NonlinEar Phenomena in floaTing offshore wind tUrbiNEs

Driven by the transition toward renewable and sustainable energies (supported by the European New Green Deal and the Italian PNRR), Floating Offshore Wind Turbines (FOWTs) are rapidly being developed worldwide. FOWTs are complex dynamic systems that must be designed to guarantee optimal operating performance, this largely depending on nonlinear phenomena, coming from aero-hydrodynamic loads (wind, waves) and their fluid-structure interaction, structural components (blades, tower), the role of moorings, and the large platform dimensions and motions.  The figure shows the environmental loads applied to a FOWT.

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NEPTUNE research project intends to characterize a FOWT as one single complex dynamic system, and is aimed at investigating its nonlinearities from a holistic viewpoint, to get a deep knowledge of the overall behavior of the entire structure, from the mooring lines up to the turbine, and to provide fundamental insight for its proper design. This is a major step forward with respect to the state-of-the-art, which is mostly focused on each single item and refers to a linear realm.

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NEPTUNE will provide advances of scientific knowledge and technology, for the understanding of the nonlinearities (i.e. the effect of internal resonance), this being fundamental for the design of FOWTs to work safely in extreme environmental conditions and extract energy in the most advantageous way (it is expect that FOWTs can produce energy exploiting nonlinearities, has already done for other energy harvesting systems). A relevant achievement will be the birth of the “NEPTUNE Italian Design Guidelines (NEPTUNE-IDG)” specific for FOWTs in the Mediterranean Sea, for the design optimization, with emphasis on floater stability, mooring system and geometry, able to account for site-specific conditions.