Optimal design of a submerged tidal device for low current environment

초록

The tidal current power is one of the reliable renewable ocean energy resources that can be deployed at the region having ocean current. The feasible current speed for the application of tidal device is known to be more than 2m/s. As there are many islands in Asia where the current speed is below than the feasible speed, the submerged device that can produce the power at lower current speed with easy deployment and retrieve is introduce. To simplify the installation and operation and maintenance, the 4-point taut mooring system is applied that can also secure the designated position. In this study, a horizontal axis turbine of 5 kW submerged tidal device is designed and analyzed for a low current region that consist of two buoyancy tanks, a yaw control strut, and a diffuser-type brimmed duct. To analyze the most stable condition, 9 different cases of width and height of the device and 8 different mooring arrangements therefore, total 72 different cases are investigated both by frequency and time domains. The result shows that pitch angle varies from 8 to 15 degrees and the variation of yaw angle is merely existed. 9.7 percent of power reduction is expected. Pitch angle and the yaw angle is the main factor that affects the power reduction, however, as the effect of yaw angle is merely exists, optimal device is designed with only considering the pitch angle. The optimal design has 4.42 meters width, 2 meters height, 30° of azimuth angle and 60° of hang-off angle. © 2023 European Wave and Tidal Energy Conference.

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