Assessment of thermochemistry modeling for hypersonic flow over a double cone

The influence of different assumptions for thermochemistry modeling in hypersonic flow over a double-cone geometry is investigated. A computational fluid dynamics analysis is used to study the double cone in three different thermochemical cases, nonequilibrium flow, equilibrium flow, and frozen flow, for four different mixtures of nitrogen and oxygen. Specific areas of interest include the thermochemistry model effects on the flowfield and surface properties. The resulting aerodynamic loads are compared with experiments and indicate that thermochemistry modeling assumptions play a significant role in determining surface properties. It is also shown that heat loading is more sensitive to thermochemical modeling than drag and suggests that an accurate measurement of surface heat transfer is of particular interest. Careful analysis also reveals that high-enthalpy and pure oxygen flows are particularly sensitive to the thermochemistry model assumed. Consistent overprediction or underprediction of pressure drag and heat load by all three chemistry models for most of the cases considered indicates a fundamental difference between the actual experiments and the simulations, thus limiting the usefulness of the double-cone data for validation of thermochemistry models.