Abstract
Heave plates which are widely attached at the base of columns of offshore floating wind turbines (OFWTs) can effectively reduce the resonance oscillations and improve the stability of OFWTs by providing additional added mass and damping. These hydrodynamic forces are strongly affected by the proximity of boundaries in shallow water. In the present work, the variations of added mass and damping coefficients as the heave plate moves a flat and stepped terrain are investigated. A column with a single solid circular heave plate is simulated in a numerical wave tank using forced oscillation tests. The added mass and damping coefficients are determined by fitting time series of the calculated force to Morison’s equation with a least squares procedure. The damping coefficients of heave plate increase with the decreasing water depth in the flat terrain (up to 60% compared to the coefficient in deep water). Similar conclusions are found when the length of stepped terrain is not less than the diameter of heave plate. However, the damping coefficients of heave plate significantly increase in the condition that the length of stepped terrain is smaller than the diameter of heave plate (up to 80% compared to the coefficient in the flat terrain).
