Investigation on the Use of a Passive Nonlinear Absorber for the Reduction of Vibration in the Mast of a Floating Offshore Wind Turbine

Antonio Cillis (1) , Emmanuelle Sarrouy (2) , Pierre-Olivier Mattei (2) , Riccardo Mariani (3) , Thomas Choisnet (4)

1 ECL - École Centrale de Lyon
2 LMA - Laboratoire de Mécanique et d'Acoustique [Marseille]
3 IDEOL
4 IDEOL

Floating Offshore Wind Turbines (FOWT's) are subjected to different types of dynamic loads such as environmental loads (wave and wind), aero-structure interaction loads and mechanical loads (inertial and controller effects). These loads induce vibrations in the WT mast that are transmitted in the floating foundation and mooring lines, increasing the overall ultimate loads and fatigue cycling. In this paper the potentiality of a passive nonlinear mechanical system for the reduction of WT mast vibrations is studied. This kind of absorber called Nonlinear Energy Sink (NES) is based on the energy pumping phenomenon. The feasibility and efficiency of the absorber is first demonstrated by means of a simplified full-scale numerical model composed of two degrees of freedom, one for the WT mast (first bending mode) and one for NES. Then, an equivalent reduced scale model is considered and analyzed by numerical simulations and experiments. The study is concluded with the sizing of an optimized absorber for the full-scale system. Some sensitivity analyses considering variations of the mast structural characteristics (stiffness and structural damping) are performed to investigate the NES efficiency limits, confirming the performances of the NES: reduction of vibratory level around 8-10 dB over a large range of functioning loads.

Domaines: Acoustique [physics.class-ph]

Antonio Cillis, Emmanuelle Sarrouy, Pierre-Olivier Mattei, Riccardo Mariani, Thomas Choisnet. Investigation on the Use of a Passive Nonlinear Absorber for the Reduction of Vibration in the Mast of a Floating Offshore Wind Turbine. Internois 2019, Jun 2019, Madrid, Spain. ⟨hal-02370353⟩