Actuator grid method for turbulence generation applied to yawed wind turbines

The aerodynamics of yawed wind turbine wakes remains a major investigation topic, especially for the use of yaw angle in control strategies. Large-Eddy Simulations are employed here to study the influence of yaw and inflow conditions on the prediction of the wind turbine wake structure. A single wind turbine setup with different yaw angles and three different inflow conditions is investigated and discussed with respect to experimental data. The wind turbine blades are modeled using the actuator line method (ALM) while tower and nacelle are represented with a body-fitted unstructured mesh. The high levels of upstream turbulence, experimentally generated by turbulence grids, are emulated here with oscillating ALM. Such approach demonstrates to be highly predictive on the turbulent flow characteristics compared to the emptied wind tunnel experimental data. Results with turbine show good agreement to the experiment data with only a slight overestimation on the magnitude of the wake deflection due to yaw. When compared to a deflection model, the confinement of the wind tunnel is highlighted. The radial and azimuthal time-averaged angle of attack exhibits a high probability of dynamic stall near the hub for a yawed turbine. These results show large discrepancies on the blade loading, highlighting the need for improved and specific models.