Control of circular cylinder wakes at relatively high Reynolds numbers

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	Control of circular cylinder wakes at relatively high Reynolds numbers
	Shao, Chuanping ; Wang, Jianming
刊名	lixue xuebaochinese journal of theoretical and applied mechanics
	2006
英文摘要	A narrow strip has been introduced as an element to control circular cylinder wakes at Reynolds numbers Re = 3.0 ?? 103-2.0 ?? 104. The strip is 0.18D (D is diameter of the cylinder) wide, 0.015D-0.025D thick and as long as the cylinder. The long margins of the strip are parallel to and coplanar with the cylinder axis. The strip is fixed by a row of small rods distributed along a meridian and perpendicularly connected to the surface of the cylinder. The rods have been proven to have negligible influence on the flow. The control parameter is strip position, which can be determined by ??/(0.5D)-(unified) distance between the cylinder axis and the length-wise centerline of the strip, and ??-angle of attack of the strip. The experiment was conducted in a low turbulence wind tunnel of test section 2 m long, 60 cm wide and 60 cm high. Two circular cylinders of diameter D = 3 cm and 5 cm were tested respectively in the range of ?? = 0??-180?? and ??/(0.5D) = 1.1-3.8. The overall information of the cylinder wake was visualized by smoke-wire technique and the detailed local information of fluctuating velocity was detected by a hot-wire anemometry at various points from Y/(0.5D) = -6.0 to 6.0 at a stream-wise station X/D = 12.5. Visualization pictures and power spectra of fluctuating velocities show that vortex shedding on both sides of the cylinder can be effectively suppressed if the strip is located in a certain zone in the near wake. The effective zones at Re = 6.3 ?? 103, 1.0 ?? 104 and 1.64 ?? 104 have been found out with accuracy 0.1 of ??/0.5D and 2.5?? of ??. The zone enlarges slightly with the increase of Re in the range tested. Distributions of turbulence intensity for various ?? from 0?? to 180?? at ??/(0.5D) = 2.9 and Re = 1.64 ?? 104 have been measured. Compare with the case without control, the turbulence intensity on both sides of the wake is reduced when ?? is in the range of 0??-50?? or in the vicinity of 180??. However, in the range ?? = 60??-120??, an increase appears on the side where the strip resides, while no increase presents on the opposite side. Total resistance on cylinder and control element for various ?? from 0?? to 180?? at ??(0.5D) = 2.9 and Re = 1.64 ?? 104 has been evaluated by momentum integration using measured velocity profiles. It shows that the total resistance in the range of ?? = 0??-40?? and in the vicinity of ?? = 180?? is obviously smaller than the resistance on bare cylinder. The maximum reduction of resistance is about 32%, which happens at ?? = 25??-30??. All the results mean, local passive interference of the strip can induce global changes of the wake at high Reynolds numbers.; EI; 0; 2; 153-161; 38
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/410182]
专题	工学院
推荐引用方式 GB/T 7714	Shao, Chuanping,Wang, Jianming. Control of circular cylinder wakes at relatively high Reynolds numbers[J]. lixue xuebaochinese journal of theoretical and applied mechanics,2006.
APA	Shao, Chuanping,&Wang, Jianming.(2006).Control of circular cylinder wakes at relatively high Reynolds numbers.lixue xuebaochinese journal of theoretical and applied mechanics.
MLA	Shao, Chuanping,et al."Control of circular cylinder wakes at relatively high Reynolds numbers".lixue xuebaochinese journal of theoretical and applied mechanics (2006).