In hypersonic flows, temperatures can be high enough to induce significant thermal and chemical nonequilibrium effects. However, few numerical studies on hypersonic boundary-layer receptivity have incorporated such real-gas effects. In this study, thermochemical nonequilibrium Direct Numerical Simulation (DNS) and Linear Stability Theory (LST) was used to investigate the boundary-layer receptivity of a 5-degree half-angle circular cone at Mach 5 to a freestream planar entropy pulse. Computations were performed for two cases with nose radii of 1 mm and 25 mm respectively. In the 1 mm nose radius case, LST predicted mode Fl to be the second mode with a large unstable supersonic mode region. The combined results of DNS and LST suggest that fast acoustic waves generated by the interaction of the planar entropy pulse with the shock excited the second mode. In the 25 mm nose radius case, preliminary DNS results did not indicate an unstable second mode region, but featured small regions of growth upstream likely due to forcing by waves generated by the shock-disturbance interaction. The second mode region in the 25 mm nose radius case is expected to occur further downstream.
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