臺灣博碩士論文加值系統

中文摘要
液體噴流的霧化在工業應用中非常廣泛，而有其重要性，但由於霧化過程非常複雜，即使是低速圓管液體噴流的液滴形成也尚未完全了解，尤其是低速液體噴流在分裂時，除了主液滴的形成之外，還有附隨液滴的存在。早期的線性間接理論僅能預測非黏性低速噴流的主液滴分裂，而忽略附隨液滴，至於間接非線性理論雖能預測主液滴與附隨液滴，但僅有三階諧波的考慮而有其限制。
本研究中，則利用直接數值分析法，來模擬低速圓管噴流表面波的成長變化，進而分析預測主液滴與附隨液滴的成形，在此直接數值分析法中，噴流擾動動量方程式中之對流項及完整的毛細壓力項將予以考慮，而此兩非線性項在過去間接線性或間接非線性理論中皆被忽略因而這些理論無法預測附隨液滴的存在。本研究在進行直接數值分析法計算分析後，並與間接線性與間接非線性理論比較，結果顯示唯有維持擾動動量方程式中的對流項及完整的毛細壓力項，才能準確地預測附隨液滴的形成，包括附隨液滴的存在。在本研究中除了利用直接數值分析法預測液滴的成形外，關於主液滴與附隨液滴的成長率也予以計算分析以進一步探討直接數值分析法與間接理論的差異，與了解低速圓管液體噴流分裂與附隨液滴形成的機制。

Abstract
The atomization of liquid jets has been widely used and of vital importance to many industrial applications. However, the breakup of drop formation has not been fully understood due to the complexity of the atomization process, even for low-speed circular liquid jets. Especially, there are satellite drops, which exist between main drops, during the breakup process of low-speed liquid jets. The early analysis of indirect linear method only predicts the formation of main drops for an inviscid liquid jet and ignores the existence of satellites while the indirect non-linear method is limited to three harmonics mode even though it can simulate main and satellite drops.
In the present study, a direct numerical method was utilized to simulate the disturbance growth on the surface of a low-speed circular liquid jet and to predict the formation of main and satellite drops. The direct numerical method considers the convective term and a full capillary pressure, which accounts for the presence of satellite drops but has been neglected in the past indirect analyses. During the present study, it is shown that the direct numerical method with the convective term and a fully capillary pressure, which should be maintained in the perturbation momentum equation, can provide better predictions including satellite formation than indirect methods. Besides the predictions of the drop formation using the direct numerical method, the growth rates of main and satellite drops were also computed to compare the differences between the present direct method and the indirect methods for further understanding the breakup mechanism and the satellite formation of low-speed circular liquid jets.

目錄
中文摘要
英文摘要
目錄------------------------------------------------------------------------------ I
表目錄--------------------------------------------------------------------------- II
圖目錄--------------------------------------------------------------------------- III
符號說明------------------------------------------------------------------------ V
第一章 緒論-------------------------------------------------------------------- 1
1-1 簡介------------------------------------------------------------------- 1
1-2 研究動機------------------------------------------------------------- 3
1-3 文獻回顧------------------------------------------------------------- 5
1-4 研究目標------------------------------------------------------------- 8
第二章 理論模式-------------------------------------------------------------- 10
2-1 Rayleigh線性理論-------------------------------------------------- 10
2-2 TVD直接數值分析------------------------------------------------- 15
第三章 結果與討論----------------------------------------------------------- 23
3-1 不穩定擾動波成長與噴流的破裂------------------------------- 23
3-2 直接數值分析與非線性間接理論之比較------------------------------------------------------------- 31
3-3 附隨液滴的形成與機制------------------------------------------------------- 40
第四章 結論與建議----------------------------------------------------------- 56
4-1 結論------------------------------------------------------------------- 56
4-2 建議------------------------------------------------------------------- 57
參考文獻------------------------------------------------------------------------ 59
表目錄
表1.1 噴流分裂歸類區域之分類------------------------------------------ 2
圖目錄
圖1.1 Rayleigh歸類區域中之噴流液滴形成--------------------------- 3
圖1.2 低速液體噴流尾端分裂出主液滴及附隨液滴----------------- 7
圖2.1 圓管狀噴流之座標系統及相關變數----------------------------- 10
圖2.2 噴流直徑、波長與液滴尺寸關係-------------------------------- 15
圖3.1 低速圓柱液體噴流表面干擾之成長率變化-------------------- 24
圖3.2 以Rayleigh線性理論模擬不同流速噴流之外形圖----------- 26
圖3.3 以Yuen非線性三階理論模擬不同流速噴流之外形圖------- 27
圖3.4 以直接數值模擬不同流速噴流之外形圖----------------------- 29
圖3.5 間接理論與直接理論的表面波成長率之比較----------------- 30
圖3.6 噴流表面擾動波成長變化之Yuen間接理論預測值( ， 、 、 、 )---------------------- 32
圖3.7 噴流表面擾動波成長變化之Yuen間接理論預測值( ， 、 、 、 )------------------------ 33
圖3.8 噴流表面擾動波成長變化之Yuen間接理論預測值( ， 、 、 、 )---------------------- 34
圖3.9 噴流表面擾動波成長變化之直接數值分析值( ， 、 、 、 )---------------------- 37
圖3.10 噴流表面擾動波成長變化之直接數值分析值( ， 、 、 、 )---------------------- 38
圖3.11 噴流表面擾動波成長變化之直接數值分析值( ， 、 、 、 )---------------------- 39
圖3.12 數值模擬噴流主液滴與附隨液滴的形成 ( ， 至 )---------------------------------------- 41
圖3.13 數值模擬噴流主液滴與附隨液滴的形成 ( ， 至 )---------------------------------------- 42
圖3.14 數值模擬噴流主液滴與附隨液滴的形成 ( ， 至 )----------------------------------------- 43
圖3.15 數值模擬噴流主液滴與附隨液滴的形成 ( ， 至 )---------------------------------------- 44
圖3.16 數值模擬噴流主液滴與附隨液滴的形成 ( ， 至 )---------------------------------------- 45
圖3.17 數值模擬噴流主液滴與附隨液滴的形成 ( ， 至 )---------------------------------------- 46
圖3.18 直接數值模擬噴流主液滴與附隨液滴的形成 ( ， 至 )---------------------------------------- 47
圖3.19 直接數值模擬噴流主液滴與附隨液滴的形成 ( ， 至 )---------------------------------------- 48
圖3.20 直接數值模擬噴流主液滴與附隨液滴的形成( ， 至 )----------------------------------------- 49
圖3.21 在不同波數擾動下噴流破裂所需之時間----------------------- 51
圖3.22 波數 時之擾動波成長率變化----------------------------- 53
圖3.23 波數 時之擾動波成長率變化----------------------------- 54
圖3.24 波數 時之擾動波成長率變化----------------------------- 55

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