Characteristics of Single Fuel Droplet Impact on Oil Film 2019-01-0304
In order to better understand the spray impingement behavior of GDI gasoline, this paper uses the laser induced fluorescence (LIF) test method to conduct basic research on fuel droplet impact onto 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 crown splashing droplets was analyzed. It is shown that after the droplet impact, the oil film can be divided into three states: stable crown, splashed crown, and fast splashed crown. The stable crown has only fuel droplet splash, the splashing droplets of splashed crown are consist of fuel and oil film. The splashing droplets of fast splashed crown mainly include the oil film. The larger the Weber number of incident droplets, the easier the oil film will splash and the more severe the morphological change, the larger the dimensionless crown height and diameter. 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 morphology and the dimensionless oil film thickness, and the relationship between the dimensionless crown height and the diameter and the Weber number were fitted.