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研究生:周明財
研究生(外文):Ming-Cai Zhou
論文名稱:乳化液潤滑中油滴行為之數值探討
論文名稱(外文):Numerical Analysis of oil Droplet Behaviors in Emulsion
指導教授:羅斯維
指導教授(外文):Sy-Wei Lo
學位類別:碩士
校院名稱:國立雲林科技大學
系所名稱:機械工程系碩士班
學門:工程學門
學類:機械工程學類
論文種類:學術論文
論文出版年:2004
畢業學年度:92
語文別:中文
論文頁數:74
中文關鍵詞:乳化液潤滑黏度金屬成形
外文關鍵詞:EmulsionLubricationViscosityMetal Forming
相關次數:
  • 被引用被引用:3
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隨著科技日新月異的在進步,機械元件運轉也朝著高轉速、高精度和高壽命方向邁進。乳化液兼備冷卻和潤滑的優良性能,目前廣泛的使用在金屬成形加工和金屬切削加工方面。
乳化液潤滑過程中,加工速度、初始油濃度和黏度對油膜的成形性、壓力分佈、集中濃度和負載力有很大的影響,甚至會產生油匱乏(starvation)現象,對機械元件的剛性和壽命以及金屬加工之影響很大。
因此,本文利用CFDRC軟體分析乳化液潤滑中油滴行為的各項特性。包括:加工速度、黏度和初始油濃度在潤滑過程中的壓力分佈情形和潤滑效果。另一方面,探討單油滴行為特性,藉以釐清油滴為何易於向前擠壓或被水向後排開等特性。
由模擬結果得知,油黏度、加工速度和初始油濃度影響潤滑過程中,初始油濃度愈濃時,其效果會近似純油性質。油黏度最易影響壓力,而速度較不影響壓力分佈的形態。
單油滴行為方面,整個流動過程中,油滴質心速度漸增,油滴之厚度也隨之減少。從扁平率顯示黏度大者較圓;黏度小者較扁。另一方面,油黏度低者,其性質像連續液體(水)般,受水流場影響大,易被水排開;油黏度高者,其性質像固體般,受水流場影響小,易被向前擠壓。將此特性應用在多油滴上,其影響作用會更加明顯。
As science and technology is progressing with rapid pace, the mechanical device is forward in higher rotational speed, higher accuracy and longer performance life. Emulsion, which combines good cooling and lubricating capabilities, are widely used in metal-forming and metal cutting.
The surface speed, initial oil concentration, and viscosity of oil have significant influences on the forming of oil film, pressure distribution, oil concentration, and load capacity during emulsion lubrication. Unsatisfied emulsion will even generate oil starvation that has substantial effects on the stiffness and life of machine elements and on metalworking.
Therefore this thesis utilizes the commercial software, CFDRC-ACE+, to analyze the behavior of a group of oil droplets in emulsion under various combinations of surface speed, oil viscosity, and initial oil concentration. Their effects on pressure distribution and lubrication efficiency are investigated. The behaviors of single oil droplet are also studied to explore the possible explanations to the forward and backward motions of droplet pushed by water flow.
The result shows that high initial oil concentration leads to the lubrication similar to that of neat oil. The oil viscosity is the most dominating variable on the pressure distribution, while the surface speed displays minor influence on the pressure distribution.
For single oil droplet, the center of droplet accelerates through the aqueduct with decreasing thickness of the droplet. The flatting ratio of droplet indicates that the droplet of high viscosity has the stronger tendency of keeping its spherical shape while the low viscosity one is easier to be flattened. The nature of low viscosity makes the discontinuous component (droplet) itself behaves as the continuous phase (water). Therefore the velocity field inside the droplet can be easily influenced by the water flow. On the other hand, the high viscosity results in a solid-like dispersion, which is easier to be pushed forward by the water. Such an effect of viscosity will become more considerable for a group of oil droplet as that happens in the emulsion.
中文摘要 --------------------------------------Ⅰ
英文摘要 --------------------------------------Ⅱ
致謝 --------------------------------------Ⅲ
目錄 --------------------------------------Ⅳ
表目錄 --------------------------------------Ⅵ
圖目錄 --------------------------------------Ⅶ
符號說明 --------------------------------------Ⅹ
第一章 緒論-----------------------------------1
1.1 前言-------------------------------1
1.2 乳化液介紹-------------------------1
1.3 文獻回顧---------------------------2
1.4 研究內容---------------------------5
第二章 乳化液潤滑基本分析--------------------11
2.1 模垢理論--------------------------11
2.2 潤滑能力與接觸角------------------11
2.3 動態集中理論----------------------13
第三章 應用軟體介紹和求解規劃----------------15
3.1 軟體介紹--------------------------15
3.1.1 CFD-GEOM軟體--------------------15
3.1.2 CFD-ACE+軟體--------------------16
3.1.3 CFD-VIEW軟體--------------------16
3.1.4 CFDRC軟體使用流程---------------16
3.2有限體積法介紹---------------------20
3.3 求解問題說明----------------------20
3.4 液體流動的基本理論----------------22
3.5 模擬規劃--------------------------24
3.5.1 模擬前之假設--------------------24
3.5.2 模擬條件之設計------------------24
3.5.3 模型建立------------------------26
3.5.4 邊界條件設定--------------------27
3.5.5 濃度判定------------------------27
3.6 模擬要點--------------------------28

第四章 模擬結果與討論------------------------29
4.1 不同速度和黏度時油滴分佈的影響----29
4.2 不同初始油濃度下對壓力分佈的影響--29
4.3 油集中濃度之變化情形--------------30
4.3.1 不同初始油濃度下油滴濃度之分佈影響---30
4.3.2 不同速度下油滴濃度之分佈影響----31
4.3.3 不同黏度下油集濃度之分佈影響----31
4.4 壓力與油濃度之變化----------------31
4.5 單油滴行為之探討------------------32
4.5.1 連續相(水)和不連續相(油)之壓力分佈---------------------------------------------32
4.5.2 單油滴之速度場------------------32
4.5.3 多油滴與單油滴之速度場----------34
4.5.4 油滴質心速度與扁平率關係--------34
4.5.5 黏度與時間之關係----------------35
第五章 結論與未來展望------------------------58
5.1 結論------------------------------58
5.2 未來展望--------------------------59
參考文獻 --------------------------------------60
附錄一 --------------------------------------61
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[8] Abhay Kumar,Steven R.Schmid and W.R.D. Wilson,”Particle behavior in two-phased lubrication”,Wear,206,pp130-135,1997.
[9] S.R.Schmid,”Hydrodynamic Segregation,Entrainment and Rejection of Oil in Emulsion Lubrication Problems”,Journal of Tribology,Vol.119,pp342-348,1997.
[10] Steven R. Schmid and W.R.D. Wilson,”Lubrication Mechanisms for Oil-in-Water Emulsions”,Lubrication Engineering Vol.52,168-175,1996.
[11] 楊春欽,1986,磨潤學原理與應用,科技圖書,pp161-162
[12] Nianxi Yan and Jacob H. Masliyah,”Effect of pH Adsorption and Desorption of Clay Particles at Oil-Water Interface”,Journal of Colloid and Interface Science,Vol.181,pp20-27,1996.
[13] Y.P.CHIU,”An Analysis and Prediction of Lubricant Film Starvation in Rolling Contact System”ASLE Trans.,Vol.17,pp22-35,1974.
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