Free-stream turbulence effects on the flow around an s809 wind turbine airfoil

Sheilla Torres-Nieves, Víctor Maldonado, José Lebrón, Hyung Suk Kang, Charles Meneveau, Luciano Castillo

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations


Two-dimensional Particle Image Velocimetry (2-D PIV) measurements were performed to study the effect of free-stream turbulence on the flow around a smooth and rough surface airfoil, specifically under stall conditions. A 0.25-m chord model with an S809 profile, common for horizontal-axis wind turbine applications, was tested at a wind tunnel speed of 10 m/s, resulting in Reynolds numbers based on the chord of Rec ≈ 182,000 and turbulence intensity levels of up to 6.14%. Results indicate that when the flow is fully attached, turbulence significantly decreases aerodynamic efficiency (from L/D ≈ 4.894 to L/D ≈ 0.908). On the contrary, when the flow is mostly stalled, the effect is reversed and aerodynamic performance is slightly improved (from L/D ≈ 1.696 to L/D ≈ 1.787). Analysis of the mean flow over the suction surface shows that, contrary to what is expected, free-stream turbulence is actually advancing separation, particularly when the turbulent scales in the free-stream are of the same order as the chord. This is a result of the complex dynamics between the boundary layer scales and the free-stream turbulence length scales when relatively high levels of active-grid generated turbulence are present.

Original languageEnglish
Title of host publicationProgress in Turbulence and Wind Energy IV - Proceedings of the iTi Conference in Turbulence 2010
EditorsAlessandro Talamelli, Joachim Peinke, Michael Holling, Martin Oberlack, Luciano Castillo
PublisherSpringer Science and Business Media, LLC
Number of pages5
ISBN (Print)9783642289675
StatePublished - 2012
Event4th Conference on Turbulence, iTi 2010 - Bertinoro, Italy
Duration: Sep 19 2010Sep 22 2010

Publication series

NameSpringer Proceedings in Physics
ISSN (Print)0930-8989
ISSN (Electronic)1867-4941


Conference4th Conference on Turbulence, iTi 2010


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