Experimental Comparison of Dividing Open-Channel with Duct Flow in T-Junction
Publication: Journal of Hydraulic Engineering
Volume 124, Issue 1
Abstract
To aid numerical modeling of T-junction flows, this paper presents experimental differences in velocity and water-surface elevation between open-channel free surface and duct symmetry plane. The data were taken in an open-channel flow with a width-to-depth ratio of 1:2, and were compared to published data for a duct flow with a width-to-depth ratio of 1:4. It was found that at a discharge ratio of 0.81 between the branch and upstream main channel, there is up to 0.36Ux/Uo difference in the near-surface velocity (the symmetry plane velocity in duct flow) at certain corresponding (same normalized x, y, and z) locations. The differences in velocity are attributed to secondary currents in open-channel flow that are not present in the duct flow. It is also found that as the flow turns to enter the branch, centrifugal forces caused up to 2.1% superelevation of the water surface. The observations suggest that caution is needed when assuming that flow in an open-channel cross section is equivalent to that in one-half of a closed conduit.
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References
1.
Abernethy, R. B., Benedict, R. P., and Dowdell, R. B.(1985). “ASME measurement uncertainty.”J. Fluids Engrg., 107(2), 161–164.
2.
Best, J. L., and Reid, I.(1984). “Separation zone at open-channel junctions.”J. Hydr. Engrg., ASCE, 110(11), 1588–1594.
3.
Brundrett, E., and Baines, W. D. (1964). “The production and diffusion of vorticity in duct flow.”J. Fluid Mech., Cambridge, U.K. 19, 375–394.
4.
Chen, H. B., and Lian, G. S. (1992). “The numerical computation of turbulent flow in tee-junction.”J. Hydrodynamics, Ser. B, Beijing, China, 3, 16–25, 50–58.
5.
Gibson, M. M., and Rodi, W.(1988). “Simulation of free surface effects on turbulence with a Reynolds stress model.”J. Hydr. Res., Delft, The Netherlands, 27(2), 233–244.
6.
Hager, W. H. (1983). “An approximate treatment of flow in branches and bends.”Proc., Instn. Mech. Engrs., London, U.K., 198C(4), 63–69.
7.
Henderson, F. M. (1966). Open channel flow. MacMillan Inc., New York, N.Y.
8.
Issa, R. I., and Oliveira, P. J.(1994). “Numerical prediction of phase separation in two-phase flow through T-junctions.”Computers and Fluids, 23(2), 347–372.
9.
Lakshmana Rao, N. S., Sridharan, K., and Baig, M. Y. A. (1968). “Experimental study of the division of flow in an open channel.”Proc., Third Australasian Conf. on Hydr. and Fluid Mech., Instn. Engrs., Sydney, Australia, 139–142.
10.
Law, S. W., and Reynolds, A. J.(1966). “Dividing flow in an open channel.”J. Hydr. Div., ASCE, 92(2), 207–231.
11.
Melling, A., and Whitelaw, J. H.(1976). “Turbulent flow in a rectangular duct.”J. Fluid Mech., Cambridge, U.K., 78(2), 289–315.
12.
Noat, D., and Rodi, W.(1982). “Calculation of secondary currents in channel flow.”J. Hydr. Div., ASCE, 108(8), 948–968.
13.
Neary, V. S. (1992). “Flow structure at an open channel diversion,” MS thesis, Univ. of Iowa, Iowa City, Iowa.
14.
Neary, V. S., and Odgaard, A. J.(1993). “Three-dimensional flow structure at open channel diversions.”J. Hydr. Engrg., ASCE, 119(11), 1223–1230.
15.
Nezu, I., Nakagawa, H., and Rodi, W. (1989). “Significant difference between secondary currents in closed channels and narrow channels.”Proc., 23rd IAHR Congress, IAHR, National Research Council, Ottawa, Canada, A125–A132.
16.
Perkins, H. J.(1970). “The formation of streamwise vorticity in turbulent flow.”J. Fluid Mech., Cambridge, U.K., 44(4), 721–740.
17.
Pizzuto, J. E.(1991). “A numerical model for calculating the distributions of velocity and boundary shear stress across irregular straight open channels.”Water Resour. Res., 27(9), 2457–2466.
18.
Popp, M., and Sallet, D. W. (1983). “Experimental investigation of one- and two-phase flow through a tee junction.”Proc., Int. Conf. on Physical Modeling of Multi-Phase Flow, BHRA, Cranfield, Bedford, England, 67–88.
19.
Ramamurthy, A. S., and Satish, M. G.(1988). “Division of flow in short open channel branches.”J. Hydr. Engrg., ASCE, 114(4), 428–438.
20.
Ramamurthy, A. S., Tran, D. M., and Carballada, L. B.(1990). “Dividing flow in open channels.”J. Hydr. Engrg., ASCE, 116(3), 449–455.
21.
Rhodes, D. G., and Knight, D. W.(1994). “Distribution of shear force on boundary of smooth rectangular duct.”J. Hydr. Engrg., ASCE, 120(7), 787–807.
22.
Taylor, E. H.(1942). “Flow characteristics at rectangular open-channel junctions.”Trans. ASCE, 107, 893–912.
23.
Tominaga, A., Nezu, I., Ezaki, K., and Nakagawa, H.(1989). “Three-dimensional turbulent structure in straight open channel flows.”J. Hydr. Res., Delft, The Netherlands, 27(1), 149–173.
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Information
Published In
Journal of Hydraulic Engineering
Volume 124 • Issue 1 • January 1998
Pages: 92 - 95
Copyright
Copyright © 1998 American Society of Civil Engineers.
History
Published online: Jan 1, 1998
Published in print: Jan 1998
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