Performance prediction of the rotational wave energy converter using single-bucket drag type turbine

Abstract

Because ocean wave propagates along water surface, wave energy resource is measured in the unit of line density (kW/m). It indicates that the output of a Wave Energy Converter (WEC) is proportional to its wave front width when we consider the scaling-up of the device. It will be a problem in the commercialization of a scaled-up WEC because the cost of device increases with size in a higher pace. With the above consideration, the authors proposed a rotary type wave energy converter. It is a drag type vertical axis water turbine with its rotational axis lying horizontally on the water surface and in parallel to the wave front. To capture the orbital fluid particle motion in wave, the turbine is composed of a bucket and a streamlined counter weight. The device can be linearly extended in the direction parallel to the wave front to obtain the merits of scale. The WEC does not have massive components because the reaction torque of electric generation can be absorbed by a relatively small float system. This paper provides the numerical test of the device in deep water wave condition. The dependencies of the output to the wave height and the submergence of the rotational axis are checked by the two-dimensional flow simulation.