Effects of the Surge Motion on the Performance of Floating Wind Turbine Considering Blade Structural Flexibility

Abstract The flexible deformation of the slender blade has non-negligible effects on the performance of modern megawatt wind turbines, especially under marine environments where additional six degrees of motion is introduced by floating platform. In this research, an aeroelastic coupling model is established based on the lifting surface free vortex wake (LS-FVW) method and geometrically exact beam theory (GEBT) method. By adopting the model developed, the effects of the surge motion on the unsteady aeroelastic performance of floating offshore wind turbines (FOWTs) are investigated with the NREL 5 MW wind turbine. The results show that, the surge motion will increase the average power and thrust of FOWT, while the blade deformation has the opposite effect. The increase of the amplitude and frequency of the surge motion will increase the fluctuation amplitude and frequency of the power, thrust and structural deformation of the wind turbine. Besides, the smaller the amplitude or frequency of the surge, the stronger the ability of the wind turbine-floating platform system to restore stability.