Uncertainty Quantification of Expanding High-Enthalpy Air Flows

In the present work, we study the sensitivity of expanding hypersonic air flows in the HEG facility with respect to the thermochemical relaxation rates and reservoir conditions, along with the impact of uncertainties in the rates and reservoir conditions on uncertainties of the free-stream parameters. A simplified 1-D formulation of the flow equations is utilized to allow for simultaneous variation of a large number (10) of uncertain parameters. The simulation results show large uncertainties in the vibrational temperature of oxygen and molar fractions of oxygen-containing species, mainly due to uncertainties in the reservoir parameters and data on thermochemical relaxation rates of molecular oxygen.