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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/16252

Title: 三維矩形槽雙面驅動穴流之流場結構分析
Three-Dimensional Flow Structure Analysis of Two-Sided Lid-Driven Cavity
Authors: CI-YOU Jheng
鄭啟佑
Contributors: NTOU:Department of Marine Engineering
國立臺灣海洋大學:輪機工程系
Keywords: 有限體積法;不可壓縮流;渦流結構;展寬比
Finite-Volume Method;Incompressible Flow;Vortex Structure;Spanwise Aspect Ratio
Date: 2010
Issue Date: 2011-06-30T08:34:39Z
Abstract: 本研究利用有限體積法求解三維不可壓縮黏性流體在一矩形槽裡被兩個平行移動且方向相反的對稱面所驅動,兩對稱面運動之速度一致且連續。本研究之數值分析結果將藉由實驗與網格獨立驗證其正確性,以分析矩形槽內部所生成之渦流結構。 本研究主要探討二個部分,第一部分為當矩形槽寬、高及展長比固定為1.96:1:6.55,雙面驅動速度分別從雷諾數Re=100增加至Re=1200。研究顯示當穴流在雙面驅動速度較小時,因小速度的驅動在矩形槽內會有兩條平行於展長方向的主要渦旋中心線產生,雷諾數繼續增加,流體在固定牆面因黏滯力減小的影響會產生兩條副渦旋中心線。持續增加雷諾數後,速度提高而黏滯力變小,兩條副渦旋中心線消失且兩條主渦旋中心線開始結合成一條主渦旋中心。當雷諾數達一定值且繼續增高後,矩形槽內部流場內渦旋中心線會呈現穩定的波狀。在雷諾數較小Re≦250的情況下,渦旋結構會呈現平行於z軸方向上的兩個渦旋結構或出現兩個小渦旋結構。雷諾數達275時,以垂直於z軸方向上來看,矩形槽內的渦流區域分裂為3個區塊。而雷諾數介於300~1200之間,渦流區域皆分裂為4個區塊。 第二部分所探討的是雷諾數固定為Re=800時,以固定高寬比AR=2,改變不同展寬比(Spanwise Aspect ratio,簡稱SAR=L/D)SAR=1~6,觀測矩形槽內流場結構與渦流的變化。研究顯示低展寬比SAR<2.25,矩形槽內之渦旋中心線是由頂面的角落至底面的對稱角落所形成,並呈現單一區塊的渦旋結構。當展寬比增加時,矩形槽內渦旋中心線逐漸形成不穩定波狀,於不同展寬比,原單一渦流區塊則分裂為二、三或四個區塊。
In this study, numerical simulation for three-dimensional incompressible viscous fluid in a rectangular container by two parallel and opposite direction driven is investigated. The numerical results are independently verified by experiments and grid independent tests, and analyzed the rectangular container inside the vortex generated. The numerical results are divided two parts. The first part, a rectangular container with (SAR=6.55 and AR=2),is observed the vortex generated by increases Reynolds number from Re=100 to Re=1200.The results have shown that, two significant main parallel vortex corelines formed in the longitudinal direction in low Reynolds number. As Re≦250, the vortex structure is formed in the z axis parallel to the two vortex structure. As Re = 275,flow eddy divides the entire rectangular into three zones. As Reynolds number is between 300 and 1200, eddy regions are divided into four zones. The second part, Reynolds number is fixed as Re = 800 and aspect ratio is AR = 2, spanwise aspect ratios SAR are changed from 1 to 6.The phoenomenon of the vortex flow in this rectangular container structure is obsered.The results shown when spanwise aspect ratio is SAR<2.25, a single zone of the vortex structure is formed. As the spanwise aspect ratio increases, the rectangular container gradually forms a instable wavy vortex coreline. The original single vortex block is split into two, three or four zone as the spanwise aspect ratios are changed.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M97660005
http://ntour.ntou.edu.tw/ir/handle/987654321/16252
Appears in Collections:[輪機工程學系] 博碩士論文

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