Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/15434
標題: 急加速啟動之流場中方柱前端馬蹄形渦流流場特性之探討
Study on the Characteristics of Horseshoe Vortex System near the Juncture of Impulsively Started Sqaure Cylinder
作者: 張育豪
Chang, Yu-Hao
關鍵字: horseshoe vortex
馬蹄型渦流
boundary layer
邊界層
出版社: 土木工程學系所
引用: 1. Schwind, R., “The Three - Dimensional Boundary Layer Near a Strut,” Gas Turbine Lab. Rep., MIT, 1962. 2. Baker, C. J., “On The Flow Characteristics of Free Overfalls,” Proceedings of the 7th International Symposium on Flow Modeling and Turbulence Measurement, pp. 55-66, 1998. 3. Hunt, J. C. R., Abell, C. J., Peterka, J. A., and Woo, H. J., “Kinematical Studies of the Flows around Free or Surface-Mounted Obstacles; Applying Topology to Flow Visualization,” Journal of Fluid Mechanics, Vol. 86, Part 1, pp. 179-200, 1978. 4. Baker, C. J., “The Laminar Horseshoe Vortex,” Journal of Fluid Mech., Vol. 95, Part 2, pp. 347-367, 1979. 5. Kimura, I.and Takamori, T., “Image Processing of Flow around a Circular Cylinder by Using Correlation Technique,” Flow Visualization IV (ed. Veret, C.), pp. 221-226, 1986. 6. Thomas, S. W., “The Unsteady Characteristics of Laminar Juncture Flow, ” Physics of Fluids, pp. 283-285, 1987. 7. Greco, J. J., “The Flow Structure in the Vicinity of a Cylinder- Flat Plate Junction: Flow Regimes, Preiodicity, and Vortex Interactions,” MS Thesis, Department of Mechanical Engineering and Mech., Lehigh University, 1990. 8. Su, T. C., Lian, Q. X., “The Tip-Ward Flow over a Surface Mounted Bluff Body,” FIV, pp. 39-44, 1990. 9. Baker, C. J., “The Oscillation of Horseshoe Vortex System,” Journal of Fluids Engineering, Vol. 113, pp. 489-495, 1991. 10. Visbal, M. R., “The Laminar Horseshoe Vortex System Formed at a Cylinder/Plate Juncture,” AIAA 22nd Fluid Dyn., Plasma Dyn., & Lasers Conf., 1991. 11. 蔡銹樺,「鈍形體馬蹄型渦流行為之探討」,國立成功大學工程科學研究所碩士論文,1993。 12. Taketoshi Okuno, Shigeru Nishino, “Observation of Horseshoe Vortex in Juncture Flow,” Third Asian Symposium on Visualization, pp. 128-133, 1994. 13. Calluaud D, David L, Texier A , Pineau G, “The Stating Flow in Front of A Prismatic Obstacle,” Proceedings of the 11th International Symposium on Flow Visualization, 2004. 14. Seal, C. V., Smith, C. R., and Rockell, D., “Quantitative Characteristics of a Laminar,Unsteady Necklace Vortex System at a Rectangular Block-Flat Plate Juncture,” Journal of Fluid Mech., Vol. 286, pp. 117-135, 1995. 15. 葉建忠,「柱體周邊三維流場之觀測與量測」,國立中興大學土木工程研究所碩士論文,1996。 16. Seal, C. V., Smith, C. R., and Rockell, D., “Dynamics of Vorticity Distribution in Endwall Junctions,” AIAA Journal, Vol. 35, No. 6, pp. 1041-1047, 1997. 17. Sumer, B. M., Christiansen, N., and Fredsoe, J., “The Horseshoe Vortex and Vortex Shedding around a Vertical Wall-mounted Cylinder Exposed to Waves,” Journal of Fluid Mech., 1997. 18. Rockwell, D., “Vortex-Body Interactions,” Annual Reviews of Fluid Mech., pp. 199-229, 1998. 19. Sarpkaya, T., “Nonimpulsively Started Steady Flow about a Circular Cylindy,” AIAA Journal, Vol. 29, pp.1283-1289, 1991. 20. 陳謹偉,「應用PIV及FLDV於矩形柱體來流端馬蹄型渦流流場之探討」,國立中興大學土木工程研究所碩士論文,1999。 21. 邱鵬豪,「應用PIV及FLDV於直立式平板前緣馬蹄型渦流特性之分析研究」,國立中興大學土木工程研究所碩士論文,1999。 22. 何宗俊,「應用PIV及FLDV於低雷諾數下鈍形體來流端穩態馬蹄型渦流特性之探討」,國立中興大學土木工程研究所碩士論文,2000。 23. 高明哲,「應用PIV於直立平板前緣穩定運動狀態馬蹄型渦流系統之特性研究」,國立中興大學土木工程研究所碩士論文,2000。 24. 黃智政,「應用PIV與FLDV於矩柱前端隻穩態馬蹄型渦流分析研究」,國立中興大學土木工程研究所碩士論文,2000。 25. 林呈、何宗俊、謝世圳、張國棟,「低雷諾數條件下直立平板來流端之穩態馬蹄型渦流特性探討」,中國土木水利工程學刊,2002。 26. 張智超,「應用PIV於低雷諾數下平板之不同寬高彼之馬蹄型渦流特性之探討」,國立中興大學土木工程研究所碩士論文,2002。
摘要: 本研究利用先進之質點影像測速儀(PIV)系統,佐以懸浮微粒可視化法,於雷諾數(Re = U0•H/ν,其中U0為模型之穩定速度,H為模型高度,ν為運動黏滯係數)為200、400、1000條件下,針對方柱於靜止流場中速度由零等加速至一定值(即在邊界層尚未發展完成) 時,其前端馬蹄型渦流隨時間發展的過程及流場型態進行定性的觀察與定量的量測。再根據量測結果對馬蹄型渦流發展過程中主渦渦心位置變化、模型迎水面停滯點高度的變化、下降流強度及環流量強度隨無因次時間T( = t•U0/H,其中t為啟動後之時間)增長之變化情形進行詳細之探討。 首先本實驗針對各實驗條件流況( U0 = 1 cm/s、2 cm/s、5 cm/s )下急加速啟動所產生的等加速度進行量測,所得等加速度分別為a1 = 9.8675 cm/s2、a2 = 33.434 cm/s2、a5 = 61.6297 cm/s2並於0.3 s ~ 0.5 s 即已完成加速的過程,達到所要求的穩定速度,符合急加速的定義。在馬蹄型渦流發展之過程中,發現下降流速度剖面型態會與渦流的結構不同而有所變化,而馬蹄型渦流結構各特性參數(主渦渦心位置、模型前緣停滯點位置、下降流、環流量)皆與無因次時間T有對數成長之關係。在停滯點之相似性探討上,發現以無因次長度參數ys/H相對於無因次時間參數T/Ts進行相關性分析時,可在各實驗流況下獲得一相似性曲線。
The characteristics of horseshoe vortex system near the juncture of a square cylinder and a base plate were studied experimentally. The incoming flow speed accelerates impulsively from zero to a constant value. The structures of horseshoe vortex were observed at low Reynolds numbers equal to 200, 400, and 1000 using particle image velocimetry (PIV) and flow visualization techniques. The characteristics of starting horseshoe vortex system were analyzed, including the position of primary vortex core, the position of stagnation point on the model, down-flow velocity profile and the circulation of primary vortex, respect to dimensionless time parameter T. In this study, it is found that the shapes of down-flow velocity profiles are similar due to the same vortex structures. The relationship between flow characteristics and dimensionless time parameter T can be described by log equation using regression analysis. The similarity of the position of stagnation point on the model is presented. It is noted that the similarity of the position of stagnation point on the model can be obtained for all conditions, using dimensionless length parameter ys/H and dimensionless time parameter T/Ts.
URI: http://hdl.handle.net/11455/15434
其他識別: U0005-2908200620254500
文章連結: http://www.airitilibrary.com/Publication/alDetailedMesh1?DocID=U0005-2908200620254500
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