摘要
本文使用套裝軟體PHOENICS對二維層流或紊流對衝流場的混合效果及流體行為做綜合性的探討與分析。在層流中，直接建立Navier-Stokes方程式，並以控制體積積分法建立有限差分方程式，按SIMPLEST計算程序求解；而在模擬二維、不可壓縮之矩形對衝紊流流場，則採用修正後之Lam— 雙方程式紊流模式，並以控制體積積分法建立有限差分方程式，按SIMPLEST計算程序求解，分別就上下噴口速度比(VR)、噴口中心間距(S)、兩平板距離(H)及橫向流的有無( )等參數變化，分析它們對流場中速度、壓力、溫度及結構的影響。
經所得結果顯示，在無橫向流的對衝流場之下，無論是單噴對衝或是雙噴對衝，紊流所得的混合效果均較層流良好。且當上下噴口速度比愈大時，其所獲得溫度分佈愈均勻，混合狀況愈佳。隨著高度增加，其混合效果逐漸變差。當有橫向流時，其速度愈大，所挾帶動量也愈大，對於對衝流場則有較差的混合效果。
綜合言之，分析對衝流場的混合效果及流場結構，有助於了解空氣和燃油的混合，且更能充分掌握影響燃燒的因子，以提供業界在設計各種燃燒室上的參考。
關鍵字：對衝流揚、燃燒室、橫向流、混合效果

Abstract
In this study, a computational fluid (CFD) code, PHOENICS is used to calculate the flow field of 2-D double impinging streams to make the exploration of the comprehensive about mixing effects and flow behavior in two-dimensional opposed streams. In the laminar flow, directly construct the Navier-Stokes equation, and the control-volume integration formula for finite difference and SIMPLEST algorithm to solute. In the turbulence flow, the Lam correctional k-e two-equation turbulence model and the control-volume integration formula for finite difference and SIMPLEST algorithm are employed to simulate the two-dimensional, incompressible flow field. The velocity ratios (VR) of top jets to bottom jets, the nozzle to nozzle centerline spacing (S), the plate to plate distance (H) and the effect of the crossflow velocity ( ) on the flow field structure will be studied.
From the numerical results, either single group or dual jets without crossflow, turbulent flow is better than laminar flow. When jets velocity ratio became larger, it got more uniform temperature distribution and mixing. But when the height is increasing, mixing quality got worst.
Finally, analyzing mixing effects in the opposing streams and field structures, it would be helpful to understand the mixing of air-fuel ratio. The numerical results could prove industry to design all kinds of combustion chambers.
Key Words：opposing streams, combustion chamber, crossflow, mixing quality

目 錄
中文摘要 Ⅰ
英文摘要 Ⅱ
目 錄 Ⅲ
表 目 錄 Ⅵ
圖 目 錄 VII
符號說明 XVII
第一章 緒論 1
1－1 前言 1
1－2 流場分析 2
1－3 文獻回顧 5
1－4 研究動機與目的 9
第二章 物理模型與統御方程式 11
2－1 物理模型 11
2－2 基本假設 12
2－3 統御方程式 13
2－4 紊流模式 15
2-4-1 標準 與Lam- 模式之統御方程式 15
2-4-2 Lam-Bremhorst－ 紊流模式 18
2－5 邊界條件 20
2－6 溫度混合指標 21
第三章 數值方法與求解程序 23
3－1 簡介 23
3－2 交錯式網格點系統 23
3－3 離散方程式的建立 25
3-3-1 差分方程式 25
3-3-2 混合法則 27
3-3-3 離散方程式的建立 31
3－4 求解程序 33
3-4-1 SIMPLE求解法 33
3-4-2 SIMPLE與SIMPLEST求解法之比較 36
3-4-3 鬆弛因子 38
3-4-4 收斂條件 39
3－5 數值模擬流程 40
第四章 結果與討論 42
4－1 前言 42
4－2 流場結構分析 43
4-2-1 單噴對衝 43
4-2-2 雙噴對衝 45
4－3 對衝流場混合效果之分析 50
4-3-1 上下噴射主流速度比對混合效果的影響 50
4-3-2 噴口中心間距對混合效果的影響 51
4-3-2 兩平板距離高度對混合效果的影響 52
4-3-4 橫向流的影響 53
第五章 結論與未來研究方向建議 54
參考文獻 56
附錄A 壁函數的說明 61
附表 65
附圖 69

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