Modeling Fidelity for Oxygen Nonequilibrium Thermochemistry in Reflected Shock Tube Flows

Abstract

The results for a set of vibrational nonequilibrium models with a range of delity are compared to experimental data for several post-normal shock test cases. The present work focuses solely on oxygen ows with an emphasis on the modeling of O 2-O. The twotemperature (2T) model is the widely used approach for hypersonic analysis and is presented as the computationally ecient, lower delity modeling approach in this work. In contrast, the full state-to-state (STS), master equation approach is presented as the higher delity modeling approach. Both approaches have several available methods for obtaining rate data that are investigated. Specically, the 2T model is driven by the rates from Millikan-White (MW) as well as recently available rates that are derived from a detailed quasi-classical trajectory (QCT) analysis for the O2-O system. The STS model uses transition rates from the forced harmonic oscillator (FHO) model and dissociation rates from previous work for O2-O system. The O2-O system uses recently available QCT results for STS transitions and dissociation. The test case results show that capturing non-Boltzmann behavior in the vibrational population distribution is critical to accurate nonequilbirium modeling of hypersonic ows containing oxygen.