the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Experimental analysis of the effect of dynamic induction control on a wind turbine wake
- 1Delft Center for Systems and Control, Faculty of Mechanical, Maritime and Materials Engineering (3mE), Delft University of Technology, Delft, The Netherlands
- 2Department of Aerodynamics, Wind Energy, Flight Performance and Propulsion, Faculty of Aerospace Engineering, Delft University of Technology, Delft, The Netherlands
- 1Delft Center for Systems and Control, Faculty of Mechanical, Maritime and Materials Engineering (3mE), Delft University of Technology, Delft, The Netherlands
- 2Department of Aerodynamics, Wind Energy, Flight Performance and Propulsion, Faculty of Aerospace Engineering, Delft University of Technology, Delft, The Netherlands
Abstract. Dynamic induction control (DIC) has proven to be an effective method of increasing the power output for a wind farm in both simulation studies and wind tunnel experiments. By pitching the blades of a wind turbine periodically, the recovery of the low velocity wake is accelerated, thereby increasing the energy available to downstream turbines. The wake itself of a turbine operating with DIC has not yet been studied experimentally. This paper presents a wind tunnel experiment where the wake of a wind turbine under periodic excitation is investigated. Using three-dimensional particle image velocimetry, the velocity field behind the turbine was reconstructed. Analysis of the velocity fields indicated that the available power in the wake increases when using DIC. This increase was partially due to a lower average thrust force experienced by the turbine with DIC. However, a large difference was seen between measurement results and actuator disk theory, indicating enhanced recovery of the wake is contributing to the increased energy. Instantaneous measurements visualizing the development of blade tip vortices also showed how the location of vortex breakdown, which is directly related to re-energizing the wake, shifts over time with DIC. We believe this shifting location is contributing to the enhanced wake recovery of DIC, providing more energy to downstream wind turbines.
Daan van der Hoek et al.
Status: final response (author comments only)
- RC1: 'Comment on wes-2021-162', Anonymous Referee #1, 25 Feb 2022
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RC2: 'Comment on wes-2021-162', Anonymous Referee #2, 14 Mar 2022
General Comments
This was a well done paper, clear writing, figures and paper structure. Believe the paper contributes very meaningfully to this area of research into dynamic axial control. The visualizations and physical explanations of the phenomena which enable DIC to increase energy available in the wake was very interesting to read and see.
Feel free to ignore this comment if it is not possible, but would a potential comparison be comparing the DIC results, to a change in the baseline controller such that it operates at the same steady Ct as the DIC controller as a supplement used in the paper of comparing to expectations from AD?
Do the authors have plans to test in a similar way the helix method of DIC?
Specific Comments
Introduction is complete and well establishes the relevant context for the paper
Page 5: Could you add a little more detail on the definition and meaning of the Strouhal number? Is 0.25 the theoretical value or an empirical selection? If empirical, is there a chance that a value selected using computer simulations might differ from a best choice for wind tunnels / field studies? (Reading ahead I see you do try a few so a little more initial context on this number would be helpful). Is there a theory as to which value should be best and why?
Page 11: How are you defining TI? Oscillation in the streamwise flow? Believe it could be an interesting comparison if making similar plots using stream-wise oscillations and cross-stream oscillations
Page 11: Fig 8: Would a difference row (as in Fig 7) be useful?
Page 16, section 3.4: If you were to look at similar visualizations as Fig 13 at Strouhal numbers where DIC was not effective, what would you see?   Would this change in the leapfrogging behavior not occur? Or would it change in a less beneficial way?
- AC1: 'Comment on wes-2021-162', Daan van der Hoek, 21 Apr 2022
Daan van der Hoek et al.
Daan van der Hoek et al.
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