The floating offshore wind turbine (FOWT) system contains a wide range of
interdisciplinary knowledge, including the aerodynamics of wind turbines, the
hydrodynamics of floating platform, and mooring system, as well as the complex
coupling interactions among these domains. Due to this inherent complexity,
achieving accurate simulation and analysis has remained a significant challenge.
To address this issue, the present study develops a coupled
aerodynamic-hydrodynamic framework based on the open-source computational fluid
dynamics (CFD) software OpenFOAM. The framework incorporates multiphase flow,
dynamic morphing and overset mesh techniques to facilitate high-fidelity
analysis of FOWT. The aerodynamic performance of the IEA 15 MW reference wind
turbine and the hydrodynamic response of the UMaine VolturnUS-S semisubmersible
platform are independently validated against OpenFAST or experiments to ensure
the reliability of the proposed framework. The results show strong agreement,
confirming that the simulations accurately capture realistic aerodynamic and
hydrodynamic performance, which are then applied in coupled aero-hydrodynamic
FOWT analysis. The effects of the wind turbine on floating platform hydrodynamic
responses and the impact of the floating platform on wind turbine aerodynamics
are investigated in the coupled simulation. The results show that the speed,
thrust, and torque of the wind turbine fluctuate with the motion of the floating
platform, which is closely linked to the surge and pitch motion. Furthermore, a
comparison of the platform response in the coupled simulation with that
considering only wave loading reveals minimal change in heave motion, but a
significant increase in surge and pitch motion due to the wind turbine
aerodynamic load. Therefore, the aerodynamic and hydrodynamic components of the
FOWT are mutually dependent, underscoring the necessity of a comprehensive
analysis to achieve accurate results.