本文使用水桌流場視流觀測及風洞壓力量測，探討鈍形體前緣馬蹄形渦管的演變行為。主要實驗參數為雷諾數、展弦比、迎風面幾何形狀及高度比。實驗過程中水桌流場的雷諾數(以H=15mm作為特徵尺寸)維持500，風洞流場的雷諾數則維持1900及3800。展弦比的變化範圍為0.67~17。迎風面幾何形狀為平面、半圓、1/4圓及楔形。高度比的變化範圍為0.1~1。實驗結果顯示︰展弦比大於10時，馬蹄形渦管會分裂成一系列近似對稱排列的U形小渦管。若加端板則會在較小的展弦比產生分裂，各分裂渦管的大小也會比較固定。適度的改變楔形角度則可以抑制馬蹄形渦管的產生及發生分裂。當高度比增加為0.2時，會在長方柱前緣產生近似對稱排列的鞍點，隨高度比的增大，會形成馬蹄形渦管並在鞍點位置產生分裂。分裂的渦管個數隨展弦比的增大而增加，但隨高度比的增大而減小。流向逆壓力梯度及橫向逆壓力梯度的減小是渦管產生分裂的主要原因。

Flow visualization and surface pressure measurements are preformed to study the evolution of a horseshoe vortex upstream of a surface mounted cylinder with aspect ratios ranging from 0.67 to 17. The Reynolds numbers are 500 for visualization experiments and 1900 to 3800 for wind tunnel tests. The cross sectional shape of the cylinder is rectangular, semi-circle, quarter-circle or triangular. The height ratio(normalized by the largest height) of the cylinder varies from 0.1 to 1. The experimental results indicate that a horseshoe vortex will branch itself into smaller regular vortices of U shape for aspect ratios greater than 10. The end planes cause the U vortices to occur at a smaller aspect ratio and also make their sizes become more uniform. The U vortices will be suppressed by changing the cross sectional shape or the height ratio. For rectangular cylinders, when the height ratio is near or greater then 0.2, a horseshoe vortex will be developed and branched subsequently. The number of branched smaller vortices increases as the aspect ratio increases, but decreases as height ratio increases further. The branching of a horseshoe vortex is caused by decreases in both the streamwise adverse pressure gradient and spanwise favorable pressure gradient upstream of the cylinder.

封面
摘要
英文摘要
誌謝
目錄
表目錄
圖目錄
符號說明
附圖目錄
一、前言
1.1 研究動機
1.2 文獻回顧
1.3 本文組織
二、實驗設備與方法
2.1 水桌實驗
2.1.1 水桌設備
2.1.2 視流設備
2.2 風洞實驗
2.2.1 風洞
2.2.2 風壓擷取系統
2.3 實驗模型
2.4 實驗參數
2.5 誤差分析
三、結果與討論
3.1 展外比對長方柱前緣馬蹄形渦管演變的影響
3.2 端板對長方柱前緣馬蹄形渦管演變的影響
3.3 迎風面幾何形狀對馬蹄形渦管分裂的影響
3.4 高度比對馬蹄形渦管演變的影響
四、結論
五、參考文獻
圖表

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