Accurate load prediction by BEM with airfoil data from 3D RANS simulations

The Science of Making Torque from Wind

Schneider, Marc S.^1 ; Nitzsche, Jens^1 ; Hennings, Holger^1

German Aerospace Center (DLR), Institute of Aeroelasticity, Bunsenstraße 10, Göttingen

37073, Germany^1

关键词: Annular sections;    CFD simulations;    Induction factors;    Load predictions;    Radial distributions;    RANS simulation;    Rotational augmentation;    Wind turbine rotors;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/753/8/082016/pdf
DOI  :  10.1088/1742-6596/753/8/082016

来源: IOP

【 摘 要 】

In this paper, two methods for the extraction of airfoil coefficients from 3D CFD simulations of a wind turbine rotor are investigated, and these coefficients are used to improve the load prediction of a BEM code. The coefficients are extracted from a number of steady RANS simulations, using either averaging of velocities in annular sections, or an inverse BEM approach for determination of the induction factors in the rotor plane. It is shown that these 3D rotor polars are able to capture the rotational augmentation at the inner part of the blade as well as the load reduction by 3D effects close to the blade tip. They are used as input to a simple BEM code and the results of this BEM with 3D rotor polars are compared to the predictions of BEM with 2D airfoil coefficients plus common empirical corrections for stall delay and tip loss. While BEM with 2D airfoil coefficients produces a very different radial distribution of loads than the RANS simulation, the BEM with 3D rotor polars manages to reproduce the loads from RANS very accurately for a variety of load cases, as long as the blade pitch angle is not too different from the cases from which the polars were extracted.