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The axial skew of flow in curved pipes

Published online by Cambridge University Press:  21 April 2006

B. Snyder
Affiliation:
Pulmonary and Critical Care Division, University of Michigan/V. A. Medical Center, Ann Arbor, MI 48109 Present address: Mechanical Engineering Department, University of Nevada-Reno, Reno, Nevada 89557.
J. R. Hammersley
Affiliation:
Pulmonary and Critical Care Division, University of Michigan/V. A. Medical Center, Ann Arbor, MI 48109
D. E. Olson
Affiliation:
Pulmonary and Critical Care Division, University of Michigan/V. A. Medical Center, Ann Arbor, MI 48109

Abstract

As a uniformly coiled pipe is wound progressively tighter, centrifugal acceleration would be expected to drive the axial flow increasingly towards the outer wall of the pipe bend. Instead, the effect of bend curvature R is found experimentally to become fully expressed at small curvature ratios (a/R < 0.02), where a is the pipe radius. No further increase in the axial skew is observed in more tightly coiled pipe sections (0.02 [les ] a/R [les ] 0.20). In this ‘asymptotic’ regime where pipe curvature is unimportant, the developing axial skew intensifies as ≈ [(Re − 100) L/a]¼, where $Re = 2\overline{W}a/\nu $ and L is the entrance length. These results suggest that the action of centrifugal force remains balanced by swirl as flow develops in tightly coiled pipes, while in loosely coiled pipes the development of centrifugal effects lags the growth of swirl.

Type
Research Article
Copyright
© 1985 Cambridge University Press

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