Underwater launching of a supercavitating projectile out of a ballistic test setup

This paper considers the investigation of the high-speed motion of specifically-shaped inert bodies (projectiles) in water. The main purpose is to determine the peculiar properties of underwater launching of supercavitating projectiles out of the bore of a test ballistic setup. Preliminary calculations of the inner ballistic parameters of a shot are performed for the given launcher and then compared with the corresponding experimental data. Examples of experimentally fired underwater shots are presented. The high-speed high-energy processes associated with the projectile released out of the bore and entering water are described. It is shown that during the underwater launching, the complex gas-dynamic conditions of multi-phase processes following the projectile release out of the bore can significantly affect the trajectory of its further motion in water. Using the experimental and calculation methods with the classical loading scheme and an acceleration bore 0.5 mm long or less under given conditions, it has been determined that the pressure at the accelerator exit increases stepwise and can significantly change the flow conditions of the projectile at the start and its further trajectory. Taking into consideration the revealed peculiarities of underwater shots and a set of technical specifications and mass-size parameters, a perspective launching ballistic setup has been designed and used to estimate the motion range of the released supercavitating projectile.