Abstract
In this study, we validated a wind-turbine parameterisation for large-eddy simulation (LES) of yawed wind-turbine wakes. The presented parameterisation is modified from the rotational actuator disk model (ADMR), which takes account of both thrust and tangential forces induced by a wind turbine based on the blade-element theory. LES results using the yawed ADMR were validated with wind-tunnel measurements of the wakes behind a stand-alone miniature wind turbine model with different yaw angles. Comparisons were also made with the predictions of analytical wake models. In general, LES results using the yawed ADMR are in good agreement with both wind-tunnel measurements and analytical wake models regarding wake deflections and spanwise profiles of the mean velocity deficit and the turbulence intensity. Moreover, the power output of the yawed wind turbine is directly computed from the tangential forces resolved by the yawed ADMR, in contrast with the indirect power estimation used in the standard actuator disk model. We found significant improvement in the power prediction from LES using the yawed ADMR over the simulations using the standard actuator disk without rotation, suggesting a good potential of the yawed ADMR to be applied in LES studies of active yaw control in wind farms.
Highlights
The potential of applying unconventional control strategies seeking globally optimal power production for an entire wind farm has recently drawn increasing interest among researchers
In agreement with the wind-tunnel measurements (Figure 4a), the simulated wakes behind a yawed wind turbine parameterised by the yawed ADM parameterisation (ADMR) (Figure 4b) are deflected towards the downstream-inclined side of the rotor disk, and the wake deflection increases with the wind turbine yaw angle
Good agreement is found between the wake-centre trajectories obtained from wind-tunnel measurements and those computed from large-eddy simulation (LES) results for all yaw angles considered here
Summary
The potential of applying unconventional control strategies seeking globally optimal power production for an entire wind farm has recently drawn increasing interest among researchers. As the ALM computes the forces induced by each wind turbine blade, it can resolve more flow structures in the wake, such as tip vortices, than the standard ADM and the ADMR parameterisations. Using the velocity component normal to the rotor disk, Jiménez et al [12] parameterised the thrust force of a yawed wind turbine in a similar fashion to the standard ADM This parameterisation was further applied by Munters et al [13] and Boersma et al [14] to investigate control strategies for yaw and axial induction in wind farms for power optimisation. Bastankhah and Porté-Agel [19] developed a Gaussian analytical model for predicting the wake behind a yawed wind turbine based on the self-similarities of the velocity deficits and the wake skew angles.
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