Effect of electronic excitation on high-temperature flows of ionized nitrogen and oxygen mixtures behind strong shock waves

Abstract

Strongly non-equilibrium flows of reacting five-component ionized mixtures of nitrogen (N2/N+2 /N/N+/e−) and oxygen (O2/O+2 /O/O+/e−) behind the plane shock wave are studied taking into account electronic degrees of freedom of both neutral and ionized species. The kinetic scheme includes non-equilibrium reactions of ionization, dissociation, recombination and chargetransfer. Two test cases corresponding to the spacecraft re-entry (Hermes and Fire II experiments) are considered; fluid-dynamic variables, transport coefficients and heat flux are calculated, and different contribution to the heat flux are analyzed. The effect of electronic excitation on the heat transfer is governed by the competition of diffusion and heat conduction; it becomes weak if diffusive processes prevail. An important role of thermal diffusion in ionized flows is emphasized. The influence of dissociation rates on the heat flux is assessed.