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The fulfillment of the aggravated demands on future small-size High-Speed Direct Injection (HSDI) Diesel engines requires next to the optimization of the injection system and the combustion chamber also the generation of an optimal in-cylinder swirl charge motion. To evaluate different port concepts for modern HSDI Diesel engines, usually quantities as the in-cylinder swirl ratio and the flow coefficient are determined, which are measured on a steady-state flow test bench. It has been shown that different valve lift strategies nominally lead to similar swirl levels. However, significant differences in combustion behavior and engine-out emissions give rise to the assumption that local differences in the in-cylinder flow structure caused by different valve lift strategies have noticeable impact. In this study an additional criterion, the homogeneity of the swirl flow, is introduced and a new approach for a quantitative assessment of swirl flow pattern is presented.

Laser induced fluorescence (LIF) is used to investigate oil transport mechanisms under real engine conditions. The engine oil is mixed with a dye that can be induced by a laser. The emitted light intensity from the dye correlates with the residual oil at the sensor position and the resulting oil film thicknesses can be precisely determined for each crank angle. However, the general expectation is not always achieved, e.g. an exact representation of piston ring barrel shapes. In order to investigate the responsible lubrication effects of this behavior, a new cavitation algorithm for the Reynolds equation has been developed. The solution retains the mass conservation and does not use any switch function in its mathematical approach. In contrast to common approaches, no vapor-liquid ratio is used, but one or several bigger bubbles are approximated, as have been observed in other experiments already.

The new Thermo-Elasto-Hydro-Dynamic (TEHD) code developed by FEV, is designed to improve the predictability of journal bearing designs and thereby increase the reliability of safety factors in the development of highly loaded internal combustion engines. Advanced analysis tools are evaluated by their performance as well as by their ease of use. High performance means on the one hand: taking into account all the important characteristics, like bearing elasticity or cavitation effects, to mention only some major parameters for modern journal bearing analysis. On the other hand: an economic run-time behavior must be a key feature concerning usability of the TEHD-demands for daily development praxis. Ease of use means also, that the TEHD model can easily be used as a plug-in routine of an already existing software package that is well known to the development departments.

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.

New power train concepts in the automobile industry will decisively change the familiar car acoustics. Secondary acoustic noise sources will be unmasked and dominate the driver's sound experience. The most important secondary noise source is the air conditioning (AC) system. Before a favorable AC sound can actively be designed, it is necessary to identify the acoustic noise sources and find means to influence them. This paper focuses on the AC outlet module which is, apart from the control unit, the only part visible to the customer. Typical acoustic spectra of flowed-through outlets show a characteristic tonality at about 3000 Hz. The knowledge of its aeroacoustic source mechanisms, the inherent implications for the customer and corrective measures especially in automobile surroundings has been limited so far. To analyze this phenomenon in detail, a simplified model outlet that shows the basic aeroacoustic behavior of a series production outlet was constructed and investigated.

The technology used in hybrid vehicle concepts is significantly different from conventional vehicle technology with consequences also for the noise and vibration behavior. In conventional vehicles, certain noise phenomena are masked by the engine noise. In situations where the combustion engine is turned off in hybrid vehicle concepts, these noise components can become dominant and annoying. In hybrid concepts, the driving condition is often decoupled from the operation state of the combustion engine, which leads to unusual and unexpected acoustical behavior. New acoustic phenomena such as magnetic noise due to recuperation occur, caused by new components and driving conditions. The analysis of this recuperation noise by means of interior noise simulation shows, that it is not only induced by the powertrain radiation but also by the noise path via the powertrain mounts. The additional degrees of freedom of the hybrid drive train can also be used to improve the vibrational behavior.

Under city driving conditions, the powertrain represents one of the major vehicle exterior noise sources. Especially at idle and during full load acceleration, the oil pan contributes significantly to the overall powertrain sound emission. The engine oilpan can be a significant contributor to the powertrain radiated sound levels. Passive optimization measures, such as structural optimization and acoustic shielding, can be limited by e.g. light-weight design, package and thermal constraints. Therefore, the potential of the Active Structure Acoustic Control (ASAC) method for noise reduction was investigated within the EU-sponsored project InMAR. The method has proven to have significant noise reduction potential with respect to oil pan vibration induced noise. The paper reports on activities within the InMAR project with regard to a passenger car oil pan application of an ASAC system based on piezo-ceramic foil technology.

In order to suppress the well-documented low frequency pressure fluctuations in open jet wind tunnels, termed ‘wind tunnel buffeting’, an Active Resonance Control (ARC) System was implemented in the Audi aero-acoustic wind tunnel several years ago. This ARC-Sys-tem reduces the periodic pressure fluctuations by up to 23 dB and completely eliminates the periodic velocity fluctuations using a simple feedback control scheme. To set up the ARC system in practice, the system's parameters are optimised once for each critical flow velocity, when the vortex shedding frequency coincides with an acoustic resonance mode of the wind tunnel. Due to the fact that both frequency and amplitude of the excited resonances not only depend on flow velocity but also on other parameters such as collector position and test-car geometry, the system has to be adjusted with regard to each of these cases.

Two single-cylinder diesel engines were optimised for advanced combustion performance by means of practical and cumulative hardware enhancements that are likely to be used to meet Euro 5 and 6 emissions limits and beyond. These enhancements included high fuel injection pressures, high EGR levels and charge cooling, increased swirl, and a fixed combustion phasing, providing low engine-out emissions of NOx and PM with engine efficiencies equivalent to today's diesel engines. These combustion conditions approach those of Homogeneous Charge Compression Ignition (HCCI), especially at the lower part-load operating points. Four fuels exhibiting a range of ignition quality, volatility, and aromatics contents were used to evaluate the performance of these hardware enhancements on engine-out emissions, performance, and noise levels.

A broad range of diesel, kerosene, and gasoline-like fuels has been tested in a single-cylinder diesel engine optimized for advanced combustion performance. These fuels were selected in order to better understand the effects of ignition quality, volatility, and molecular composition on engine-out emissions, performance, and noise levels. Low-level biofuel blends, both biodiesel (FAME) and ethanol, were included in the fuel set in order to test for short-term advantages or disadvantages. The diesel engine optimized in Part 1 of this study included cumulative engine hardware enhancements that are likely to be used to meet Euro 6 emissions limits and beyond, in part by operating under conditions of Homogeneous Charge Compression Ignition (HCCI), at least over some portions of the speed and load map.

Improving fuel efficiency while meeting relevant emission limits set by emissions legislation is among the main objectives of engine development. Simultaneously the development costs and development time have to be steadily reduced. For these reasons, the high demands in terms of quality and validity of measurements at the engine test bench are continuously rising. This paper will present a new methodology for efficient testing of an industrial combustion engine in order to improve the process of decision making for combustion-relevant component setups. The methodology includes various modules for increasing measurement quality and validity. Modules like stationary point detection to determine steady state engine behavior, signal quality checks to monitor the signal quality of chosen measurement signals and plausibility checks to evaluate physical relations between several measurement signals ensure a high measurement quality over all measurements.

Beside the traditional prediction of stresses and verification by mechanical testing the optimization of cylinder liner bore distortion is one of today's most important topics in crankcase structure development. Low bore distortion opens up potentials for optimizing the piston group. As the piston rings achieve better sealing characteristics in a low deformation cylinder liner, oil consumption and blow-by are reduced. For unchanged oil consumption and blow-by demands, engine friction and subsequently, fuel consumption could be reduced by decreasing the pre-tension of the piston rings. From the acoustical point of view an optimization of piston-slap noise is often based on an optimized bore distortion behavior. Apart from basics to the behavior of liner bore distortion the paper presents advanced analytical and empirical methods for detailed prediction, verification and optimization of bore distortion taking into account the effective engine operation conditions.

Powertrain noise is a significant factor in determination of the overall vehicle refinement expected by today's discriminating automotive customer. Development of a powertrain to meet these expectations requires a thorough understanding of the contributing noise sources. Specifically, combustion noise greatly impacts the perception of sound levels and quality. The relevance of combustion noise development has increased with the advent of newer efficiency-driven technologies such as direct injection or homogeneous charge compression ignition. This paper discusses the application of a CSL (Combustion Sound Level) analysis-a method for the identification and optimization of combustion noise. Using CSL, it is possible to separate mechanical and combustion noise sources.

The recent growth of available computational resources has enabled the automotive industry to utilize unsteady Computational Fluid Dynamics (CFD) for their product development on a regular basis. Over the past years, it has been confirmed that unsteady CFD can accurately simulate the transient flow field around complex geometries. Concerning the aerodynamic properties of road vehicles, the detailed analysis of the transient flow field can help to improve the driving stability. Until now, however, there haven’t been many investigations that successfully identified a specific transient phenomenon from a simulated flow field corresponding to driving stability. This is because the unsteady flow field around a vehicle consists of various time and length scales and is therefore too complex to be analyzed with the same strategies as for steady state results.

The overall perception of a vehicle's quality is significantly influenced by its interior noise characteristics. Therefore, it is important to strike a balance between “pleasant” and “dynamic” sound that fits the customer requirements with respect to vehicle brand and class [1]. Typically, a significant share of the interior vehicle noise is transferred through structure-borne paths. Hence, the powertrain mounting system plays an important role in designing the interior noise. This paper describes an application of the method of vehicle interior noise simulation (VINS) to achieve a characteristic interior sound. This approach is based on separate measurements (or calculations) of excitations and transfer functions and subsequent calculation of the interior noise in the time domain.

Fast and exact measurement of engine oil consumption is a very difficult task. Our aim is to achieve this measurement at a common test bed without engine modifications. We resolved this problem with a new technique using Laser Mass Spectrometry to detect appropriate tracers in the raw engine exhaust. The tracers are added to the engine oil. to the engine oil. For detection of these tracers we use a Laser Mass Spectrometer (LAMS). This is a combination of resonant laser ionization (with an all-solid-state laser) and Time-of-Flight Mass Spectrometry. Currently this is the only way to detect oil originated molecules (like our tracers) in the raw exhaust very fast (50 Hz) and sensitive (ppb-region). Thus, engine mapping of oil consumption over load and speed can be performed in 1-2 days with about 90 measurements. Even measurement during dynamic engine operation is possible, but not quantitative (due to the lack of information about dynamic exhaust gas mass flow).

Combustion and pollutant formation in a new recently introduced Common-Rail DI Diesel engine concept with roof-shaped combustion chamber and tumble charge motion are numerically investigated using the Representative Interactive Flamelet concept (RIF). A reference case with a cup shaped piston bowl for full load operating conditions is considered in detail. In addition to the reference case, three more cases are investigated with a variation of start of injection (SOI). A surrogate fuel consisting of n-decane (70% liquid volume fraction) and α-methylnaphthalene (30% liquid volume fraction) is used in the simulation. The underlying complete reaction mechanism comprises 506 elementary reactions and 118 chemical species. Special emphasis is put on pollutant formation, in particular on the formation of NOx, where a new technique based on a three-dimensional transport equation within the flamelet framework is applied.

A customer's perception of vehicle quality very closely parallels the noise vibration and harshness (NVH) characteristics of the vehicle. Consequently, automotive manufacturers are investing significant resources into optimizing the NVH performance of their vehicles. Automatic transmission shift quality is one of a number of attributes where NVH optimization is critical towards providing customers with a pleasant driving experience. This paper addresses various aspects of understanding, quantifying and optimizing a vehicle's shift quality characteristics. Following an introductory treatment of automatic transmission planetary gear systems, the interaction between the engine/transmission system during shifts is summarized. Various shift quality metrics used to quantify a vehicle's response and its sensitivity to transient inputs are provided. Approaches to manage the engine torque output during the shifts are discussed.