Coupled Analysis and Numerical Model Verification for the 2MW Floatgen Demonstrator Project With IDEOL Platform

Abstract

Floating wind solutions have developed significantly in the recent years, moving from single demonstrators to having several floating wind pilot wind farms currently under development and even in operation. This is an important step for the industry allowing the market to gain confidence in these solutions for offshore wind. Ideol is a leading floating platform designer and they have been working on a demonstration project for their innovative platform in France. The Floatgen demonstration project consists of a 2MW wind turbine mounted on the Damping Pool platform. During the design phase of the project, the coupled analysis of the full system — turbine, tower, floating platform and moorings needs to be carried out to verify the loading on the turbine and platform, adapt the turbine controller for the floating application and re-design the tower and transition piece. For this project, DNV GL performed the aforementioned analysis in Bladed whilst Ideol performed parallel analysis in OrcaFlex, focusing on the platform and mooring design. It is crucial that both numerical models used in the different software tools and parallel analysis workflows are equivalent and lead to the same overall system behavior. This paper describes the numerical model used for coupled analysis in Bladed and its verification against Ideol’s OrcaFlex model, with emphasis on the aspects related to the platform modelling. For the hydrodynamic loading of the platform, boundary element method was considered together with global and local viscous drag terms. To compare and verify the coupled model results in Bladed to Ideol’s own numerical results, a set of static and dynamic tests were run and the resultant kinematics were compared. Ideol’s model was previously validated against tank test experiments giving confidence in its behavior. The viscous drag coefficients in the Bladed model were adjusted to ensure a good agreement between the kinematics of Ideol’s model of the system and the Bladed model. This paper summarizes the results of this verification exercise, along with some recommendations on areas of further research in the floating wind modelling domain.

Validation of a panel method with full-scale FOWT measurements and verification with engineering models

“…Frequency-dependent coefficients for the engineering methods were estimated using Ansys AQWA [28], a commercial hydrodynamic software. The OrcaFlex model was calibrated with measurement data in advance in a conservative manner [2], [3]. Unfortunately these data were not available for the calibration of the other two models.…”

“…OpenFAST [1]. In addition to others, frequency-domain based methods were often used to estimate the hydrodynamic forces on the platform [2,3]. These methods rely on frequency-dependent coefficients which are calculated in advance on the basis of linearized boundary element methods (BEM).…”

Floating wind turbines: marine operations challenges and opportunities

“…The Floatgen project by Ideol (France) is another project that employs barge-type substructures (Alexandre et al, 2018;Ideol, 2021). They can be fabricated using steel and concrete, which can help promote the use of local content and employment.…”

Current Status and Future Trends for Mooring Systems of Floating Offshore Wind Turbines

“…Such a novel mooring system satisfies two seemingly paradoxical requirements at the same time. One is the competitive fabrication and installation cost and the other is the ability to keep the floater stable in rough seas [17] .…”