Title : Turbulence in Wind Energy Applications
Contact : Martin Obligado
Abstract : Turbulence plays an important role in various aspects of wind energy. First of all, the atmospheric boundary layer in which wind turbines operate is naturally turbulent. This is shown to increase the fatigue loads, which decrease the lifetime of wind turbines. Second, the local aerodynamics of the rotor blades are impacted by the turbulence in the inflow. Third, a turbulent wake evolves downstream of a turbine which prompts the questions of the recovery of the velocity deficit and the turbulence evolution in the wake, as downstream turbines will operate in the conditions induced by upstream turbines.
This talk addresses some of the problems introduced above by showing recent results of wind tunnel studies, focusing mainly on the wind turbine wake. The wake of a wind turbine is investigated by means of hot-wire anemometry. The turbulence evolution within the wake will be discussed briefly, showing that the wake can be divided into different turbulence regions, among others a core region with strong features of homogeneous isotropic turbulence in the far wake. To improve the understanding of the wake dynamics, the connection to modeling of turbulent bluff body wakes will be drawn : While an analytical description of the velocity and the turbulence downstream of a wind turbine is still missing, such a model exists for the self-preserving axisymmetric turbulent wake. Here, it will be discussed to what extend this model can be applied to the wake of a wind turbine and it will be shown how engineering wake models can benefit from features of the bluff-body wake model.
Finally, some examples of aerodynamic investigations of airfoils in turbulent inflows will be also briefly presented.