How Do Uncertain Flow Parameters Affect the Shock Pattern in Nonequilibrium Gas Flows Around Blunt Bodies?

We investigate the role of uncertainty in hypersonic inviscid gas flows with thermochemical nonequilibrium. Namely, we numerically assess how the uncertainty affecting flow parameters influences the flow pattern developing around blunt bodies. The Computational Fluid Dynamics model is that implemented within the SU2-NEMO open-source suite, coupled to the Mutation++ library to accurately simulate the interaction mechanisms typical of hypersonic flows. The solver is also coupled to an in-house grid adaptation tool, for improving the resolution of simulations. The considered test case consists in a hypersonic air flow, at Mach number of 9 and a freestream pressure of 390 Pa, over a double-wedged geometry. For a freestream temperature of either 1000 K or 300 K, we first provide a benchmark comparison of our predictions against data available in literature. For a freestream temperature of 1000 K, we forward propagate the uncertainty affecting the freestream Mach number, temperature, pressure and fluid composition, by means of a Polynomial Chaos Expansion approach. The uncertainty quantification analysis allows for obtaining the statistical low-order moments associated to numerical predictions from the computational model. Moreover, we carry out a sensitivity analysis and obtain some physics insights concerning the complex flow developing around the targeted geometry.