Large eddy simulation of the curled wake structure behind a yawed wind turbine

The yaw control strategy of wind turbines for wake-redirection is used to avert the turbine wake to minimize the velocity deficit footprint on the downstream turbines in attempt to increase the collective power generation of wind farms. The wake behind a yawed wind turbine undergoes a deflection and deformation process from an elliptical structure to a curled wake. To maximize the benefits of the wake-redirection approach, a better understanding of the transforming wake structure is essential. In the present study, the curled wake generated by various yaw inputs were investigated to characterize the wake deflection and its deformation. The large-eddy simulation and the actuator disk model augmented with rotation were used to simulate the wake behind a yawed wind turbine exposed to an atmospheric flow. The profiles of velocity and turbulent intensity within the wake region were compared with the previous experimental data. The transition from an elliptical structure to the kidney-shape was found to be attributed to the wake rotation and the counter-rotating vortex pair generated by the yawed rotor.