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Turbulence Amplitude Amplification in an Externally Forced, Subsonic Turbulent Boundary Layer

Ranade, Piyush and Duvvuri, Subrahmanyam and McKeon, Beverley and Gordeyev, Stanislav and Christensen, Kenneth and Jumper, Eric J (2019) Turbulence Amplitude Amplification in an Externally Forced, Subsonic Turbulent Boundary Layer. In: AIAA JOURNAL, 57 (9). pp. 3838-3850.

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Official URL: https://dx.doi.org/10.2514/1.J057871


Experimental studies of the changes in turbulence characteristics inside a boundary layer due to external forcing were performed using hot-wire anemometry. The forcing was created by a periodically forced shear layer that was external to a compressible subsonic turbulent boundary layer. The convecting coherent structures in the shear layer create a concomitant unsteady pressure and velocity field and provide an external disturbance for the turbulent boundary layer on the wall of the tunnel close to the forced shear layer. Both the pressure and velocity fluctuations inside the boundary layer were simultaneously measured along with the forcing signal, and a phase-locked analysis was performed. Regions of amplified turbulence inside the boundary layer were observed. Near the wall, the region of amplified turbulence was slightly upstream or lagging of the external forcing and away from the wall it was downstream or leading the forcing signal. Analysis of the convective speeds in the region of amplified turbulence supported the existence of the critical layer inside the wake region of the boundary layer, and the critical layer is believed to be responsible for the amplified levels of the turbulence in the wake region. Various modulation and amplification correlation coefficients were computed and analyzed, and the results also indicated the presence of the critical layer. Examination of the phase-locked turbulence revealed similarities between the turbulence amplitude amplification results due to these externally forced experiments and modulation response of an internally forced, subsonic boundary layer in the literature.

Item Type: Journal Article
Publication: AIAA JOURNAL
Additional Information: 54th AIAA Aerospace Sciences Meeting / AIAA Science and Technology Forum and Exposition (SciTech), San Diego, CA, JAN 04-08, 2016
Department/Centre: Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited: 09 Jan 2020 06:56
Last Modified: 09 Jan 2020 06:56
URI: http://eprints.iisc.ac.in/id/eprint/64310

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