TY - GEN
T1 - Transitional shock wave boundary layer interactions on a compression ramp at mach 4
AU - Threadgill, James A.S.
AU - Little, Jesse C.
AU - Wernz, Stefan H.
N1 - Funding Information:
This investigation has been made possible by the support of the Raytheon Company and is greatly appreciated. The authors also thank Sathyan Padmanabhan and Jorge Castro Maldonado who assisted with experimentation. The high-speed camera was graciously loaned by the University of Arizona Boundary Layer Stability and Transition Laboratory directed by Prof. S. Alex Craig.
Publisher Copyright:
© 2019, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.
PY - 2019
Y1 - 2019
N2 - Strong laminar/transitional Shock Boundary Layer Interactions (SBLIs) have been investigated in the Mach 4 vacuum driven wind tunnel at the University of Arizona, with supporting CFD analysis. Such flows are extremely susceptible to large-scale separation which can limit control authority on high-speed vehicles. The research community has heavily focused on turbulent interactions, leaving little understanding on how laminar/transitional cases scale with varying external parameters. Four ramp angles of 15◦, 18◦, 22◦, and 28◦ have been tested on a flat plate (unit Reynolds number Re1 = 4.56 × 106 1/m) with a range of external length scales (Rex varies between 1.2 × 105 and 2.5 × 105 at the ramp corner). The low-Reynolds number test conditions provide an excellent opportunity for supporting DNS/LES studies. Separation length L/δ0 scales mildly with Reynolds numbers, increasing proportionally with Re1/4 δ0. Transitional reattachment behavior is found on strong SBLIs, located furthest downstream. Upon observation with high-speed schlieren, the separation shock demonstrates low-frequency unsteadiness at StL = 0.025, consistent with turbulent SBLIs. Further analysis of the data shows no upstream influence and that motion of the shear layer and reattachment shock precede motion of the separation shock foot. In addition, a slow moving density disturbance within the bubble is observed to propagate towards the shock foot and directly lead to shock motion. This configuration represents an excellent opportunity to study dynamic mechanisms within SBLIs, through elimination of upstream effects.
AB - Strong laminar/transitional Shock Boundary Layer Interactions (SBLIs) have been investigated in the Mach 4 vacuum driven wind tunnel at the University of Arizona, with supporting CFD analysis. Such flows are extremely susceptible to large-scale separation which can limit control authority on high-speed vehicles. The research community has heavily focused on turbulent interactions, leaving little understanding on how laminar/transitional cases scale with varying external parameters. Four ramp angles of 15◦, 18◦, 22◦, and 28◦ have been tested on a flat plate (unit Reynolds number Re1 = 4.56 × 106 1/m) with a range of external length scales (Rex varies between 1.2 × 105 and 2.5 × 105 at the ramp corner). The low-Reynolds number test conditions provide an excellent opportunity for supporting DNS/LES studies. Separation length L/δ0 scales mildly with Reynolds numbers, increasing proportionally with Re1/4 δ0. Transitional reattachment behavior is found on strong SBLIs, located furthest downstream. Upon observation with high-speed schlieren, the separation shock demonstrates low-frequency unsteadiness at StL = 0.025, consistent with turbulent SBLIs. Further analysis of the data shows no upstream influence and that motion of the shear layer and reattachment shock precede motion of the separation shock foot. In addition, a slow moving density disturbance within the bubble is observed to propagate towards the shock foot and directly lead to shock motion. This configuration represents an excellent opportunity to study dynamic mechanisms within SBLIs, through elimination of upstream effects.
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U2 - 10.2514/6.2019-0343
DO - 10.2514/6.2019-0343
M3 - Conference contribution
SN - 9781624105784
T3 - AIAA Scitech 2019 Forum
BT - AIAA Scitech 2019 Forum
PB - American Institute of Aeronautics and Astronautics Inc, AIAA
T2 - AIAA Scitech Forum, 2019
Y2 - 7 January 2019 through 11 January 2019
ER -