Effects of non-maxwellian distributions on shock-layer radiation from hypersonic reentry flows

A study was conducted to investigate effects of non-Maxwellian distributions on shock-layer radiation from hypersonic reentry flows. A description of the quasi-steady-state assumption (QSS) was presented for the investigations. It was found that the atomic electronic states were excited and de-excited by collisional and radiative processes under nonequilibrium flow conditions, which were described by a rate equation approach to calculate the electronic state populations. The QSS solution of the system of rate equations was also obtained in addition to modeling these processes directly in the DSMC simulations to calculate the populations of the electronically excited state species. The steady-state DSMC simulations without electronic excitation mechanisms were also used to provide local electron temperature and concentrations, along with atomic and ion number densities to compute the rates required to evaluate the QSS expression.