Supercavitation mechanics of rotating projectile: Insights from potential flow and computational fluid dynamics

Supercavitation projectiles rely on a cavity enveloping the projectile to reduce drag and achieve high-speed motion. Meanwhile, projectile rotation can enhance its anti-interference capability and trajectory stability. However, when the attack angle and rotation act in synergy, the cavity evolution process is disturbed, thereby altering the projectile's motion behavior. This paper addresses the issue of asymmetric cavity deflection of rotating supercavitation projectiles at attack angle by combining numerical simulation with theoretical analysis. Numerical simulations were conducted on the cavity evolution characteristics of rotating supercavitation projectiles at different attack angles using the volume of fluid multiphase flow model and overset mesh technology. Furthermore, a theoretical prediction model for cavity center offset was established based on potential flow theory. The results indicate that the theoretical model can accurately predict the cavity deflection behavior. Compared with numerical simulation results, under un-wetted conditions, the maximum prediction error of the theoretical model does not exceed 2.78%. Within the wetted region under un-wetted conditions, the prediction error remains below 4.62%. The degree of cavity deflection exhibits a significant positive correlation with attack angles. Moreover, a pronounced twisting phenomenon is observed during the cavity development process, with the deflection distance accumulating as the axial distance increases. This study provides a theoretical basis and numerical reference for understanding the cavity evolution mechanism under the synergistic action of attack angle and rotation.