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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.

A conventional coil ignition system and two breakdown ignition systems with different electrode configurations were compared in M.I.T.'s transparent square piston engine. The purpose was to gain a deeper understanding of how the breakdown and glow discharge phases affect flame development and engine performance. The engine was operated with a standard intake valve and with a shrouded intake valve to vary the characteristic burning rate of the engine. Cylinder pressure data were used to characterize the ignition-system performance. A newly developed schlieren system which provides two orthogonal views of the developing flame was used to define the initial flame growth process. The study shows that ignition systems with higher breakdown energy achieve a faster flame growth during the first 0.5 ms after spark onset for all conditions studied.

Two-stage variable compression ratio (VCR) systems for spark ignited engines offer a CO2 reduction potential of approx. 5%. Due to their modularity, connecting rod based VCR-systems can be integrated into existing engine assembly systems, where engines can be built in parallel with or without such a system, depending on performance and market requirements. In order to comply with the new RDE emission standards with high specific power engine variants, VCR systems enable high load engine operation without fuel enrichment. The interactions between the hydraulic-, mechanical - and oil supply systems of a VCR-system with variable connecting rod length are complex and require a well-developed and adapted layout of all subsystems. This demands the use of tailored measurement and simulation tools during the development and application phases. In this context, Advanced Functional Pulse Testing enables single-parameter analyses of VCR con rods.

This study investigated dual-fuel operation with a light duty Diesel engine over a wide engine load range. Ethanol was hereby injected into the intake duct, while Diesel was injected directly into the cylinder. At low loads, high ethanol shares are critical in terms of combustion stability and emissions of unburnt hydrocarbons. As the load increases, the rates of heat release become problematic with regard to noise and mechanical stress. At higher loads, an advanced injection of Diesel was found to be beneficial in terms of combustion noise and emissions. For all tests, engine-out NOx emissions were kept within the EU-6.1 limit.

The improvement of engine efficiency, without adversely affecting oil consumption, blowby-gas, wear, or costs are desirable objectives for today's engine manufacturers as they strive to improve engine performance while trying to meet increasingly stringent emissions regulations. In this context the development of piston ring designs as well as optimized surface texturing and lubricating oil formulation is of main interest. The combination of simulation programs and the application of dynamic online oil emission measurement techniques lead to a target oriented development and a deeper understanding of the mechanisms causing oil consumption. The paper presents the results of the experimental and theoretical investigations of oil consumption mechanisms. A mass spectrometric method developed by the author et al., was used to measure the online oil emission in the exhaust gas by means of direct analysis of the lubricating oil molecules.

For gasoline engines controlled autoignition provides the vision of enabling the fuel consumption benefit of stratified lean combustion systems without the drawback of additional NOx aftertreatment. In this study the potential of certain biofuels on this combustion system was assessed by single-cylinder engine investigations using the exhaust strategy "combustion chamber recirculation" (CCR). For the engine testing sweeps in the internal EGR rate with different injection strategies as well as load sweeps were performed. Of particular interest was to reveal fuel differences in the achievable maximal load as well as in the NOx emission behavior. Additionally, experiments with a shock tube and a rapid compression machine were conducted in order to determine the ignition delay times of the tested biofuels concerning controlled autoignition-relevant conditions.

In the recent years diesel engine developers and manufacturers achieved a great progress in reducing the most important diesel engine pollutants, NOX and particulates. But nevertheless big efforts in diesel engine development are necessary to meet with the more stringent future emission regulations. To improve the knowledge about particle formation and emission an insight in the cylinder is necessary. By using the fast gas sampling technique samples from the cylinder were taken as a function of crank angle and analyzed regarding the soot particle size distribution and the particle mass. The particle size distribution was measured by a conventional SMPS. Under steady state conditions the influence of aromatic and oxygen content in the fuel on in-cylinder particle size distribution and particle mass inside a modern 4V-CR-DI-diesel-engine were determined. After injection and ignition, mainly small soot particles were formed which grow and in the later combustion phase coagulate.

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.

The influence of oil related emissions became more important in the past due to reduced engine-out emissions of combustion engines. Additionally the efficiency of exhaust gas after treatment components is influenced by oil derived components. A balancing of relevant engine oil components (Ca, Mg, Zn, P, S, Mo, B, Fe, Al, Cu) is presented in this paper. The oil components deposited in the combustion chamber, in the exhaust system as well as in the aftertreatment devices were determined and quantified. Therefore a completely cleaned DI Diesel engine with oxidation catalyst, Diesel particulate filter (DPF) and NOx adsorber catalyst (LNT) was operated in different operating conditions for 500 h in a development test cell. The operation included lean/rich cycling for NOx trap regeneration. After finishing the 500 h test procedure the engine was completely disassembled and all deposits were analyzed.

This paper introduces different modeling approaches of crankshafts, compares the refinement levels and discusses the difference between the results of the crankshaft durability calculation methodologies. A V6 crankshaft is considered for the comparison of the refinement levels depending on the deviation between the signals such as main bearing forces and deflection angle. Although a good correlation is observed between the results in low speed range, the deviation is evident through the mid to high speed ranges. The deviation amplitude differs depending on the signal being observed and model being used. An inline 4 crankshaft is considered for the comparison of the durability results. The analysis results show that the durability potential is underestimated with a classical crankshaft calculation approach which leads to a limitation of maximum speed of 5500 rpm.

Future demands for modern emission free drivetrains using hydrogen or liquid e-fuels also necessitate a fundamental reduction in oil emissions. Entry of lubrication oil into the combustion chamber can lead to pre-combustion phenomena (LSPI) in downsizing or hydrogen engines and is a cause of particle emissions, which play a significant role especially if fuel related particle emissions are already low. A fundamental understanding of the oil film behavior on the piston assembly and cylinder liner surface are crucial to avoid oil ingress into the combustion chamber. The processes involved take place mainly around the piston group. In particular, the area of the piston rings with the prevailing pressure and temperature conditions as well as the component geometries has a high influence on the exchange of media between the crankcase and combustion chamber. The objective of this paper is to increase the understanding of the processes leading to oil ingress into the combustion chamber.

In this paper different compressor/expander concepts including mechanical superchargers, turbochargers and two-stage charging concepts are analysed with regard to their suitability for fuel cell applications. Special attention is focused on system designs which use the energy of the tail gases for driving the compressor. The net efficiencies of different system concepts at full load were calculated with a simulation model, based on Matlab/Simulink‘ and show, that with a single stage turbocharger in combination with a tail gas burner good efficiencies and high power densities can be obtained at a pressure level of more than 2.5 bar.

An increasing environmental consciousness as well as the awareness for sustained preservation of natural resources causes new regulations for emissions and great efforts for fuel economy and increasing oil service intervals. For a better understanding of the process generating pollutants, the emissions of every phase of the combustion cycle have to be monitored online. Moreover, it is important to measure the raw exhaust gas during different driving cycles and investigate the influence of different parameters as for example changing engine operating conditions. The new mass spectrometer (MS) based measurement system allows the direct detection of unburned gaseous oil HC without tracers. The gas inlet system enables crank angle resolved monitoring of different raw exhaust gas compounds in the exhaust manifold or directly in the cylinder.

The increasingly stringent limits on pollutant emissions from internal combustion engine-powered vehicles require the optimization of advanced combustion systems by means of virtual development and simulation tools. Among the gaseous emissions from spark-ignition engines, the unburned hydrocarbon (HC) emissions are the most challenging species to simulate because of the complexity of the multiple physical and chemical mechanisms that contribute to their emission. These mechanisms are mainly three-dimensional (3D) resulting from multi-phase physics - e.g., fuel injection, oil-film layer, etc. - and are difficult to predict even in complex 3D computational fluid-dynamic (CFD) simulations. Phenomenological models describing the relationships between the physical-chemical phenomena are of great interest for the modeling and simplification of such complex mechanisms.

In order to lower friction losses and hence ensure low fuel consumption of internal combustion engines, borderline design of hydrodynamic cranktrain bearings is often unavoidable. To realize this without the risk of failures, detailed modelling of hydrodynamic effects is gaining more and more relevance. In this publication, an approach using flow simulation to couple hydrodynamic bearings with each other, will be introduced. This allows the state variables of the fluid in the supply bore of the crankshaft to be calculated transiently. One important aspect of this concerns the solubility of gas in oil. This paper demonstrates that the gas fractions in the supply bore of the crankshaft influence the pressures at the hydrodynamic bearings. Additionally, simulation results will be shown and also validated with measurement data.

The application of technologies such as direct injection, turbo charging and variable valve timing has caused a significant evolution of the gasoline engine with positive effects on fuel consumption and emissions. The current developments are primarily focused on the realization of improved full load characteristics and fuel consumption reduction with stoichiometric operation, following the downsizing approach in combination with turbo charging and high specific power. The requirements of high specific power in a relatively small cylinder displacement and a wide range of DI injection specifications lead to competing development targets and to a high number of degrees of freedom during engine layout and optimization. One of the major targets is to assess the stability of the combustion system in the early development phase.

In the present paper the results of a set of experimental investigations on LSPI are discussed. The ignition system of a test engine was modified to enable random spark advance in one of the four cylinders. LSPI sequences were successfully triggered and exhibited similar characteristics compared to regularly occurring pre-ignition. Optical investigations applying a high speed camera system enabling a visualization of the combustion process were performed. In a second engine the influence of the physical properties of the considered lubricant on the LSPI frequency was analyzed. In addition different piston ring assemblies have been tested. Moreover an online acquisition of the unburned hydrocarbon emissions in the exhaust gas was performed. The combination of these experimental techniques in the present study provided further insights on the development of LSPI sequences.

Increased quantities of fuel in the lubricating oil of CI engines pose a major challenge to the automotive industry in terms of controlling the oil aging and the wear caused by dilution. Due to a lack of methods to calculate the oil-fuel-composite transport across the ring pack, predicting the fuel ratio in the oil sump has been an extremely challenging task for engine manufacturers. An accurate and computationally efficient simulation model is critical to predict the quantity of fuel diluted in the oil in the preliminary development stage of automotive engines. In this work, the complex composite transport across the piston ring pack was reduced to a simple transport model, which was successfully implemented into a multi-body simulation of the ring pack. The calculation domain was partitioned into two parts, the ring grooves and the piston lands. Inside the grooves the oil flow caused by the pumping and squeezing action of the piston rings was calculated using the Reynolds equation.

The limitation of fuel entry into the oil sump of an internal combustion engine during operation is important to preserve the tribological properties of the lubricant and limit component wear. For observation and quantification of the effects leading to fuel entry, a highly sensitive and versatile measurement system is essential. While oil sampling from the sump followed by laboratory analysis is a common procedure, there is no system for automatic sampling of all the positions and fast online analysis of the samples. For the research project ‘Fuel in Oil’, a measurement system was developed especially for the described tasks. The system is placed next to the engine in the test cell. Sampling points are the target point of the fuel injector jet and the liner below, the oil sump and the crankcase ventilation system.

This paper focusses on the supply conditions of a connecting rod bearing. Thereto, a novel simulation approach is presented, which is based on a transient 3D-CFD multiphase flow simulation including the ability of gas dissolution and diffusive mass transfer. The model determines the pressure behavior and the gas bubble development in the oil supply system of a connecting rod bearing. It allows to visualize the flow behavior and the existence of gas bubbles in order to get a detailed impression of the physical occurrences. The experimental results from Maaßen [5], where a big gas bubble is formed in the supply bore by gas cavitation, are confirmed and used for validation. Further the flow behavior of free air ratios is investigated. The paper concludes that the supply conditions of a connecting rod bearing are strongly influenced by the gas bubble in terms of the fluid composition and the volume flow rate at the connecting rod bearing inlet.