Wind Tunnel Study of a "floating" Wind Turbine's Wake in an Atmospheric Boundary Layer with Imposed Characteristic Surge Motion

Abstract

Floating offshore wind turbines (FOWTs) are a potential source for increased offshore energy production. As the technology is still in a pre-industrial state several questions remain to be addressed where little field data is available. This study uses physical modelling at a reduced scale to investigate the unsteady behaviour and the development of the wake in a simplified FOWT model. A porous disc model is placed in an atmospheric wind tunnel and subjected to a range of different motions. The effects of induced sinusoidal surge motion on the characteristics of the model's wake at a fixed downstream distance of 4.6D are studied. First results show unchanged mean velocity values but modified turbulence intensity and turbulent kinetic energy profiles. Spectra taken in the wake show shifts to higher frequencies in the longitudinal flow component while the opposite is true for the vertical flow component. Further research into spatial characteristics of the wake are necessary to confirm these results.