A novel coupling framework for integrating turbine and substructure dynamics of floating offshore wind turbines

This study presents OrcaWind, a novel aero-hydro-servo-elastic coupling framework that seamlessly integrates OpenFAST and OrcaFlex to address critical limitations of single-tool approaches in floating offshore wind turbine (FOWT) simulations. By synergizing OrcaFlex's superior modeling capacities in hydrodynamics and multi-body system with OpenFAST's validated aerodynamic methodologies, the framework enables efficient and accurate multi-physics simulations. Rigorous validation against OpenFAST benchmarks confirms its accuracy in predicting coupled dynamic responses, including servo-control behaviors, aerodynamic loads, platform motions, and mooring tensions. A case study of a 15 MW FOWT with a constant tension mooring system (CTMS) further demonstrates OrcaWind's unique capability to evaluate complex platform-mooring interactions. By contrast to conventional tools, the framework explicitly resolves nonlinear mooring line dynamics, delivering more reliable and comprehensive dynamic assessments. These advancements establish OrcaWind as an advanced tool for optimizing FOWTs with innovative substructures or mooring configurations. The framework will be publicly released following article publication to support offshore wind energy development.