The influence of exchange chemical reactions models on the parameters of air flows behind strong shock waves

Abstract

In the paper non-equilibrium flows of the 5-component air mixture N2/O2/NO/N/O behindstrong shock waves are numerically studied using the most accurate state-to-state approach. This approach describes strongly non-equilibrium vibrational and chemical kinetics in a flow under the assumption of equilibrium distributions over translation and rotation degrees of freedom. The characteristic times of vibrational and chemical relaxation are supposed to be of the same order as macroscopic parameters changing. The equationsfor vibrationallevelpopulations of molecular species and atomic numberdensities are coupled to the conservation equationsforimpulse and total energy and solved numerically for a1-Dquasi-stationary flow. Various vibrational energy transitions as well as dissociation, recombination and exchange reactions aretakeninto account.Fourdifferent modelsforstate-depending rate coefficients of exchange reactionsfor NO formation are used in numerical calculations and the comparison of the results obtained using various models is presented. The influence of a choice of a model for exchange reactions on level populations, mixture composition and gas temperature in the shock heated air mixture flow behind a shock wave is studied.

Keywords:

non-equilibrium kinetics in the air, vibrational distributions, chemical composition, dissociation, recombination, exchange reactions