Comparisons of Quantitative Heat Flux on a Hypersonic Expansion-Compression Geometry

Infrared thermography (IRT) derived-heat flux maps have been obtained on a 7° cone-slice-ramp (CSR) model in the Sandia Hypersonic Wind Tunnel at Mach 5 and 8 to capture the three-dimensional shock boundary-layer interaction region. The IRT technique and heat flux derivation were validated using Mach 8 stagnation point heating on a PEEK hemisphere model to within 5% of the Fay and Riddell theoretical prediction. Simultaneous flow visualization of the CSR flow field was acquired using high-speed schlieren imaging to estimate the slice boundary layer separation and resultant shear layer reattachment on the ramp, which were compared to surface oil flow visualization and the IRT. The results were quantitatively compared to Reynolds averaged Navier Stokes (RANS) computational fluid dynamic (CFD) simulations to understand the effect of different turbulence models on the predicted separation size and peak heat flux levels. It was found that both models struggled to predict peak heating at reattachment and accurate separation locations, though the Spalart-Allmaras (SA-neg) model demonstrated superior overall quantitative agreement while the Shear Stress Transport (SST-V) model was able to resolve more complex heating patterns and separation features exhibited in the experimental IRT results.