Experimental Investigation of Hydrodynamic Coefficients of a Pitch-Inclined Column–Heave-Plate Component for Floating Offshore Wind Turbines

As offshore wind development moves toward deeper waters, floating offshore wind turbines have become essential for carbon-neutral energy systems. This study experimentally investigates the hydrodynamic coefficients of typical column–heave-plate components under forced oscillations, focusing on the influence of pitch-induced inclination. A circular column without a heave plate and a circular column equipped with a hexagonal heave plate were tested under heave and surge motions with varying periods, amplitudes, and static inclination angles. The static inclinations were used to represent the attitude variation of platform components during large-amplitude pitch responses. Added mass and damping coefficients were identified using the least squares method. The results show that for the heave-plate-equipped column, increasing the inclination from 0° to 5° and 10° reduced the nondimensional heave added mass by approximately 4.3% and 5.9%, respectively, and reduced the nondimensional heave damping by approximately 7.1% and 6.8%. The corresponding reductions in surge added mass were approximately 5.3% and 10.5%, whereas the reductions in surge damping reached approximately 8.2% and 16.4%, indicating that the surge damping is most sensitive to static inclination. These variations may be associated with the altered geometric projection and disturbed flow symmetry of the inclined component, which may affect the attached-fluid volume and energy-dissipation process during forced oscillation. Future studies should further verify the corresponding local separation and vortex-formation mechanisms through detailed flow-field measurements, PIV, or CFD.