Short-crestedness effect on the dynamic response of offshore floating wind turbines

Abstract

Previous investigations on the performance of offshore floating wind turbines mostly adopted the long-crested wave model, which propagates along one single direction. In practice, the ocean waves are short-crested and three-dimensional.Unfortunately, the performance of offshore floating wind turbines in shortcrested waves is not fully understood. The primary objective of the present research is to form a better understanding of the dynamics of offshore floating wind turbines in multi-directional waves. The short-crested waves are modelled using a spreading exponent function. The wave directionality effect on the dynamic performance of a semisubmersible offshore floating wind turbine is studied. In short-crested wave, the longitudinal response is reduced whereas the lateral response is amplified. The tower base fore-aft bending moment and the mooring line tension force are reduced. In the meanwhile, the fatigue damages of critical points at tower base are also reduced. It is concluded that shortcrestedness is beneficial to the structural integrity. The present research reveals the importance of wave short-crestedness effect on the performance of offshore floating wind turbines.