Characteristics of Single Fuel Droplet Impact on Oil Film 2019-01-0304

In order to better understand the spray impingement behavior of the gasoline direct injection (GDI) engine, this paper used the laser induced fluorescence (LIF) test method to conduct basic research on the fuel droplet impact onto the oil film. The effects of different incident droplet Weber number, dimensionless oil film thickness and oil film viscosity on the morphology of oil film after impact were investigated. And the composition of splashing droplets after impingement was analyzed. The morphology of oil film after impact was divided into three categories: stable crown, delayed splash crown, and prompt splash crown. The stable crown has only splashing fuel droplets, the splashing droplets of delayed splash crown are consist of fuel and oil film. The splashing droplets of prompt splash crown mainly include the oil film. It is shown that the larger the Weber number of incident droplets, the larger the dimensionless crown height and diameter, the easier the oil film will splash. Under the same Weber number and dimensionless oil film thickness, both the dimensionless crown height and diameter decrease with the increase of oil film viscosity. Under the same Weber number and oil film viscosity, with the increase of dimensionless oil film thickness, the dimensionless crown height first increasing and then decreasing, the dimensionless crown diameter is continuously decreasing. According to the experimental data, the relationship between the critical Weber number of different crown regimes and the dimensionless oil film thickness was fitted.