Response of underwater cylindrical shell subjected to supercavitating projectile trans-medium penetration: Experiment and simulation

Abstract

To investigate the dynamic response of the cylindrical shell targets to supercavitating projectile trans-medium penetration and the penetration mechanism, experiments and numerical simulations were conducted. Simulations examined the effects of entry water velocity and impact angle on penetration behavior. The results indicate that, upon water entry, the supercavitating projectile transfers its kinetic energy to the surrounding water medium, causing a sudden rise in local pressure. This creates an approximately hemispherical pressure field in the water medium ahead of the nose of the projectile, where the pressure distribution and magnitude are positively correlated with the velocity of the projectile. As the pressure field approaches the cylindrical shell, the area around the impact point experiences pre-stress and deformation due to the hydrodynamic pressure, which is known as the hydrodynamic ram effect. The deformation of the cylindrical shell caused by the hydrodynamic ram effect increases with increasing velocity of the projectile and exhibits a non-linear relationship with the impact angle, first decreasing and then increasing as the impact angle rises. Additionally, the hydrodynamic ram effect leads to greater local deformation and higher peak stresses in the cylindrical shell, which reduces the penetration drag force faced by the projectile in water compared to air, indicating a lower ballistic limit for underwater targets. During the penetration process, as the impact angle increases, the supercavitating projectile undergoes repetitive bending deformation and even brittle fracture, while the failure mode of the target is characterized by ductile hole expansion. Furthermore, the critical penetration velocity required to perforate the cylindrical shell target increases with increasing impact angle.