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The aerodynamic properties of a BMW car model, representing a 40%-scaled model of a relevant car configuration, are studied computationally by means of the Unsteady RANS (Reynolds-Averaged Navier-Stokes) and Hybrid RANS/LES (Large-Eddy Simulation) approaches. The reference database (geometry, operating parameters and surface pressure distribution) are adopted from an experimental investigation carried out in the wind tunnel of the BMW Group in Munich (Schrefl, 2008). The present computational study focuses on validation of some recently developed turbulence models for unsteady flow computations in conjunction with the universal wall treatment combining integration up to the wall and high Reynolds number wall functions in such complex flow situations. The turbulence model adopted in both Unsteady RANS and PANS (Partially-Averaged Navier Stokes) frameworks is the four-equation ζ − f formulation of Hanjalic et al. (2004) based on the Elliptic Relaxation Concept (Durbin, 1991).

Automotive suppliers provide multi-layer trims mainly made of porous materials. They have a real expertise on the characterization and the modeling of poro-elastic materials. A dozen parameters are used to characterize the acoustical and elastical behavior of such materials. The recent vibro-acoustic simulation tools enable to take into account this type of material but require the Biot parameters as input. Several characterization methods exist and the question of reproducibility and confidence in the parameters arises. A Round Robin test was conducted on three poro-elastic material with four laboratories. Compared to other Round Robin test on the characterization of acoustical and elastical parameters of porous material, this one is more specific since the four laboratories are familiar with automotive applications. Methods and results are compared and discussed in this work.

Impact noise, inside a car, due to tire-launched gravel on the road can lead to loss of quality perception. Gravel noise is mainly caused by small-sized particles which are too small to be seen on the road by the driver. The investigation focuses on the identification of the mechanisms of excitation and transfer. The spatial distribution of the particles flying from a tire is determined, as well as the probable impact locations on the vehicle body-panels. Finally the relative noise contributions of the body-panels are estimated by adding the panel-to-ear transfer functions. This form of Transfer-Path-Analysis allows vehicle optimization and target setting on the level of the tires, exterior panel treatment and isolation.

Vehicle driveability evolves more and more as a key decisive factor for marketability and competitiveness of passenger cars, since the final decision of customers to buy a car is usually taken after a more or less intensive test drive. Car manufacturers currently evaluate vehicle driveability with subjective assessments and by having their experienced test drivers fill out form sheets. These assessments are time and cost intensive, limited in repeatability and not objective. The real customer requirements cannot be recognized in detail with this method. This paper describes a completely new approach for an objective and real time evaluation of relevant driveability criteria, for use in a vehicle and on a high dynamic test bed. The vehicle application enables an objective comparison between vehicles and an application as a development tool in many development and calibration phases, where ever fast and objective driveability results are required.

In the present work we investigated experimentally and computationally the unsteady flow around a BMW car model including wheels*. This simulation yields mean flow and turbulence fields, enabling the study aerodynamic coefficients (drag and lift coefficients, three-dimensional/spatial wall-pressure distribution) as well as some unsteady flow phenomena in the car wake (analysis of the vortex shedding frequency). Comparisons with experimental findings are presented. The computational approach used is based on solving the complete transient Reynolds-Averaged Navier-Stokes (TRANS) equations. Special attention is devoted to turbulence modelling and the near-wall treatment of turbulence. The flow calculations were performed using a robust, eddy-viscosity-based ζ - ƒ turbulence model in the framework of the elliptic relaxation concept and in conjunction with the universal wall treatment, combining integration up to the wall and wall functions.

For car manufacturers, seating comfort is becoming more and more important in distinguishing themselves from their competitors. There is a simultaneous demand for shorter development times and more comfortable seats. Comfort in automobile seats is a multi-dimensional and complex problem. Many current sophisticated measuring tools were consulted, but it is unclear on which factors one should concentrate attention when measuring comfort. The goal of this paper is to find a model in order to predict the overall seating discomfort based on body area ratings. Besides micro climate, the pressure distribution appears to be the most objective measure comprising with the clearest association with the subjective ratings. Therefore an analysis with three different test series was designed, allowing the variation of pressure on the seat surface. In parallel the subjects were asked to judge the local and the overall sensation.

This paper deals with fleet management systems and the means to integrate new communication and computer technologies to improve transportation companies efficiency. It focuses on the integration of embedded electronic systems for communication and data management through the use of on-board computers, taking the point of view of the truck manufacturer. It introduces the idea of making the vehicle a nod of a complete communication network. After briefly presenting fleet management problematic and some of the major existing solutions, it analyzes how new technologies can be integrated and what major advantages they would bring.

The reduction of nitrous oxides in the exhaust gases of internal combustion engines using a urea water solution is gaining more and more importance. While maintaining the future exhaust gas emission regulations, like the Euro 6 for passenger cars and the Euro 5 for commercial vehicles, urea dosing allows the engine management to be modified to improve fuel economy as well. The system manufacturer Robert Bosch has started early to develop the necessary dosing systems for the urea water solution. More than 300.000 Units have been delivered in 2007 for heavy duty applications. Typical dosing quantities for those systems are in the range of 0.01 l/h for passenger car systems and up to 10 l/h for commercial vehicles. During the first years of development and application of urea dosing systems, instantaneous flow measuring devices were used, which were not operating fully satisfactory.

Underbody aerodynamics has become increasingly important over the last three decades because of its vital contribution to improving a vehicle's overall performance. This was the motivation for the research conducted by BMW Aerodynamics, concerning the determination of the overall pressure distribution on the underbody of a series-production vehicle. Static pressure measurements have been taken under various test conditions. Real on-road tests were carried out as well as wind tunnel experiments under application of different road simulation techniques. The analyzed vehicle configurations include wheel rim-tire and body modifications. The results presented include surface pressure data, drag and lift coefficients, ride heights, pitch and roll angles. The acquired data is used to examine the underbody flow topology and determine how the diverse attempts to represent the real on-road conditions affect its pressure distribution.

The introduction of more stringent standards for engine emissions requires continuous improvement of exhaust gas aftertreatment systems. Modern systems require a combined design and application of different aftertreatment devices. Computer simulation helps to investigate the complexity of different system layouts. This study presents an overall aftertreatment modeling framework comprising dedicated models for pipes, oxidation catalysts, wall flow particulate filters and selective catalytic converters. The model equations of all components are discussed. The individual behavior of all components is compared to experimental data. With these well calibrated models a simulation study on a DOC-DPF-SCR exhaust system is performed. The impact of pipe wall insulation on the overall NOx conversion performance is investigated during four different engine operating conditions taken from a heavy-duty drive cycle.

In the environmentally conscious world we live in, auto manufacturers are under extreme pressure to reduce tailpipe emissions from cars and trucks. The manufacturers have responded by creating clean-burning engines and exhaust treatments that mainly produce CO2 and water vapor along with trace emissions of pollutants such as CO, THC, NOx, and CH4. The trace emissions are regulated by law, and testing must be performed to show that they are below a certain level for the vehicle to be classified as road legal. Modern engine and pollution control technology has moved so quickly toward zero pollutant emissions that the testing technology is no longer able to accurately measure the trace levels of pollutants. Negative emission values are often measured for some pollutants, as shown by results from eight laboratories independently testing the same SULEV automobile.

Cutting development times in car manufacturing means bringing forward the knowledge processes. Simulations based directly on CAD data reduce or replace time-consuming hardware loops significantly and therefore make a significant contribution to this. Ergonomic product design is an area that is challenged as far as the further development of virtual methods is concerned. Simulation of the static and quasi-static positions of passengers inside the car is the current state of the art in ergonomic product design. For this reason, interest is strongly focused on the simulation of complex movement processes within the context of enhancing simulation tools. For the car manufacturer, the manner in which people enter and leave the car is of particular interest. Getting into the car is the customers' first actual contact with it. It may also develop into a serious problem for car drivers, as they get older.

Future catalyst systems need to be highly efficient in a limited packaging space. This normally leads to a design where the flow distribution, in front of the catalyst, is not perfectly uniform. Measurements on the flow test bench show that the implementation of perforated foils for the corrugated and flat foils has the capability to distribute the flow within the channels in the radial direction so that the maximum of the given catalyst surface is of use, even under very poor uniformity indices. Therefore a remarkable reduction in back pressure is measured. Emission results demonstrate cold start improvement due to reduced heat capacity. The use of LS - structured ( Longitudinal structured ) corrugated foils creates a high turbulence level within the single channels. The substrate lights-up earlier and the maximum conversion efficiency is reached more quickly.

In the near future the effort on the development of exhaust gas treatment systems must be increased to meet the stringent emission requirements. If the relevant physical and chemical models are available, the numerical simulation is an important tool for the design of these systems. This work presents a CFD model that allows to cover the full range of applications in this area. After a detailed presentation of the theoretical background and the modeling strategies results for the simulation of a close-coupled catalyst are shown. The presented model is also applied to the oxidation of nitrogen oxides, to a diesel particle filter and a fuel-cell reformer catalyst.

For many years, bearing suppliers have been using the specific pressure to evaluate the fatigue risk of conrod bearings. However, modern engines have made the bearing more sensitive to various phenomena such as the thermal expansion or the elasticity of the conrod housing. These effects modify the stresses in the bearing layers and consequently fatigue risk. In this paper, we propose a new way to determine the bearing fatigue resistance. To achieve that, we analyze the elastic and plastic behavior of the bearing along the engine life. We detail and provide the analytical relationships which determine stresses in the overlay and in the substrate of the bearing in order to analyze their fatigue resistance. Various physical loads are taken into account such as the thermal load, the hydrodynamic pressure field, the fitting load, the free spread load. A good knowledge of the relationships between those physical phenomena helps to understand the mechanical behavior of the bearing.

The current trend of downsizing used in gasoline engines, while reducing fuel consumption and CO2 emissions, imposes severe thermal loads inside the combustion chamber. These critical thermodynamic conditions lead to the possible auto-ignition (AI) of fresh gases hot-spots around Top-Dead-Center (TDC). At this very moment where the surface to volume ratio is high, wall heat transfer influences the temperature field inside the combustion chamber. The use of a realistic wall temperature distribution becomes important in the case of a downsized engine where fresh gases hot spots found near high temperature walls can initiate auto-ignition. This paper presents a comprehensive numerical methodology for an accurately prediction of thermodynamic conditions inside the combustion chamber based on Conjugate Heat Transfer (CHT).

In this study, different designs of intake ports for two-stroke Ultra Low Cost Gasoline Direct Injection Engine (ULC-GE) has been analyzed to conclude on best design using steady state analysis in STAR-CD. The four types of intake ports design with two cylinders, each having fourteen ports, have been studied. The basic differences in designs are horizontal inlet entry (perpendicular to cylinder axis) and vertical inlet entry (in-line with cylinder axis) having rotation of flow clockwise and anticlockwise. Each type is further differentiated in eight cases with varying distances between axis of two-cylinder as 85mm, 88mm, 91 mm, 94 mm, 97 mm, 100 mm, 105 mm and 112 mm. These designs are analyzed for four different pressure drops as 10 mbar, 50 mbar, 100 mbar and 150 mbar.

A specific objective of the European Mg-Engine project is to qualify at least two die cast Mg alloys with improved high temperature properties, in addition to satisfactory corrosion resistance, castability and costs. This paper discusses the selection criteria for high temperature alloys leading to four candidate alloys, AJ52A, AJ62A, AE44 and AE35. Tensile-, creep- and fatigue testing of standard die cast test specimens at different temperatures and conditions have led to a very large amount of material property data. Numerous examples are given to underline the potential for these alloys in high temperature automotive applications. The subsequent use of the basic property data in material models for design of automotive components is illustrated.

Software-intensive systems and functions drive innovations in cars today. OEMs and suppliers face multiple challenges to take advantage of possibilities in this area. The rapidly developing field of software-intensive systems and software-based features in the automotive domain asks for dedicated engineering approaches, models, and processes. This paper defines the characteristics of software engineering for automotive systems and discusses methodological, technological, and organizational implications. These are used to pinpoint promising research areas as well as educational ramifications.

The paper gives an overview of the partially extremely complex problem when looking into commonalities and differences of the three main application areas of engines and powertrains - automotive, agricultural tractors, and industrial engines, the last being predominantly but not exclusively focused on construction equipment. The modern “platform” approach has been used in the automotive world to a large extent and the learned experiences may be of interest for the agricultural tractors and/or the construction equipment manufacturers. On the other hand the truck engine engineers and manufacturers will learn more about the special requirements of the tractor and the industrial engines fields, and thus influence concepts and development procedures and also the production of the automotive engines which in many cases serve as the basis for derivate engines.