Numerical simulation of high-speed oblique water entry of a cylindrical projectile and investigation of the projectile circular motion (Spin) on the water entry dynamics

Among the air-to-water projectiles, the gyroscopic stabilizes ones, have economic and operational advantages over other types. The air stability of such projectiles can be achieved with the gyroscopic effect of the spin. However, maintaining stability of the projectile inside the cavity, is a challenging effect from design and practical point of view. Therefore, it will be important to figure out parameters which effects on the underwater projectile stability. It should be noted that experimental study of the underwater projectile dynamics requires a very precise and expensive equipment. Hence, the numerical approach can be used in the design process. The first section of the study, proposed a dynamic model of an air-to-water supercavitating cylindrical projectile. The 6DOF dynamics of the projectile investigated using the Star-CCM+ commercial code. The model's ability to simulate the water entry physical phenomena validated via within literature experimental results and both are in good agreement. Then, the water entry of the projectile was simulated in two situations of having spin and without spinning dynamic, and the results were compared. The results of this study show that, in the oblique water entry process, the existence of circular motion will not have a significant effect on the dynamic and kinematic behavior of the cylindrical projectile. This research proves that, the high-speed oblique water entry dynamics of a supercavitating projectile can well approximated with planar motion in the x-y plate. Proof of this assumption can lead to significant simplifications in laboratory and numerical modeling of such dynamics in the future.