Dynamic performance optimization of a floating offshore wind turbine based on fractal-inspired design principles

As the development of onshore and fixed offshore wind turbines approaches saturation, floating offshore wind turbines (FOWTs) are increasingly gaining attention due to their ability to operate in deeper waters and harness more stable wind resources. However, the dynamic responses of FOWTs are amplified significantly under the complex sea conditions, posing challenges to the overall system stability. This study proposes a novel semi-submersible platform featuring fractal structure inspired by Victoria Amazonica as solutions to the overall system stability of FOWTs. The computational fluid dynamics method, integrated with dynamic fluid-body interaction and volume of fluid wave model, is used to examine the aero, hydro, and mooring dynamics of the FOWT. A parametric model of the fractal structure with different branch levels is constructed by recursive method. Firstly, the hydrodynamic performance of the novel platforms with multi-level branch structures is examined under single wave conditions. The results show that vortices in fractal structures present higher velocity gradients and greater viscous dissipation, thereby effectively absorbing wave energy. The stability of the platform improves progressively as the branch levels increase. Subsequently, the dynamic responses of the full-configuration FOWT mounted on the platform with 8-level fractal structure (8LFS-FOWT) are further evaluated under wind-wave coupling conditions. The results reveal that 8LFS-FOWT achieves superior hydrodynamic performance with the most notable improvement in pitch amplitude of 25.22 % decrease. This enhancement also brings a 12.75 % reduction in the standard deviation of power output, forming positive feedback to ensure safe and stable operation of the system. The findings provide a valuable reference for promoting the innovative platform design of FOWTs.