Dynamic stability enhancement and mechanism analysis of a 15 MW wind turbine supported by a novel tree-like fractal floating platform

The long-term integrity and operational reliability of a floating offshore wind turbine (FOWT) is conditioned by the platform's ability to maintain dynamic stability under persistent combined wind-wave forcing. Inspired by natural fractal structures, a novel tree-like fractal platform (TFP) is proposed and integrated with the IEA 15 MW reference wind turbine (IEA 15 MW RWT) to achieve enhanced dynamic stability of the wind turbine system. To enable comprehensive dynamic assessment, a fully integrated simulation framework is developed by leveraging the complementary capabilities of OpenFAST-OrcaFlex (OFOF), allowing detailed evaluation of platform motions, mooring line tensions, and generator power for both the original platform and the TFP under multiple load cases (LCs). Statistical analyses indicate that the TFP significantly reduces the overall platform response levels and improves dynamic stability compared with the original system. In addition, the TFP effectively mitigates both the mean level and fluctuation intensity of mooring line tensions. Although the TFP slightly reduces the average power output of the wind turbine system, it provides a smoother and more stable power generation profile. Furthermore, the mechanisms underlying the enhanced dynamic stability are elucidated through analysis of TFP-induced pressure and vorticity evolution. Quantitative evaluation metrics are proposed, including the hierarchical pressure attenuation index (HPAI) and the fractal vorticity cascade efficiency (FVCE). The hierarchical fractal geometry of the TFP generates a significantly strengthened stratified pressure attenuation effect under wave loading, thereby reducing the transmission of dynamic pressures into the interior of the structure. Simultaneously, the fractal boundaries induce multiscale coherent-structure breakup and accelerate energy dissipation toward smaller scales, demonstrating enhanced energy cascade–dissipation capability. The results reveal that the TFP suppresses external excitations and reduces response instabilities through the synergistic action of pressure-layered dissipation and vorticity-cascade dissipation mechanisms. This study confirms that the TFP represents a structurally feasible and physically grounded alternative for enhancing the dynamic stability of FOWTs and contributes to improving the operational reliability of offshore wind energy systems.