Experimental Study on Hypersonic Boundary Layer Mack Second Mode Instability Affected by Nose Tip Geometry

초록

In hypersonic vehicles, boundary-layer transition results in a significant increase in heat flux, leading to surface damage and performance degradation. This study examines the transition behavior on a 7 degrees half-angle, 610 mm-long cone using the Inha Hypersonic Shock Tunnel at Mach 6.81, with 0.1 mm Sharp and 5.0 mm Blunt tips across Reynolds numbers ranging from 3.3 to 11.0 & times; 10(6)/m. Power Spectrum Density and Time-developing power spectrum analyses, based on PCB pressure sensors along with Schlieren images, were employed to detect Mack second-mode instabilities and turbulent energy dispersion. For the Sharp tip, increasing the Reynolds number resulted in an earlier transition and a more pronounced Mack mode. Conversely, the Blunt tip delayed the transition, maintaining laminar flow at 4.4 & times; 10(6)/m and exhibiting downstream transition with reduced instability amplitude at 11.0 & times; 10(6)/m. These findings validate the impact of tip bluntness on transition behavior.

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