| Summary: | 碩士 === 國立臺灣大學 === 工程科學及海洋工程學研究所 === 106 === In bad weather like typhoon, waves are always considered as a key environmental factor in ocean engineering. In this condition, motions of Floating Kuroshio Turbine (FKT) could be induced by wave exciting forces, and some problems may be caused, such as the performance of power generation reduced and even damaged. In the present study, simulation software OrcaFlex is applied to simulate the dynamic responses and performance variation of the Floating Kuroshio Turbine under the action of waves.
This study builds an environmental flow field for FKT simulation in OrcaFlex, considering waves of different wavelengths and wave height ratio acting on the FKT located at 25m under water surface (normal operation depth) to investigate the influence of waves to the FKT. Furthermore, by adding the wave exciting forces of different wavelengths to the FKT located at 10m under water surface (shallow depth) and 40m under water surface (deeply submerged condition for avoiding long waves), the wave effects to the FKT depending on its submerged depth are investigated. Since FKT rotor could suffer significant oscillations under the wave effects, this study revised the torque performance of the generator so that the maximum speed of the rotor can be kept without over the rated speed too much.
According to the simulation results, FKT dynamics including vertical and longitudinal motions, pitch motions may become significant and then not only the performance of power generation will be reduced, but also tension variation of mooring line will be caused. This phenomenon is even significant at submerged depth of 10m, but it can be improved at submerged depth of 40m. In the future, when the FKT operates in real sea, the issue like cable fatigue damage caused by long waves should be also concerned.
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