TY - GEN
T1 - Free-stream turbulence effects on the flow around an s809 wind turbine airfoil
AU - Torres-Nieves, Sheilla
AU - Maldonado, Víctor
AU - Lebrón, José
AU - Kang, Hyung Suk
AU - Meneveau, Charles
AU - Castillo, Luciano
N1 - Publisher Copyright:
© Springer-Verlag Berlin Heidelberg 2012.
PY - 2012
Y1 - 2012
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85035140461&partnerID=8YFLogxK
U2 - 10.1007/978-3-642-28968-2_59
DO - 10.1007/978-3-642-28968-2_59
M3 - Conference contribution
AN - SCOPUS:85035140461
SN - 9783642289675
T3 - Springer Proceedings in Physics
SP - 275
EP - 279
BT - Progress in Turbulence and Wind Energy IV - Proceedings of the iTi Conference in Turbulence 2010
A2 - Talamelli, Alessandro
A2 - Peinke, Joachim
A2 - Holling, Michael
A2 - Oberlack, Martin
A2 - Castillo, Luciano
PB - Springer Science and Business Media, LLC
T2 - 4th Conference on Turbulence, iTi 2010
Y2 - 19 September 2010 through 22 September 2010
ER -