Comparative analysis of three-column and three-column with central column semi-submersible platforms for floating wind turbines

Floating offshore wind turbines (FOWTs) are gaining increasing attention as a promising solution for harnessing wind energy in deep-water regions, where traditional bottom-fixed turbines are not feasible. Among the various floating platform designs, semi-submersible platforms have emerged as a leading candidate due to their balance of stability, adaptability, and cost-effectiveness. This paper presents a detailed comparative analysis of two typical types of semi-submersible platforms: the three-column design and the three-column with central column design. The study employs a coupled aero-hydro-mooring simulation system using OpenFOAM to evaluate the hydrodynamic, aerodynamic, and mooring dynamics of both platform configurations. High-fidelity computational fluid dynamics (CFD) simulations, along with a lumped-mass mooring model and the actuator line model (ALM), are employed to capture the coupled fluid-structure interactions and mooring line dynamics. The results reveal significant differences in platform behavior, highlighting the impact of platform geometry on dynamic stability and mooring line response. The additional central column significantly improves pitch stability, reducing the maximum pitch angle by 38.7 % under combined wind and wave loading, indicating enhanced dynamic stability of the additional central column design. Additionally, an economic assessment is provided to evaluate the material costs, installation, and operational expenses for each platform type. The findings suggest that both configurations offer distinct advantages depending on operational and environmental conditions, contributing to the optimization of FOWT platform selection for future offshore wind farms. • Three-column and three-column with a central column semi-submersible platform for floating wind turbines are compared. • A hybrid model couples actuator line method and RANS-based CFD to simulate full aero-hydro-mooring interaction. • Platform surge and pitch modulate wake symmetry, causing periodic stretching and compression of vortex filaments. • The central column improves pitch stability, reducing the maximum pitch angle by 38.7% under wind and wave. • Adding a central column lowers material cost for large-scale turbines with deep-draft platform designs.