An efficient multi-temperature approach to simulation of non-equilibrium oxygen chemistry

This work aims to construct a reduced-order model to capture strong non-equilibrium states of the internal energy levels of O₂ (X3Σ⁻_g) and apply it to CFD simulations for a double-cone case. To this end, a multi-temperature coarse-grained modeling (CGM) approach applied to state-to-state kinetics (StS), enabled to differentiate internal temperature from the translational temperature, is developed to model the dynamics of O₂ + O chemical system. Given the high computational cost associated with StS scattering calculations of diatom-diatom systems, the multi-group maximum entropy linear model (MGMEL) approach which combines the Quasi- Classical Trajectory (QCT) calculations with the CGM is used to obtain the rate constants and energy transfer coefficients for O₂ + O₂ chemical system. A mixture of the two chemical systems is then used to perform several 0-D isothermal, 0-D adiabatic and 2-D Navier-Stokes CFD calculations. Accurate and efficient simulation results have been demonstrated in comparison to the benchmark data from literature.