Performance of the NREL S826 airfoil at low to moderate Reynolds numbers — A reference experiment for CFD models
Journal article, Peer reviewed
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Date
2019Metadata
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Original version
European journal of mechanics. B, Fluids. 2019, 75 180-192. 10.1016/j.euromechflu.2018.10.002Abstract
Lift, drag and surface pressure measurements are performed on a wing section
of the NREL S826 wind turbine airfoil at eight Reynolds numbers ranging from
0:5_105 to 6:0_105. Alongside with the measurements two types of Reynolds
averaged Navier-Stokes (RANS) simulations are performed, one of which in-
cludes a laminar to turbulent transition model. The lift and drag characteristics
are observed to be dominated by low Reynolds number e_ects for Re < 0:7_105,
related to the presence of laminar separation bubbles (LSBs) on the suction side
of the pro_le. For Re _ 0:7_105 the airfoil's performance is rather independent
of the Re-number for the present free stream turbulence intensities, while sig-
ni_cantly higher peak lift is measured than in earlier experiments on the same
airfoil. At high angles of attack, strong three-dimensional spanwise surface ow
distribution reminiscent of a single stall cell is observed. The RANS simulations
in a two-dimensional domain including the Langtry-Menter ����� Re_ transition
model accurately predict lift and drag coe_cients as long as the ow is fairly
attached. Further, the ����� Re_ model simulations are observed to predict the
location and average size of the LSBs in this region.