不同发射深度下导弹水下点火气水流体动力计算

从流体动力角度研究了不同发射深度下，导弹水下点火这一非定常非线性过程。整个系统分为外部水流场、喷管流场和燃气泡流场三个区域加以考虑。水流场采用不可压势流模型，用边界元方法求解；喷管内流场采用非定常一元流动模型，用特征线差分法求解，并设置了激波检测功能；燃气泡采用基于质量和能量守恒的零维计算模型。在时间域中用步进方法实现了三个流场的耦合求解。给出了四种发射深度下的数值计算结果，展示了导弹水下点火的一

Gas-Water Dynamic Calculation for the UnderwaterIgnition of a Missile at Different Depths

ocusing on the fluid dynamic characteristics, an unsteady, nonlinear process of the underwaterigintion of a missile at different water depths is investigated in this paper. The whole flow system is di-vided into three regions: the external water flow resion , the gas flow in the nozzle and the gas flow ina bubble formed in water by sas inJection from the nozzle. For the water flow region, negiecting thecompressibility, the viscosity and the surface tension in the bubble interface, the potential flow modeland the boundary element method is used. The nonlinear dynamic and kinetic boundary condition atthe bubble interface is written in begransian form. The Riabouchinshy image body is first introducedin the unsteady flow for the closure of bubblefs free-surface. Por the gas flow in the nozzle, one-di-niensional unsteady flow model and the characteristics method with inverse marching finite differencegrids are adopted. with which the shock position can be detected. In addition, a zero-dimensional mod-el based on the niasa and energy conservation is utilized for the gas flow in the bubble. Then by usingthe time-steping methed, the three coupled flow fields are solved numerically in the time domain.Computational results are provided for four cases of different water depths and the results reveal someprincipal properties of the underwater ignition of missiles. It is shown that the Mech-numbre at the exitof nozzle is very complex before the gas flow in the nozzle reaches stability , after that, the propellantforce of missile ensine can exactly be represented in a sinsle form. The water depth strongly effectsthe presaure in the bubble. When the water depth increases, the pressure in the bubble is pulsing,which induces the pulsation of hydredynamics force on the missle.