TY - JOUR
T1 - Unsteady effects on a pitching airfoil at conditions relevant for large vertical axis wind turbines
AU - Brunner, C. E.
AU - Kiefer, J.
AU - Hansen, M. O.L.
AU - Hultmark, M.
N1 - Funding Information:
This work was funded by the United States National Science Foundation under grant CBET 1652583, and by the United States National Defense Science and Engineering Graduate Fellowship. The authors would like to thank Dan Hoffman at the Princeton Gas Dynamics Laboratory for his great help and advice in setting up the experiment.
Publisher Copyright:
© 2020 Published under licence by IOP Publishing Ltd.
PY - 2020/9/22
Y1 - 2020/9/22
N2 - Interest in offshore vertical axis wind turbines (VAWTs) has created a need to study VAWTs at much higher Reynolds numbers than they have previously been studied at. VAWTs are characterised by unsteady aerodynamics, and high Reynolds numbers have the potential to alter the blade aerodynamics significantly. Here, results are reported on an airfoil that is pitched sinusoidally around zero angle of attack at Rec = 1 × 106, at a reduced frequency k = 0.15 and amplitudes of 5? < α < 20?. Since the static stall angle is not exceeded, no stall effects occur. Nevertheless, lift, drag and moment coefficients show noticeable hysteresis. Despite the high amplitudes of oscillation, lift and moment coefficients show reasonable agreement with unsteady aerodynamic theories by Theodorsen and Motta et al. with regard to the width of the hysteresis loops, but have noticeably steeper slopes.
AB - Interest in offshore vertical axis wind turbines (VAWTs) has created a need to study VAWTs at much higher Reynolds numbers than they have previously been studied at. VAWTs are characterised by unsteady aerodynamics, and high Reynolds numbers have the potential to alter the blade aerodynamics significantly. Here, results are reported on an airfoil that is pitched sinusoidally around zero angle of attack at Rec = 1 × 106, at a reduced frequency k = 0.15 and amplitudes of 5? < α < 20?. Since the static stall angle is not exceeded, no stall effects occur. Nevertheless, lift, drag and moment coefficients show noticeable hysteresis. Despite the high amplitudes of oscillation, lift and moment coefficients show reasonable agreement with unsteady aerodynamic theories by Theodorsen and Motta et al. with regard to the width of the hysteresis loops, but have noticeably steeper slopes.
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U2 - 10.1088/1742-6596/1618/5/052065
DO - 10.1088/1742-6596/1618/5/052065
M3 - Conference article
AN - SCOPUS:85092340593
SN - 1742-6588
VL - 1618
JO - Journal of Physics: Conference Series
JF - Journal of Physics: Conference Series
IS - 5
M1 - 052065
T2 - Science of Making Torque from Wind 2020, TORQUE 2020
Y2 - 28 September 2020 through 2 October 2020
ER -