Simulations of Non-Equilibrium Air Chemistry Compared To Hypersonic Wind Tunnel Experiments

Computational fluid dynamics simulations of hypersonic flow over a finite-span cylindrical test article are presented and compared to laser absorption spectroscopy measurements obtained in a high-enthalpy reflected shock tunnel. The experimental dataset consists of simultaneous measurements of rotational temperature, vibrational temperature and mass density of nitric oxide in the freestream and post-shock region surrounding the test article. The partially measured freestream along with computational fluid dynamics simulations of the shock tunnel nozzle are used to characterize the un-measured freestream properties required to set the boundary conditions for the test article simulations. Synthetic measurements are post-processed on the simulation results to convert simulation flow field data into a form that is more appropriate for comparison with the experimental line of sight laser diagnostic measurements. The computational fluid dynamics simulations use the Modified MarroneTreanor nonequilibrium chemical kinetics model and new vibrational relaxation time constants for five species air that are based on quantum chemistry calculations.