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標題: 半圓柱體尾流流場之實驗探討
Experimental Study on Wake Structures behind a Semi-Circular Cylinder
作者: 賴玟妤
Lai, Wen-Yu
關鍵字: Semi-Circular Cylinder;半圓柱
出版社: 土木工程學系所
引用: 1. Roshko, A., “On the wake and drag of bluff bodies”, Journal of the Aeronautical Sciences, Vol. 22, pp. 124-132 (1955). 2. Perry, A. E., Chong, M. S., & Lim, T. T., “The vortex shedding process behind two-dimensional bluff bodies”, Journal of Fluid Mechanics, Vol. 116, pp. 77-90 (1982). 3. Cantwell, B. & Coles, D., “An experimental study of entrainment and transport in the turbulent near wake of a circular cylinder”, Journal of Fluid Mechanics, Vol. 136, pp. 321-374 (1983). 4. Hussian, A. K. M. F. & Hayakawa, M., “Eduction of large-scale organized structures in a turbulent plane wake”, Journal of Fluid Mechanics, Vol. 180, pp. 193-229 (1987). 5. Antonia, R. A., Browne, L. W. B., & Bisset, D. K., “A description of the organized motion in the turbulent far wake of a cylinder at low Reynolds number”, Journal of Fluid Mechanics, Vol. 184, pp. 423-444 (1987). 6. Steiner, T.R. and Perry, A.E., “Large-scale vortex structures in turbulent wakes behind bluff bodies. Part 2. Far wake structure”, Journal of Fluid Mechanics, Vol. 174, pp. 271-298 (1987). 7. Kiya, M. & Matsunura, M., “Incoherent turbulence structure in the near wake of a normal plate”, Journal of Fluid Mechanics, Vol. 190, pp. 343-356 (1988). 8. Zhou, Y. & Antonia, R. A., “Convection velocity measurements in a cylinder wake”, Experiments in Fluids, Vol. 13, pp. 63-70 (1992). 9. Kwon, T.S., Sung, H.J. and Hyun, J.M., “Experimental investigation ofuniform-shear flow past a circular cylinder”, Journal of Fluids Engineering ASME, Vol. 114, pp. 457-460 (1992). 10. 方明仁:「圓柱近域尾流場特性之實驗研究」,國立中興大學土木工程研究所碩士論文 (1995)。 11. Chen, J.M. and Fang, Y.C., “Strouhal numbers of inclined flat plates”, J.Wind Eng. and Industrial Aerodynamics, Vol. 61, pp. 99-112 (1996). 12. 林呈、顏光輝、郭正雄:「矩形柱體尾流流場組織結構之實驗研究」,中國土木水利工程學刊,第七卷,第二期 (1995)。 13. 林 呈、方明仁、顏光輝:「圓柱尾流場渦流結構與泰勒假設適用性之實驗探討」,中華民國第八屆水利工程研討會論文集,第 419-430 頁 (1996)。 14. 林 呈、顏光輝、孫洪福、邱鵬豪:「應用質點影像測速儀於圓柱近域尾流場之研究」,第二十屆海洋工程研討會論文集,第 297-304 頁 (1998)。 15. 徐華勇:「應用PIV探討圓柱及平板尾流流場之速度分佈特性」,國立中興大學土木工程研究所碩士論文 (2002)。 16. Takama, Y., Suzuki, K. and Rathakrishnan, E., “Visualization and size measurement of vortex shedding by flat and arc plates in an uniform flow”, (2007送審中).
本研究所使用之高速 PIV 量測系統主要為利用高速攝影機及高功率氬離子雷射光源並配合數位影像強化處理技術,係使用 Phantom Camera Control軟體中Image Processing 的 filter Edge Laplacian 5×5 模式來進行流場質點影像的顆粒對比與邊緣銳利化之強化並消除泛光及雜訊影響;且利用高速攝影機之連續影像擷取特性,改善傳統 PIV 量測系統僅能以單一時間間距進行分析流體質點速度之缺點,改採用多時間間距之速度計算方式。此外,本文利用所建置之高速 PIV 量測系統,對半圓形柱體的尾流流場之特性進行實驗研究,除利用高速攝影機之高頻連續影像擷取探討尾流流場平均速度場之相似性之外,更以可視化連續影像擷取來探討尾流流場之紊流特性。
本文主要針對半圓柱尾流流場於流場雷諾數 Re = 990 ~ 6540 之來流條件下於迴流區內之流場特性進行分析,主要分析項目包括尾流流場中心軸速度變化、各斷面之速度剖面分佈、迴流區長度的量測與特性分析,以瞭解無後體效應之影響。

The main instrument of this experiment is the particle image velocimetry (PIV),and the PIV was based on phantom camera and Ar+ laser system.Image processing techniques are utilized in the study to improve time and space resolution of the PIV by using high pass filter(Edge Laplacian 5×5 method).The result obtained is much better than the traditional PIV.
The PIV system was used to measure the wake structures behind a two-dimensional semi-circular cylinder and partial trajectory photography was used for flow visualization to observe flow field behind a semi-circular cylinder.
Measurements and analysis of mean velocity characteristics in the wake structures behind a two-dimensional semi-circular cylinder for various Reynolds numbers ranging over 990 ~ 6540 were performed respectively.
Furthermore,the investigation of various non-dimensional characteristics in terms of the centerline velocity,the velocity profile for a given cross-section,the length of recirculation were also measured in order to establish the flow-field similarity and treat of after-body's effect on a bluff-body.
其他識別: U0005-0109200813363100
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