Influence of Environmental Disturbances on Hypersonic Crossflow Instability on the HIFiRE-5 Elliptic Cone
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2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. An experimental study was performed to examine environmental disturbance effects on crossfiow instability on a 2:1 elliptic cone, which is a canonical geometry with an extensive knowledge base. The present experiments were performed in the TAMU Mach 6 Quiet and ACE hypersonic wind tunnels. The wind tunnel data includes surface temperature/heat fiux maps and surface pressure fiuctuation spectra. The nominal freestream disturbances were less than 0.1% for Re/m = 6-10x106 in the Mach 6 Quiet Tunnel, and 0.5% for Re/m < 2.8x106 and 1.5% for Re/m > 3.0x106 in the ACE (conventional) Tunnel. The majority of data were acquired at zero incidence, with one case, in the M6QT, at 1-degree yaw. The transition process on the 2:1 elliptic cone was observed to vary both qualitatively and quantitatively across the freestream environmental changes. The high heat fiux crossfiow induced transitional fronts were altered in shape and occurred at significantly lower Reynolds numbers under noisy conditions. Modal content was observed in the crossfiow region across the free stream disturbance range for frequencies less than 500 kHz, including stationary waves. However, ACE, modal growth occurred at significantly lower Reynolds numbers and appeared to be directly triggered by the freestream content change due to the wind tunnel nozzle boundary layers transitioning. Higher spectral content (500 - 1000 kHz) was observable under quiet conditions, with only modest corresponding content under noisy conditions. The near centerline axial instabilities were excited first under noisy conditions, where the opposite was observed under quiet conditions.
