封闭水箱内发动机尾流特点研究

【作者】 俞点； 李世鹏；

【机构】 北京理工大学；

【摘要】 为了研究固体火箭发动机在封闭水域中工作时尾流场特性参数变化规律,建立三维几何模型,忽略重力等体积力,且不考虑燃气与水之间的换热,选用Realizable k-ε湍流模型,VOF多相流模型,压力求解采用PRESTO离散格式,体积分数方程采用Geo-Reconstruct格式,能量方程采用二阶迎风离散格式,针对不同水深条件(欠膨胀/完全膨胀/过膨胀)下的发动机在气水混合封闭域内的工作过程进行数值模拟。得出结论:对于给定的喷管,封闭水域内燃气泡形貌和尾流场压强变化规律呈现不完全对称分布;射流中心气路内部不稳定的激波运动宏观表现为射流界面的不稳定胀鼓和颈缩位置的后移;在模拟深水域情况下水箱内靠近喷管出口的舱体壁面承受了更大的压强,高背压环境下水箱壁面更易受到低频小幅压强振荡冲击,需要在实际水箱设计和试验中考虑。更多还原

【Abstract】 The flow structure of gaseous jets injected into water is key element which has an important influence on the characteristics of solid rocket motor used in submarine-launched vehicles. In order to study the flow field of solid rocket motor working in closed water, a 3 D geometric model which neglects volumetric forces such as gravity and the phase transitions is utilized for numerical simulation of the working process in closed water. Turbulence model and VOF multi-phase flow model are adopted to get the simulation results of wake field. The numerical simulation for under-expansion and over-expansion has been completed. The results indicate that, the shape of the gas bubble and the pressure change rule of gaseous jets injected into water do not exhibit a completely axisymmetric distribution; the unstable shock wave motion in the central gas path is macroscopically characterized by the unstable bulging of the jet interface and the backward displacement of the neck; the pressure of the tank wall which is near the nozzle outlet is greater; the wall of the water tank is more susceptible to low-frequency and small-amplitude pressure oscillation under high back pressure. The numerical calculation results can provide a theoretical reference for the actual water tank experiment.更多还原