Preprints
https://doi.org/10.5194/wes-2021-65
https://doi.org/10.5194/wes-2021-65

  16 Aug 2021

16 Aug 2021

Review status: this preprint is currently under review for the journal WES.

Development of a Curled Wake of a Yawed Wind Turbine under Turbulent and Sheared Inflow

Paul Hulsman1, Martin Wosnik2, Vlaho Petrović1, Michael Hölling1, and Martin Kühn1 Paul Hulsman et al.
  • 1ForWind – Institute of Physics, University of Oldenburg, Küpkersweg 70, 26129 Oldenburg, Germany
  • 2University of New Hampshire, Department of Mechanical Engineering, S102 Chase Ocean Engineering Laboratory, 24 Colovos Road, Durham NH 03824, United States

Abstract. A potential technique to reduce the negative wake impact is to redirect it away from a downstream turbine by yawing the upstream turbine. The present research investigated the wake behaviour for three yaw angles [−30°, 0°, 30°] at different inflow turbulence levels and shear profiles under controlled conditions. Experiments were conducted using a model wind turbine with 0.6 m diameter (D) in a wind tunnel. A short-range dual-Doppler Lidar WindScanner facilitated mapping the wake with a high spatial and temporal resolution in vertical, cross-stream planes at different downstream locations and in a horizontal plane at hub height. This versatile equipment enabled the fast measurements at multiple locations in comparison to the well known hot-wire measurements. The flow structures and the energy dissipation rate of the wake were measured from 1D up to 10D, and for one inflow case up to 16D, downstream of the turbine rotor. A strong dependency of the wake characteristics on both the yaw angle and the inflow conditions was observed. In addition, the curled wake that develops under yaw misalignment due to the counter-rotating vortex pair was more pronounced with a boundary layer (sheared) inflow condition than for uniform inflow with different turbulence levels. Furthermore, the lidar velocity data and the energy dissipation rate compared favourably with hot-wire data from previous experiments with a similar inflow condition and wind turbine model in the same facility, lending credibility to the measurement technique and methodology used here. The measurement campaign provided a deeper understanding of the development of the wake at different inflow conditions, which will advance the process to improve existing wake models.

Paul Hulsman et al.

Status: open (until 01 Oct 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on wes-2021-65', Anonymous Referee #1, 17 Sep 2021 reply
  • RC2: 'Comment on wes-2021-65', Anonymous Referee #2, 17 Sep 2021 reply

Paul Hulsman et al.

Paul Hulsman et al.

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Short summary
Due to the possibility of mapping the wake fast at multiple locations with the Windscanner, a thorough understanding of the development of the wake is acquired at different inflow conditions and operational conditions. The lidar velocity data and the energy dissipation rate compared favourably with hot-wire data from previous experiments, lending credibility to the measurement technique and methodology used here. This will aid the process to further improve existing wake models.