封闭水域内固体火箭发动机尾流结构数值研究

Numerical Study on Wake Structures of Underwater Solid Rocket Motor in Confined Space

关键词:  固体火箭发动机  封闭水域  气液两相流  激波运动  颈缩胀鼓  射流不稳定

Key words:  Solid rocket motor  Confined water space  Gas-liquid two-phase flow  Shock wave motion  Bulging and necking  Instability of jet

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，建立三维空间模型，忽略重浮力等体积力及燃气与水之间的换热传质，采用Realizable k-ε湍流模型与VOF（Volume of fluid）多相流模型，针对试验水箱内固体发动机在不同水深条件下的工作过程进行数值模拟，获得尾流流场燃气射流形貌，以及水箱壁面受力与压强振荡规律。研究结果表明：三维空间模型的仿真结果与试验结果较为符合；燃气泡的形貌结构及尾流场特性参数变化在受限空间内分布呈非轴对称性；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；深水条件下试验水箱壁面靠近喷管出口位置承受压强幅值更大，高背压环境中水箱壁面更易受到局部低频小幅压强冲击。

Abstract:

In order to investigate the wake field characteristics of underwater solid rocket motor in confined space， three-dimensional model was established for numerical studies which neglected the heat and mass transfer process between gas and water， and body forces such as gravity and buoyancy. Realizable k-ε turbulence model and VOF（Volume of fluid） multi-phase model were adopted to get the simulation results of solid rocket motor working process in confined space with different water depths. The gaseous jet feature of wake flow field beyond the nozzle exit was analysed and the oscillation of pressure on experimental water tank was monitored. The results indicate that the simulation results of the three-dimensional model are consistent with the experimental results. The shape of gas bubble and the pressure change rule of gaseous jets injected into water in confined space are non-axisymmetric. 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 bubble neck. The deeper the water is， the greater the pressure of the tank wall near the nozzle exit is. The tank wall is more susceptible to low-frequency and small-amplitude pressure oscillation under high back pressure.