The GustoMSC Tri-Floater is a slender and robust three-column semi-submersible supporting an offshore wind turbine. Model tests were performed for a Tri-Floater equipped with an operational wind turbine and mooring system exposed to wind and waves in the offshore basin at MARIN. A high quality wind setup and special low Reynolds number blades were used, aiming at delivering the Froude scaled thrust. The base scope of experiments was performed with fixed blade pitch angle and generator speed. Some of the experiments were repeated with active blade pitch and generator torque control using a dedicated algorithm developed by ECN. The experiments covered typical operational and survival design conditions. Numerical simulations for the same wave and wind conditions were performed using ANSYS-AQWA coupled with PHATAS. The paper describes the setup and results of both the model tests and the simulations.
From the comparison of the numerical and experimental results, it is concluded that coupled aero-hydro-servo-elastic simulations can be used to predict the response of the floating offshore wind turbine to a sufficiently accurate level for design purposes. Furthermore, it is shown that the Tri-Floater motion response is very favorable and that the nacelle accelerations, air gap and mooring loads comply with the design requirements.
