Insight into wind turbine stall and post-stall aerodynamics

The objective of this study was to evaluate measured NASA Ames Unsteady Aerodynamic Experiment post-stall blade element data and to provide guidelines for developing an empirical approach that predicts post-stall aerofoil characteristics. Blade element data were analysed from the five radial stations of the baseline 5.03 m radius rotor. A lifting surface/prescribed wake performance prediction method was used to determine a reference angle of attack that corresponds to the measured blade element data. Using the measured normal and tangential force coefficients and estimated angle of attack, spanwise distributions of lift and drag performance characteristics were derived along with the circulation distributions. Guidelines for a new stall and post-stall model based on the measured trends in the aerofoil performance characteristics, along with flat plate theory, are proposed for predicting the peak and post-peak power. Copyright (C) 2004 John Wiley Sons, Ltd.