Numerical Simulation of Air Ionization in the RAM-C-II Flight Experiment

A two-dimensional numerical analysis of experimental data on the degree of ionization of a compressed layer near the surface of a spacecraft having the shape of a cone blunted in a sphere at a flight velocity of more than 7 km/s at altitudes of 61–81 km is presented. The discussed data of the flight experiment were obtained within the framework of the RAM-C research project. A model of nonequilibrium physicochemical processes in a compressed layer behind the front of the head shock wave, whose gas dynamics is described by the Navier–Stokes equations, is discussed. Various models of chemical kinetics are studied taking into account the processes of nonequilibrium dissociation and associative ionization. When using models of nonequilibrium dissociation, a good description of flight data on the electron density was achieved not only under conditions close to equilibrium, but also in the absence of thermalization of the internal degrees of freedom of high-temperature air molecules in the compressed layer.