Over the past decade, many simulators dedicated to the behaviour of floating wind turbines have been developed. The vast majority of these models are based on a multi-body formulation where the floating wind turbine is represented as a set of deformable and rigid bodies interconnected. The blades, the tower, the rotor shaft and the anchor lines are generally considered deformable while the platform and the floating support are assumed to be rigid.
While this approach may be sufficient for medium power rotors, the recent development of 10 to 15 MW rotors will require larger foundations for which the hydro-elastic effects should become significant.
Scientific advances and innovation
To cope with this new design challenge, LHEEA plans to expand the capabilities of its current floating turbine simulator. This project aims to develop a hydro-elastic solver for the calculation of structural loadings sustained by floating wind foundations. This work will involve the coupling of an “in-house” hydrodynamic solver based on a unsteady potential theory with a structural solver based on a finite element formulation. A second task will focus on the experimental validation that will be conducted at Centrale Nantes with a segmented model of a SPAR-type floating foundation .
Expected technical and economic impact
The scientific and technical impact of the project is on both the numerical and the experimental aspects of the project:
- The numerical modelling of the hydroelastic behavior of floating wind turbine foundations by means of a unstationary potential model would be a first of its kind in the floating wind energy community.
- Experimental results of floating wind turbine foundations with segmented models are very few; the proposed experimental campaign will be then strongly valuable for the community.
Key project milestones
- 05/04/2019 - Kick-Off
- 2019 - Numerical developments
- 2020 - Experimental tests
- March 2021 - End of the project
The first year of the HeLoFOW project has seen the development of a structural solver based on a finite element formulation and its coupling with the unsteady potential code of the LHEEA WS_CN. This new solver has made it possible to make the first simulations applied to offshore wind energy
A first case of application to offshore wind, which is part of the verification-validation process of the numerical developments carried out, has consisted in modeling the structural loads on a fixed foundation of offshore wind turbine of monopole type. Simulations for different wave conditions have been performed and the results have been compared to small scale tests performed at NTNU and numerical simulations performed by NTNU with the Sima code. This validation work is being finalized, a 1st conference communication was made during the DeepWind conference in January 2020.
Still within the framework of the verification-validation process, a 2nd application case has been considered where this time a floating substructure was considered. The platform considered is a SPAR, the design was taken from the literature and is dedicated to supporting a 10MW horizontal axis wind turbine. This work has begun during the 1st year and will continue in the 2nd year.
Publications and papers published
- Jean-Christophe Gilloteaux, FAID, Advanced Modeling and tank testing of FOWT, Boston – 18-19 mars 2019
- Nonlinear hydroelastic responses of monopile and spar wind turbines in regular waves. Vincent Leroy, Jean-Christophe Gilloteaux, Erin E. Bachynski, Aurélien Babarit, Pierre Ferrant. EERA DeepWind’2020, 17th Deep Sea Offshore Wind R&D Conference, Trondheim, Norway, 15 – 17 January 2020