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博碩士論文 etd-0209110-140012 詳細資訊
Title page for etd-0209110-140012
論文名稱
Title
剪切流場內不同質量圓柱振動研究
Flow induce vibration of a circular cylinder with different mass ratio in shear flow
系所名稱
Department
畢業學年期
Year, semester
語文別
Language
學位類別
Degree
頁數
Number of pages
68
研究生
Author
指導教授
Advisor
召集委員
Convenor
口試委員
Advisory Committee
口試日期
Date of Exam
2010-01-28
繳交日期
Date of Submission
2010-02-09
關鍵字
Keywords
渦流引致振動、剪切流場、二維圓柱
two-degree-of-freedom cylinder, vortex-induce vibration, shear flow
統計
Statistics
本論文已被瀏覽 5665 次,被下載 1377
The thesis/dissertation has been browsed 5665 times, has been downloaded 1377 times.
中文摘要
本文以實驗方式探討不同質量的二維彈性圓柱於剪切水流場內的振動情形,而不同於以往的是利用自然頻率較高的彈性圓柱進行實驗,水流速範圍是0.2 m/s到1.67m/s,由實驗發現,質量的大小對振幅是有明顯的影響,質量越大,圓柱於低流速時越不易受到渦流的影響,而高流速時振動軌跡也會越穩定,另外彈性係數較高,當渦流強度不夠時,圓柱自身振動頻率響應會大於渦漩剝離頻率響應,因此不利藉由圓柱振動觀察渦漩剝離頻率隨流速的變化,而剪切流場對圓柱振動的影響,當剪切參數K^* 越大會使圓柱所受到的阻力減小,而圓柱所受到的昇力確實會因為剪切參數增大而增大,圓柱的振動軌跡會出現不對稱的現象,圓柱在低流速邊會有較大的位移量。
Abstract
This thesis is an experimental study of shear effect of a two-degree-of-freedom cylinder in fluid flow in terms of different mass ratio. This study is done using an elastic cylinder of high natural frequency, and the free stream velocity is 0.2m/s to 1.5m/s. The results show that as mass ratio increases, the motion of cylinder becomes more stable and small, and the frequency response of cylinder self-excited is bigger than vortex-shedding response when spring constant is bigger enough. Thus it is not easy to observe the vortex-shedding frequency variation with respect to various velocities by dint of cylinder vibration. When it come to the shear effect, the effect of shear flow could decreases the drag force, and increases the lift force. Orbits of cylinder vibration is not symmetric; the displacement is more significant on low velocity side.
目次 Table of Contents
謝誌 III
摘要 IV
Abstract V
圖目錄 VIII
表目錄 XIII
符號說明 XIV
一、 前言 1
1-1. 研究動機 1
1-2. 文獻回顧 2
1-3. 實驗目的 5
1-4. 研究中使用的無因次參數定義 6
二、 實驗儀器設備與方法 7
2-1. 實驗設備 7
2-2. 實驗儀器 8
2-3. 實驗方法 9
三、 結果與討論 11
3-1. 測試段入口剪切流場速度分佈 11
3-2. 不同質量比對振動的影響 13
3-3. 不同速度梯度流場對振動的影響 16
3-4. 不同圓柱直徑對振動的影響 18
四、 結論與建議 19
4-1. 結論 19
4-2. 建議 20
參考文獻 21
參考文獻 References
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[7.] Govardhan, R. & Williamson, C.H.K., 2000, "Modes of vortex formation and frequency response of a freely vibrating cylinder", Journal of Fluid Mechanics, 420, 85-130.
[8.] Govardhan, R. & Williamson, C.H.K., 2002, "Resonance forever: existence of a critical mass and an infinite regime of resonance in vortex-induced vibration", Journal of Fluid Mechanics, 473, 147-166.
[9.] Humphries, J.A. & Walker, D.H., 1988, "Vortex-excited response of large-scale cylinder in sheared flow", ASME Journal of Offshore Mechanics and Arctic Engineering, 110, 272-277.
[10.] Jeon, D. & Gharib, M., 2001, "On circular cylinders undergoing two-degree-of-freedom forced motions", Journal of Fluids and Structures, 15, 533-541.
[11.] Jauvtis, N., Williamson, C.H.K., 2003, "Vortex-induced vibration of a cylinder with two degrees of freedom", Journal of Fluids and Structures, 17, 1035-1042.
[12.] Jauvtis, N. & Williamson, C.H.K., 2004, "The effect of two degrees of freedom on vortex-induced vibration at low mass and damping", Journal of Fluid Mechanics, 509, 23-62.
[13.] Kotansky, D.R., 1966, "The Use of Honeycomb for shear flow generation", A.I.A.A. Journal, 4, 1490-1491.
[14.] Kiya, M., Tamura, H. & Arie, M., 1980, "Vortex shedding from a circular cylinder in moderate-Reynolds-number shear flow", Journal of Fluid Mechanics, 141, 721-735.
[15.] Khalak, A. & Williamson, C.H.K., 1997, "Investigation of relative effects of mass and damping in vortex-induced vibration of a circular cylinder", Journal of Wind Engineering and Industrial Aerodynamics, 69-71, 341-350.
[16.] Khalk, A. & Williamson, C.H.K., 1997, "Fluid forces and dynamics of a hydroelastic structure with very low mass and damping", Journal of Fluids and Structures, 11,973-982.
[17.] Khalk, A. & Williamson, C.H.K., 1999, "Motions, forces and mode transitions in vortex-induced vibrations at low mass-damping", Journal of Fluids and Structures, 13, 813-851.
[18.] Lei, C., Cheng L. & Kavanagh, K., 2000, "A finite difference solution of the shear flow over a circular cylinder", Ocean Engineering, 27, 271-290.
[19.] Raghavan, K., 2007, "Energy extraction from a steady flow using vortex induced vibration", Ph. D. thesis, Department of Naval Architecture and Marine Engineering, University of Michigan.
[20.] Sarpkaya, T., 2004, "A critical review of the intrinsic nature of vortex-induced vibrations", Journal of Fluids and Structures, 19,389-447.
[21.] Sumner, D. & Akosile, O.O., 2003, " On uniform planar shear flow around a circular cylinder at subcritical Reynolds number", Journal of Fluids and Structures, 18, 441-454.
[22.] Stansby, P. K., 1976, “The locking-on of vortex shedding due to the cross-stream vibration of circular cylinders in uniform and shear flows”, Journal of Fluid Mechanics ,74, part4, 641-665.
[23.] Williamson, C.H.K & Govardhan, R., “Vortex-Induced Vibrations”, Annu. Rev. Fluid Mechanics, 2004,36,413-455.
[24.] Thomson, W.T. & Dahleh, M.D., 1998, "Theory of Vibration with Applications", ed. 5th, Prentice-Hall, New Jersey, PP. 27-35.
[25.] 劉俊男,2007,水洞剪切流場內圓柱振動的探討,國立中山大學機械與機電工程研究所碩士論文。
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