Detailed thermochemical modeling of O₂-ar in reflected shock tube flows

Simulation results are presented of a set of vibrational nonequilibrium models with a range of fidelity and are compared to experimental data for several post-normal reflected shock test cases of O₂-Ar mixtures. Three different modeling approaches with a range of fidelity are used to determine the vibrational nonequilibrium of the post-normal shock flows. The twotemperature (2T) model is the widely used approach for hypersonic analysis and is presented as the computationally efficient, lower fidelity modeling approach in this work. In contrast, the full state-to-state (STS) model, a master equation approach for each vibrational state, is presented as the higher fidelity modeling approach. Both approaches have several available methods for obtaining rate data that are investigated. The STS approach uses rate data from the forced harmonic oscillator (FHO) approach and quasi-classical trajectory analysis (QCT) for the O₂-Ar, O₂-O, and O₂-O₂ systems. The simulated vibrational temperatures and state-specific vibrational level concentrations are compared to experimental measurements. The experimental measurements have a low level of uncertainty and allow for insight into the performance of the nonequilibrium modeling. A rate sensitivity study is also completed that shows how sensitive the results are to certain rates at each experimental condition.