz. the turbulence intensity and length scale, can impact the simulation results significantly, even with the same turbulence model. However, none of these studies encompasses the significance of these two boundary specifications on the CFD analysis of a realistic racecar model. Against this backdrop, the purpose of this study is to systematically investigate the effect of different freestream turbulence specifications on the CFD predictions of the aerodynamic characteristics of a latest generation NASCAR Cup racecar model.

This paper discusses a realistic approach of simulating a generic idealized car model (Ahmed body) moving in close proximity to a Side-wall using transient CFD. This phenomenon is very important in motorsports where racing very close to the safety barrier is very common. Driving in close proximity to a Side-wall alters the aerodynamic characteristics of the vehicle significantly, however, only a handful of published work exists in this area. Additionally, the experimental studies conducted in the past suffer from certain inadequacies especially in properly emulating the Side-wall, which cast some uncertainty as to their applicability to the real world. As such, the present study attempted to imitate the real world flow phenomenon by taking a non-traditional CFD approach in which the body is translated relative to the stationary surrounding fluid and Side-wall instead of the classical method of flowing air over a stationary object.

Computational Fluid Dynamics (CFD) tools play an important role in the early stages of vehicle aerothermal development. Arguably, the RANS (Reynolds Averaged Navier-Stokes) approaches are most widely used in industry due to their acceptable accuracy with affordable computational cost and faster turnaround time. In many automotive flows, RANS models cannot very accurately capture the absolute flow features or even the integral force coefficients. In spite of this, the RANS based CFD prediction results can conveniently be used to assess the magnitude and direction of a trend. However, even for such purposes, notable disagreements often exist between the flow features predicted by different RANS turbulence models. Whilst comparisons of different RANS models for various applications are abundant in literature, such evaluations on full-car models are limited, especially the evaluations of the cooling airflow inside the underhood compartment.

Innovative solutions for reducing particulate emissions will be necessary in order to comply with the even more stringent exhaust-gas standards of the future. The potential of a diesel nozzle with variable orifice geometry has long been common knowledge in the area of engine construction. But up to now, a fully functional solution of such a nozzle has not appeared which operates with a reduced orifice at low engine speeds and/or low loads. Here with regard to target costing, the requirements implicit in function and manufacture must also be taken into account. Using calculations on nozzle interior flow and injection-spray investigations, it will be shown which nozzle geometries best fulfill the various requirements. In order to achieve low levels of particulate emission in an engine with a combustion chamber designed for optimum use of a hole-type nozzle, the injection-spray direction and its geometry must to a large extent correspond to those of a hole-type nozzle.

The dynamometer evaluation of internal combustion engines has involved a great deal of tedious interpretation and presentation of results. In the past, engine test cells have not been fully utilized, and skilled test engineers have been occupied with routine work, time which could better be spent in actual development work. This paper describes steps taken by Robert Bosch GmbH in its new engine test laboratory, to streamline procedures for observation, computation, plotting, and presentation of results. Measurements from the engine test cell are delivered electrically to a central data processing center. These data are recorded, computed electronically, and plotted on an electric plotting machine functioning from punched paper tape.

All networking systems proposed for the automobile are serial in nature. Most of these systems are also multimaster. A requirement common to all of these systems is the ability to separate framing information from data. This is achieved by some form of code violation for the framing bits which violates the code form for standard data bits. In the Manchester and PWM bit representations this code violation can be signalled within a single bit, NRZ requires more bits. The concept of code violation is also used for signalling errors within a message frame. Clock tolerance is dependent on the length of time over which synchronisation between the serial bit stream and receiving circuitry must be maintained. With a given physical bus line bandwidth, the transport capacity of a protocol is a function of the number of time slots needed to transfer a given number of data bytes.

Aerodynamic styling is playing an increasing role in the design of today's passenger cars. The profile sections of the frontends of cars imply that the available installation space for the headlamps - particularly its overall depth and height is decreased in size. New types of headlamps had to be developed. One result of extensive investigations are stepped reflectors with up to six paraboloids with different focal lengths arranged around the same focal point. This type of reflector (called homofocular reflector) cannot be formed from sheet steel but from plastic by injection molding. Depending on thermal, mechanical and geometric boundary conditions three different reflector materials can be used: lacquered thermosets, unlacquered thermoplastics by one or two material injection moldings. Similar to sheet steel the use of glass lenses reduces considerably the freedom of the designer. This disadvantage of offset by the use of plastic lenses.