Examining the flow pattern suitability of fishway design by 3-D simulation taking Ma-Ann dam as an example

• Main Authors: CHIH-HUNG YEH, 葉治宏
• Other Authors: SHAO-HUA HSU
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/98935388545140227712

碩士 === 逢甲大學 === 水利工程與資源保育研究所 === 98 === Most rivers in Taiwan are steep with fast flow, and extremely different discharges in season due to unevenly distributed rainfall. For hydro-power generation or water resources purposes, weirs across river are usually built to facilitate water intakes, which may block the pass of fishes. As a result, fishway is important to help fish species to pass the constructed structures and maintain their population and good gene. Successful design of a fishway is a key element to a successful fishway. In this study, a three dimensional flow simulation model, FLUENT, was employed to simulate flow patterns and its three-dimensional velocity fields in a particular fishway with pool type in a hydro-power dam in Da-Jia river, central Taiwan. Measurement data, by other people, in a physical model was used for verification and comparison. In order to have a convergent numerical solution, local refinement of computational grid size around all openings, such as orifices, is needed. The grid size should at least be smaller than half the narrow width of each opening. The upper or lower boundary will affect the flow pattern up to its near-by four pools in sequence. So, at least ten pools are needed in simulation in order to have a central pool which is not affected by either upstream or downstream boundary. The simulated results show that the averaged velocities at all openings are less than the upper-limit design flow-velocity, which is 1.5 to 1.7 m/sec. Within the pool, flow pattern is stable and no significant circulation or up-lifting flow which can lead the fish in pool lost their way. Only the free surface flow across the Ice Harbor Weir indicates streaming flow pattern, which is not suitable for fish of surface type to take rest after each jump. To enlarge the longitudinal distance does not improve this drawback.