臺灣博碩士論文加值系統

本研究在一衝射凹面型微流振盪器內使用非牛頓流體carbopol 934水溶液，利用混合量化、流場可視化與頻率響應分析，探討非牛頓流體在不同幾何外形設計之微流振盪器內，改變Reynolds number對振盪頻率與混合效率的影響。
本研究中使用時間平均混合效率 作為微流振盪器的混合量化指標。由流場可視化和混合量化結果可發現，在同一幾何外形設計之微流振盪器內使用非牛頓流體，其混合效果皆優於使用牛頓流體時，這是因為carbopol 934水溶液為擬塑性流體，在剪應力變大時黏滯係數反而較小之特性所致。此外，導入圓角設計可增加凹面弧長，增強由Görtler渦漩所引起的不穩定性，因此混合效率明顯高於銳角設計。而在入口匯流處加入突擴設計，可增加流體不穩定性，降低臨界Reynolds number，當Re 110時， 值皆高於直管與突縮入口設計，但當Re 155時，由於在同一Reynolds number下，突縮入口設計可使射流流速變快，進而增強非牛頓流體之剪切稀化特性激發Kaye效應，故在Re > 155時，突縮入口設計 值高於其他入口設計。對於微流振盪器R300C，在Re 155時 值即高達0.9，為本研究中混合效率最佳之微流振盪器設計。
由頻率響應分析得知，隨入口速度增加，擋體後方尾流振盪頻率亦增加，在不同幾何形狀設計的微流振盪器內使用非牛頓流體，入口速度與振盪頻率皆呈線性關係，不受入口型態、擋體凹面半徑與圓角設計的影響。經由無因次分析可發現，非牛頓流體所得之Strouhal number在不同Reynolds number及幾何形狀設計下皆維持常數，為St = 3.7´10-6，低於先前研究[9]使用牛頓流體的情況。

In this study, the behaviors of non-Newtonian fluid flows through a microfluidic oscillator are investigated using carbopol 934 aqueous solution. Mixing quantification, flow visualization, and spectrum analysis are carried out to evaluate the influences of the Reynolds number in mixing efficiency and oscillation frequency of microfluidic oscillator.
Comparing to Newtonian fluid flows, we find that using non-Newtonian fluid always leads to higher in the same microfluidic oscillator. This is because carbopol 934 solutions are pseudoplastic fluid, and viscosity reduces as shear stress increases. Furthermore rounding the corner of the bluff body increases the arc length of concave cavity and thus enhances the Görtler vortex instability, resulting in an enhancement of . For Re 110, sudden-expansion confluence also helps to promote flow instability, causing a decrease in the critical Reynolds number. Nevertheless, microfluidic oscillators with a sudden-contraction confluence perform better in mixing for Re 155. This is because faster jet velocity helps to initiate the Kaye effect. In the present work, microfluidic oscillator R300C results in the best mixing performance, i.e. is able to achieve 0.9 at Re = 155.
Moreover, the spectrum analysis reveal that the oscillation frequency increases with the inlet velocity. For non-Newtonian fluid flows in microfluidic oscillator, the Strouhal number remains a constant, i.e. St = 3.7x10-6.

摘要 i
Abstract ii
目錄 iii
符號索引 vi
表目錄 ix
圖目錄 x
第一章 導論 1
1.1 前言 1
1.2 文獻回顧 1
1.3　研究動機 4
第二章 元件製程與實驗程序 5
2.1　微流振盪器製作 5
2.1.1　矽晶圓清洗 7
2.1.2　微影製程 7
2.1.3　PDMS製程 9
2.2　混合量化實驗 10
2.2.1 實驗設備與架構 10
2.2.2 實驗程序 12
2.3流場可視化實驗 16
2.3.1實驗設備與架構 16
2.3.2實驗程序 18
2.4　不確定性分析 19
2.4.1　體積流率之相對不確定性 20
2.4.2　入口平均流速之相對不確定性 21
2.4.3　體積莫耳濃度之相對不確定性 22
2.4.4　正規化濃度之相對不確定性 22
2.4.5　正規化螢光強度之相對不確定性 23
2.4.6　時間平均之正規化螢光強度的相對不確定性 23
2.4.7　 (mixing efficiency) 之不確定性 24
2.4.8　振盪頻率之相對不確定性 25
2.4.9　Reynolds number之相對不確定性 26
2.4.10　Strouhal number之相對不確定性 26
2.4.11　Péclet number之相對不確定性 27
2.4.12　Deborah number之相對不確定性 28
第三章　可視化與濃度場結果 29
3.1　流場可視化結果 29
3.1.1　拓撲分析 29
3.1.2　流場型態 31
3.1.3　入口型態的影響 38
3.1.4　擋體凹面半徑的影響 40
3.1.5　圓角的影響 41
3.1.6　非牛頓流體的影響 41
3.2　螢光濃度場結果 43
3.2.1　濃度場型態 43
3.2.2　入口型態的影響 46
3.2.3　擋體凹面半徑的影響 48
3.2.4　圓角的影響 48
3.2.5　非牛頓流體的影響 49
第四章　混合量化分析與頻率響應 51
4.1　混合量化結果 51
4.1.1　入口型態的影響 51
4.1.2　擋體凹面半徑的影響 53
4.1.3　圓角的影響 54
4.1.4　非牛頓流體的影響 55
4.2 微流振盪器內的混合機制 57
4.3 非牛頓流體對壓力振盪頻率的影響 57
4.4 振盪頻率的無因次化 58
第五章 結論與建議 60
5.1 結論 60
5.2 建議 61
參考文獻 62

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