Large eddy simulation of hypersonic boundary layer transition on the hypersonic transition research vehicle model lifting body at high angles of attack

Large eddy simulations are performed to investigate transition of the hypersonic boundary layer over the Hypersonic Transition Research Vehicle lifting body at angles of attack of 7°, 9°, 11°, and 13°. The freestream Mach number is 6 with a unit Reynolds number of 1.0×107 m−1. Increasing the angle of attack drives a pronounced reorganization of the leeward flow topology, partitioning transition into a top region governed by a merged vortex converging near the centerline, and an outer shoulder region of persistent separation and crossflow. Transition in both regions shifts upstream with an increasing angle of attack. Simultaneously, the band of high friction in the top region contracts toward the centerline, while the footprint in the shoulder region splits from a single band into two, demonstrating a tendency toward multiple branches at the highest angle of attack. Spectra of the wall pressure and spectral proper orthogonal decomposition reveal that the earlier convergence and upward lifting of the top vortex core shift its dominant instability to lower frequencies. Concurrently, the shoulder region evolves into a compound system of two branches, featuring structures of high energy that are spatially separated yet spectrally coupled within the frequency band of the crossflow.