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研究生:李盈樺
研究生(外文):En-Haw Lee
論文名稱:楔形流場中氣膠微粒傳輸機制之研究
論文名稱(外文):A Study of Transport Mechanisms of Aerosol Particles on the Wedge Flows
指導教授:蔡瑞益蔡瑞益引用關係
指導教授(外文):R. Tsai
學位類別:碩士
校院名稱:中原大學
系所名稱:機械工程研究所
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:2002
畢業學年度:90
語文別:中文
論文頁數:79
中文關鍵詞:微粒附著沉積率楔形流熱泳效應慣性效應
外文關鍵詞:thermophoresiswedge flowparticle deposition ratesinertial
相關次數:
  • 被引用被引用:0
  • 點閱點閱:133
  • 評分評分:
  • 下載下載:12
  • 收藏至我的研究室書目清單書目收藏:1

流體與懸浮微粒流經物體表面,其微粒附著沉積現象在一般生活上是常見的。其相關之研究在工程應用上及室內環境品質也日益重要。當流體與物體表面間存在溫度差時,熱泳效應形成一推力將微粒推向冷壁;而且在高性能設備的要求,慣性機制亦受到相當的重視。
本文研究之目的即探討慣性機制偶合熱泳,和布朗擴散對微粒附著沉積物體表面之影響。這三種傳輸機制的交互作用,對微粒附著率具有相當重要性,而控制慣性機制的無因次參數是修正史托克數。本文採二維楔形流模形。分析方法以相似法將偏微分之物理模式轉成相似或非相似形式,再以區塊消除法及有限差分法求得沉積率,微粒粒徑選擇0.01~100。
我們發現當微粒粒徑很小時,微粒附著率乃受擴散及熱泳機制支配;但當微粒粒徑增大時,擴散效應減少而改由熱泳及慣性機制支配。而且針對不同角度之楔形板塊,微粒受慣性效應影響情形亦不相同。另外當板壁溫度小於流體溫度時,微粒附著率會增大;當板壁溫度大於流體溫度時,由於熱泳將微粒推離壁面,造成微粒附著率降低。


The problems of airborne particles deposition onto surface are a commonly observed phenomenon and their studies have gained importance for engineering applications or indoor environments. Owing to nonisothermal convection gaseous flow, thermophoresis plays a significant role in enhancing small particle moving to cold surfaces. The study in the particle transport by combined effects of inertia, thermophonesis and other mechanisms is important for the control of aerosol particles.
The goal of this study is to examine the coupling effect of inertia, thermophoresis and others on particle deposition onto surfaces. The interaction between these three transport mechanisms is expected to be very important for particle deposition rate. We define a dimensionless parameter that controls inertial effect as modified Stokes number. In the article the flow is modeled as a two-dimension wedge flow. The governing partial differential equations are transformed to be a system of similar or nonsimilar equations by using similarity analysis. Block-elimination method and finite difference scheme are used to solve those equations and defermine the deposition rates. Particles selected are in a range of 0.01~100.
We can find that particle deposition rates are controlled by the effects of Brownian diffusion and thermophoresis for small particles . However, with increasing particle sizes the inertial effects become important. Moreover, the inertial effects on particle deposition rates in different wedge angles are also examined. When wall temperature is smaller than free stream temperature, the deposition rates will increase. When then wall temperature is smaller than free stream temperature, the deposition rates will increase. As a result of the thermophoretic effect, the particles blown away from the heated wall, the deposition rates will decrease.


中文摘要Ⅰ
ABSTRACTⅡ
誌謝Ⅳ
目錄Ⅴ
圖目錄Ⅶ
表目錄Ⅹ
符號說明ⅩⅡ
第一章、 導論1
1-1、 前言1
1-2、 研究動機與目的3
1-3、 文獻回顧4
第二章、 物理模型與相似方程式之建立6
2-1、問題描述6
2-2、基本假設6
2-3、統御方程式7
2-4、相似轉換9
第三章、 微粒附著速度的計算15
3-1、小粒徑15
3-2、大粒徑15
第四章、 計算方法17
4-1、流場、溫度場之計算方法17
4-2、濃度場之計算方法17
4-2-1、小粒徑17
4-2-2、大粒徑18
第五章、 結果與討論25
5-1、楔形流之濃度場分布26
5-1-1、冷壁26
5-1-2、熱壁27
5-2、楔形流之微粒附著速度27
5-2-1、板塊角度及慣性效應對微粒附著速度之影響28
5-2-2、熱泳效應及慣性效應對微粒附著速度之影響29
5-2-3、流場速度及熱泳效應對微粒附著速度之影響29
5-2-4、無因次長度及慣性效應對微粒附著速度之影響30
第六章、 結論與建議60
參考文獻61
簡歷64


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