Experimental study on the rebound characteristics of high temperature alumina droplets impacting on an inclined cold wall

Abstract

The rebound characteristics of high-temperature alumina droplets impacting on the cold wall of a solid rocket motor are of great significance for the accurate prediction of initial slag deposition and calculation of two-phase flow inside motors. In this paper, the impact experiment of alumina droplets on an inclined cold wall is carried out by a high-temperature alumina droplet impaction experiment system. The study shows that as the impact angle increases from 10° to 45°, three types of morphologies of rebound droplets are observed, namely multiple sharp corners mode, single “tail” mode, and “heart” mode, respectively. Under 10° impact angle condition, the first sharp angle is dominated by the tangential momentum component and the condensation on the wall; as the impact angle increases to 30°, the tangential momentum component has an increased influence on the rebound morphology, and the form of “tail” is influenced by the tangential momentum component and wall condensation; when the impact angle increases to 45°, the left contact surface partial detachment is dominated by rolling inertia. The study also found that the droplet size will profoundly affect the morphology of the droplet when it rebounds, and the phenomenon of “sharp corners” and “tail” gradually disappears as the droplet diameter decreases. As the impact angle increases, the dimensionless contact time of the droplet decreases, and the relationship between the dimensionless contact time and the normal Weber number of the droplet is obtained.