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内容記述 |
Chemically nonequilibrium, quasi-one-dimensional flows of partially ionized, monatomic and diatomic gases through a convergent-divergent nozzle are studied theoretically. Condition at the plenum chamber, with which a nozzle of prescribed shape is connected, is assumed to be in chemical equilibrium. In the flow of monatomic gas, ionization-recombination nonequilibrium flow of argon is considered; degree of ionization, electron number density, pressure, density, species temperature, and velocity are calculated through the nozzle. Each species is assumed to have different temperature from other. The electron temperature is in excess of the ion and atom temperatures. An example is shown in which the ion temperature is in slight excess of the atom temperature far downstream. In the flow of diatomic gas, ionization-recombination, dissociation-recombination, and vibrational nonequilibrium flow of nitrogen is considered. The effects of charge transfer and dissociative recombination reactions are also taken into account. In the plenum chamber there exist five species: N2+, N, N2+, N+, and electron. Electron temperature is assumed to be different from those of heavier species, and an electron energy equation which includes e-N2, e-N, e-N2+, and e-N+ collision terms is solved together with species rate equations and macroscopic conservation equations. Species number densities, pressure, density, electron temperature, temperatures of heavy particles, vibrational energy of N2, Mach numbers, and velocity are calculated through the nozzle. Properties in dissociation-recombination equilibrium flow and perfect(frozen) flow of nitrogen are also calculated and some of them are compared with the nonequilibrium flow properties. The electron temperature considerably in excess of the temperature of heavy particles is again obtained. The flow velocity generally lies between the equilibrium and frozen velocities. However, at some region downstream the throat, the nonequilibrium flow velocity is in slight excess of the equilibrium velocity when the temperature is high and pressure is low at the plenum chamber. This phenomenon is ascribed to density decrement due to the heat release by recombination reactions. |
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