- 學位論文
在層流平板流中慣性與熱泳效應影響微粒附著沉積率之研究
A Study of Effects of Inertia and Thermophoresis on Particle Deposition Rate in Laminar Plate Flows
摘要
本文目的在於了解偶合慣性與熱泳效應對微粒附著於平板表面的影響，所討論的平板流場包括有軸對稱與楔形板流。統御方程式有質量、動量與微粒傳輸等三個守恆方程式，採用相似法將這些偏微方程式轉換為數值分析較易處理的形式。這些方程式的解以及微粒的濃度場皆使用區塊法求得。在熱泳效應作用下所解得的答案可藉由Friedlander 的“無塵層”方法所獲得的解相互比較驗證。 慣性效應可以使用修正之Stokes數來衡量它的重要性。在軸對稱流修正之Stokes數, , 而在楔形板流則定義為 。研究結果顯示隨著粒子增大或流場強度增強(亦即修正之Stokes數)，慣性效應對微粒沉降速率的影響增加。同時，慣性效應在各種楔形板的角度上微粒沉降速率的影響也加以討論；在楔形板的角度考慮由 至 ，在角度為 時，慣性效應使得微粒沉降速率減少，然而在大角度則讓微粒沉降速率隨角度之增加而增加。在熱泳效應和慣性效應影響沉降速率之偶合作用也同時計算檢驗。
並列摘要
Coupling inertia and thermophoresis on particle deposition rates onto plate surface was reported. The flow fields of plate surface discussed include axisymmetric and wedge flows. The governing equations include the conservation of mass, momentum, and particle transport. Simlarity method was used to transform these governing equations in order to take a help in numerical solution. The solution of these equation and particle concentration field were solved using box method. The validity of solution considered with thermophoresis can be checked by Friedlander’s DFL method. The inertial effect can be measured using a modified Stokes number. The modified Stokes number is defined as in axisymmetric flow and in wedge flows, respectively. Results showed that the inertial effects on particle deposition velocity increase with an increase in particle size or the flow strength that induces an increase in modified Stokes number. Moreover, the inertial effects on particle deposition rates for different wedge angles are examined. The variation of wedge angles is considered from to here. The inertial effect makes particle deposition rates decrease for wedge angle . Nevertheless, particle deposition rates increase as wedge angles increase for big wedge angles. Effect coupling thermophoresis and inertia on particle deposition rates is also simultaneously calculated and examined.
參考文獻
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