Double slapping effects on a supercavitation projectile

Based on the theory of rigid body kinematics, a double slapping theoretical model is established for supercavitation projectile. And a parabolic simplification model is used for replacing the supercavitation equation in the part region of the cavity. Meanwhile, a time interval of two slapping impacts formula is derived from the parabolic simplification model. Then, the Logvinovich bubble expansion equation is discretized by using the Compound Simpson Formula and the cavity cross-section area of the projectile tail is solved in the condition that the projectile decelerates movement underwater. And, the cavity radius value of the projectile tail is obtained from Logvinovich bubble expansion equation, and it is substituted into the time interval formula. Compared with the experimental results, it demonstrates the rationality of the parabola simplification model and time interval formula. The projectile slapping impact, which is the main mode of motion in the cavity, is closely related to the stability of the underwater trajectory. This conclusion has a specific significance for studying the instability of the underwater trajectory.