Validation of vibration-dissociation coupling models in hypersonic non-equilibrium separated flows

Abstract

The validation of recently developed models of vibration-dissociation coupling is discussed in application to numerical solutions of the Navier–Stokes equations in a two-temperature approximation for a binary N2/N flow. Vibrational-translational relaxation rates are computed using the Landau–Teller formula generalized for strongly non-equilibrium flows obtained in the framework of the Chapman–Enskog method. Dissociation rates are calculated using the modified Treanor–Marrone model taking into account the dependence of the model parameter on the vibrational state. The solutions are compared to those obtained using traditional Landau–Teller and Treanor–Marrone models, and it is shown that for high-enthalpy flows, the traditional and recently developed models can give significantly different results. The computed heat flux and pressure on the surface of a double cone are in a good agreement with experimental data available in the literature on low-enthalpy flow with strong thermal non-equilibrium. The computed heat flux on a double wedge qualitatively agrees with available data for high-enthalpy non-equilibrium flows. Different contributions to the heat flux calculated using rigorous kinetic theory methods are evaluated. Quantitative discrepancy of numerical and experimental data is discussed.