Hydrodynamic loads associated with nonlinear wave kinematics have important effects on the structural behaviour of offshore wind turbines. Recent literature has shown that steep non-breaking waves are responsible for triggering resonant vibrations of the tower with significant implications in terms of structural safety. In this paper, a new fast hydrodynamic solver, which combines a linear and a fully nonlinear high-order boundary-element wave solver within a domain decomposition strategy, is integrated into a full hydro-aero-elastic algorithm in order to assess the effects of nonlinear contributions on the whole system, including the rotor blades. High-frequency blades oscillations caused by the wave impacts produce high-frequency load cycles in the tower loads, revealing a complete hydro-elastic coupling of the whole system. Standard linear wave theory leads to dangerous inaccuracies, not only in the tower but also in the blades responses.
Aero-hydroelastic Instabilities on an Offshore Fixed-Bottom Wind Turbine in Severe Sea State / E. Marino ;C. Lugni; C. Borri. - STAMPA. - (2014), pp. 1-8. (Intervento presentato al convegno 11th International Conference on Hydrodynamics (ICHD 2014) tenutosi a Singapore nel 2014).