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Supercharging as the method of increasing the output of diesel engines has a long history. Recently, because the potential for lower exhaust emissions for a given power output, supercharging has been considered as a method to reach increasingly strict emissions standards. Some research investigating the effects of supercharging has shown favorable results in terms of emissions(e.g.[1][2][3] *). Also some fundamental studies have examined the effect of ambient pressures on the characteristics of spray and ignition in constant volume combustion borb[4][5][6][7]. However, for further improvement of combustion when utilizing supercharging, more detailed information inside of the combustion chamber is needed about the effects of supercharging on fuel spray and combustion. In order to gather this information, it is necessary to observe the processes within the combustion chamber of a supercharged engine.

Three dimensional computational model has been developed to predict the macroscopic behavior of the fuel spray in D. I. diesel engines. The model was based on the KIVA-II code with modification of some submodels that it can deal with the observed phenomena such as liquid column near the nozzle tip and spray impingement on a wall. Firstly, this model was verified by comparing the prediction with the experimental results in a constant volume vessel. Secondly with application to a D.I. diesel engine, the detailed behavior of the spray in a combustion chamber was revealed. Moreover, the engine performance under different spray angles were discussed with the prediction of this model.