Experimental and numerical investigation on the geometric optimization of a twin-hull BBDB-OWC platform

Floating offshore platforms deployed in deep waters often face long-term power supply issues. Due to the superiority of the backward-bent-duct-buoy (BBDB) oscillating-water-column (OWC) wave energy converter (WEC) in harvesting wave energy, combining the floating platform with the BBDB OWC is a viable solution. In this study, a twin-hull BBDB-OWC integrated with a platform is proposed and its dimensions and geometric shape are optimized through experimental and numerical research. Through wave flume experiments of a scaled-down prototype of the combined platform, the influence of the draft, the air chamber opening diameter, and the wave period on the wave energy capture efficiency is investigated. Apart from that, numerical investigations based on a Taguchi method are conducted to perform geometric optimization of the twin-hull platform, with a focus on key factors such as the shape of the back bottom angle, the number of duct openings, the shape of the buoyancy chamber, the extension length of the damping plate, and the spacing between two hulls. Results show that the most significant factors affecting the bandwidth and capture width ratio are the shape of the buoyancy chamber and the extension length of the damping plate. Based on the geometric shape optimized by Taguchi method, further research using genetic algorithms is conducted for the duct bottom shape, which is parametrically defined. The maximum capture width ratio of the platform under the optimized shape reached 215.5 %.