DSMC Modeling of NO Formation for Simulation of Radiation in Hypersonic Flows

Abstract

The current work has implemented in DSMC discrete vibrational levels of N2 and the transitions between them as well as the dissociation of nitrogen molecules and formation of NO molecules. The vibration-translation transition models assessed include LarsonBorgnakke, Schwartz-Slawsky-Herzfeld (SSH), and Forced Harmonic Oscillator (FHO) models. Total Collision Energy (TCE) and QCT models for the NO formation reaction are considered. The effect of the models on the flowfield is explored and comparisons are made. Improved NO radiation modeling is proposed by employing quenching rates from most-recent experiments. Comparisons of electronic state populations and the corresponding radiative spectra among the neutral-impact excitation models are made. It is validated that vibrational band spectral structure of NO radiation is strongly influenced by vibrational temperature profiles along a line of sight.

State Specific Vibrational Relaxation and Dissociation Models for Nitrogen in Shock Wave Regions

“…[1][2][3] For Mach numbers in the range of 13 -20 (moderate Mach numbers), there is sufficient molecular nitrogen dissociation such that the fidelity of the dissociation and vibrational-translational (V-T), vibrational-vibrational (V-V) models significantly impacts the shocklayer features. For lower Mach numbers, 4 there is insufficient dissociation for the dissociation models to play an important role whereas for high Mach numbers (greater than 20, i.e. Stardust reentry flow 5 ), complete dissociation occurs.…”