弹道枪不同水深下全淹没式发射膛口流场的数值分析

为了解弹道枪水下全淹没发射时，水深对膛口流场演化特性的影响，建立了二维轴对称非稳态膛口流场模型。采用流体体积函数多相流模型、标准k-ε湍流模型和Schnerr-Sauer空化模型，结合动网格及用户自定义函数技术，对水下全淹没发射膛口流场演变全过程进行了数值模拟。搭建了弹道枪水下可视化射击实验平台，对12.7 mm口径弹道枪在水中全淹没式发射时膛口流场演化过程进行了观测，并验证了数值模型的合理性。在此基础上，对比了不同水深下（h=1～100 m）膛口流场的演化特性。通过对比发现:在不同水深条件下，在膛口流场影响范围内，弹丸膛外行程随时间的变化均满足指数函数规律；水越深，膛口流场典型波系结构形成所需时间越长，且燃气在膛口轴向马赫盘处的温度和压力峰值越低，压力振荡幅度也越小，更快趋于平稳，但在径向上，水越深，压力振荡持续时间越长。

Numerical investigation on the muzzle flow field of an underwater submerged launched ballistic gun at different water depths

To investigate the influence of water depth on the evolution characteristics of the muzzle flow field of an underwater submerged launched ballistic gun, a two-dimensional axisymmetric transient muzzle flow field model was established. The fluid volume function multiphase flow model, standard k-ε turbulence model, Schnerr-Sauer cavitation model, combined with dynamic grid and user-defined function technology, are used to numerically simulate the evolution process of underwater muzzle flow field. An underwater visualized shooting experimental platform for a ballistic gun was built. The evolution process of the muzzle flow field when the 12.7 mm ballistic gun was fully submerged in water was observed, and the rationality of the numerical model was verified. Based on this, the evolution characteristics of the muzzle flow field at different water depths (h=1?100 m) are analyzed and compared. Through comparison, it is found that within the range of the muzzle flow field, the projectile displacement meets the exponential function with time under different water depths; the deeper the water, the longer it takes for the typical wave structure of the muzzle flow field to form, and the lower the peak temperature and pressure of the gas at the axial Mach disc, the smaller the pressure oscillation amplitude, the faster it stabilizes. but in the radial direction, the deeper the water depth, the longer the duration of pressure oscillations.