Journal ArticleDOI
Curved Ducts With Strong Secondary Motion: Velocity Measurements of Developing Laminar and Turbulent Flow
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In this paper, two 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.Abstract:
Two 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.read more
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Journal ArticleDOI
Experimental investigation on turbulent flow in a circular-sectioned 90-degree bend
K. Sudo,M. Sumida,H. Hibara +2 more
TL;DR: In this article, the steady, turbulent flow in a circular-sectioned 90° bend with smooth walls has been investigated experimentally and the velocity fields of the primary and secondary flows, and the Reynolds stress distributions in the cross section were illustrated.
Journal ArticleDOI
An experimental and numerical study of the Dean problem : flow development towards two-dimensional multiple solutions
TL;DR: In this paper, an experimental and numerical study investigating the flow development and fully developed flows of an incompressible Newtonian fluid in a curved duct of square cross section with a curvature ratio of 15.1 is presented.
Journal ArticleDOI
Developing Turbulent Flow in a U-Bend of Circular Cross-Section: Measurement and Computation
TL;DR: In this paper, a semi-elliptic truncation of the Reynolds equations is used to predict the secondary flow reversals in a strongly curved 180 deg pipe and its downstream tangent.
Journal ArticleDOI
LDA investigation of the flow development through rotating U-ducts
TL;DR: In this paper, the authors used laser-Doppler anemometry (LDA) to measure the mean and fluctuating flow field in a U-bend of strong curvature, Rc/D = 0.65, that is either stationary or rotating in orthogonal mode.
Journal ArticleDOI
The development and structure of primary and secondary flow in a curved square duct
TL;DR: In this paper, the development of laminar flow in a 180° section of a curved square duct (R/d = 6.45) was studied by laser-Doppler anemometry (LDA).