Considerations on vortex methods for aerodynamic analyses of wind turbines

Abstract

Aeroelastic, control, and floating characteristics of large offshore wind turbines often challenge classical approaches, such as the blade element momentum (BEM), beyond its capabilities. Vortex methods have been proven to be an alternative to BEM with a good compromise between fidelity and computational cost. In this sense, the present work compares experimental data, free vortex wake (FVW) methods, an unsteady lifting line formulation, and the BEM model. Expected motions during the operation of wind turbines, such as platform surge and variations of the pitch angle of the blades are investigated. The results indicate good agreement between experimental data and FVW methods. To reduce the computational cost of FVW approaches, a method to prescribe the wake shedding is suggested. Coupling the unsteady lifting line with the Øye dynamic inflow model also leads to good results with reduced computational costs.