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

TL;DR

This study compares various methods for calculating the angle of attack on wind turbine blades using CFD data, highlighting their accuracy and potential for calibrating BEM models under axial inflow conditions.

Contribution

It evaluates and compares multiple methods for determining the angle of attack and induced velocity on wind turbine blades using CFD results, providing insights into their applicability and accuracy.

Findings

Methods agree well at mid-span of blades.

Deviations occur at root and tip regions.

CFD data can calibrate BEM induction models.

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 (CFD). Several methods are examined and their advantages, as well as shortcomings, are presented. The investigations are performed for two 10MW reference wind turbines under axial inflow conditions, namely the turbines designed in the EU AVATAR and INNWIND.EU projects. The results show that the evaluated methods are in good agreement with each other at the mid-span, though some deviations are observed at the root and tip regions of the blades. This indicates that CFD results can be used for the calibration of induction modeling for Blade Element Momentum (BEM) tools. Moreover, 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.