高空羽流场的DSMC计算和实验研究

以小推力发动机的高空羽流场为研究对象，实现了高空小喷管氮气流DSMC方法数值模拟，验证了DSMC方法在高空膨胀流中的可用性，并在现有设备基础上，进行一组高空羽流试验，给出试验与计算的对比结果。结果表明：喷管出口附近能得到满意结果，由于实现设备能力所限，远场试验没有达到预期效果。

Experimental and numerical investigation of a high-altitude plume flow using DSMC method

The plume flows exhausted from a micro-nozzle of a low-thrust engine at high-altitude have been first simulated numerically through using a DSMC method. The feasibility of DSMC method on high-altitude expanded flows is tested. Nitrogen gas is considered. Molecule velocity field meets the Maxwell random distribution, and molecule locations near the nozzle are axisymmetric. Variation of molecule location with time is obtained by calculating molecule collision number and new molecule velocity. During molecule collision course, the transfer of both translation energy and rotation energy are assumed. A velocity modification of axisymmetric body is given. Molecule rotation relaxation probability function has a physical-DSMC form and its quanta effect is neglected. Then, a set of tests related to the high-altitude plume flows are implemented using available equipment. Comparison of experiment and calculation is also carried out. Results show that measure data near the nozzle are satisfactory, and that far field measure is not so good as to be expected due to the limitation of available equipment.