For effective operation of Floating Offshore Wind Turbine (FOWT), comprehensive investigations are required, not only focusing on the turbine aerodynamics, but also on the global motion behaviours including the motion stability and risk assessment under failure scenarios. This paper presents numerical simulations of the IEA 15 MW offshore wind turbine under mooring failure scenarios in extreme environments. For the numerical analysis, a coupled framework was employed, combining the Computational Fluid Dynamics (CFD) software, STAR-CCM+, and the lumped-mass mooring dynamics code, MoorDyn. The turbulent flow fields around the turbine and floating platform were resolved using the CFD solver, while the dynamic response of the mooring system was analysed using MoorDyn. In the scenario where one of the 3-catenary mooring lines is broken, the variations in the 6-DOF motion response of FOWT were investigated with respect to the turbine blade pitch angles (i.e., normal and feathered blades). Additionally, the dynamic tensions in the remaining two lines were observed. The results indicate that feathered blade pitch angle can effectively reduce the motion response of FOWT. For instance, the platform pitch motion was reduced by more than half compared to the normal blade configuration, highlighting the importance of blade feathering for maintaining stability. In contrast, the normal blade configuration may lead to significantly larger platform responses under failure scenarios.
Do et al. (Wed,) studied this question.