Numerical Modelling of Novel Floating Offshore Wind Turbine Concept

Abstract This paper describes the numerical modelling of a novel floating offshore wind turbine (FOWT), a next-generation concept which aims to combine the best features of traditional spar and semi-submersible platforms, coupled with a modular design for ease of manufacturing and assembly. The study was conducted as part of Phase IV of OC6 (Offshore Code Comparison Collaboration, Continued, with Correlation and unCertainty), an international research project focused on verifying and validating numerical modelling tools used in the analysis of floating offshore wind systems. In this study, numerical modelling is performed using a mid-fidelity tool which performs fully coupled aero-hydro-servo-elastic simulations in the time domain. The simulation model is based on a full-scale demonstrator version of the FOWT concept hosting a 3.6 MW turbine, which has been deployed offshore and is fully operational since 2021. Results from the numerical model are validated by comparisons with experimental data from a 1:43 Froude-scale test performed in the University of Maine’s Ocean Engineering Laboratory. Beginning with fundamental test cases, including static equilibrium, surge offsets, and free-decay simulations, the scenarios advance in complexity to include wind-only loads, wave-only forces, and a combination of wind and wave conditions. Key parameters of interest include aerodynamic forces, motions of the floating support structure, tower base moments, mooring line tensions, and keel line tensions. Overall, the results show a strong correlation with the empirical data. This paper complements the research work undertaken in OC6 Phase IV, further substantiating its insights into the dynamic responses of floating offshore wind turbines.