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SPECIAL SECTION ON THE FLUID MECHANICS AND RHEOLOGY OF NONLINEAR MATERIALS AT THE MACRO, MICRO AND NANO SCALE

Vortex Motion in a Swirling Flow of Surfactant Solution with Drag Reduction

[+] Author and Article Information
Mizue Munekata

Department of Mechanical Engineering and Materials Science, Kumamoto University, 2-39-1, Kurokami, Kumamoto, 860-8555, Japanmunekata@gpo.kumamoto-u.ac.jp

Kazuyoshi Matsuzaki

 Tokyo Electron LTD., 650 Mitsuzawa, Hosaka-cho, Nirasaki City, Yamanashi, 407-0192, Japankazuyoshi.matsuzaki@tel.com

Hideki Ohba

Department of Mechanical Engineering and Materials Science, Kumamoto University, 2-39-1, Kurokami, Kumamoto, 860-8555, Japanohba@gpo.kumamoto-u.ac.jp

J. Fluids Eng 128(1), 101-106 (Apr 25, 2005) (6 pages) doi:10.1115/1.2136927 History: Received August 11, 2004; Revised April 25, 2005

Surfactants are well known as additives which induce drag reduction in the straight (nonswirling) pipe flow. However, in industrial applications of the drag-reducing effect, many flow fields besides the straight pipe flow need to be considered. The purpose of this study is to investigate the flow characteristics of the surfactant solution in swirling pipe flow. The drag-reducing effect is estimated from the measurement of wall pressure drop and velocity profiles on various pipe sections by two-dimensional LDV (Laser Doppler Velocimeter). Since the surfactant solution has viscoelasticity, interesting flow characteristics are obtained. The decay of swirl, the vortex type and the turbulence intensity are discussed, compared with the swirling flow of the water. As the results, it is concluded that the change from Rankin’s combined vortex to the forced vortex at a more upstream section by suppressing progress of free vortex and stretch of forced vortex introduces considerable drag reduction. Oscillation of the vortex core is also investigated, and it is found that the oscillation is independent of swirl number.

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Copyright © 2006 by American Society of Mechanical Engineers
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Figures

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Figure 2

Experimental setup

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Figure 3

Friction coefficient vs. Re

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Figure 4

Drag-reducing rate compared with the friction coefficient in Newtonian swirling flow

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Figure 5

Decay of Sw in the stream wise direction at α=60deg; solid lines and dashed lines indicate approximate expressions of swirl decay in Rankin’s combined vortex and the forced vortex, respectively

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Figure 6

Axial velocity profiles (Vb=0.95m∕s at α=60deg)

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Figure 7

Tangential velocity profiles (Vb=0.95m∕s at α=60deg)

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Figure 8

Turbulence intensity profiles of axial velocity fluctuations (Vb=0.95m∕s at α=60deg)

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Figure 9

Turbulence intensity profiles of tangential velocity fluctuations (Vb=0.95m∕s at α=60deg)

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Figure 10

Fluctuation of nondimensional tangential velocity at r∕R≈0 (Vb=0.95m∕s at α=60deg)

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Figure 11

Autocorrelation coefficient of Vt′ at r∕R≈0

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