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http://dx.doi.org/10.1016/j.ijnaoe.2021.01.008

The effects of geometrical buoy shape with nonlinear Froude-Krylov force on a heaving buoy point absorber  

Kim, Sung-Jae (Department of Naval Architecture and Ocean Engineering, Inha University)
Koo, Weoncheol (Department of Naval Architecture and Ocean Engineering, Inha University)
Kim, Moo-Hyun (Department of Ocean Engineering, Texas A&M University)
Publication Information
International Journal of Naval Architecture and Ocean Engineering / v.13, no.1, 2021 , pp. 86-101 More about this Journal
Abstract
This study examined the effects of buoy shape and Nonlinear Froude-Krylov force (NFK) on a heaving-buoy-type Wave Energy Converter (WEC). Based on the Maclaurin expansion, the theoretical solutions of the NFK were derived for three different buoy shapes; hemispheric buoy, circular vertical cylinder, and truncated conical cylinder. A hydraulic power take-off system was adopted, and the latching control strategy was applied to maximize the extracted power from the WEC. The nonlinear effects of the Froude-Krylov force and restoring force on the heaving point absorber were investigated by comparing the heave Response Amplitude Operator (RAO) and time-averaged power extraction. The results showed that the conventional linear analyses were overestimated by up to 50% under the high amplitude wave condition. The latching control strategy was the most effective when peak wave period of regular or irregular wave was 0.4-0.45 times the heave natural period of the buoy.
Keywords
Nonlinear Froude-Krylov force; Buoy shape; Wave energy converter; Response amplitude operator; Hydraulic power take-off system; Latching control strategy;
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