臺灣博碩士論文加值系統

本研究以光電毛細管配合CFX數值模擬來瞭解黏度對盤式直葉攪拌翼的氣體分散影響，所研究的氣穴主要為大氣穴。就整槽的觀點，隨著黏度的增加，在同轉速下液體所能處理的氣體量也會增加，氾濫點會延後出現。對於高黏度溶液，假如迴轉速夠大，在攪拌翼後方的氣穴結構就能發展的十分穩定，功率消耗曲線會十分靠近。若是迴轉速較低，或有氾濫的情形發生，其功率消耗曲線便會另成一區，與穩定狀態分成兩群。
利用模擬結果之壓力分佈圖來確定氣穴區與非氣穴區的範圍。隨著黏度的增加，氣穴周圍之紊流動能和剪應力大小隨著增加。氣穴邊緣處的紊流動能及剪應力大小相較於氣穴尾端之漩渦處為較小；由光電毛細管所量得之氣泡大小，亦符合計算所得之結果，可以驗證這個論點。

To investigate the effect of viscosity on gas dispersion mechanisms around the disc turbine, both the photoelectric capillary method and the numerical simulation techniques were adopted to analyze large cavity behind the blade. With the increase of the viscosity of the fluid, we can handle more gas under the same rotation speed. For high viscous fluid, the cavity structure will be very stable if the rotation speed is large enough. The power consumption curves are gathering very close. However, if the rotation speed is not large enough, the curves will separate into groups.
The interface between cavity and fluid is depicted by the pressure contours. Turbulent kinetic energy and shear stress around the cavity are increasing with the increase of viscosity. Turbulent kinetic energy and shear stress of the boundary of the cavity are smaller than those at the vortex at the end of the cavity. From the bubble size measured by the photoelectric capillary method, the computation results are proved reliable.

液體黏度對攪拌槽中之氣體分散的影響
THE EFFECT OF FLUID VISCOSITY ON GAS DISPERSION
IN STIRRED TANKS
目 錄
頁次
誌謝……………………………………………………….………………….…..I
中文摘要……………………………………………………………………….II
英文摘要……………………………………………………...……………….III
目錄……………………………………………………………..……………...IV
圖索引………………………………………………….…..………..…….…VIII
表索引………………………………………………………………..…………X
第一章緒論………………………………………………….………..…1
第二章文獻回顧…………………………………………..………..…5
2-1氣液攪拌槽內氣體分散機構之探討….……………..6
2-2高黏性流體氣液攪拌槽內之探討……………......10
2-2-1氣體分散與氣穴結構………………..…….....11
2-2-2氣體包含量………..…………………...……..15
2-2-3功率消耗………..……………………..……....17
2-3氣液攪拌槽內氣體分散機構之探討……….…….20
第三章 實驗裝置與實驗方法……………………………...…….25
3-1攪拌功率消耗之量測……………………………..…..25
3-1-1量測原理及方法………………..…….……....26
3-1-2量測裝置………..……………………...……..28
3-1-3實驗流程………..……………………...……..31
3-2 局部氣含量之量測……………………..……………31
3-2-1量測原理及方法………………..…….……....31
3-2-2量測裝置………..……………………...……..32
3-2-3抽裂氣泡的處理方式………..………...……..36
3-2-4實驗流程………..……………………...……..40
3-3實驗之流體及流體黏度之量測……..…………43
3-3-1量測原理及方法…………………..…….…....41
3-3-2量測裝置………..……………………...……..42
3-3-3實驗所用之液體………..……….……..……..44
第四章 以模擬方法研究黏度改變流場
對氣體分散之影響…………………………...……..…..46
4-1CFX流場計算流體…………………….…………46
4-1-1CFX之數值計算原理…………….….……….46
4-1-2CFX之數值計算方法……………….………..48
4-1-3紊流模式………..……….………...…...……..49
4-2各項條件設定…………………………………....53
4-2-1攪拌槽幾何條件…………….……………....……..50
4-2-2邊界條件……………………………………..…..51
4-2-3計算網格設定………………………………..…..51
4-2-4其他條件………………………………...…….…..52
4-3攪拌翼後方之氣穴結構分析……….…...…...….53
4-3-1攪拌翼附近之壓力分佈…………….…....……..54
4-3-2氣穴位置、幾何形狀及大小……….……..…..63
4-3-3氣穴各處之紊流動能…………………………65
4-3-4氣穴各處之剪應力大小………………………66
4-4黏度改變對氣體分散之影響………………….67
4-5結論………………………………………………..…69
第五章以實驗量測探討黏度對功率消耗
及氣體分散之影響……………......….71
5-1不同溶液之功率消耗曲線圖……...……….……71
5-2光電毛細管量測氣泡大小分佈………………...77
5-2.1光電毛細管之量測位置…………………....…..77
5-2.2氣泡大小分佈之量測結果………………..….…78
5-3結論…………………………….………..………….84
第六章結論………………………………………..……..…………….85
符號說明………………………………..……………………………………..87
參考文獻………………………………..……………………………………..89
中英對照……………………………………..…………………………….….93

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