A solution-based stall delay model for horizontal-axis wind turbines

This work proposes a new solution-based stall delay model to predict rotational effects on horizontal-axis wind turbines. In contrast to conventional stall delay models that correct sectional airfoil data prior to the solution to account for three-dimensional and rotational effects, a novel approach is proposed that corrects sectional airfoil data during a blade element momentum solution algorithm by investigating solution-dependent parameters such as the spanwise circulation distribution and the local flow velocity acting at a section of blade. An iterative process is employed that successively modifies sectional lift and drag data until the blade circulation distribution is converged. Results obtained with the solution-based stall delay model show consistent good agreement with measured data along the National Renewable Energy Laboratory Phase VI and Model Experiments in Controlled Conditions rotor blades at low and high wind speeds.