Abstract
A swirl-type injector, which is commonly used for gasoline direct injection (DI) engines, is an important part to accomplish the stratified or homogeneous charge combustion. So far, the process of air-fuel mixture formation in gasoline DI engines is not well clarified. In this study, an evaluation of a numerical simulation model is made under different ambient pressure conditions. As a result, it has been shown that D32 takes the maximum value with a coefficient in the wave breakup model of B0=0.09 although the child droplet diameter becomes small with small B0 in ambient pressure of 0.1MPa, and that as the calculations cannot reproduce the spray shapes in the ambient pressure of 0.5MPa, investigations on the initial conditions or breakup models should be made.