Evaluation of different methods for determining the angle of attack on wind turbine blades with CFD results under axial inflow conditions

Abstract

This work presents an investigation on different methods for the calculation of the angle of attack and the underlying induced velocity on wind turbine blades using data obtained from three dimensional computational fluid dynamics. Several methods were examined and their advantages as well as shortcomings were presented. The investigations were performed for flows past two 10MW reference wind turbines under axial inflow conditions, namely the 10MW turbines designed in the EU AVATAR and INNWIND.EU projects. The results shown that the evaluated methods are in good agreement with each other at the mid-span, though some deviations were observed at the root and tip regions of the blades. Using any of the proposed methods, it is possible to obtain airfoil characteristics for lift and drag coefficients as a function of the angle of attack. Furthermore, by using the extracted data new correction models can be derived for blade element momentum calculations.