An Electronic State-to-State Analysis Method for nonequilibrium Air Flows

Abstract

In the present study, the three different electronic state-to-state methods were developed to analyze the nonequilibrium air flows behind the strong shock wave. In the first approach, denoted as ‘2T-QSS’, the conventional two-temperature (2T) model was utilized together with the quasi-steady state (QSS) assumption. In the second and the third methods, a three-temperature (3T) model was devised, and was tightly coupled with the atomic electronic master equation (EM), and the atomic as well as the diatomic EMs. They were denoted as ‘EM-atom’ and ‘EM-air’, respectively. Then, the predictions of the measured nonequilibrium radiation were performed for the three different flow conditions. In the first case, the influence of the diatomic non-Boltzmann distributions was critical. As a result, the EM-air model represented the best accuracy for predicting the initial rising rate and the peak value of the intensity. On the other hand, the 2T-QSS approach highly overestimated. In the second and the third cases, the spatial intensity distributions were more accurately predicted by the EM coupled models than the 2T-QSS approach, which failed to determine the proper starting position of the intensity increment. It was found that the nonequilibrium air flows can be predicted with an improved accuracy by using the EM coupled models comparing with the conventional 2T-QSS approach.