Abstract
In this talk, we present our recent research on oscillating-water-column (OWC) wave energy converters. In contrast to designs developed for deployment in high wave energy environments for grid applications, our concepts target mild wave conditions, keeping economic viability in mind. One concept is Halona, which is a point absorber designed to meet power needs of 100 Ws. This design can find applications such as charging underwater vehicles and providing power for aquaculture farms. Results from a set of large-scale wave basin tests on a fixed Halona and a floating Halona will be presented. Hoopale is another concept, which has OWCs integrated with slotted barriers (OWC-SB) to form a dual-function breakwater for constructing energy self-sufficient harbors or ports. The benefits of this design will be highlighted. Experimental studies of two OWC-SB designs will be presented. One OWC-SB design is an array of OWC-piles, with each OWC-pile being a circular OWC supported by a coaxial tube-sector-shaped structure. The other OWC-SB design integrates a rectangular OWC with a slotted barrier. Numerical simulation results and theoretical analysis will also be presented to help understand the experimental results. In the experiment, orifices were used for PTO due to the small size of the models used in the experiment. The theoretical analyses were performed in the frequency domain using potential flow theory, with the orifices being parameterized using a quadratic pressure drop; therefore, the theoretical analysis is quasi-linear in nature. The numerical simulations were performed using OpenFOAM. A new approach to speed up the OpenFOAM simulations of OWC devices will be presented as well. Large-scale wave-basin experiment has been planned to test the second OWC-ST design, and some new results from this experiment will be presented as well.