The development of floating platforms for offshore wind turbines, to replace fixed foundations, paves the way for the harnessing of wind reserves in ultra-deep offshore zones. The potential is promising, estimated to represent 16 GW in France by 2040a.

The design and dimensioning of these new structures are dependent on the calculation of the forces generated by swell and movements induced on the floater. These calculations are currently carried out using dedicated software, from the offshore oil industryb, based on simplified hydrodynamic models. Moreover, the behavior of a floating wind turbine is relatively far-removed from that of an oil platform and both the economic stakes and the industrial risks also differ. With this in mind, IFPEN is re-evaluating current dimensioning methods and tools.

The methodology consists in comparing CFDc simulations of a moving floating wind turbine, conducted using open sourced software with results obtained from conventional simplified models. The objective is to evaluate the relevance of the latter and improve them where necessary, either by revising their formulation or by recalibrating them. This approach was firstly employed on simple cases involving — a fixed floater with swell, on the one hand, and a moving floater without swell, on the other — thereby enabling comparison with experimental results. Deployed to evaluate movement damping systems (figure), it produced satisfactory results (1-2)

Science 34
Visualization of the velocity field surrounding
a damping plate, during vertical movement
of the floater.

The same approach, implemented for a floater developed jointly with SBM Offshore, delivered first promising results concerning the improvement of the hydrodynamic models used in IFPEN’s design tools.

a - Les Echos 02/19/2018
b - DeepLines Wind software developed with Principia
c - Computational Fluid Dynamics
d - OpenFOAM software


(1) P. Bozonnet, A. Emery, CFD Simulations for the Design of Offshore Floating Wind Platforms Encompassing Heave Plates, 25th International Ocean and Polar Engineering Conference, 21-26 June, Kona, Hawaii, USA.  https://www.onepetro.org/conference-paper/ISOPE-I-15-382

(2) A. Emery, P. Bozonnet, Heave plate damping and added mass evaluation based on CFD simulations for floating wind turbine platforms. Submitted to Applied Ocean Research.

Scientific contact: pauline.bozonnet@ifpen.fr