Importance of Flexible Structure Modeling of a Floating Wind Platform

Abstract Recently, the ultra large wind turbines push floating wind platform’s size to a gigantic scale. The most recent 15MW wind turbine brings a lot of challenges to the floating structure design. Rigid body assumptions of the floating body and wind turbine tower may not be valid for such a large scale. Flexible body modeling of these large floating wind platforms allows the consideration of flexibility of the structures and results in a more accurate prediction of the design loads and the structure behavior. In this case study, we used a generic floating 15MW wind turbine model similar to UMaine 15MW wind turbine semisubmersible and a patented PyraWind™ 15MW wind turbine platform for a comparative study. For each of the two platforms, an OrcaFlex model with flexible body assumption is compared with an OrcaFlex model with rigid body assumption. The global performance and design loads of the two models are compared in detail. For different hull structures, due to the differences in the rigidity of the supporting structure, there is a difference in the tower behavior with or without flexible body modeling. This paper lays the groundwork for future research on flexible body modeling in the design of floating offshore wind turbines (FOWT).