Stability analysis and control of supercavitation projectile

Supercavitation projectile underwater has low resistance, high speed and efficient performance. But the existence of supercavitation affects the trajectory as well as the stability of motion of projectile. This paper investigated the stability models of supercavitating projectile without thrust device. In particular studied the frequency and force of the `tail-slaps´ which occur while the tail of projectile touched the cavity wall. The nonlinear dynamics equations motion in body coordinates were obtained via analysed the hydrodynamic of supercavitation projectile. And a simple control device was designed to control the attack angle of cavitator in order to obtain the better stability performance. Simulation results indicate that the pitching angle increases at the same time till it impacts back by the wall, and the max pitching angle becomes bigger because the velocity of center velocity reducing, then the control effect is appeared, Which provides a shift angle to prevent the max pitching angle bigger. Thus the projectile has a stability motion with little pitching angle and impact force at the control of cavitator shift device. This study is of engineering signification.