https://scholars.lib.ntu.edu.tw/handle/123456789/80884
標題: | 聲波引致懸浮微粒聚結的理論研究及數值計算(2/2) Theoretical and numerical study of acoustic coagulation of suspended particles |
作者: | 李雨 | 關鍵字: | 聲波微粒聚結;旅波與駐波;理論分析;數值模擬;acoustic coagulation of small particles;traveling and standing wave;theoretical analysis;numerical calculation | 公開日期: | 31-七月-2003 | 出版社: | 臺北市:國立臺灣大學應用力學研究所 | 摘要: | 本計劃延續上年度計劃,以數值計算方法研究二相懸浮流中微粒的聲波聚結問題。本 文完成之工作有二:(1)就旅波(traveling wave)中微粒聚結的數值計算方面,本文解決了上 年度計劃中採用流力作用(hydrodynamic interaction)模式及聲波尾跡(acoustic wake)模式計 算時質量不守恆的問題。雖然本文的計算結果較前人者更接近實驗結果,但如同上年度計 劃中所採用的正動力作用(orthokinetic interaction)模式的模擬結果,我們需要採用一經驗的 碰撞效率係數方可使數值計算與實驗結果相吻合。這顯示目前文獻中現有的碰撞頻率函數 理論模式並不完備,有進一步研究的必要。(2)就駐波(traveling wave)中微粒聚結的數值計 算方面,本文對微粒顆數濃度隨體積分佈的廣義動力方程式,提出一項可對總顆數濃度作 分析模擬的簡化理論計算模式;假設微粒顆數濃度隨體積分佈呈對數常態分佈(log-normal distribution),則我們可將廣義動力方程式此一微積分方程式(integral-differential equation)簡 化為一偏微分方程式,而可大幅降低數值模擬所需的時間。此一簡化理論計算模式所獲結 果與實驗結果吻合,而可應用於聲波集塵器的參數分析及設計。 This second year project studies numerically the acoustic coagulation of small particles in a two-phase suspension flow. Two topics have been completed in the present work. (1) For the acoustic coagulation of particles in the traveling wave, we have solved the false mass conservation problem for the simulation using both the hydrodynamic interaction and the acoustic wake model in the last year. Although the agreement between the present calculations and the experiments is better than the calculations in the literatures, we still need to incorporate an empirical collision efficiency factor in the calculation, as that in the last year using orthokinetic interaction model. This indicates that the available models for the collision frequency function in the literatures have certain drawbacks, and further theoretical analyses are required. (2) For the acoustic coagulation of particles in the standing wave, we proposed a simplified theoretical model for the general dynamic equation of the continuous distribution function of particles. The log-normal distribution of particles is assumed, and a resulting partial differential equation is obtained from the integral-differential general dynamic equation. Numerical results of such partial differential equation agree nicely with the experiments. Thus the proposed simplified model can be applied for the parameter analyses and the design of the acoustic agglomerator. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/21681 | 其他識別: | 912212E002074 | DOI: | 10.1063/1.2721398 | Rights: | 國立臺灣大學應用力學研究所 |
顯示於: | 應用力學研究所 |
檔案 | 描述 | 大小 | 格式 | |
---|---|---|---|---|
912212E002074.pdf | 388.18 kB | Adobe PDF | 檢視/開啟 |
在 IR 系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。