An efficient modular aero-hydro-servo framework for floating offshore wind turbines

Floating offshore wind turbines (FOWTs) require highly efficient and versatile simulation tools to facilitate extensive design load case evaluations and advanced control co-design. To address the computational challenges in fully coupled analyses, this study proposes OrcaWind-Aero, an open-architecture aero-hydro-servo coupled framework based on the rigid-rotor assumption. The framework integrates the AeroDyn aerodynamic module with the OrcaFlex hydrodynamic and multi-body solver through a customized Python data bus. A systematic comparative analysis using the 5 MW and 15 MW reference turbines first justifies the rigid-rotor assumption, demonstrating that neglecting structural flexibility yields negligible errors in predicting platform motions and mooring tensions. The developed framework is then rigorously validated against monolithic OpenFAST simulations across the full operational envelope, exhibiting excellent time-domain and statistical consistency under distinct servo-control actions. Leveraging the flexible cross-system data exchange capabilities, a novel mooring-informed blade pitch control strategy is proposed and evaluated. The active tension feedback controller significantly mitigates the low-frequency resonant responses, achieving a 9.2% reduction in ultimate tension and a 32.8% decrease in standard deviation for the most heavily loaded mooring line. These results establish OrcaWind-Aero as a highly reliable and agile platform for the integrated dynamic analysis and advanced control optimization of next-generation FOWTs.