臺灣博碩士論文加值系統

本實驗係在環境風洞中進行模擬重質氣體意外溢漏時，二維阻牆對重質氣體擴散影響之研究。實驗中之重質氣體採用二氧化碳，並選擇不同初始密度福祿數 (Frs=8、14、20)、阻牆間隙率(P=50%、70%、85%)與不同阻牆高度(H =1hs、2hs，hs為溢漏源高度)等參數，探討在這些不同參數下重質氣體擴散之特性。
實驗結果發現，溢漏重質氣體之稀釋能力因流場受阻牆干擾而有所影響。當溢漏之初始密度福祿數越大時重質氣體之濃度越容易向下游擴展，但初始密度福祿數對於溢漏排放重質氣體沉降性的影響不大。相較於一倍排放管高的阻牆，兩倍排放管高的阻牆後方下游處，重質氣體之濃度值會比較小，而且會有因紊流造成濃度偏移中心軸的情形；另外其下游濃度也沒有像一倍排放管高的阻牆時，可以明顯的看出重質氣體沉降的效應。當阻牆間隙率為50%時，對於下游濃度的擴散效果最佳，最容易達到快速稀釋的效果。
以水平向擴散尺度而言，無論是一倍排放管高或是兩倍排放管高之阻牆隨下游距離增加，水平擴散尺度幾乎都會趨近至一個定值，尤其是當阻牆間隙率為50%時。以垂直向擴散尺度而言，隨著阻牆下游距離增加而趨近於一個定值，兩倍排放管高之阻牆相較於一倍排放管高之阻牆下，在較靠近阻牆處之垂直擴散尺度變化較為紊亂。

摘要 I
Abstract II
目錄 III
表目錄 VI
圖目錄 VII
符號說明 XVIII
第一章 導 論 1
1.1前言 1
1.2 研究目的 3
1.3 前人研究 3
1.4 研究方法與內容 5
第二章 風洞模擬之理論 7
2.1 中性大氣紊流邊界層之風場特性 7
2.1.1大氣邊界層厚度 8
2.1.2 風洞模擬中性大氣紊流邊界層之基本假設 8
2.1.3 平均風速剖面 9
2.1.4 紊流強度 11
2.1.5 雷諾應力 13
2.2 重質氣體擴散之物理特性 13
2.3 阻體後方煙流擴散特性 14
2.4風洞模擬之相似性法則 15
2.5重質氣體擴散之因次分析探討 18
第三章 實驗設計與配置 21
3.1實驗設計 21
3.1.1實驗流程 21
3.1.2實驗設計之條件 22
3.2實驗配置 25
3.2.1迫近流場模擬 25
3.2.2迫近流場量測設計 26
3.2.3風阻牆模型設計 27
3.2.4追蹤氣體溢漏設計 28
3.3實驗儀器 30
3.3.1環境風洞 30
3.3.2 迫近流場量測儀器 30
3.3.3 迫近流場量測 33
3.4 濃度場量測與儀器 36
3.4.1 追蹤氣體排放系統 36
3.4.2 追蹤氣體採樣系統 37
第四章 實驗結果與分析討論 39
4.1 迫近流場模擬結果 39
4.1.1平均風速剖面(Mean Velocity Profile) 39
4.1.2 紊流強度 40
4.1.3 雷諾應力 40
4.2重質氣體擴散特性 40
4.2.1 濃度場分佈特性 41
4.2.2最大濃度分佈綜合比較 46
4.2.3地面濃度分佈綜合比較 48
4.2.4擴散尺度的分佈特性 49
第五章 結論 54
參考文獻 57
附表 61
附圖 63
致謝 146

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