Wind Turbine Aerodynamics Prediction Using Free-Wake Method in Axial Flow

Wind turbine aerodynamics remains a particularly challenging and crucial research for wind energy industry. The blade element momentum theory is the most widely used in predicting the performance of wind turbine, since the method is simple and fast numerical algorithm. The flow field generated by rotary wing is considerably important and complicated, however, the BEM method has some limitations to model the unsteady effects. To overcome these limitations, the aerodynamic analysis using a time-marching free-vortex wake method was performed in this paper. Moreover, the inboard region of the blade experience a delay in stall and enhanced values of the normal force coefficient because of rotational boundary layer augmentation and three-dimensional effects. For this reason, Raj-Selig stall delay model was applied in this research. The numerical results were compared with experimental data, and the present results show excellent agreement with experiment.