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Blade element moment (BEM) is a widely used technique for prediction of wind turbine aerodynamics performance,the reliability of airfoil data is an important factor to improve the prediction accuracy of aerodynamic loads and power using a BEM code.The method of determination of angle of attack on rotor blades developed by SHEN,et al is successfully used to extract airfoil data from experimental characteristics on the MEXICO (Model experiments in controlled conditions) rotor.Detailed surface pressure and particle image velocimetry (PIV) flow fields at different rotor azimuth positions are examined to determine the sectional airfoil data.The present technique uses simultaneously both PIV data and blade pressure data that include the actual flow conditions (for example,tunnel effects),therefore it is more advantageous than other techniques which only use the blade loading (pressure data).The extracted airfoil data are put into a BEM code,and the calculated axial and tangential forces are compared to both computations using BEM with Glauert’s and SHEN’s tip loss correction models and experimental data.The comparisons show that the present method of determination of angle of attack is correct,and the re-calculated forces have good agreements with the experiment.