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The effects of fuel injection rate shaping and injection pressure on flame temperature and soot production in intermittent spray combustion were investigated. Two-color technique was applied to the luminous image of free spray flame captured by an ICCD camera to evaluate the 2-D temperature and soot distributions in flame. In addition to the experiments, CFD calculations using KIVA-3V code were carried out and compared with the experimental data. The experimental and computational results showed that fuel injection rate shaping affected the temporal change of flame temperature and the emission of NOx. The optimal mode of injection rate shaping, in terms of NOx reduction, varied according to injection pressure. Concerning the soot production, fuel injection rate shaping affected the regions of soot production and the injection pressure affected soot oxidation especially in the latter stage of combustion.

The effects of fuel injection rate shaping and injection pressure on diesel combustion were investigated using an electronically controlled fuel injection system. An analysis of non-evaporating spray reveals that the rate of injection rate increase affects temporal spray evolution, and also that higher injection pressures enhance spray development, particularly in terms of spray width, for all modes of injection rate shaping. From photographs of spray flame and luminous flame radiation data, it is clarified that the enhancement of spray development significantly influences the growth of the spray flame in the initial stages of combustion and affects main combustion. The optimum mode of injection rate shaping, in terms of shortening the main combustion period, varies according to injection pressure.