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Low-frequency unsteadiness of swept shock-wave/turbulent-boundary-layer interaction

Published online by Cambridge University Press:  11 October 2018

Xin Huang  and
David Estruch-Samper Open the ORCID record for David Estruch-Samper [Opens in a new window]
Xin Huang
Affiliation:
Department of Mechanical Engineering, National University of Singapore, 117575, Singapore
David Estruch-Samper*
Affiliation:
Department of Mechanical Engineering, National University of Singapore, 117575, Singapore
*
†Email address for correspondence: mpedavid@nus.edu.sg
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Abstract

High-speed turbulent boundary-layer separation can lead to severe wall-pressure fluctuations, often extending over a swept shock region. Having noted the shear layer’s influence within axisymmetric step flows, tests go on to experimentally assess the unsteadiness of a canonical swept separation, caused by a slanted $90^{\circ }$-step discontinuity (with varying azimuthal height) over an axisymmetric turbulent boundary layer. Results document an increase in shock pulsation frequency along the swept separation region ($\unicode[STIX]{x1D6EC}\leqslant 30^{\circ }$ sweep angles) – whereby the recirculation enables downstream feedback via the reverse flow – as the local streamwise separation length is reduced. A link between the spanwise variation in the separation shock’s low-frequency instability and the downstream mass ejection rate, as large shear-layer eddies leave the bubble, is sustained. The local entrainment-recharge dynamics of swept separation are thereby duly evaluated.

JFM classification

Aerodynamics: Aerodynamics Boundary Layers: Boundary layer separation Aerodynamics: High-speed flow
Type
JFM Papers
Information
Journal of Fluid Mechanics , Volume 856 , 10 December 2018 , pp. 797 - 821
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Copyright
© 2018 Cambridge University Press 

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