A study on the cavitation vortex dynamics and loads of water-exiting axisymmetric projectile

Abstract

This paper analyzes the cavitation vortex dynamics and load characteristics of projectiles launched underwater at different angles of attack. The results show that as the velocity of the projectile decreases during the underwater cruising stage and the cavitation number continuously increases, the cavity begins to shed. This phenomenon occurs because of the development of a re-entrant jet at the end of the cavity. As the angle of attack (0°–8°) increases, the cavity asymmetry is strengthened and the scale of the cavity shedding increases. The cavity prevents the generation of hairpin vortex packages. This phenomenon is more pronounced in cavities with a larger angle of attack. As the angle of attack increases (4°–8°), the turbulent vortex structures of the wall and free wake are further developed and enriched. The vortex legs of wall hairpin vortices are significantly elongated at large angles of attack, which may be the result of the combined effect of the cavity and transition area. During the water-exiting stage, the collapse of isolated vacuoles generated by the cavitation flow generates a significant collapse load. The collapse position undergoes at least two pressure pulsation peaks or increases, with the first peak or increase occurring during the initial underwater cruising stage.