Parabolized Stability Equation Analysis of Crossflow Instability on HIFiRE-5b Flight Test

Basic state calculations were performed for the Hypersonic International Flight Research Experiment 5 geometry for both flight and wind-tunnel conditions using the US3D flow solver. Linear parabolized stability equation calculations were performed for the crossflow instabilities, and linear stability theory calculations were performed for the second-mode instabilities using the LASTRAC3d (the three-dimensional Langley stability and transition analysis code) stability suite. Conditions were chosen to represent the flight conditions at a time when a three-lobed transitional front was observed experimentally. Preliminary N-factor thresholds of N=18 for the second mode and N=10 for stationary crossflow provided a lower bound for the transitional N factor for the observed transitional front during flight conditions over much of the acreage of the vehicle. Applying the same criterion to conditions of recent wind-tunnel tests also reasonably reproduced observed transitional behavior, indicating that the relative physics were accurately captured.