Transport coefficients for high-temperature nonequilibrium air flows

A transport coefficient model based on the first approximation of the Chapman-Cowling theory was implemented into the URANUS nonequilibrium Navier-Stokes code to predict reentry flows more accurately. This model is compared to the widely used, simplified model of Gupta and Yes. The simplifications used to obtain the latter model are described in detail. The transport coefficients computed with both methods differ by up to a factor of two in the case of partially ionized air under equilibrium conditions. Therefore, the new model allows a more accurate description of the thermochemical relaxation in the shock region of significantly ionized, high-temperature hows. The differences in surface heat fluxes between the new model and the model of Yos and Gupta are smaller than 4%.