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研究生:張德偉
研究生(外文):Darry Jang
論文名稱:微擴流器閥整流效率之數值分析
論文名稱(外文):Numerical Analysis of the Rectification Efficiency of Microdiffuser Valves
指導教授:王逸君
指導教授(外文):Yi-Chun Wang
學位類別:碩士
校院名稱:國立成功大學
系所名稱:機械工程學系碩博士班
學門:工程學門
學類:機械工程學類
論文種類:學術論文
論文出版年:2008
畢業學年度:96
語文別:中文
論文頁數:95
中文關鍵詞:整流效率微擴流器羅緒科數
外文關鍵詞:Micro-diffuserRoshko numberRectification efficiency
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本研究以數值方法分析圓錐型微擴流器閥與平板型微擴流器閥之整流效率,探討擴流器閥之暫態流場與整流效率之關係,找出最佳整流效率及其所對應的相關參數,同時提出不同的幾何模型,期望將整流效率提升。研究中針對擴張全角10度細長比7.5之微擴流器閥,在致動頻率1~400Hz的範圍內進行分析,使用的流體為氨水,這些分析參數所對應的羅緒科數為0.44~176.87。分析結果發現,影響整流效率的原因與流道中渦流的形成及特性有關。影響渦流的主要因素為擴流器的致動頻率與幾何模型,致動頻率影響渦流生成的時機,而擴流器的幾何模型則會影響渦流的出現位置。一般而言,低羅緒科數下整流效率較低,隨著羅緒科數增加,整流效率亦隨之提升至最佳值,之後隨著羅緒科數之增加,整流效率會再度降低。從模擬結果得知,傳統上在擴流器入口設計圓角,在低羅緒科數之範圍,確實可提升整流效率,但在高羅緒科數時,入口為尖角之擴流器閥整流效率反而優於入口為圓角者。本研究提出含套袋設計之微擴流器閥,結果顯示可大幅提升圓角微擴流器閥的整流效率。
A numerical analysis is presented to study the rectification efficiency of conical and planar micro-diffuser valves. The primary goal is to understand how the unsteady flow characteristics in the diffuser valve influence its rectification efficiency, and then to propose several geometrical models for increasing the rectification efficiency. The simulations are performed for diffusers with diverging angle of and slenderness of 7.5, under excitation frequencies of 1~ 400Hz, NH3 is selected as the working fluid, and these parameters correspond to a range of Roshko number between 0.44 and 176.87.
Numerical results show that the timing of the vortex formation and the variation of the vortices have a direct impact on the rectification efficiency. The excitation frequency and the geometrical model are the major parameters which influence the behavior of the vortices. The excitation frequency determines the timing of the vortex formation and the geometry of the diffuser valve affects the location of the vortices. In general, the rectification efficiency is poor in low Roshko number and increase to an optimum at some specific Roshko number, and then drops down fast thereafter. It is found that diffusers with rounded-entrance indeed exhibit a much better rectification efficiency than those of sharp entrance. However, the latter show a higher efficiency in the high Roshko number range. Equipped with a pocket design, the rectification efficiency of the rounded-entrance diffusers can be greatly improved. From simulation results we know that the micro-diffuser with the pocket in diverging angle , slenderness of 7.5 will arise the rectification efficiency of rounded-entrance diffuser.
摘要 I
Abstract II
誌謝 III
目錄 IV
圖目錄 VII
表目錄 X
符號說明 XI
第一章 序論 1
1-1 前言 1
1-2 文獻回顧 2
1-3 研究動機 7
第二章 無閥式微泵及微擴流器 9
2-1 無閥式微泵之工作原理 9
2-2 無閥式微泵之整流效率 10
2-3 微擴流器閥之幾何模型 10
第三章 參數分析及數值方法 15
3-1 無因次化參數分析 15
3-2 基本假設 17
3-3 初始及邊界條件 17
3-4 統御方程式 18
3-5 FLUENT數值方法設定 19
3-6 參數設定 20
3-7 空間網格與網格獨立性測試 22
第四章 圓錐型微擴流器閥之整流效率 29
4-1擴流器入口圓角對整流效率的影響 31
4-1-1 幾何模型與研究目的 31
4-1-2 流場與結果比較 31
4-2渦流產生器對整流效率的影響 36
4-2-1 幾何模型與研究目的 36
4-2-2 渦流產生器對整流效率的影響 36
4-3含套袋設計的微擴流器閥 38
4-3-1 幾何模型與研究目的 38
4-3-2 單一套袋對整流效率的影響 39
4-3-3 套袋位置對整流效率的影響 41
4-3-4 多套袋設計對整流效率的影響 41
第五章 平板型微擴流器閥之數值分析 83
5-1 平板型微擴流器閥之數值分析結果 83
5-2 分析結果與文獻之比較 85
第六章 結論與未來展望 90
6-1 結論 90
6-2 未來展望 92
參考文獻 94
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