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Large cyclic variability along with increased combustion noise present in low temperature combustion (LTC) modes of internal combustion engines has driven the need for fast response, robust sensors for diagnostics and feedback control. Accelerometers have been shown as a possible technology for diagnostics and feedback control of advanced LTC operation in internal combustion engines. To make better use of this technology, an improved understanding is necessary of the effect of energy release from the combustion process on engine surface vibrations. This study explores the surface acceleration response for a single-cylinder engine operating with homogeneous charge compression ignition (HCCI) combustion. Preliminary investigation of the engine surface accelerations is conducted using a finite element analysis of the engine cylinder jacket along with consideration of cylindrical modes of the engine cylinder.

A method of investigating intake-port wall-wetting via liquid phase entrainment into the gas phase was developed using a single-cylinder port fuel injected CFR engine and externally-clocked single-component phase-doppler anemometry. The effects of fuel drop size, injection timing and valve timing on drop trajectory and entrainment into the gas phase flow were examined. It was found that entrainment of the liquid phase into the gas phase is a function of both drop size and of the local rate of change of the gas phase velocity vector. It is suggested that drop size distribution instead of a simple mean size should be considered when evaluating the performance of an injector. It appears that for a fuel drop to be entrained, small drops must be generated and introduced during a period of time with low gas phase velocity vector gradients.