A semi-analytical hydrodynamic model for floating offshore wind turbines (FOWT) with application to a FOWT heave plate tuned mass damper

This paper proposes a semi-analytical MacCamy-Fuchs-Morison (MFM) hybrid hydrodynamic model for very efficient simulations of FOWT responses without resorting to potential flow solvers. First, closed-form expressions of the 6-by-6 added mass matrix and 6-dimensional complex wave load transfer function are derived based on the Morison equation. Comparison of the wave load models show that the pure Morison model over predicts high-frequency wave loads above the diffraction limit, while the pure MacCamy-Fuchs model performed poorly at low frequencies due to the existence of heave plates. The MFM hybrid model resolves both issues and gives good agreement with the potential flow theory at all frequencies. The proposed MFM hybrid model is then employed to a representative application case, i.e. a semi-submersible FOWT installed with heave plate tuned mass dampers (HPTMDs). It is shown that implementing a deep installation of the HPTMDs effectively suppresses foundation roll, heave responses and tower side-side vibrations.