考虑活塞回复的侧向后喷武器两相流数值模拟

为研究活塞回复运动对火药燃气流动的影响，基于两相流理论对活塞控制侧向后喷武器的发射过程进行了数值模拟研究。考虑控制侧向后喷通道开闭的活塞-弹簧系统的往复运动，建立了结合膛内气固两相流、活塞腔内流固耦合和侧向排气管内气体瞬态流动的武器发射过程数学模型，并将数值模拟结果与相关文献进行了比较验证。得到了该武器发射过程中膛内流场分布与稀疏波传播特性，并与普通武器的膛内流场进行了对比分析。进一步研究了活塞回复运动对火药燃气流动和减后坐效率的影响。结果表明:相对于不考虑活塞的回复运动，在弹丸初速都降低1.52%的情况下，因为活塞回复关闭后喷通道，其减后坐效率由38.86%下降到32.88%，说明在此类武器研究中，不可忽视活塞回复运动。

Numerical simulation of two-phase flow in a side spray gun considering piston reset motion

In order to study the effect of the piston reset motion on the flow of propellant gas in a piston-controlled side spray gun, the propulsion process of the gun was modeled and simulated based on the one-dimensional two-phase flow interior ballistic theory. First, by considering the reciprocating motion of the piston-spring system that controls the opening and closing of the rear spray channel, a mathematical model of the gun propulsion process was established. It combines the gas-solid two-phase flow in the barrel, the fluid-solid coupling between the piston and the gas in the piston cavity, and the transient gas flow in the exhaust pipe. The flow field coupling between the barrel and the piston cavity, and the flow field coupling between the piston cavity and the exhaust pipe were modeled, respectively, and the solution procedure was displayed. The MacCormack scheme and the Runge-Kutta method were used in the simulations, and the accuracy of the numerical method was validated by the published data. Next, the propagation law of the rarefaction wave in the barrel during the firing cycle was gained. The projectile velocity and the pressure at the projectile base and the breech were presented. Then, the distributions of the pressure, the gas velocity, and the solid velocity in the barrel of the piston-controlled side spray gun were compared with those in the traditional gun. Finally, the effects of the piston reset motion on the propellant gas flow and the recoil reduction efficiency were analyzed. The results show that compared with the situation ignoring the piston reset motion, when the muzzle velocity is reduced by 1.52%, the recoil reduction efficiency of the case considering the reset motion drops from 38.86% to 32.88% because the piston closes the rear spray channel during the reset process. Therefore, the reset motion of the piston cannot be ignored in the numerical simulation on the gun firing process.