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Amplification and structure of streamwise-velocity fluctuations in compression-corner shock-wave/turbulent boundary-layer interactions
Published online by Cambridge University Press: 31 January 2019
Abstract
In this work, we study the effect of the compression-corner angle on the streamwise turbulent kinetic energy (sTKE) and structure in Mach 2.8 flow. Krypton tagging velocimetry (KTV) is used to investigate the incoming turbulent boundary layer and flow over $8^{\circ }$, $16^{\circ }$, $24^{\circ }$ and $32^{\circ }$ compression corners. The experiments were performed in a 99 % $\text{N}_{2}$ and 1 % Kr gas mixture in the Arnold Engineering Development Complex (AEDC) Mach 3 Calibration Tunnel (M3CT) at $Re_{\unicode[STIX]{x1D6E9}}=1750$. A figure of merit is defined as the wall-normal integrated sTKE ($\overline{\text{sTKE}}$), which is designed to identify turbulence amplification by accounting for the root-mean-squared (r.m.s.) velocity fluctuations and shear-layer width for the different geometries. We observe that the $\overline{\text{sTKE}}$ increases as an exponential with the compression-corner angle near the root when normalized by the boundary-layer value. Additionally, snapshot proper orthogonal decomposition (POD) is applied to the KTV results to investigate the structure of the flow. From the POD results, we extract the dominant flow structures and compare each case by presenting mean-velocity maps that correspond to the largest positive and negative POD mode coefficients. Finally, the POD spectrum reveals an inertial range common to the boundary-layer and each compression-corner flow that is present after the first ${\approx}10$ dominant POD modes.
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- © Cambridge University Press 2019. This is a work of the U.S. Government and is not subject to copyright protection in the United States.
References
Mustafa et al. supplementary movie 1
8 degree corner instantaneous fluorescence exposures and corresponding velocity profiles.
Mustafa et al. supplementary movie 2
16 degree corner instantaneous fluorescence exposures and corresponding velocity profiles.
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