The Hypersonic International Flight Research Experimentation program is a hypersonic flight test program. It successfully measured the three-dimensional transition front on a cone at angle of attack in hypersonic flight during its reentry. The test article consisted of a nonablating, 7 deg half-angle, axisymmetric cone with a small bluntness of 2.5 mm radius. During transition, angle of attack dropped from 13 to 5 deg and freestream unit Reynolds number increased from 2×106 to 8×106/m. Mach number during this time was approximately seven. Earliest transition, determined from fluctuating pressures, occurred on the leeward meridian, at Rex=3.1×106, α=13 deg, and M=7. Attachment line transition occurred at Rex=4.7×106, α=9 deg, and M=7. The latest transition occurred off the windward meridian at Rex=6.0×106 and [phi]=30 and 280 deg. Transition occurred at lower Reynolds numbers than the α=0 deg transition measured during ascent (Rex=11×106 at M=5.2). The azimuthally averaged transition Reynolds number determined from thermocouples was Rex=4.9×106. Away from the windward meridian, wind-tunnel transition occurred at lower Reynolds numbers than in flight. However, the decrement in transition Reynolds number due to wind-tunnel noise was not as severe as at zero angle of attack. Wind-tunnel windward transition occurred at a higher Reynolds number than in flight. It is posited that the destabilizing effects of wall cooling, which was higher in flight (Tw/T0=0.18) than in ground test (Tw/T0=0.56), outweighed the effect of wind-tunnel noise on the windward transition. High-bandwidth instrumentation recorded periodic pressure fluctuations approximately midway between the windward and leeward meridians before transition. However, they could not be positively identified as a crossflow instability. Presented as Paper 2012-1087 at the AIAA Aerospace Sciences Meeting, Nashville, TN, 9-12 January 2012
Boundary-Layer Transition Experiment During Reentry of HIFiRE-1
Journal of spacecraft and rockets ; 52 , 3
2015
Article (Journal)
English
HIFiRE-1 Data Analysis: Boundary Layer Transition Experiment During Reentry
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