3D Shear layer simulation model for the mutual interaction of wind turbine wakes: Description and first assessment

Other literature type English OPEN
Trabucchi, Davide ; Vollmer, Lukas ; Kühn, Martin (2017)
  • Journal: (issn: 2366-7451, eissn: 2366-7451)
  • Related identifiers: doi: 10.5194/wes-2017-1
  • Subject:
    arxiv: Physics::Accelerator Physics | Physics::Plasma Physics | Physics::Fluid Dynamics

The number of turbines installed in offshore wind farms has strongly increased in the last years and at the same time the need for more precise estimation of the wind farm efficiency. In this sense, the interaction between wakes has become a relevant aspect for the definition of a wind farm layout, for the assessment of its annual energy yield and for the evaluation of wind turbine fatigue loads. For this reason, accurate models for multiple wakes are a main concern of the wind energy community. Existing engineering models can only simulate single wakes which are superimposed when they are interacting in a wind farm. This method is a practical solution, but it is not fully supported by a physical background. The limitation to single wakes is given by the assumption that the wake is axisymmetric. As alternative, we propose a new shear layer model which is based on the existing engineering wake models, but is extended to simulate also non-axisymmetric wakes. In this paper, we present the theoretical background of the model and two application cases. First, we proved that for axisymmetric wakes the new model is equivalent to a commonly used engineering model. Then, we evaluated the improvements of the new model for the simulation of multiple wakes using large eddy simulations as reference. In particular, we report the improvements of the new model in comparison to a sum-of-squares superposition approach for the simulation of three interacting wakes. The remarkable lower deviation from the reference in terms of rotor equivalent wind speed considering two and three interacting wakes encourages the further development of the model, and promises a successful application for the simulation of wind farms.
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