Effects of wind-wave misalignment in the case of nonlinear hydrodynamic loading of offshore wind turbines

This paper introduces an assessment study on the effect of wind–wave misalignment on the dynamic response of a monopile supported offshore wind turbine. The harsh offshore conditions expose wind turbines to steep waves, the passage of which may cause dangerous nonlinear resonant oscillations. It has recently been shown that such oscillations occur in parked state due to the reduced damping response of the whole system. On the contrary, in the operating condition the effect of nonlinear waves is almost negligible. These previous studies, however, are limited to the cases of co-directional wind – nonlinear waves. The current study will analyse the turbine tower forces, bending moments and displacements under varied angles between wind and wave directions in nonlinear irregular waves, in order to determine whether wind-wave misalignment has a substantial influence on the dynamic system response. The study will provide considerations for more efficient offshore wind turbine designs.