碩士 / 國立臺灣大學 / 生物環境系統工程學研究所 / 94 / A cave at backside of vertical drop energy-dissipators is called fish refuge groundsills, which provide a shelter for fish as flood over this zone. This type cave often appears and drop flow scouring forms that. Simplified models are considered here and only flow field structures are emphasized and discussed. The flow field measurements in fish refuge groundsills are performed using Particle Image Velocimetry (PIV) in this thesis. There are three types of physical models are used for different purposes.
To ensure the correctness of PIV operations and post-process analysis, the flow fields of cubic lid-driven cavity at Re = 400, 1000 and 2000 are first carried out and compare the velocity profiles along the horizontal and vertical center lines with benchmark by numerical simulations. The flow fields in 3/4 cavity from Re = 100 to 2000 are then executed. Two phenomena are observed in series of runs: 1) the several vortices appear with this cavity due to geometry and Reynolds number changing. 2) flow field becomes unsteady as Reynolds number more than 1200.
The flow field in vertical drop energy-dissipators with and without cave under skimming and napped flow conditions are finally considered. Single inflow discharge is supplied, but the skimming and napped flow conditions are created by adjusting the distance between drop and sills. For skimming flow, the vortex in the pool driven by flow skimming stretch into the fish refuge groundsills and it then occupies all area of cavity but low velocity. The variations of the horizontal velocities at various locations within fish refuge groundsills are obscure. For another case, napped flow, a stronger clockwise vortex is generated due to tailwater attaching bottom. This vortex fully extends into the fish refuge groundsills, and variations of the horizontal velocities at various locations within fish refuge groundsills are obvious relative to skimming flow. Traditional drop flow is studied for consideration of energy dissipations. These series of measurements are first handled and preliminarily performed to start for the biological problems.
| Identifer | oai:union.ndltd.org:TW/094NTU05404024 |
| Date | January 2006 |
| Creators | Yu-Sheng Chen, 陳昱升 |
| Contributors | 譚義績 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 166 |
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