Predictions of nonequilibrium radiation: analysis and comparison with EAST experiments

We simulate the relaxation processes behind a strong shock by means of an electronically specific collisional radiative model for atomic species. Test conditions are taken from the experimental campaign carried out in the EAST facility in the framework of the NASA Crew Exploration Vehicle Aeroscience Project. The present work is committed to the partial validation of the collisional-radiative model against the recent experimental data. A direct comparison among experimental and simulated radiative intensity profiles shows a reasonable agreement even for the low pressure cases where the flow is in strong nonequilibrium condition. In the rapidly ionizing regime behind strong shock waves, the electronic energy level populations depart from Boltzmann distributions since the high lying bound electronic states are depleted. A detailed analysis of the elementary kinetic processes occurring in the relaxation zone revealed that improvement of the agreement among simulation and experiments can be obtained using the recent rate constant compiled by Frost et al..

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