Validation and comparison of aerodynamic modelling approaches for wind turbines

F Blondel,C Lienard,G Ferrer,D Teixeira,M Milekovic,R Boisard

doi:10.1088/1742-6596/753/2/022029

Abstract

The development of large capacity Floating Offshore Wind Turbines (FOWT) is an interdisciplinary challenge for the design solvers, requiring accurate modelling of both hydrodynamics, elasticity, servodynamics and aerodynamics all together. Floating platforms will induce low-frequency unsteadiness, and for large capacity turbines, the blade induced vibrations will lead to high-frequency unsteadiness. While yawed inflow conditions are still a challenge for commonly used aerodynamic methods such as the Blade Element Momentum method (BEM), the new sources of unsteadiness involved by large turbine scales and floater motions have to be tackled accurately, keeping the computational cost small enough to be compatible with design and certification purposes. In the light of this, this paper will focus on the comparison of three aerodynamic solvers based on BEM and vortex methods, on standard, yawed and unsteady inflow conditions. We will focus here on up-to-date wind tunnel experiments, such as the Unsteady Aerodynamics Experiment (UAE) database and the MexNext international project.

Highlights

IntroductionMost of the design software rely on the Blade Element Momentum models [10]
Nowadays, most of the design software rely on the Blade Element Momentum models [10]
Three different solvers have been compared and validated: a first solver based on the Blade Element Momentum theory, a second based on the Prandtl lifting-line theory, and a third one based on the more recent Mudry’s theory

Summary

Introduction

Most of the design software rely on the Blade Element Momentum models [10]. Those methods are based on strong hypotheses, partially overcame through analytical corrections, that introduce empiricism in the models. More physical models, such as the vortex methods, that require less analytical corrections, are being increasingly used. Vortex methods provide different solutions to model the wake, such as vortex points, filaments or panels. The two lifting-line solvers are based on different wake models, a free-wake vortex filaments model and a free-wake vortex panel wake model. Induction factors, which represent the momentum loss due to the presence of the rotor, are computed in both axial and tangential directions along the blade span. In order to overcome the major limitations of the classical BEM theory, corrections have been implemented to account for hub and tip losses, turbulent wake state, tower shadowing, dynamic inflow (i.e. unsteady BEM), dynamic stall, as well as skewed rotor configurations

CASTOR

Conclusion