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Abnormal fuel injection in light-duty, high-speed diesel engines was analyzed by developing a mathematical simulation program. It predicts the transient hydraulic phenomena and the dynamics of the mechanical components by applying the injection system design data. The results show the existence of marked changes of injection quantity against residual pressure, cavity content and pump speed, in the case of abnormal fuel injection. Closer observation reveals that the injection rate change from two-stage to one-stage causes a marked change in injection quantity.

Simultaneous OH- and formaldehyde planar-LIF measurements have been performed in an optical engine using two laser sources working on 283 and 355 nm, respectively. The engine used for the measurements was a car Diesel engine converted to single-cylinder operation and modified for optical access. The fuel, n-heptane, was injected by a direct injection common rail system and the engine was also fitted with an EGR system. The engine was operated in both HCCI mode and Diesel mode. Due to the low load, the Diesel mode resulted in low-temperature Diesel combustion and because of limitations in maximum pressure and maximum rate of pressure increase of the optical engine, the Diesel mode was run at a higher EGR percentage than the HCCI mode to slow down the combustion. A third mode, pilot combustion, was also investigated. This pilot combustion is created by an injection at 30 CAD before TDC followed by a second injection just before TDC.