NONEEQUILIBRIUM PHNOMENA OF LOW-DENSITY JETS IN SPACE

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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.