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Wind Energy Science The interactive open-access journal of the European Academy of Wind Energy
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https://doi.org/10.5194/wes-2020-54
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/wes-2020-54
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

  20 Mar 2020

20 Mar 2020

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A revised version of this preprint is currently under review for the journal WES.

Laminar-turbulent transition characteristics of a 3-D wind turbine rotor blade based on experiments and computations

Özge Sinem Özçakmak1, Helge Aagaard Madsen1, Niels Nørmark Sørensen1, and Jens Nørkær Sørensen2 Özge Sinem Özçakmak et al.
  • 1DTU Wind Energy, Technical University of Denmark, Aerodynamic Design, Frederiksborgvej 399, 4000 Roskilde, Denmark
  • 2DTU Wind Energy, Fluid Mechanics, 2800 Lyngby, Denmark

Abstract. Laminar-turbulent transition behaviour of a wind turbine blade section is investigated in this study by means of field experiments and 3-D computational fluid dynamics (CFD) rotor simulations. The power spectral density (PSD) integrals of the pressure fluctuations obtained from the high frequency microphones mounted on a blade section are analyzed to detect laminar-turbulent transition locations from the experiments. The atmospheric boundary layer (ABL) velocities and the turbulence intensities (T.I.) measured from the field experiments are used to create several inflow scenarios for the CFD simulations. Results from the natural and the bypass transition models of the in-house CFD EllipSys code are compared with the experiments. It is seen that the bypass transition model results fit well with experiments at the azimuthal positions where the turbine is under wake and high turbulence, while the results from other cases show agreement with the natural transition model. Furthermore, the influence of inflow turbulence, wake of an upstream turbine and angle of attack (AOA) on the transition behaviour is investigated through the field experiments. On the pressure side of the blade section, at high AOA values and wake conditions, variation of the transition location covers up to 44 % of the chord during one revolution, while for the no wake cases and lower AOA values, variation occurs along a region that covers only 5 % of the chord. The effect of the inflow turbulence on the effective angle of attack as well as its direct effect on transition is observed. Transition locations for the wind tunnel conditions and field experiments are compared together with 2D and 3D CFD simulations. In contrast to the suction side, significant difference in the transition locations is observed between wind tunnel and field experiments on the pressure side for the same airfoil geometry. It is seen that the natural and bypass transition models of EllipSys3D can be used for transition prediction of a wind turbine blade section for high Reynolds number flows by applying various inflow scenarios separately to cover the whole range of atmospheric occurrences.

Özge Sinem Özçakmak et al.

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Özge Sinem Özçakmak et al.

Özge Sinem Özçakmak et al.

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Latest update: 13 Aug 2020
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Short summary
Accurate prediction of the laminar-turbulent transition process is critical for design and prediction tools to be used in the industrial design process, particularly for the high Reynolds numbers experienced by modern wind turbines. Laminar-turbulent transition behaviour of a wind turbine blade section is investigated in this study by means of field experiments and 3-D computational fluid dynamics (CFD) rotor simulations.
Accurate prediction of the laminar-turbulent transition process is critical for design and...
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