Prediction of the Wind Turbine Performance by Using a Modified BEM Theory with an Advanced Brake State Model

:A mathematical model for fluid dynamics wind turbine design and rotor performance prediction (based on the blade element momentum theory) has been implemented and enhanced. Particular attention was paid to the brake state model to correctly determine axial and tangential induction factors for different wind speed ranges, to the stall delay model in order to consider the centrifugal pumping effects caused by the radial flow along the blades (Himmelskamp effect), and to the models for the representation of the aerodynamic coefficients in pre-stall and post-stall regions. With the numerical codes given in this work, the aerodynamic forces and the power for a NREL wind rotor were predicted. The mathematical simulations results have been compared with experimental data and mathematical models considered in the literature, and are found to be reliable and satisfactory.