Method for Calculation of the One-dimensional Nonequilibrium Flow of a General Gas Mixture Through a Hypersonic Nozzle

Book excerpt: The work described is a continuation of that reported previously in AEDC-TN-61-65 (calculation of the one-dimensional nonequilibrium flow of air through a hypersonic nozzle). In particular, a method is presented for the exact numerical calculation of the one-dimensional nonequilibrium flow of a general gas mixture through a converging-diverging nozzle. General equations are given for a mixture of perfect gases with an arbitrary number of species undergoing an arbitrary number of chemical and vibrational rate processes. An inexact but accurate method, similar in form to the method employed in the nonequilibrium case, is also given for calculating the corresponding one-dimensional equilibrium flow. The numerical method of solution applicable to both cases is described, including a simple procedure for starting the nonequilibrium calculations from an equilibrium condition and an improved method for controlling integration step size. The factors that affect over-all computation time are discussed. A computer program for an IBM 7090 has been written for the general gas mixture. Specific calculations are reported for a model of air consisting of O, N, NO, N2, and O2 and including eight chemical reactions plus the vibrational processes of the three diatomic species.