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標題: 錯列雙圓柱尾流場被鎖定之特性研究
Investigation on Locked-on characteristics of wake behind staggered circular cylinders
作者: 呂瑋庭
Lu, Wei-Ting
關鍵字: staggered cylinders;錯列圓柱;gap flow;lock-on;narrow wake;wide wake;間隙流;尾流鎖定;窄域尾流;寬域尾流
出版社: 機械工程學系所
引用: 1.Kiya, M., Vortex shedding from two circular cylinders in staggeed arrangement. Journal of Fluids Engineering, Transactions of the ASME, 1980, 102, pp. 166-173 2.Ko, N. W. M., Wong, P. T. Y., and Leung, R. C. K., Interaction of flow structures within bistable flow behind two circular cylinders of different diameters. Experimental Thermal and Fluid Science, 1996, 12, pp. 33-44 3.Spivack, H. M., Vortex frequency and flow pattern in the wake of two parallel cylinder at naried spacing normal to an air stream. Aeronautical Sciences, 1946, 13, pp. 289-297. 4.Baek, S. J., and Sung, H. J., Numerical simulation of the flow behind a rotary oscillating circular cylinder. Physics of Fluids, 1998, 10, pp. 869-876 5.Baek, S. J., and Lee, S. B., and Sung, H. J., Response of a circular cylinder wake to superharmonic excitation, Journal of Fluid Mechanics, 2001, 442, pp. 67-88 6.Sumner, D., Wong, S. S. T., and Price, S. J., Fluid behaviour of side-by-side circular cylinders in steady cross-flow. Journal of Fluids and Structures, 1999, 13, pp. 309-338. 7.Lee, S. J.,and Lee, J. Y., PIV measurements of the wake behind a rotationally oscillating circular cylinder, Journal of Fluids and Structures, 2008, 24, pp. 2-17 8.Wang, Z. J. and Zhou, Y., Vortex interactions in a two side-by-side cylinder near-wake. International Journal of Heat and Fluid Flow, 2005, 26, pp. 362-377 9.Xu, S. J., Zhou, Y., and So, R. M. C., Reynolds number effects on the flow structure behind two side-by-side cylinder. Physics of Fluids, 2003, 15, pp. 1214-1219 10.Lu, X. Y., Numerical study of the flow behind a rotary oscillating circular cylinder. International Journal of Computational Fluid Dynamics, 2002, 16, pp. 65-82 11.Zhou, Y., Reynolds number effect on the wake of two staggered cylinders, 2009, 21, pp.1-14 12.Bearman, P. W., Circular cylinder wakes and vortex-induced vibrations, Journal of Fluids and Structures, 2011, 27, pp.648-658 13.Alam, M. M., Zhou, Y., Zhao, J. M., Flamand, O., Boujard, O., Classification of the tripped cylinder wake and bi-stable phenomenon, International Journal of Heat and Fluid Flow, 2010, 31, pp.545-560 14.Blevins, R. D.,Flow-Induced vibration, second Edition. Van Nostrand Reinhld International Company. 1990, 15.ProVISION-XS User Manual, 2007, 16.陳信安,小波方法分析並列雙圓柱尾流場鎖定特性,中興大學 機械工程系 碩士論文, 2002 17.李宜儒, 運用小波方法分析並列雙圓柱尾流的長時間特性,中興大學 機械工程系 碩士論文, 2006 18.張修豪,具有兩倍直徑比之錯列雙圓柱下漩流場特性之研究,中興大學 機械工程系 碩士論文, 2010 19.謝偉麟,撓性尾鰭下游之流場結構與推力之實驗探討,中興大學 機械工程系 碩士論文, 2010
本研究以雷射都普勒量測系統、質點影像測速系統及流場可視化,利用快速傅立葉轉換與小波轉換方法,探討錯列雙圓柱下游尾流被鎖定之特性。雷諾數為600時、fos為大圓柱自然脫離頻率、對寬域尾流施加不同頻率的週期性旋轉擾動、直徑比為2、不同中心間距、旋轉振幅為 10°。實驗結果顯示:在Mode 2的流場結構中。當中心間距為T/D=1.5,L/D=0時,大圓柱下游的寬域尾流被鎖定的頻段為fe/fos=0.93~1.1、2.93~3.07,此兩鎖定頻段分別對應於fe/fos=1.0及3.0;當被鎖定時,渦漩結構之相位差與單一圓柱者相同。但是,窄域尾流並未被鎖定,其特徵頻率稍高但接近單一小圓柱者。當中心間距為T/D=1.5,L/D=0.5時,寬域尾流的鎖定頻段位在1倍頻的左側(即fe/fos=0.867~1.0);小圓柱下游的窄域尾流並未被鎖定,其特徵頻率稍高於但接近單一小圓柱者。在Mode 1的流場結構中。當中心間距為T/D=1.5,L/D=-1.0時,小圓柱下游的寬域尾流的鎖定頻段位於1倍頻的右側(fe/fos=2.0~2.13);但是,大圓柱下游的窄域尾流並未被鎖定,其特徵頻率稍高於但接近單一大圓柱者。

This study was conducted experimentally by using the PIV system, the LDA system, and flow visualization techniques. The spectral and phase data are analyzed by the Fourier transformation and the cross wavelet transformation to investigate the locked-on characteristics of the wake flows behind two staggered circular cylinders with diameter ratio D/d=2. All the experiments were performed in a low-speed recirculation water channel. The wide wakes were perturbed with various excitation frequencies while the maximum rotating amplitude was maintained at ±10°. The Reynolds number is 600 and the fos respresents the natural shedding frequency behind a single cylinder. The important results show that for side-by-side case (T/D=1.5, L/D=0, mode 2), the locked-on frequency bands lie within fe/fos=0.93~1.1 and 2.93~3.07 for the cases of the primary and the 1/3 subharmonic lock-on. These locked-on frequency bands distribute symmetrically about fe/fos=1.0 and 3.0, respectively. When the wide wakes were locked-on, the phase shifts of the vortex structures in the wake are the same as those of a single cylinder. When the center spacing is T/D=1.5, L/D=0.5 (mode 2), the locked-on frequency band of the wide wake shifts to the left ( fe/fos=0.867~1.0). While the center spacing is T/D=1.5, L/D=1.0 (mode 1), the locked-on frequency band of the wide wake shifts to the right side (fe/fos=2.0~2.13). For all the cases studied herein, the narrow wakes are not locked-on with its dominant frequency slightly higher than, but close to, that of a single cylinder.
其他識別: U0005-2408201111205200
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