小推力发动机高空羽流场数值模拟

以小推力发动机的高空羽流场为研究对象，完成了氮气流的DSMC方法数值模拟研究，对计算的可靠性进行了实验对比验证，分析了高空羽流场特性及高空稀薄流动的非平衡效应。结果表明，用DSMC方法与加密网格技术结合可有效模拟高空羽流场，且必须计及气体非平衡效应。皮托压力的数值结果与实验符合得很好。

NUMERICAL INVESTIGATIONS OF A SMALL THRUSTER PLUME AT HIGH ALTITUDE

A small thruster plume flow of nitrogen at high altitude is numerically investigated by using a DSMC method. A hard sphere model is employed to simulate nitrogen molecule. The collision frequency is calculated through using the random sampling frequency method for each cell. An axisymmetrc model based on a two-dimensional modification is introduced to model the flow field. To raise the computation efficiency of the DSMC method, both a grid domain decomposition method and a local grid clustering technique are enforced. An inner flow numerical result is considered as the outflow conditions of the thruster, a escaping boundary condition is implemented at far-field boundary, and a perfect scatter reflection model is chosen as the solid wall boundary condition. Moreover, molecule rotation energy included in inner energy is considered besides translation energy. The reliability of the numerical method is demonstrated by comparing with the relevant experimental results. Both the properties of plume flow at high altitude and the nonequilibrium effect related to rarefied gases are analyzed. Results show that the DSMC method coupled with a fine grid technique is an effective approach for high altitude plume simulations, and that the nonequilibrium effect of gases must be numerically dealt with. Moreover, pitot pressures are given numerially in good agreement with measured data.