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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).

Modern gasoline direct injection engines with spray-guided combustion processes require a stable and reliable fuel mixture formation as well as an optimal stratification at time of ignition. Due to the limited time for this process the temporal and spatial analysis of the in-cylinder flow field and its influence is of significant interest. The application of a piezo injector with outward opening nozzle and its capability to realize multiple injections within the compression stroke provides additional degrees of freedom for the stratified engine operation. To improve the performance of this combination a detailed knowledge of the in-cylinder flow field and its interaction with the spray propagation during and after multiple injections is essential. The flow field measurements were applied in an optical borescope single-cylinder research engine using a high-speed particle image velocimetry (HSPIV) setup.