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The investigation of transient engine operation plays a key role of the future challenges for individual mobility in terms of real driving emissions (RDE). A fundamental investigation of the transient engine operation requires the simultaneous application of measurement technologies for an integrated study of mixture formation, combustion process and emission formation. The major prerequisite is the combustion cycle and crank angle resolved analysis of the process for at least several individual consecutive combustion cycles during transient operation. The investigations are performed with a multi cylinder DISI engine at an Engine-in-the-Loop test bench, able to operate the engine in driving cycles as well as within target profiles (e.g. speed and torque profiles). The research project describes the methodology of analyzing elementary transient operational phases, (e.g. different variants of load steps).

Investigations of the fuel injection processes in a spark ignition direct injection engine have been performed for two different fuels. The goal of this research was to determine the differences between isooctane, which is often used as an alternative to gasoline for optical engine investigations, and a special, non-fluorescing, full boiling range multicomponent fuel. The apparent vaporization characteristics of isooctane and the multicomponent fuel were examined in homogeneous operating mode with direct injection during the intake stroke. To this end, simultaneous Mie scattering and planar laser induced fluorescence imaging experiments were performed in a transparent research engine. Both fuels were mixed with 3-Pentanone as a fluorescence tracer. A frequency-quadrupled Nd:YAG laser was used as both the fluorescent excitation source and the light scattering source.