Experimental investigation on trajectory stability of high-speed water entry projectiles

• DOI: 10.1016/j.oceaneng.2019.02.021
• Publication Date: 2019-02-10T13:42:30Z
• Authors: Tuo Chen; Wei Huang; Wei Zhang; Yafei Qi; Zitao Guo
• Keywords: 0209 industrial biotechnology; 02 engineering and technology

Abstract Trajectory stability of high-speed water-entry projectiles is investigated experimentally in the present paper. The effects of nose shape, impact velocity, and water-entry attitude angle on the trajectory stability of the slender projectiles are identified and quantified respectively. Particular attention is related to the deviation of the centroid trajectory, and the deflection of the attitude angle. To better understand the mechanism of the stability of the trajectory, the evolution of the cavity and velocity attenuation of projectile are performed subsequently during the stage of cavitating sailing. The high-speed projectile is fired with different impact velocities and attitude angles by a light gas gun system, and a dynamic-photographic method is employed to provide digital photographic data in detail. The results show that the peak pressure generated by the flat projectile is the largest, and it exhibits a perfect trajectory stability. In contrast, the ogival projectile with the largest nose shape coefficient shows significant instability of trajectory and attitude deflection. For the same type of projectile, the trajectory instability increases with the increasing impact velocity and water-entry attitude angle. The drag coefficient of the cavitating flat projectile undergoes a prominent drop as the penetration increases.