Numerical study on the multiphase flow characteristics of gas curtain launch for underwater gun

Abstract

A new launching method which can reduce the water resistance in the barrel and realize continuous launching by forming gas curtain without any complex device is proposed for underwater gun. A simulation-experimental platform is set up for the underwater gas-curtain launch. Based on the theory of gas jets in water and interior ballistics, a mathematical physical model for underwater gas curtain launch is established to predict the launching process of the underwater gun. The calculation results show that when the gun is launched in air and underwater, the muzzle velocity of the gas curtain launch reaches 90.9% of that launched in air under the conditions that the maximum pressure is equivalent. However, the muzzle velocity of underwater full-submerged launch is only 66.7% of that launched in air. The gas curtain can be effectively formed with the center nozzle, providing a gas path for the interior ballistics motion of the projectile. During the formation and expansion process of the gas curtain, the projectile head pressure fluctuates between 3 MPa and 6 MPa before the projectile starts to move. It can be seen that the underwater gas curtain launch can effectively form the gas curtain and realize the underwater low-resistance launch, gaining interior ballistics performance comparable to that of air launch. Compared with the conventional underwater full-submerged launch, underwater gas curtain launch can achieve preferable interior ballistics performance.