CFD studies on rotational augmentation at the inboard sections of a 10 MW wind turbine rotor

In the analysis of the aerodynamic performance of wind turbines, the need to account for the effects of rotation is important as engineering models often failed to predict these phenomena. Investigations are carried out by employing an unsteady computational fluid dynamics (CFD) approach on a generic 10MW AVATAR (Advanced Aerodynamic Tools for Large Rotors) blade. The focus of the studies is the evaluation of the 3D effect characteristics on thick airfoils in the root area. For preliminary studies, 2D simulations of the airfoils constructing the blade and 3D simulations of the turbine near the rated conditions are carried out. The 2D simulations are in good agreement with available measurements within the linear lift region, but the accuracy deteriorates in the post stall region. For the 3D wind turbine rotor results, the prediction is consistent with other CFD computations obtained from the literature. Further calculations of the rotor are conducted at 5 different wind speeds ranging from below to above the rated conditions, which correspond to 5 different angles of attack. The CFD simulations demonstrate that the lift coefficient increases in the blade root region compared to the 2D conditions caused by the centrifugal pumping and Coriolis force via the reduction of the boundary layer thickness and separation delay. The Coriolis force effect decreases with the increasing wind speed and radial position. In addition, the aerodynamic behaviour of the blade inboard region is influenced by the shedding direction of the trailing vortices. The occurrence of downwash is observed causing a local increase in the drag coefficient. Published by AIP Publishing.