HYDRODYNAMIC RESPONSE OF SEMI-SUBMERSIBLE PLATFORM OF FLOATING OFFSHORE WIND TURBINE UNDER EXTREME WAVES

Offshore wind turbine play a key role in the renewable energy strategy due to the advantage like the faster wind speed in offshore area and higher power generation reliability. As the development of offshore wind turbine (OWT) from near coastal area to the deep sea, floating type foundation is the inevitable direction for OWT. The hydrodynamic performance analysis of floating offshore wind turbine (FOWT) is required under different marine conditions to improve the structure safety and stability and ensure the power generation efficiency. However, the study of extreme wave condition interaction with FOWT, like tsunami waves, incidental rogue wave etc., remains a difficult scientific research challenge. In this paper, the hydrodynamic performance of Semi-submersible platform of FOWT is modeled and analyzed under extreme waves using Hydrodynamic-Coupling (HDC) method. HDC is a coupling method between the fully nonlinear potential flow (FNPF) solver and Computational fluid dynamics (CFD) solver within the open-source hydrodynamics framework REEF3D. This method satisfied the computational efficiency and high fidelity of the simulation of extreme wave events by using FNPF to provide far-field wave generation and propagation information and adopting CFD to calculate the near fluid field physical characteristics and impact details required when modeling the process of extreme state. The dynamic responses including surge and heave motion of a semi-submersible under extreme wave are carried out under typical extreme wave conditions. The numerical model is validated against experiments of rogue waves interaction with a semi-submersible platform. The HDC method achieved a computational efficiency of the same wave condition.