Cylinder-Induced Hypersonic Transitional Shock Wave Boundary Layer Interactions: Pressure Fluctuations and Thermal Loading
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2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. Vibrational and thermal loads constitute two of the most relevant surface factors affecting hypersonic vehicle design. These quantities were experimentally investigated for a canonical 3-D shock wave boundary layer interaction flow at Mach 6, where the interaction was varied from laminar, through transitional, to turbulent. The model consisted of a 2-D wedge with a cylindrical shock generator mounted on the surface downstream of a spanwise array of boundary layer trips. Fast response Kulite and PCB transducers measured surface pressure fluctuations throughout the interaction. Spectra from the baseline configuration (untripped, no shock generator) indicated content near 40 kHz, which is the expected frequency for the second mode instability. The addition of the trips promoted a 115 kHz instability that transitioned near Re=7x106 m-1. The presence of the shock generator added low-frequency 1.0-1.5 kHz content, with an energy level about an order of magnitude higher than the baseline boundary layer flow, from the separation shock motion. Modal growth was observed just downstream of separation, and root mean square fluctuations markedly increased closer to the base of the cylinder. Infrared thermography provided insight regarding the extent of elevated heating, and the regions of maximum heating, and corroborated some flow features from the schlieren photography. Notably, the supersonic jet prompted film coefficient values in excess of 700 Wm-2 K-1 on the cylinder surface. Fluctuation levels and heat transfer values were dramatically reduced by sweeping the cylinder 15 or 30 degrees back from perpendicular.
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22nd AIAA International Space Planes and Hypersonics Systems and Technologies Conference
