NONEEQUILIBRIUM PHNOMENA OF LOW-DENSITY JETS IN SPACE

得到了以下结果：1)建立了从孔口进入低压环境的自由射流结构的DSMC分析，从而揭示了不同Knudsen数下的自由射流结构。2)利用DSMC解决了空间射流冲击问题，对垂直、平行和斜向射流冲击流场进行了数值分析。数值计算结果与德国航空航天研究所的实验结果进行了比较，得到了较好的一致性。3)采用空气、平动温度、氮气振动温度、氧气振动温度、一氧化氮振动温度、一氧化氮离子振动温度和电子温度等六种温度模型，对电弧加热高温气体射流中的非平衡现象进行了数值研究。数值结果表明，热平衡存在。4)建立了共振增强多光子电离（REMPI）技术，研究了REMPI光谱的基本性质。推导了电离过程的模型，并从溶液中预测了离子电流。计算了理论REMPI光谱，并与实验结果进行了比较。5)利用激光诱导荧光法的流动可视化技术已经得到了发展，并应用于三维自由射流结构的研究。

The following results were obtained :1) The DSMC analysis for investigating the free jet structure issuing from an orifice into a low-pressure circumstance has been established, whreby the free jet structure for various Knudsen numbers has been revealed.2) Jet impingement problems in space have been solved using the DSMC and the flow fields of nomal, parallel and oblique jet impingements have been numerically analyzed. The numerical results have been compared with the experiments made in German Aerospace Research Establishment and good agreements have been obtained.3) Nonequilibrium phenomena in arc-heated high-temperature gas jet considered for an arc jet thruster and thermal protection system experiment have been numerically investigated using a six temperature model, namely in a case of air, translational temperature, nitrogen vibrational temperature, oxygen vibrational temperature, nitric oxide vibrational temperature, nitric oxide ion vibrational temperature and electron temperature. Numerical results show that there exists thermal nonequilibrium.4) REMPI (Resonantly Enhanced Multiohoton Ionization) technique has been developed and the fundamental properties of the REMPI spectra have been investigated. The modeling of the ionization process is derived and the ion current is predicted from the solution. In addition, the theoretical REMPI spectra are calculated and compared with the experiments.5) Flow visualization technique using a laser-induced fluorescence method has been developed and applied to the investigation of three-dimensional free jet structure.