Numerical Investigation on Cavity Evolution and Motion Characteristics of High Speed Water Entry Ogival Projectiles with Different Headforms

At present, the trans-media weapon is one of research hotspot in the military field. Based on the Reynolds time-averaged Navier-Stokes (N-S) equation, volume of fluid (VOF) multiphase flow model and modified Realizable k-ε turbulence model, a three-dimensional numerical simulation method is constructed to study the cavity evolution and motion characteristics of ogival projectiles with different headforms during high-speed vertical water entry. The influence of headforms on the cavitation evolution and motion characteristics is also analyzed. The results show that the numerical simulation and experimental data have good consistency in the evolution of cavity shape and motion velocity. The geometry of the projectile headform significantly affects the formation mechanism of the cavity and the motion characteristics of the projectiles. The cavity of ogival projectile and double-cone ogival projectile initially appears in the shoulder of the projectile, while that of cone-cylinder ogival nose projectiles starts in the head and quickly wraps the entire projectile body. Combined with the analysis of the fluid pressure field, it is shown that a low-pressure area appears on the double-cone ogival projectile, which leads to the slowdown of the projectile velocity attenuation. The head of the cone-cylinder ogival projectile forms a typical high-pressure area, which leads to the acceleration of the projectile velocity attenuation. In addition, the axial acceleration of the cone-cylinder ogival projectile is more than twice that of the other two projectiles.