Spar platforms are floating vertical cylinders stabilized by a ballast that are used to support offshore oil and gas drilling and production activities offshore wind turbines. Heave damping elements reduce floaters’ motion response. Heave plates are commonly used for
Spars. Evaluation of damping and its frequency-dependent behavior will be useful for optimum design. Experimental and numerical investigations of heave damping of Spars with a few
configurations of heave plates have been carried out using a 1:100 scaled model. The applicability of the linear and quadratic damping models has been assessed for all configurations. The effects of parameters such as heave plate diameter, location of heave plate above the keel, and spacing between two heave plates on damping and added mass have also been studied. Flow fields obtained from numerical simulations are presented, and their
implications on damping are discussed. Added mass effect is also visualized using a novel flow visualization technique, by visualizing flow acceleration. The damping and added mass of the spar in pitch were also studied using pitch decay numerical simulations. It is also important to
obtain these hydrodynamic parameters of the floater not only at its natural frequency but also
at other frequencies because the floater response over a wide range of amplitudes and frequencies is of interest. Hence forced heave oscillation tests of the same scale model of spar with various configurations of heave plate in otherwise calm water have been conducted to
investigate heave added mass and damping at various frequencies and amplitudes. The least square method was used to determine the added mass and damping using three damping models, namely, linear, quadratic, and linear-plus-quadratic, and their applicability was
assessed. The effects of amplitude and frequency of oscillation on the damping and added mass are discussed for spars with various heave plate configurations with the aid of flow visualization from numerical simulations. The scale effect on the hydrodynamic coefficients
was also addressed. Effects of the parameters such as damping plate diameter, location of attachment, spacing between two plates, and current speed were also studied numerically. The effect of the flexibility of the heave plate on the heave damping of the spar was also explored using forced oscillation tests and numerical simulations. The effect of mass ratio and material damping on the total heave damping and added mass are also discussed.