Advanced efficiency improvement of a sloping wall oscillating water column via a novel streamlined chamber design

Abstract

Despite the huge potential of ocean waves as an alternative renewable energy resource, very low wave to wire efficiency of wave energy converters (WECs) hampers its commercialization. In this study, a novel streamlined chamber design has been proposed for performance improvement of an oscillating water column (OWC) with a sloping wall. Physical experiments are carried out for the calculation of capture width ratio (CWR) as a measure of hydrodynamic performance for various levels of PTO damping and sea conditions. The results are compared with those of a classical OWC chamber design. It is found that streamlined chamber design has an important bearing on OWC efficiency. As opposed to classical chamber shape, proposed streamlined chamber geometry increases the OWC performance as much as 31% for the incident waves under which the OWC operates efficiently. Further, results show that optimal level of PTO damping that for utmost energy extraction depends on the chamber design. Streamlined chamber geometry even further improves the OWC efficiency even when dominant sloshing water column motion is present in the chamber with a maximum and average value of 54% and 44%, respectively, however, chamber design has no influence on the mechanism that generates sloshing phenomenon in the chamber.