Numerical study on a novel backward bent duct buoy wave energy converter with ‘ducktail’ deflector

Abstract

On the basis of the backward bent duct buoy (BBDB) wave energy converter (WEC), this paper proposes a novel BBDB WEC with a ‘ducktail’ deflector, aiming to further improve capture width ratio (CWR), expand efficient working range, and increase annual power generation. For developing the new device, a 32.5 m-wide numerical wave channel is established and validated. The validated numerical model is used to explore the performance of the 6.5 m-wide full-scale new device, especially the influence of ‘ducktail’ deflector's geometric parameters on the CWR and frequency response bandwidth of the new device. The optimal deflector width, length, inclination angle, as well as the horizontal and vertical distances between the deflector and the BBDB are obtained. The results reveal that, compared with the original BBDB WEC without deflector, CWR of the optimized new device with a deflector increases by 18.5 % under the typical wave condition of the planned deployment site (wave period 4.25s, wave height 1 m), and the wave period range with CWR higher than 1.0 is expanded by 100 % (wave height 1 m). Also, the mechanisms underlying CWR improvement and efficient working range expansion by using the ‘ducktail’ deflector under various waves are revealed from different perspectives.