Non-equilibrium nozzle flow of a partially ionized gas
Thames, Joe Murray
Wierum, Frederick A.
Master of Science
The one-dimensional non-equilibrium flow of a pure monatomic plasma in a deLaval nozzle has been numerically calculated. The plasma has been considered as a mixture of perfect gases whose components are reacting chemically with finite reaction rates. Two simultaneous differential equations describing the gas dynamic behavior, coupled with non-equilibrium chemistry, have been derived. A general recombination coefficient which allows variation of both temperature and density dependence has been used. The numerical integration was started from an equilibrium flow of helium for which the stagnation temperature = 28,522°K, the stagnation degree of ionization = .50, and the critical mass flow rate = 1.35951 gm/sec. The nozzle used was quasi-conical with a half angle of 30 degrees and a throat area of 1/8 inch. The gas used was helium. The assumptions were that the flow was steady, inviscid, adiabatic, and one-dimensional; that there were no body forces present; that diffusion currents were negligible; and that chemical reactions with the nozzle walls were negligible. The results obtained specifically indicate that if the integration is started from an equilibrium flow in which the frozen Mach number is less than unity, there is a unique starting point for which the flow will become supersonic. The results also indicate that the effects of density dependence of the reaction rate can be significant.