FEASIBILITY STUDY OF MAGNETOHYDRODYNAMICS ACCELERATION OF UNSEEDED AND SEEDED AIR-FLOWS

Nonequilibrium, reacting, ionized gas flow modeling is used to study t he feasibility of magnetohydrodynamics (MHD) acceleration of airflows for the energy addition wind tunnel, The kinetic model incorporates eq uations of one-dimensional magnetogasdynamics, the master equation for vibrational level populations of diatomic species, equations of chemi cal and ionization kinetics, and the Boltzmann equation for electrons. The model is validated by comparison with the experiments in MHD acce lerators. Calculations are made for two accelerator schemes, tile firs t using an electron beam to sustain nonequilibrium ionization in unsee ded air and the second using alkali seeded air, The results are compar ed with the target flow parameters of the transatmospheric vehicle. Th e unseeded how calculations show that the use of external ionization i n high-pressure MHD flows is inefficient due to fast electron loss. Al though at low pressures external ionization allows substantial increas e of the flow total enthalpy, the obtained test section pressure is mu ch lower than required, and the flow quality is poor, Calculations for alkali-seeded Rows predict test section flow parameters closer to the target values, with O atom and NO concentrations lower than in the e- beam-controlled hows. Flow stability is analyzed using the linear stab ility theory. A thermodynamic energy addition criterion is used to dem onstrate the advantage of direct kinetic energy increase in MHD accele ration over thermal energy addition methods.