Abstract: During the cleaning process of aero-engine, the engine online washing is realized by the impact of cleaning droplet and blade fouling. Therefore, the research on the impact, spreading and infiltration of droplet on random rough surface is of great significance for improving the cleaning effect of engine online washing. In order to obtain the impact characteristics of the droplet impacting on random rough surface, the dynamic behavior of impacting, spreading and infiltrating of the cleaning droplet on random rough surface is studied. The effects of droplet diameter and impact velocity on the impact characteristics are analyzed stressfullly. The results show that, compared with the smooth wall, due to the effect of wall roughness, many broken small droplets will be generated at the spreading edge of the droplet, and the bulge and gap of the rough structure will cause bubbles in the gap, which affects the infiltration effect. The spreading diameter of droplet is positively correlated with droplet diameter and impact velocity, which helps to offset the droplet splash caused by wall roughness. The infiltration degree of the wall increases with droplet diameter and impact velocity, while the impact velocity has little effect on the infiltration degree of the core area. The research results in this paper can provide a certain theoretical basis for optimizing the parameters of aero-engine online washing process.

Key words: droplet impact, spreading diameter, volume of fluid (VOF), numerical simulation