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International Journal of Rotating Machinery
Volume 2, Issue 3, Pages 209-218
http://dx.doi.org/10.1155/S1023621X96000085

Turbulence and Scale Measurements in a Square Channel with Transverse Square Ribs

1Wright Laboratory, Aero Propulsion and Power Directorate, Wright-Patterson Air Force Base, 45433-7251, Ohio, USA
2Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh 15213-3890, Pennsylvania, USA
3Mechanical Engineering Department, University of Pittsburgh, Pittsburgh 15261, Pennsylvania, USA

Copyright © 1996 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Hot-wire measurements of the mean flow, turbulence characteristics, and integral scale in a square channel roughened with transverse ribs mounted on two opposing sidewalls are presented for three rib configurations: single rib, in-line multiple ribs, and staggered multiple ribs. Test conditions for multiple ribs use p/H = 10, H/D 0.17, and ReD 23,000. Measured results highlight the spatial distribution and evolution of turbulence intensity and integral scale from the flow entrance of the first period to the developed regime near the exit of the third period. The highly turbulent, shear layer initiated near the trailing upper-edge of a rib elevates the turbulence level in the mainstream of the channel. The magnitude of turbulence intensity in the channel core rises from 0.7% in the approaching flow to about 20–25% near the exit of the third period. The integral scale dominating the mainstream flow increases from approximately one-half the rib-height, 0.5H, in the approaching flow to 1.5-2.5H behind the first rib and further downstream.