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Further improvements of internal combustion engines to reduce fuel consumption and to face future legislation constraints are strictly related to the study of mixture formation. The reason for that is the desire to supply the engine with homogeneous charge, towards the direction of a global stoichiometric blend in the combustion chamber. Fuel evaporation and thus mixture quality mostly depend on injector atomization features and charge motion within the cylinder. 3D-CFD simulations offer great potential to study not only injector atomization quality but also the evaporation behavior. Nevertheless coupling optical measurements and simulations for injector analysis is an open discussion because of the large number of influencing parameters and interactions affecting the fuel injection’s reproducibility. For this purpose, detailed numerical investigations are used to describe the injection phenomena.

The industry is working intensively on the precision of thermal management. By using complex thermal management strategies, it is possible to make engine heat distribution more accurate and dynamic, thereby increasing efficiency. Significant efforts are made to improve the cooling efficiency of the engine water jacket by using 3D CFD. As well, 1D simulation plays a significant role in the design and analysis of the cooling system, especially for considering transient behaviour of the engine. In this work, a practice-oriented universal method for creating a 1D water jacket model is presented. The focus is on the discretization strategy of 3D geometry and the calculation of heat transfer using Nusselt correlations. The basis and reference are 3D CFD simulations of the water jacket. Guidelines for the water jacket discretization are proposed. The heat transfer calculation in the 1D-templates is based on Nusselt-correlations (Nu = Nu(Re, Pr)), which are derived from 3D CFD simulations.

More than 20 years after the first presentation of the heat transfer equation according to Bargende [1,2], it is time to introduce some useful additions and enhancements, with respect to new and advanced combustion principles like diesel- and gasoline- homogeneous charge compression ignition (HCCI). In the existing heat transfer equation according to Bargende the calculation of the actual combustion chamber surface area is formulated in accordance with the work of Hohenberg. Hohenberg found experimentally that in the piston top land only about 20-30% of the wall heat flux values from the combustion chamber are transferred to the liner and piston wall. Hohenberg explained this phenomenon that is caused by lower gas temperature and convection level in charge within the piston top land volume. The formulation just adds the existing piston top land surface area multiplied by a specified factor to the surface of the combustion chamber.

Thixoforming is another word for Semi-Solid-Metalforming (SSM) which means that metal will be formed between solid and liquid temperature. In this state the material behavior is thixotropic. Aluminum alloys can be formed in this thixotropic state when 30 to 40% of the material is liquid. In this case it is possible to form the aluminum in a process that is located between the die-casting and the forging technology. The thixoforming process allows it to produce Near Net Shape aluminum-parts with high quality for the automotive industry. This paper is intended to give the reader some examples about and some insights into the possible applications of the thixoforming process.

Cars cause a lot of pollutants during the utilization phase. Within the last years environmental legislation tried to reduce the emissions by the introduction of very tight laws. The results are impressive: Most of the car exhaust emissions like carbonmonoxid and nitrous oxides have been reduced. At this stage new emission reduction limits in Europe as well as in the United States can only be achieved if the formulation of the catalyst system is significantly changed. An increased use of precious metals and rare earth materials is the result of such a modification which succeeds in a more expensive design of the total catalyst systems. More expensive means not only cost aspects but also the environmental burdens related to the increased production of precious metals and other catalyst components. The Life Cycle Engineering (LCE) of the catalyst system which achieves the new legislation is demonstrated as well as the effects to the usage phase.

The Institute for Polymer Testing and Polymer Science of the University of Stuttgart has been investigating automotive parts, structures and cars during their life cycle in plenty cooperation with the European automobile producers and their suppliers for the last 9 years. Therefore a holistic approach has been developed to combine tasks from technique, economic and environment in a methodology called Life Cycle Engineering (LCE). The goal is to find a way to support designer and engineers as well as police makers and public with this three-dimensional interrelated information to have the possibility to manufacture future products in a more sustainable way without loosing contact two the traditional parameters technique and costs.

In this paper, a simulation approach is introduced which takes into account all relevant heat sources and sinks in the combustion engine and in the engine compartment. With this approach, it is possible to calculate the appearing power flow and enthalpy flow as well as the component temperatures. Therefore, the complex thermodynamic and friction processes in the engine are described as simple as possible; the complete system can still be described reliably within certain limits, and the effects of different thermal optimization measures can be shown. It is an essential point for the modeling that only two integral quantities are necessary (the high pressure efficiency and the high pressure wall heat loss) for the complete combustion model.

Improvement of heat-transfer calculation for SI-engines in the three-dimensional simulation has been achieved and widely been tested by using a phenomenological heat-transfer model. The model is based on the local application of an improved Re-Nu-correlation (dimensional analysis) proposed by Bargende [1]. This approach takes advantage of long experience in engine heat transfer modeling in the real working process analysis. The results of numerous simulations of different engine meshes show that the proposed heat-transfer model enables to calculate the overall as well as the local heat transfer in good agreement with both real working process analyses and experimental investigations. The influence of the mesh structure has also been remarkably reduced and compared to the standard wall function approach, no additional CPU-time is required.

The strong demand for advanced lightweight structures in the automotive industry has increased activities in the development of new structural materials with low densities and tailored properties. Weight savings in the wheel suspension by the use of lightweight materials provide the additional benefit of an improvement in comfort behavior and driveability. The replacement of iron based materials with ceramics offers the possibility for a significant mass reduction. In the case of high tribological, environmental and thermal loads, ceramics provide the additional advantages of excellent wear, corrosion and temperature resistance with tailored properties for application as brake disk material. Silicon carbide (SiC) ceramics are promising structural materials in various high temperature and tribological applications.

The real cycle simulation is an important tool to predict the engine efficiency. To evaluate Extended Expansion SI-engines with a multi-link cranktrain, the challenge is to consider all concept specific effects as best as possible by using appropriate submodels. Due to the multi-link cranktrain, the choice of a suitable heat transfer model is of great importance since the cranktrain kinematics is changed. Therefore, the usage of the mean piston speed to calculate a heat-transfer-related velocity for heat transfer equations is not sufficient. The heat transfer equation according to Bargende combines for its calculation the actual piston speed with a simplified k-ε model. In this paper it is assessed, whether the Bargende model is valid for Extended Expansion engines. Therefore a single-cylinder engine is equipped with fast-response surface-thermocouples in the cylinder head. The surface heat flux is calculated by solving the unsteady heat conduction equation.

The fluorescence characteristics of different carbonyl compounds were investigated in a pressurized bomb using an excimer laser (308 nm) for excitation. The partial pressure of the carbonyl compounds and air was varied between 0 - saturation pressure and 0 - 5 bar, respectively. The fluorescence signal of different ketones increased almost linearly with vapour pressure. It was found to be almost independent of air pressure indicating only a weak quenching influence of oxygen. Ethylmethylketone (EMK) has a boiling temperature and vapour pressure similar to gasoline. Therefore, the applicability of EMK for measuring 2-D fuel distributions in a combustion chamber was tested in a transparent SI square piston engine. EMK was injected into the intake manifold by a conventional injector for studying the fuel/air mixing during the intake and compression stroke at 1.000 rpm. From the 2-D fluorescence signals 2-D air/fuel ratios were calculated using calibration data from bomb experiments.

A numerical simulation program for the design of the cooling air duct and the cooling system of vehicles for stationary operating conditions is introduced. This program allows the simulation of interactions with the system environment resp. an air conditioning. Hot recirculations of air in the front part of the car and the inhomogenious flow through the heat exchangers radiator and condensor in their affects on the heat transfer capacity are simulated. The power demand of the fan, the water pump and the compressor is taken into account for calculating the heat flow from the engine into the cooling water.

The influence of internal mixture formation oil hydrogen combustion in a SI engine was investigated using high speed Schlieren photography. To this end a computer controlled high pressure injection system for direct injection of gaseous hydrogen was developed. The injection system for hydrogen direct injection consists of an electronic control unit, a solenoid valve and a purpose developed injector. The timing and the duration of the hydrogen injection are controlled by an electronic unit. The fuel-air ratio was varied by adjusting the opening time of the solenoid valve. The hydrogen was fed into the combustion chamber of the engine with a pressure of 6.0 MPa. With this injection system and injection pressure it, is possible to inject the hydrogen into the combustion chamber of the engine even during hydrogen combustion. In order to compare the results of internal mixture formation, experiments with external mixture formation were also performed.

According to the present state of knowledge, the use of “Tailored Blanks” with different sheet thicknesses and/or grades represents an interesting manufacturing alternative in the design and development of sheet metal parts in the automotive industry. In order to assess the forming behavior, fundamental research was conducted on laser and mash seam welded blanks. Based on this experimental findings, a segmented draw die was designed and built to determine the limits of the metal forming process by deep drawing of car body parts. The results with this draw die showed that a uniform blankholder pressure must be guaranteed during the forming process in the flange region of the part. This necessitated definite slots in the region of the weld line for the mash seam welded blanks. Furthermore, a die concept was presented to enable an equalization of both sheet thickness steps and sheet thickness fluctuations, without requiring replacement of the respective draw die components.

During sheet metal forming processes, the friction conditions have a decisive influence on forming limits, the robustness of the production process and the quality of the parts produced, with significant forces required to overcome friction between the sheet and the tools. If lot-to-lot reproducibility is to be guaranteed, an appropriate method of characterizing the sheet surface topography is needed to monitor the sheet metal fabrication process. Newly developed optical measurement techniques and computer workstation technology are presented which enable the topography of sheet surfaces to be described in three dimensions.

A two-dimensional technique for the quantitative determination of the fuel-air ratio in hydrogen fuelled engines has been developed. The technique is based on the spontaneous Raman scattering of the hydrogen molecules (Stokes Q-branch) and the simultaneous measurement of the pressure inside the combustion chamber. From these data the local partial pressure of the hydrogen and, therefore, the fuel-air ratio can be calculated. This method was applied in a single cylinder direct injection research engine in order to prove the applicability of this technique under real engine conditions. The measurements inside the side chamber of the engine show a fast mixing process of the compressed air and the injected hydrogen (6 MPa injection pressure) independent of the injection timing.

Quantitative Laser-Induced Incandescence (LII) has been applied to investigate the soot formation in a combusting Diesel jet for various conditions. For the quantification of the LII signal the local soot volume fraction of a diffusion flame burner was measured using laser beam extinction. These data were used for the calibration of the LII signal. The investigation of the soot formation in a combusting Diesel jet was performed in a high pressure, high temperature combustion chamber with optical access. A wide range of pressure (up to 10 MPa) and temperature (up to 1,500 K) conditions could be covered using a hydrogen precombustion, which is initiated inside the chamber before fuel injection. The influence of different gas atmospheres have been investigated by varying the gas composition (H2, O2 and N2) inside the chamber.

The use of gas springs with a surge tank to generate blank holding forces in drawing tools is increasing. These gas spring systems are characterized by an almost constant behaviour of the spring force over the spring displacement. To prevent an increase of the normal pressure with increasing stroke in a drawing process, it is advantageous to obtain a degressive force-displacement behaviour of the gas springs. For this reason, a gas spring system was developed to realize a decrease of the blank holding forces over the stroke without large additional expenditure. The technical realization takes place in an exact controlling of the upper and lower pressure chamber of the nitrogen cylinder.

The Institute for Polymer Testing and Polymer Science (IKP) is an independent institute of the University of Stuttgart. For approximately 8 years work is done on the field of Life Cycle Engineering. The first couple of years knowledge about the production of materials was collected within plenty industrial cooperation. Parallel to this a methodology for the Life Cycle Engineering approach and a software system (GaBi 1.0-2.0) were developed. Based on these information, projects for balancing single parts like bumpers, fender, air intake manifolds and oil filters followed by projects handling more complex parts or processes like several body in white, headlights, fuel tanks, green tire or coating processes were done to establish the methodology of Life Cycle Engineering as a tool for decision makers and weak point analysis. Parallel to this a methodology for an Life Cycle Inventory (LCI) for the system automobile was developed in cooperation with the Volkswagen AG in 1993.