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The open jet wind tunnel is a widespread test section configuration for developing full scale passenger cars in the automotive industry. However, using a realizable nozzle cross section for cost effective aerodynamic development is always connected to the presence of wind tunnel effects. Wind tunnel wall interferences which are not present under open road conditions, can affect the measurement of aerodynamic forces. Thus, wind tunnel corrections may be required. This work contains the results of a CFD (Computational Fluid Dynamics) approach using unsteady Delayed Detached Eddy Simulations (DDES) to evaluate wind tunnel interferences for open jet test sections. The Full Scale DrivAer reference geometry of the Technical University of Munich (TUM) using different rear end shapes has been selected for these investigations.

The performance of environment perceiving sensors such as e.g. lidar, radar, camera and ultrasonic sensors is safety critical for automated driving vehicles. Therefore, one has to assess the sensors’ performance to assure the automated driving system’s safety. The performance of these sensors is however to some degree sensitive towards adverse weather conditions. A challenge is to quantify the effect of adverse weather conditions on the sensor’s performance early in the development of an automated driving system. This challenge is addressed in this work for lidar sensors. The lidar equation was previously employed in this context to derive estimates of a lidar’s maximum range in different weather conditions. In this work, we present a stochastic simulation framework based on a probabilistic extension of the lidar equation, to quantify the effect of adverse rainfall conditions on a lidar’s raw detection performance.

This study deals with the experimental investigation of the mechanical properties of a lithium-ion pouch cell and its modelling in an explicit finite element simulation code. One can distinguish between ‘macroscopic’ and ‘microscopic’ modelling approaches. In the ‘macroscopic’ approach, one material model approximates the behaviour of multiple inner cell layers. In the ‘microscopic’ approach, which is used in the present study, all layers and their interactions are modelled separately. The cell under study is a pouch-type lithium-ion cell with a liquid electrolyte. With its cell chemistry, design, size and capacity it is usable for automotive applications and can be assembled into traction batteries. One cell sample was fully discharged and disassembled, and its components (anode, cathode, separator and pouch) were examined and measured by electron microscopy. Components were also tensile tested.

The present paper reveals the design concept as well as results of experimental investigations, which were conducted in the early design stage of the planned AUDI Aero-Acoustic Wind Tunnel. This low-noise open-jet facility, featuring a nozzle exit area of 11 m2 and a top speed of approximately 60 m/s, enables aerodynamic as well as acoustic testing of both, full-scale and model-scale ground vehicles. Ground simulation is provided by means of a moving-belt rig. The surrounding plenum is designed as a semi-anechoic chamber to simulate acoustic free-field conditions around the vehicle. Fan noise will be attenuated below the noise level of the open jet. The work reported herein, comprises 1/8-scale pilot-tunnel experiments of aerodynamic and acoustic configurations which were carried out at the University of Darmstadt.

Strategies for weight reduction have driven the noise treatment advanced developments with a great success considering the already mastered weight decreases observed in the last years in the automotive industry. This is typically the case for all soft trims parts. In the early 2010's a typical european B-segment car soft trims weights indeed 30 to 40% less than in the early 2000's years. The main driver behind such a gap has been to combine insulation and absorption properties on a single part while increasing the number of layers. This product-process evolution was conducted using a significant improvement in the simulation capacities. In that sense, several studies presenting very good correlation results between Transmission Loss measurements and finite elements simulations on dashboard or floor insulators were presented. One may consider that those kinds of parts have already achieved a considerable improvement in performance.

The anti-lock braking system (ABS) is a widespread driver assistance system which allows a short braking distance while simultaneously maintaining the stability and steerability of the car. Vehicles with electric single-wheel drive offer many possibilities of improving the energy efficiency and the braking performance during ABS braking. In this paper, two different ways of including the electric machines in the ABS are analyzed in detail: the damping of torsional drive train vibrations in combination with recuperation and the dynamic split of the braking torque, where the hydraulic braking torque is kept constant and the dynamic modulation of the braking torque is performed by the electric machines. The damping algorithm is developed on the basis of a linearized model of the drive train and the tire-road contact by using state feedback and pole placement methods. Simulation results with a detailed multi-body system show the effectiveness of the control algorithms.

Cooling drag is the increase in the total drag due to the internal flow in the cooling system. Because of the high flow resistance in the heat exchanger the momentum of the fluid needed for engine cooling usually is dissipated nearly completely. The resulting drag penalty can be approximated by the so called ram drag. For ground vehicles the cooling drag is typically lower than this approximation due to positive interference of the cooling flow with the general flow around the vehicle. Different mechanisms for the positive interference have been described in the literature. Inlet interference as well as outlet interference can result in significant reduction of the share of the cooling drag. Positive outlet interference is obtained, when the remaining kinetic energy of the cooling flow contributes significant thrust to the overall momentum balance.

In open jet wind tunnels with high blockage ratios a sharp rise in drag is observed for models approaching the nozzle exit plane. The physical background for this rise in drag will be analyzed in the paper. Starting with a basic analysis of the dependencies of the effect on model and wind tunnel properties, the key parameters of the problem will be identified. It will be shown using a momentum balance and potential flow theory that interaction between model and nozzle exit can result in significant tunnel-induced gradients at the model position. In a second step, a CFD-based investigation is used to show the interaction between nozzle exit and a bluff body. The results cover the whole range between open jet and closed wall test section interaction. The model starts at a large distance from the nozzle, then moves towards the nozzle, enters the nozzle and is finally completely inside the nozzle.

GTL (Gas-To-Liquid) fuel is well known to improve tailpipe emissions when fuelling a conventional diesel vehicle, that is, one optimized to conventional fuel. This investigation assesses the additional potential for GTL fuel in a GTL-dedicated vehicle. This potential for GTL fuel was quantified in an EU 4 6-cylinder serial production engine. In the first stage, a comparison of engine performance was made of GTL fuel against conventional diesel, using identical engine calibrations. Next, adaptations enabled the full potential of GTL fuel within a dedicated calibration to be assessed. For this stage, two optimization goals were investigated: - Minimization of NOx emissions and - Minimization of fuel consumption. For each optimization the boundary condition was that emissions should be within the EU5 level. An additional constraint on the latter strategy required noise levels to remain within the baseline reference.

Fully variable valve trains provide comprehensive means of adjustment in terms of variable valve timing and valve lift. The efficiency of the engine is improved in the operating range and in return, an increasing complexness of the mechanical design and control engineering must be handled. For optimization and design of these kinds of complex systems, detailed simulation models covering different physical domains, i.e. mechanics, hydraulics, electrodynamics and control are needed. Topic of this work is the variable valve train named Audi valvelift system (AVS) e.g. used in the Audi 2.8l V6 FSI engine. The idea of AVS is to use different cam lobes at different operating points. Each intake valve can be actuated by a large and a small cam. For full load, the two inlet valves are opened by the large cam profile - ideal for high charge volumes and flow speeds in the combustion chamber. Under partial load, the small cam profiles are used.

More and more high-level algorithms are emerging to improve the existing systems in a car. Often these algorithms only need a platform with a bus connection and some resources such as CPU time and memory space. These functions can easily be integrated into existing systems that have free resources. This paper describes some encapsulation techniques and mechanisms that can be used in the automotive domain. The discussion also takes into account the additional resources consumed on the microcontroller to meet these requirements and by the software to implement the encapsulation mechanisms. Overviews of some general concepts of software-architectures that provide encapsulation are also shown.

In this work we extended the findings from a previous study by the authors on the mechanisms and influence factors of deposit formation in urea-based selective catalytic reduction systems (SCR) [1]. A broader range of operating conditions was investigated in detail. In order to quantify the boundary conditions of deposition, a representative set of deposits was studied during formation and decomposition. A box of heat resisting glass was equipped with a surrogate mixing element to monitor solidification timescales, temperatures and deposit growth. A chemical analysis of the deposits was performed using thermogravimetry. The depletion timescales of individual deposit components were systematically investigated. A moderate temperature increase to 350 °C was deemed sufficient to trigger fast decomposition of deposits formed below 250 °C.

One main goal of the automotive industry is to reduce the aerodynamic drag of passenger vehicles. Therefore, a deeper understanding of the flow field is necessary. Time-resolved data of the flow field is required to get an insight into the complex unsteady flow phenomena around passenger vehicles. This data helps to understand the temporal development of wake structures and enables the analysis of the formation of vortical structures. Numerical simulations are an efficient method to analyze the time-resolved data of the unsteady flow field. The analysis of the steady and unsteady numerical data is only relevant for aerodynamic developments in the wind tunnel, if the predicted temporal evolving structures of a passenger vehicle’s simulated flow field correspond to the structures of the flow field in the wind tunnel. In this study, time-resolved measurements of the empty wind tunnel and a notchback passenger vehicle in the wind tunnel are conducted.

The potential of determining the change of injury severity in the accident event taking passive as well as active measures into account at the vehicle (integral systems) are at present limited to pedestrian protective systems. Therefore, an extension of the existing methods for the application with common integral systems (front protection, side protection, etc.) is suggested. Nowadays the effectiveness of passive safety systems is determined in crash tests with very high accident severities. However, approximately 90% of real-world accidents have a lower accident severity as the required crash tests. Thus, this paper will present a method calculating the effectiveness of such an integral system based on real-world accident data. For these reasons, this paper is presenting a method for a more valid prediction of injury severity. The German In-Depth Database GIDAS allows clustering the accident event in relevant car-to-car scenarios.

A region with floor boundary-layer suction upstream of the vehicle to remove the oncoming boundary layer is often used in automotive wind tunnels. These suction systems inevitably change the empty-tunnel pressure gradient. In this paper, the empty-tunnel pressure gradient created by the use of boundary layer suction and its effect on measured drag are investigated. By using excess suction - more suction than necessary to remove the floor boundary layer – it was possible to show experimentally that the major part of the drag increase due to boundary layer suction is created by unintended gradient effects. Only a minor part of the drag increase is due to the increased flow velocities at the lower parts of the vehicle, or in other words, due to the improved ground simulation. A theoretical model, using the concept of horizontal buoyancy to predict the gradient effect, is proposed. The model is compared to the experimental results as well as to CFD calculations.

Longitudinal models are used to evaluate different vehicle-engine concepts with respect to driving behavior and emissions. The engine is generally map-based. An explicit calculation of both fluid dynamics inside the engine air path and cylinder combustion is not considered due to long computing times. Particularly for dynamic certification cycles (WLTC, US06 etc.), dynamic engine effects severely influence the quality of results. Hence, an evaluation of transient engine behavior with map-based engine models is restricted to a certain extent. The coupling of detailed 1D-engine models is an alternative, which rapidly increases the model computation time to approximately 300 times higher than that of real time. In many technical areas, the Fourier transformation (FT) method is applied, which makes it possible to represent superimposed oscillations by their sinusoidal harmonic oscillations of different orders.

The lightweight construction strategies that are demanded by the automobile industry are being employed more and more. These strategies lead to the increasing importance of the forming method and types of materials used. Especially forming technologies based on liquid media have the potential to meet these demands. These forming technologies make it possible to produce parts that have both, more complex geometries and optimized characteristics. This forming technology constitutes an intelligent process management including the significant materials parameters and behavior, the simulation and some new developments especially for the optimization of the quality and the cycle time. Hydromechanical sheet forming (AHU®) is an alternative production (forming) process, with very interesting results and developments for the manufacture of specific automobile components.

Multicore-based ECUs are increasingly used in embedded automotive software systems to allow more demanding automotive applications at moderate cost and energy consumption. Using a high number of parallel processors together with a high number of executed software components results in a practically unmanageable number of deployment alternatives to choose from. However correct deployment is one important step for reaching timing goals and acceptable latency, both also a must to reach safety goals of safety-relevant automotive applications. In this paper we focus at reducing the complexity of deployment decisions during the phases of allocation and scheduling. We tackle this complexity of deployment decisions by a mixed constructive and analytic approach.

Today's car designers ask for compact and light-weighted headlamps with several new functional features and special stylistic elements. This yields in new lighting technology such as modern free form and ellipsoid module reflectors with small dimensions and the need to use highly sophisticated materials. Both of this is sensitive to the amount of temperature and at a critical level may cause irreversible damage. Therefore, it is necessary to predict temperature loads at an early development stage in order to ensure new headlamp concepts and to shorten development time. An approach to calculate and analyze temperatures in headlamps by continuum fluid dynamic methods (CFD) is presented which can be compared and correlated to measurements carried out with infrared thermography and demonstrates the benefit of this method.

Audi's new full scale aeroacoustic wind tunnel is under full operation now. The new facility is designed for full scale automotive testing of aerodynamics and aeroacoustics for vehicles up to 3 m2 frontal area at wind speeds up to 300 kph. The highlights are the unique ground simulation system with boundary layer suction and a 5-belt-system, and the extremely low background noise of only 60 dB(A) at 160 kph. First the background of the project is illustrated and the need for the special features of the tunnel is deduced form the industrial requirements. Then an overview of the facility design is given with a detailed description of the key technical components. The calibration of the self-correcting test section will be discussed and the physical background for it will be examined more closely. For the calibrated wind tunnel the results of two correlation tests including open jet as well as closed wall wind tunnels show a reasonable conformity.