Numerical simulation and analysis of the 3D transient muzzle flow field of underwater artillery

The in-depth study of the muzzle flow field contributes to the improvement of the gun and the design of the projectile. This study establishes an unsteady muzzle multiphase flow model of the underwater sealed launch with a three-dimensional scale. Among that, the VOF model is employed to trace the two-phase interface and the gas-liquid turbulent mixing is described by the standard k-& epsilon; turbulence model. Also, the established numerical model was validated by comparing underwater sealed launching experimental results. On this basis, numerical analysis on the muzzle flow field of the 30 mm artillery under different launching conditions were carried out by coupling with revised interior ballistic equations. The results show that the "necking" phenomenon occurs during gas-expansion process due to the interaction between water and projectile. Then, a "bowl-shaped" shock area is obviously formed at the muzzle. In addition, the Mach disk diameter and the corresponding growth rate are closely related to the projectile head cavitation diameter. The growth rate of Mach disk diameter increases with an increase of the cavitation diameter. When the muzzle velocities are different, the positions of the Mach disk formed are also different, presenting that the Mach disk is farther away from the muzzle with the increase of muzzle velocity.