研究生: |
蔡博欽 Bo-chin Tsai |
---|---|
論文名稱: |
圓柱管噴流在靜止及橫流環境下的實驗研究 An experimental study of a round tube jet in a stationary environment and a cross-flow environment |
指導教授: |
林怡均
Yi-Jiun Peter Lin |
口試委員: |
張倉榮
none 朱佳仁 none 陳明志 Ming-Jyh Chern |
學位類別: |
碩士 Master |
系所名稱: |
工程學院 - 機械工程系 Department of Mechanical Engineering |
論文出版年: | 2012 |
畢業學年度: | 100 |
語文別: | 中文 |
論文頁數: | 145 |
中文關鍵詞: | 封閉式垂直橫流水洞 、流場可視化 、質點影像速度儀 、渦流環 、噴流軌跡 |
外文關鍵詞: | vertical closed-loop water tunnel, flow visualization, Particle Image Velocimetry(P.I.V.), vortex ring formation, jet trajectory |
相關次數: | 點閱:270 下載:3 |
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本論文主要探討圓柱管噴流在靜止流體中的特性以及圓柱管噴流在橫流中的噴流軌跡分析。本實驗在封閉式垂直橫流水洞進行,分別藉由流場可視化以及質點影像速度儀 (P.I.V.) 觀察流場結構。
圓柱管噴流在靜止流體中的特性中,探討層流範圍時,不同雷諾數下,空間參數對於噴流流量的改變以及噴流中心線速度衰減的特性。質點影像速度儀使用兩個不同的計算解析度分析擷取的影像。當使用較小的解析度時,分析結果較為接近理論模型的估算。實驗結果顯示,渦流環的產生對噴流的流量及速度造成顯著的改變。噴流出口速度剖面的衍化結果顯示,渦流環產生之後的速度剖面接近 Schlichting 理論的速度分布。
圓柱管噴流在橫流中實驗結果的軌跡分析顯示,以流線、速度及渦度方式定義的三種噴流軌跡在速度比小於3及大於9時有較明顯的差異。本研究以流線軌跡分析噴流軌跡在橫流環境下的表現,分別以相同速度比以及相同橫流速度兩種條件比較噴流軌跡的改變,實驗結果顯示,雷諾數為主要影響噴流軌跡的參數,當噴流雷諾數在層、 紊流過渡區域時,噴流軌跡有轉折的現象。當噴流雷諾數越接近紊流區域時,噴流軌跡越接近過去文獻的經驗公式。
The research studies the features of round tube jets in a stationary environment and the trajectory analysis of round tube jets in a cross-flow environment. The experiments were carried out in a vertical closed-loop water tunnel. Flow structures were observed by using flow visualization and Particle Image Velocimetry(P.I.V.) techniques respectively.
For round tube jets in a stationary environment, the characteristics of the flow rate and the maximum axial velocity are different for the round tube jets having different Reynolds numbers. Particle Image Velocimetry uses two interrogation cells to analyze captured images. A finer cell has results approaching to the theoretical model. Experimental results show that, the vortex ring formation changes the flow rate and the velocity field of the jet significantly. The velocity profile of the jet is closer to that of Schlichting theory after the vortex ring formation.
For the trajectory analysis results of round tube jets in a cross-flow environment, three different trajectories determined by streamline, velocity and vorticity are notably different when the velocity ratio is less than 3 or larger than 9. This research uses streamline trajectory to analyze a round tube jet in a cross-flow environment. Experimental data are analyzed under two specific conditions of the same velocity ratio and the same cross-flow velocity. Experimental results show that Reynolds number is an important index for jet trajectory for these two conditions. When the Reynolds number of the jet is in the transition region, the trajectory of the jet shows some changes, especially the maximum axial distance which the jet can reach. When the Reynolds number is in the turbulent region, the jet trajectory is similar to those reported in the previous literature.
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