Coupled Time-Domain Investigation on a Vertical Axis Wind Turbine Supported on a Floating Platform

The dynamic responses of a floating vertical axis wind turbine (VAWT) are assessed on the basis of an aero-hydro-mooring coupled model. The aerodynamic loads on the rotor are acquired with double-multiple stream tube method. First- and second-order wave loads are calculated on the basis of 3D potential theory. The mooring loads are simulated by catenary theory. The coupled model is established, and a numerical code is programmed to investigate the dynamic response of the semi-submersible VAWT. A model test is then conducted, and the numerical code is validated considering the hydrodynamic performance of the floating buoy. The responses of the floating VAWT are studied through the numerical simulation under the sea states of wind and regular/irregular waves. The effects of the second-order wave force on the motions are also investigated. Results show that the slow-drift responses in surge and pitch motions are significantly excited by the second-order wave forces. Furthermore, the effect of foundation motion on aerodynamic loads is examined. The normal and tangential forces of the blades demonstrate a slight increase due to the coupling effect between the buoy motion and the aerodynamic loads.