雙狹縫延伸機構流體力學分析

Fluid Mechanics Analysis of Two-Sided Slit Extension

曾繁欣(Fan-Hsin Tseng)

指導教授 ： 蘇淵源

國立臺北科技大學/工程學院/化學工程研究所/碩士(2010年)

摘要

人造纖維依賴的石油原料逐漸枯竭，因此以天然纖維素為原料之溶液抽絲法近幾年來逐漸吸引業界投入研發，其中又以能提高紡絲效率及減少環境傷害之雙狹縫抽絲與延伸一次完成之程序最受矚目。
纖維素/NMMO溶液由紡絲口自然垂流，藉由機構內高速水流達到延伸效果，然而因雙狹縫機構操作常致使空氣捲入，進而導致放絲不順影響抽絲的流暢性。為深入探討此問題，本研究利用有限體積法模擬三維抽絲之雙狹縫機構流體流動，並搭配兩相流中之VOF法，觀察兩不互溶流體間交界面之形成及其演化，且採用穩態與多種非穩態紊流模式，探討雙狹縫機構內之高速流場分佈，以建立一次抽絲及延伸之操作視窗，期望本研究所得之操作視窗，可作為未來製程設計放大時之重要參考。
模擬結果顯示，在多種非穩態紊流模式下，以Standard κ-ε model最佳；若引導鞘層流體方向，對延伸段內流場之穩定性及減少逆流發生有一定的正面效應，但納入隔板厚度後，流速降低非常明顯，若要達到預期延伸效果，必須要再增大鞘層流速，若不想或無法再增加鞘層流速，則勢必提高雙狹縫延伸機構並縮小延伸段的寬度。

關鍵字

Fluent ； 雙狹縫機構 ； 流體力學 ； 有限體積法 ； 纖維素/NMMO 溶液

並列摘要

In the foreseeable future, the raw material of oil that synthetic fibers depend on is running out. For this reason the raw materials from natural cellulose solution spinning method gradually attracted industry research and development in recent years. To increase the efficiency of spinning, and reduce environmental damage, two-sided slit spinning and extension of the completion the procedure are most attractive.
A solution of cellulose / NMMO flows by the spinneret of natural vertical. And with the high-speed fluid inside the mechanism to reach extending effects. However, two-sided slit extension mechanism often sucks in air at operation, leading to falter wire releasing and influence the fluency of spinning. To explore this issue, this study use finite volume method to simulate three-dimensional spinning of two-sided slit extension mechanism fluid flow. And combine with the two-phase flow of the VOF method to observe the formation and evolution of the interface between two immiscible fluids. Using steady state and different kinds unsteady state turbulence models to investigate the distribution of high-speed flow field in the two-sided slit extension mechanism. Set up spinning and extension of the operation window which can be used as an important reference as the future process design when enlarged.
Simulation results showed that using Standard κ-ε model is the best under a variety of unsteady state model in turbulent flow. If it is to guide the direction of sheath fluid, there is a certain positive effect on the extension of stability and the reduction of reflux. Consider the thickness of the wall, the flow rate reduces significantly. Increasing sheath flow is the method to achieve the desired effect of extending. When the sheath flow rate can’t be increased, there must be elevation on the two-sided slit extension mechanism and the reduction on the extension of the width

並列關鍵字

Fluent ； Two-Sided Slit Extension Mechanism ； Fluid Mechanics ； Finite Volume Method ； Cellulose / NMMO solution

參考文獻

[6]陳進來，"人造纖維產品現況與發展趨勢"

[35]許書政，"氣水混合輸送泵浦的設計"，崑山科技大學，2003

[2]黃琦冠，"異型紡嘴模具與材料性質及溫度對熔融紡絲之變異度探討"，台北科技大學，2009

[7]H.-P Fink*, P. Weigel, H.J. Purz, J. Ganster，"Structure Formation of Regenerated Cellulose Materials From NMMO-Solutions"，Process in Polymer Science, 26，1473-1524，2001

[11]S. Kase and T. Matsuo，"Studies on Melt Spinning. I. Fundamental Equation on the Dynamics of Melt Spinning"，Journal of Applied Polymer Science, Vol. 3, pp. 2541-2554，1965