Modeling of Rotational Nonequilibrium in Post-Normal Shock Flow Analyses

Abstract

Recent modeling of thermal nonequilibrium processes in simple molecules like hydrogen and nitrogen has indicated that rotational nonequilibrium becomes as important as vibrational nonequilibrium at high temperature. In this study, to analyze rotational nonequilibrium, the rotational mode is separated from the translational-rotational mode that is usually considered in two-temperature models. Then, the translational, rotational, and electron-electronic-vibrational modes are considered separately in describing the thermochemical nonequilibrium behind a strong normal shock wave. The energy transfer for each energy mode is described by recently evaluated relaxation time parameters including rotation-to-vibration energy transitions and state-to-state kinetics. One-dimensional post-normal shock flow equations are constructed with these thermochemical models, and post-normal shock flow calculations are performed for the conditions of existing shocktube experiments and various re-entry points. In analyzing the shock-tube experiments, it is shown that the present thermochemcial model is able to describe the rotational and electron-electronic-vibrational relaxation processes behind a strong shock wave.