A numerical investigation of the geometric characteristics of floating wind turbine wakes under axial and yawed rotor conditions

Abstract

The physics of wind turbine wakes on fixed foundations have been extensively studied through numerical modelling and measurements over the recent decades. While research initiatives in the field of floating wind turbines have increased significantly, various aspects characterising floating turbine wakes are still not well understood. This paper applies a freewake vortex model to derive the geometric characteristics of the wake of a surging rotor under axial and yawed rotor conditions. The study examines the influence of platform motion on the wake boundaries and centreline up to four rotor diameters downstream. It is shown that floating turbine wakes experience a higher degree of perturbation as compared to those of fixed turbines. This is highly dependent on the sea state and suggests the need to develop new analytical wake models for the wind industry that are able to account the effect of platform motion on wake behaviour.