Numerical study on the influence of vehicle diameter reduction and diameter expansion on supercavitation

Previous studies mainly focused on the geometric effects of cavitators on supercavity. The vehicle shape, especially the tail size, considerably affects supercavity but is rarely studied. This paper presents numerical results on the tail expansion and shrinkage impact on supercavitation. Particular attention is given to the influence of tail smooth expansion, unsmooth expansion, and shrinkage on the cavity profile and jet flow re-entry. Several vehicle models are built to study the different phenomena of cavitation evolution to explore the influence mechanism of the vehicle tail shape on cavitation. The study shows that the cavity around the vehicle is primarily affected by the vehicle tail. For smooth expansion models, the reasonable expansion of tail diameter can reduce the upward movement of the back jet, but it will destroy the cavity induced by the cavitator. Compared with smooth expansion, the unsmooth models at the same expansion angle will induce a new re-jet flow at the corner. For tail shrink models, with the decrease in tail diameter, the tail re-jet flow will climb along the body, causing the separation and shedding of cavity.