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標題: | 質點影像測速儀應用於魚窪地固床工流場之試驗及分析 An experimental study of flow field in fish refuge groundsills using Particle Image Velocimetry techniques |
作者: | Yu-Sheng Chen 陳昱升 |
指導教授: | 譚義績 |
共同指導教授: | 賴進松 |
關鍵字: | 質點影像測速儀,魚窪地固床工,漩渦結構, PIV,fish refuge groundsills,vortex, |
出版年 : | 2006 |
學位: | 碩士 |
摘要: | 為了解魚窪地固床工內棲息空間的流場,因此將幾何邊界較複雜的魚窪地固床工,簡化成幾何邊界較簡單的多邊形模型,稱之為魚窪地固床工模型,並配合不同流況條件下,探討魚窪地固床工凹穴內漩渦流場。
本文主要應用質點影像測速儀(Particle Image Velocimetry, PIV )對一模擬魚窪地固床工之模型,於滑流與舌流流況條件下進行全域速度場之量測,在這之前,將魚窪地固床工試驗簡化成3/4孔穴流試驗,量測不同雷諾數下三維3/4孔穴流於中心對稱斷面上之二維速度場,並利用質點軌跡追蹤法將流場可視化。 模型則由透明壓克力板構成正立方體之孔穴,並於孔穴模型頂部設置傳輸皮帶構成五面為固定邊界及一面為移動邊界之封閉空間。研究中首先針對正立方體孔穴流進行雷諾數400、1000及2000之量測及流場可視化,並與前人之數值模擬結果比較,其目的為檢查模型製作是否符合要求及驗證PIV之操作與資料分析之正確性。再者修正正立方體孔穴模型為3/4孔穴流模型並於雷諾數由100至2000範圍中進行9組不同雷諾數之流場量測及分析;觀察3/4孔穴中於不同雷諾數時流場變化、漩渦結構之觀察、各漩渦之生成及其結構之幾何分析,以及當雷諾數持續增大時流場由穩態轉變非穩態時,其二維漩渦結構隨時間之震盪變化。最後探討魚窪地固床工考慮不同流況流況條件下(滑流與舌流),觀察垂直式跌水消能池與魚窪地固床工之流場特性與兩者相互之間流場比較。 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. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/33205 |
全文授權: | 有償授權 |
顯示於系所單位: | 生物環境系統工程學系 |
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