Experimental study on the trajectory of projectile water entry with asymmetric nose shape

Abstract

In this study, we investigated the water entry trajectory characteristics of a projectile with an asymmetric nose shape at different initial impact velocities and impact angles experimentally. With high speed photography, the water entry cavities and projectile motions were captured to obtain the trajectory curve and the attitude angle of the projectile. Compared to the projectile with a flat nose shape, the experimental results presented that the trajectory of the projectiles with asymmetrical nose shapes shows obvious deflection during the water entry process, and the deflection amplitude of the trajectory increases as the cut angle decreases under the same water entry conditions. It is found that the change trend of the projectile's attitude angle is the almost same under different impact angle conditions. In addition, for the same type of asymmetric nose shape, the trajectory deflection increases with the increase in impact velocity. Finally, a theoretical model of the water entry trajectory was established to predict the projectile motion and trajectory of the projectile with an asymmetric nose shape before the tail-slap process. We compared the experimental data with the calculated results, and the theoretical calculation gave a good approximation with the experimental results. The maximum error of the displacements between the theoretical results and the experimental results is only 3.25%.