Modeling of nitrogen monoxide formation and radiation in nonequilibrium hypersonic flows

The interactionbetweennitrogen vibrational-translational relaxationwith different chemistrymodels in a hypersonic shock is studied. The vibrational-translational transitionmodels considered include the Larsen-Borgnakke, Schwartz-Slawsky-Herzfeld, and forced harmonic oscillator models; and the nitrogen monoxide formation reaction was studied using the total collision energy chemistry model and reaction cross sections obtained from quasi-classical trajectory simulations. Using direct simulationMonteCarlo solutions that incorporate thesemodels, improved nitrogenmonoxide spectral radiation modeling was performed by employing quenching rates from recent experiments. Comparisons of electronic state populations and the corresponding radiative spectra for the different vibrational-translational and chemistrymodels are presented, and it is shown that the vibronic spectral structure of the nitrogenmonoxide radiation could provide a way to test the fidelity of the internal energy transfer and chemistry models.