Experimental Assessment of Hydrodynamic Coefficients for a Heave Plate Executing Pitch Oscillations

Abstract

A submerged oscillating heave plate is utilized as a mechanism in some marine structures for vibration reduction. Quantifying the hydrodynamic properties in axial (heave) oscillations has been extensively archived in published research. However, the rotational hydrodynamic properties of an isolated plate under forced oscillation have not been investigated, which may be of relevance when such structures undergo roll or pitch oscillations. This paper reports on an experimental study that aims to find the trends of the rotational hydrodynamic coefficients versus vibration amplitude for an isolated disk. Furthermore, formulae for nondimensional rotational coefficients based on empirical fits to experimental data will help to generalize these coefficients to full scale. The experimental tests were conducted in two sets. In the first set, disks of different sizes were excited in rotation around their central axis, whereas in the second set the disks were oscillated at a distance from the rotational axis. Generally and in accordance with results for heave oscillations, the results of the hydrodynamic coefficients show an increasing linear trend versus vibration amplitude.