臺灣博碩士論文加值系統

本文所要探討內容為於均勻二維穩態流場中，風刀隨著上緣導流板突出長度之改變對於射流流場造成之影響。並以CFD軟體FLUENT作為流場數值運算模擬工具，觀察方式為針對導流板不同突出長度時，比較不同射流距離之剪力層寬度、紊流強度、動量通量及體積流率等相關變化。
結果顯示：對於導流板突出長度0.5mm的情況，其射流流場抑制擴散之效果並不明顯，而當導流板突出長度介於1.5mm~2.5mm時，風刀射流距離由200mm起，其剪力層寬度隨著導流板突出長度增加而漸小，當射流距離達250mm時，其流場抑制擴散現象為最明顯，其中導流板突出長度1.5mm和2.5mm時抑制擴散提升效果分別為對稱風刀之29％和33％。而各個型式風刀之動量通量分佈皆呈現隨著導流板突出長度增加而遞減的趨勢分佈，整體而言導流板突出長度0.5mm和2.5mm動量通量分別降低3％和10％。
對於導流板突出長度1.0mm~2.0mm之風刀，射流傾角會隨著突出長度增加而變大，當導流板突出長度介於2.0mm~2.5mm，角度則介於-1.17°~-1.7°間震盪。風刀射流之引流倍率，於射流距離達150mm時約為30倍，當距離達到250mm時，風刀導流板突出長度為1.5mm~2.5mm之引流倍率約為47倍。

The objective of this research is to investigate the flow phenomena of steady two dimensional jet from an air knife with an extended sidewall by using CFD software FLUENT. With different sidewall extension lengths, the width of velocity profile, the width of shear layer, turbulent intensity, momentum flux, and volume flow rate at various distances from the jet exit are studied and compared.
It is observed that the jet suppression effect is not obvious for the extension length less than 0.5mm. As the extension length between 1.5 and 2.5mm, the width of the shear layer decreases with increasing the extension length. The suppression ratios are 29% and 33%, comparing with the symmetry air knife, for extension length 1.5mm and 2.5m respectively. The momentum flux decreases with increasing the extension length, which reduces 3% and 10% for extension length 0.5mm and 2.5mm respectively. For the extension length between 1.0 and 2.0mm, the jet flow slant angle increases with increasing the extension length. However, the slant angle oscillates between -1.17°~-1.7° while the extension length between 2.0 and 2.5mm. The induction flow rate ratio is 47 while the extension length between 1.5 and 2.5mm.

中文摘要.................................... Ⅰ
英文摘要.......... .......................... Ⅱ
目錄........................................ Ⅳ
圖目錄...................................... VI
表目錄...................................... X
符號說明.......... .......................... XI
第一章 緒論............................... 1
　　1.1 前言................................ 1
　　1.2 文獻回顧............................ 3
　　1.3 研究動機與目的...................... 6
第二章 理論分析........................... 9
　　2.1 物理模型及基本假設.................. 9
　　2.2 統御方程式.......................... 10
　　2.3 邊界條件............................ 11
　　2.4 紊流模式(Turbulence Model).......... 12
　　2.5 分析定義各參數...................... 15
第三章 數值模擬方法........................ 17
　　3.1 模擬方法............................. 17
　　3.2 求解流程............................. 18
　　3.3 數值模擬流程......................... 18
　　3.4 網格配置............................. 20
第四章 結果討論............................ 26
　　4.1 未添加導流板之對稱風刀............... 27
　　　4.1.1 對稱型式尖銳噴嘴風刀............. 27
　　　4.1.2 對稱型式鈍角噴嘴風刀............. 27
　　4.2 於風刀上部增加突出導流板............. 34
　　　4.2.1 導流板突出長度0.5 mm............. 34
　　　4.2.2 導流板突出長度1.0 mm............. 35
　　　4.2.3 導流板突出長度1.5 mm............. 36
　　　4.2.4 導流板突出長度2.0 mm............. 36
　　　4.2.5 導流板突出長度2.1 mm............. 37
　　　4.2.6 導流板突出長度2.2 mm............. 37
　　　4.2.7 導流板突出長度2.3 mm............. 38
　　　4.2.8 導流板突出長度2.4 mm............. 39
　　　4.2.9 導流板突出長度2.5 mm............. 39
　　4.3 結果比較............................. 55
　　4.3.1 速度分佈........................... 55
　　4.3.2 剪力層寬度......................... 57
　　4.3.3 紊流強度........................... 58
　　4.3.4 動量通量........................... 61
　　4.3.5 射流傾角........................... 63
　　4.3.6 體積流率........................... 64
第五章 結論................................ 76
參考文獻.......... ........................... 80
致謝......................................... 82

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