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Curved ducts with strong secondary motion - Velocity measurements of developing laminar and turbulent flowTwo orthogonal components of velocity and associated Reynolds stresses are determined in a square-sectioned, 90 degree bend of 2.3 radius ratio by utilizing laser-Doppler velocimetry for Reynolds numbers of 790 and 40,000. Results show that boundary layers at the bend inlet of 0.25 and 0.15 of the hydraulic diameter create secondary velocity maxima of 0.6 and 0.4 of the bulk flow velocity, respectively. It is concluded that the boundary layer thickness is important to the flow development, mainly in the first half of the bend, especially when it is reduced to 0.15 of the hydraulic diameter. Smaller secondary velocities are found for turbulent flow in an identical duct with a radius ratio of 7.0 than in the strongly curved bend, although their effect is more important to the streamwise flow development because of the smaller pressure gradients. In addition, the detail and accuracy of the measurements make them suitable for evaluation of numerical techniques and turbulence models.
Document ID
19820061245
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Taylor, A. M. K. P.
(Imperial Coll. of Science and Technology London, United Kingdom)
Whitelaw, J. H.
(Imperial Coll. of Science and Technology London, United Kingdom)
Yianneskis, M.
(Imperial College of Science and Technology London, United Kingdom)
Date Acquired
August 10, 2013
Publication Date
September 1, 1982
Subject Category
Fluid Mechanics And Heat Transfer
Accession Number
82A44780
Distribution Limits
Public
Copyright
Other

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