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Coincident 3-d velocity measurements in the flat combustion chamber of a motored single cylinder engine have been performed using Laser-Doppler-Velocimetry. The 3-d LDV System consisted of three beampairs (514nm, 488nm and 476.5nm) and two fiberoptic probes operated in 90° cross-scatter mode obtaining high spatial and temporal resolution as well as high signal quality. Burst Spectrum Analyzers have been thereby used for signal processing. The time histories of the three velocity components have been acquired for moderate engine speeds (600, 1000 and 1500RPM). The swirling motion in the cylinder was also varied by choosing different fixed positions of a shrouded intake valve relative to the intake port. Several measuring locations in the combustion chamber have been studied in order to investigate homogeneity. Mean velocities and fluctuation intensities of the turbulent field were evaluated using ensemble averaging.

Numerical and experimental investigations are presented with regard to homogeneous-charge-compression-ignition for two different fuels. N-heptane and n-butane are considered for covering an appropriate range of ignition behaviour typical for higher hydrocarbons. One fuel is closer to diesel (n-heptane), the other closer to gasoline ignition properties (n-butane). Butane in particular, being gaseous under atmospheric conditions, is used to also guarantee perfectly homogenous mixture composition in the combustion chamber. Starting from detailed chemical mechanisms for both fuels, reaction path analysis is used to derive reduced mechanisms, which are validated in homogeneous reactors. After reduction, reaction kinetics is coupled with multi zone modeling and 3D-CFD through the Conditional Moment Closure (CMC) approach in order to predict autoignition and heat release rates in an I.C. engine. Multi zone modeling is used to simulate port injection HCCI technology with n-butane.

Coincident 3-D velocity measurements have been made in a single-cylinder, motored research engine using a six-beam, three-wavelength LDV system. The engine had a pancake combustion chamber, a compression ratio of 8.0 and was operated with a fixed intake shroud valve position. Measurements have been performed at 600, 1000 and 1500 RPM and at three distinct locations within the combustion chamber. Software coincidence filtering and ensemble averaging have been thereby used for data processing.

Measurements of instantaneous in-cylinder heat transfer have been performed at a selected location of the cylinder head in a super long stroke, low speed, two-stroke experimental diesel engine operating under various conditions. The temperatures of both the wall and the process have been varied either by locally using titanium instead of steel as wall material or correspondingly by operating the engine with an unusually high equivalence ratio. A standard case with a steel wall and a typical full load point has been used as reference. For all conditions, measurements of the wall temperature very close to the surface of the apparent radiation temperature of the combustion chamber contents and of the gas temperature across the boundary layer (the latter by means of a for this purpose specifically developed fiber-optical sensor) have been carried out. As a result, the total heat flux as well as its two components, convection and radiation, have been determined.