Hydrodynamic Motion Behavior of Air-Cushion-Supported Hexagonal Floating Platform for Offshore Wind Turbine

This paper presents an experimental study of a new floating platform, being supported by air-cushion modules. The platform consists of six hexahedron air cushion units in which their bottom is open to the water surface. A moonpool is placed in the middle of the platform. A 1:47 scale model was used for the measurement of heave, pitch and surge motions in regular wave conditions. To evaluate the effect of a hexahedron air cushion unit, that of barge-type model was tested. The results show that the motion behaviors of the hexagonal air-cushion-type platform are better than those of the barge-type platform in short wave conditions, while behaviors in long wavelength are almost the same. To evaluate the stability of the hexagonal air-cushion-type platform in windy conditions, a wind turbine of a circular disc-shape was installed on the platform. The thrust acting on the wind turbine and the wind velocity were measured simultaneously. Further, the inclination test of a three-blade wind turbine model was carried out. The results show that the tested hexagonal air-cushion-type platform is sufficiently stable for the practical use of wind turbines of a 20MW capacity. Similarly, platforms of larger size could be used for wind turbines larger than 20MW.