Context

When designing offshore wind turbines for a specific site, the industry has to analyse the Ultimate Limit State (ULS) of the structure, i.e. the maximum expected response that the offshore wind turbines will experience over its lifetime. In the assessment of the ULS, the effects of energetic steep or breaking waves (hereinafter ESBW) are thought to be responsible for considerable uncertainties. As well documented in the oil and gas or fixed offshore wind turbines literature, ESBW may excite the first structural modes (the so-called ringing in presence of steep non-breaking waves), cause damages due to vertical water excursion (run-up) or submersion of the platform (green water) or local deteriorations due to slamming loads. Numerical modelling of a full-scale floating offshore wind turbines (FOWT) even showed that the blade tips could hit the water in presence of realistic ESBW.

Objectives

To provide the floating offshore wind turbine industry with less conservative certification guidelines and an appropriate engineering tool accounting for the effect of ESBW in terms of slamming, run-up, green water and vibration-induced effects.

Scientific and technical contents

• Field experiment from the full-scale floating offshore wind turbine Unitech Zefyros.
• Wave tank experiments in sea states of growing steepness up to the occurrence of large breaking waves.
• Numerical simulations of ESBW interacting with a floating offshore wind turbine.

Resources

DIMPACT project sheet (PDF)

Partners and funding

This project is led by France Energies Marines.

The total project budget is €2,144K.

This project receives funding from France Energies Marines and its members and partners, as well as French State funding managed by the National Research Agency under the Investments for the Future Programme (ANR-10-IEED-06-34).

Photo credit: Saskia 1310 / Pixabay