Title: Influence of free-stream turbulence on the boundary layer stability of a wind turbine airfoil and near wake
Authors: Fava, Thales C. L.
Lobo, Brandon A.
Nogueira, P. A. S.
Schaffarczyk, Alois P.
Breuer, Michael 
Henningson, Dan S.
Hanifi, Ardeshir
Language: eng
Keywords: Transition;Turbulence;Stability
Subject (DDC): 000 Informatik, Information & Wissen, allgemeine Werke
500 Naturwissenschaften
600 Technik
Issue Date: 2023
Publisher: Bristol
Document Type: Article
Source: Journal of Physics: Conference Series 2505 (2023) 012002
Journal / Series / Working Paper (HSU): Journal of Physics: Conference Series
Volume: 2505(2023)
Issue: 012002
Page Start: 1
Page End: 10
Edition: IOP
Free-stream turbulence (FST) alters the boundary layer of wind turbine blades, changing the hydrodynamic stability and near wake. Large-eddy simulations (LES) of a blade section with a laminar separation bubble for several turbulence intensities (TI) and a Reynolds number of 10^5 are performed. The effects of boundary-layer streaks generated by FST on Tollmien-Schlichting (TS) and Kelvin-Helmholtz (KH) instabilities are analyzed with a model based on the parabolized stability equations (PSE). Two competing effects on flow stability are identified. The spanwise-averaged mean-flow distortion stabilizes primary TS/KH modes forincreasing TI. However, this contribution seems dominant only for TI ≥ 8.6%. For lower TI, the spanwise-oscillating distortion caused by streaks destabilizes the flow, and the growth rates of secondary modal instabilities increase with the streak amplitude. The destabilization occurs mainly at spanwise locations with negative streaks since the inflection point shifts away from the wall, enhancing inviscid instabilities. Inflection points in the spanwise direction formed by the streaks also contribute to the destabilization. The modal structures from PSE and LES agree. Finally, the trailing-edge near-wake coherent structures are more energetic for TI ≥ 8.6% due to the partial stabilization of modal instabilities, delaying the turbulent breakdown.
Open Access
Organization Units (connected with the publication): Strömungsmechanik 
Publisher DOI: 10.1088/1742-6596/2505/1/012002
Appears in Collections:3 - Reported Publications

Show full item record

CORE Recommender

Google ScholarTM




Items in openHSU are protected by copyright, with all rights reserved, unless otherwise indicated.