Experimental analysis of the MoonWEC floating model in a wave flume

This document aims to show the experiments conducted in order to validate the MoonWEC’s theoretical floating model, together with the description of relative results. The MoonWEC is a wave energy converter prototype designed as a point absorber working as an oscillating body in heave. It’s composed of a cylindrical floating body with a cylindrical hollow inside it which works as a moonpool when filled by water, and from which the device also takes its name. The device exploits the relative motion between the floater and the moonpool for energy conversion and, in order to maximize said relative motion, the two bodies have to resonate synchronously but with opposite phases. A scale model of the MoonWEC was realized and used for the experiments that were carried out at the LIDR (Hydraulic laboratory of the Alma Mater Studiorum Università di Bologna) with the purpose of studying the floater’s motion and response in terms of degrees of freedom when subject to the action of different wave conditions. The model was placed inside a wave flume equipped with a wave generator, its motion when subject to the action of the different test waves was recorded using a GoPro video camera, while a set of wave gauges recorded the water level variation and a pulsed ultrasound velocimetry device, the DOP2000, sampled the water level and velocity profiles inside the moonpool. The data collected from these three different instruments were analyzed and compared through MATLAB. The test waves parameters were obtained from the zero-crossing analysis of the gauges data; the surge, heave and pitch responses of the floater could be obtained through a video analysis of the MoonWEC’s motion; and the DOP analysis supplied the moonpool’s water level oscillations. All the signals were then compared with each other both in the time and frequency domains and the response amplitude operator (RAO) was evaluated for each degree of freedom of the floater.