| Summary: | 碩士 === 國立臺灣海洋大學 === 系統工程暨造船學系 === 103 === An outer direct-driven ocean current generator with single duct is manufactured and tested in Large Cavitation Tunnel at NTOU. The test results are compared with those of CFD. Besides, a dual-duct ocean current generator is designed, and the influence of geometric parameters, such as inner duct and its centerbody, on the power coefficient of generator is investigated by CFD.
From the test results, it is found that the difference between experiment and computation is significant due to the low Reynald’s number, 2*106 for the duct, which is far lower than the critical Reynald’s number for turbulence boundary layer. However, the flow field of CFD computation is assumed to be turbulent. Therefore, separation happened at the rear part of diffuser and the measured turbine torque is reduced. However, a dual-duct generating system is able to raise power coefficient up to over 1.05 under the assumption of turbulent flow. The geometry parameters of inner duct and inner duct centerbody both have important influences on the power coefficient.
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