Characterizing the transient growth mechanism on a hypersonic blunt body at a high angle of attack
2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. The effect of uniformly distributed surface roughness on the onset of boundary layer transition for a capsule geometry was experimentally investigated in a conventional hypersonic blowdown wind tunnel. The thin-walled scale model of the Orion Crew Exploration Vehicle used in this study was mounted at a 28 degree angle of attack in the Adjustable Contour Expansion wind tunnel. A test matrix of 24 runs was developed to investigate this application of transient growth scaling. Tests were conducted for four different Reynolds numbers at six uniform surface roughness height distributions. The tunnel was nominally set to Mach 6.0 and a total temperature of 430 K for each run. Infrared thermometry was used to measure the surface temperature distribution. Heat transfer rates generated through a series of surface temperature maps were processed into normalized Stanton number centerline plots. These plots directly indicated the boundary layer transition location. Oil flow visualization was conducted to show transition was not caused by other instability mechanisms. Analysis of the results indicated that transient growth scaling matched the experimental data.