Performance and flow characteristics of single and a novel double oscillating water column devices

The performance of a single Oscillating water column (OWC) in normal and opposite configuration employing a Savonius rotor is investigated. For the normal OWC, the peak performance occurred at wave period T = 1.7 s with rotor speed of 86 rpm at wave height H = 80 mm. The opposite OWC recorded peak performance at the same wave period and the rotor had a maximum speed of 65 rpm at H = 80mm. Furthermore, a novel double OWC configuration was tested and the peak performance of the rotor in the front and rear OWC occurred at T = 1.675 s with respective rotor speeds of 74 rpm and 53 rpm. The double OWC was analyzed by combining the performance of the rotor in the front and rear OWC. The Particle image velocimetry (PIV) results showed regions of re-circulating flow in the chamber as well as around the rotor. It was interesting to note that when comparing the advancing flow and the retreating flow, the flow had more energy when retreating hence suggesting more energy is imparted onto the rotor during this time. The PIV results provided a deeper insight into the flow characteristics and the rotor performance.