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For studying the effects of injection system properties and combustion chamber conditions on the penetration lengths of both the liquid and the vapor phase of fuel injectors in Diesel engines, a holistic injection model was developed, combining hydraulic and spray modeling into one integrated simulation tool. The hydraulic system is modeled by using ISIS (Interactive Simulation of Interdisciplinary Systems), a one dimensional in–house code simulating the fuel flow through hydraulic systems. The computed outflow conditions at the nozzle exit, e.g. the dynamic flow rate and the corresponding fuel pressure, are used to link the hydraulic model to a quasi–dimensional spray model. The quasi–dimensional spray model uses semi–empirical 1D correlation functions to calculate spray angle, droplet history and droplet motion as well as penetration lengths of the liquid and the vapor phases. For incorporating droplet vaporization, a single droplet approach has been used.

The study of oil emission is of essential interest for the engine development of modern cars, as well as for the understanding of hydrocarbon emissions especially during cold start conditions. A laser mass spectrometer has been used to measure single aromatic hydrocarbons in unconditioned exhaust gas of a H2-fueled engine at stationary and transient motor operation. These compounds represent unburned oil constituents. The measurements were accompanied by FID and GC-FID measurements of hydrocarbons which represent the burned oil constituents. The total oil consumption has been determined by measuring the oil sampled by freezing and weighing. It has been concluded that only 10 % of the oil consumption via exhaust gas has burned in the cylinders. A correlation of the emission of single oil-based components at ppb level detected with the laser mass spectrometer to the total motor oil emission has been found.

Synthetic fuels for internal combustion engines offer CO2-neutral mobility if produced in a closed carbon cycle using renewable energies. C1-based synthetic fuels can offer high knock resistance as well as soot free combustion due to their molecular structure containing oxygen and no direct C-C bonds. Such fuels as, for example, dimethyl carbonate (DMC) and methyl formate (MeFo) have great potential to replace gasoline in spark-ignition (SI) engines. In this study, a mixture of 65% DMC and 35% MeFo (C65F35) was used in a single-cylinder research engine to determine friction losses in the piston group using the floating-liner method. The results were benchmarked against gasoline (G100). Compared to gasoline, the density of C65F35 is almost 40% higher, but its mass-based lower heating value (LHV) is 2.8 times lower. Hence, more fuel must be injected to reach the same engine load as in a conventional gasoline engine, leading to an increased cooling effect.

For development of new engines a ‘general purpose ECU’ for spark ignition engines with up to 12 cylinders has been developed. As part of this ECU a DSP (Digital Signal Processor)-based measurement unit for high frequency combustion analysis has been integrated. In this paper, details about this signal processing platform are given. The DSP-unit has 24 analog input channels. 12 channels are used for cylinder pressure measurement; the other 12 channels are general purpose ones. For example, they can be used for ionic current analysis. Additional digital inputs allow measurement of crank speed and crank speed variations. This is an important topic for misfire detection as part of the OBD regulations.

In response to ever more stringent emission limits (EURO IV, SULEV), engine developers are increasingly turning their attention to engine start-up and warm-up phases. Since in this phase the catalytic converter has not yet reached its operating temperature, problems occur especially with regard to hydrocarbon emissions (HC) which are emitted untreated. Secondary air injection represents one option for heating up the catalytic converter more quickly. The engine is operated during the heating up cycle with retarded ignition angles and a rich mixture. Ambient air (secondary air) is injected close to the exhaust valve seat. During the spontaneously occurring post oxidation phase, the reactive exhaust components ignite and heat up the catalytic converter while simultaneously reducing HC. The various processes which affect the post oxidation, are not well known up to now. In order to achieve concrete improvements, detailed knowledge of its influences are necessary.

In this article model-based controller design techniques are investigated for the transient operation of a common-rail diesel engine in order to optimize driveability and to reduce soot emissions. The computer-aided design has benefits in reducing controller calibration time. This paper presents a nonlinear control concept for the coordinated control of the exhaust gas recirculation (EGR) valve and the variable geometry turbocharger (VGT) in a common-rail diesel engine. The overall controller structure is set up to regulate the total cylinder air-charge with a desired fresh air-charge amount by means of controlling the intake manifold pressure and estimating the fresh air-charge inducted into the cylinders. During varying engine operating conditions the two control loops are coordinated by a compensation of the EGR valve action through the VGT controller.

The current is an investigation of the effects of charge motion, namely tumble, on the burn characteristics of the new Chrysler Hemi SI engine. In order to reduce prototyping, several combustion system designs were evaluated; some of which were eliminated prior to design inception solely based on CFD simulations. The effects of piston top and number of spark plugs were studied throughout the conceptual stage with the AVL-FIRE CFD code. It has been concluded that large-scale, persistent and coherent tumbling flow structures are essential to charge motion augmentation at ignition only if such structures are decimated right before ignition. Piston top had a detrimental effect on tumbling charge motion as the piston approaches the TDC. When compared to single spark plug operation, dual spark plug reflected considerable improvement on burn characteristics and engine performance as a consequence. The CFD simulations demonstrated good correlation with early dynamometer data.

The paper describes results from investigating Common Rail (CR) injection in a dedicated optical engine with optimum access to the whole cross section of the engine cylinder through piston. This engine maintains all production-type details of the combustion chamber geometry being crucial to the flow fields required for optimum engine performance. This optical engine is used along with 2D optical diagnostics for temperature, soot and OH as well as spray shadowgraphy to analyze all phases of injection and combustion under virtually real engine conditions. By using special prototype CR injectors, the effects of engine design and operation strategies on ignition, combustion and pollutant formation are studied and controlling parameters are isolated. Special emphasis is devoted to the effects of injector stability, spray symmetry, nozzle geometry, injection rate, pilot injection and swirl effects.

The NO distribution in a directly-injected Diesel engine with realistic combustion chamber geometry was investigated with laser-induced fluorescence (LIF) imaging with KrF excimer laser excitation. The highest possible level of selectivity has been ensured using spectrally resolved LIF investigations inside the Diesel engine. To minimize interference from both, oxygen and polycyclic aromatic hydrocarbon (PAH) LIF the NO signal was detected around 237 nm, blue-shifted compared to the excitation wavelength resulting in a background contribution below 10% at the earliest detection timing possible in the engine under study (20°ca after top dead center, TDC). The in-cylinder NO LIF intensities were compared for different injection systems and operating conditions and correlated to variations in pressure traces and soot temperature measurements.

To meet LEV and EU Stage III emission requirements, it is necessary for new catalytic converters to be designed which exceed light-off temperature as quickly as possible. The technical solutions are secondary air injection, active heating systems such as the electrically heated catalytic converter, and the close coupled catalytic converter. Engine control functions are extensively used to heat the converter and will to play a significant role in the future. The concept of relocating the converter to a position close to the engine in an existing vehicle involves new conflicts. Examples include the space requirements, the thermal resistance of the catalytic coating and high temperature loads in the engine compartment.

The integration of CAD/CAM/CAE in product development is the key to realize concurrent engineering. Generally, different systems are employed in product development department. These different systems create a lot of troubles such as difficult communication, misunderstanding and so on. A new approach to integrate CAD/CAM/CAE in one system based on CATIA for the end-to-end process in cylinder head development is presented. Multi-Model Technology (MMT) is used to create consistent and associated CAD models for the end-to-end process in cylinder head development. The concept and method to create and organize multi- models are discussed. A typically four-layer structure of MMT for mechanical products is defined. The multi-level structure of the cylinder head models based on MMT is provided. The CAD models of cylinder head created based on MMT can be used as the consistent model.