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TECHNICAL PAPERS

Edge Effects on the Flow Characteristics in a 90deg Tee Junction

[+] Author and Article Information
N. P. Costa

Departamento de Engenharia Civil, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugalncosta@fe.up.pt

R. Maia

Departamento de Engenharia Civil, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugalrmaia@fe.up.pt

M. F. Proença

Departamento de Engenharia Civil, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugalfproenca@fe.up.pt

F. T. Pinho1

Centro de Estudos de Fenómenos de Transporte, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200- 465 Porto, Portugal and Universidade do Minho, Largo do Paço, 4704- 553 Braga, Portugalfpinho@fe.up.pt

1

Corresponding author.

J. Fluids Eng 128(6), 1204-1217 (May 07, 2006) (14 pages) doi:10.1115/1.2354524 History: Received September 09, 2005; Revised May 07, 2006

Measurements of pressure drop were carried out for the flow of a Newtonian fluid in 90deg tee junctions with sharp and round corners. Rounding the corners reduced the energy losses by between 10 and 20%, depending on the flow rate ratio, due to the reduction in the branching flow loss coefficient, whereas the straight flow basically remained unaffected. The corresponding detailed measurements of mean and turbulent velocities for a Reynolds number of 31,000 and flowrate ratio of 50% showed that rounding the corner lead to an increase in turbulence in the branch pipe. The increased turbulence diffused momentum more efficiently thus reducing the length of the recirculation by 25% with its width and strength also decreasing in magnitude. The overall effect of the increased dissipation due to turbulence and reduced dissipation due to mean flow irreversibilities in the recirculation was a decrease in the corresponding loss coefficient.

Copyright © 2006 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Schematic representation of the experimental set-up: (1) Tee test section (flow field characterization), (2) pipe test section (pressure field characterization), (3) flowmeter, (4) tank, (5) pump, (6) valve, (7) pulsation dampener

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Figure 2

Test section drawings and co-ordinate system: (a) Bifurcation piece: Comparison between sharp-edge tee (left) and rounded-edge tee (right). Dimensions in [mm]; (b) coordinate system, position of some diametric measuring planes and terminology.

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Figure 3

Variation of the local loss coefficient K31 in a sharp edge 90deg tee: (a) Effect of Reynolds number and flow rate ratio; (b) comparison with literature

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Figure 4

Variation of the local loss coefficient K32 in a sharp edge 90deg tee: (a) Effect of Reynolds number and flow rate ratio; (b) comparison with literature

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Figure 5

Comparison between the literature and measured velocity profiles upstream of the tee junction (−10 and −5D): (a) Axial velocity (in wall coordinates); (b) axial rms velocity; (c) radial rms velocity; (d) tangential rms velocity

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Figure 6

Radial profiles of the normalized axial mean flow upstream of the tee junction (−10 and −5D) at Re=35,000

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Figure 7

Radial profiles of mean (closed symbols) and rms axial velocity (open symbols) in the bifurcation region of the sharp-edge tee: −1D(엯), −0.5D(▵); vertical cross-stream profile at −1D (×)

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Figure 8

Vector plot of the mean velocity in the horizontal diametric plane x-y of the bifurcation of the sharp-edge tee for Re=32,000 and Q1∕Q3=50%. The scale vector corresponds to u∕U=1.

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Figure 9

Radial profiles of streamwise velocity in the branch pipe of the sharp-edge tee for Re=32,000 and Q1∕Q3=50%

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Figure 10

“Radial” profiles of w∕U(엯,●) and w′∕U(×,+) measured 10mm above (엯,×) and 10mm below (●,+) the diametric horizontal plane at 2.0′D for the sharp edge tee flow at Re=32,000 and Q1∕Q3=50%

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Figure 11

Radial profiles of streamwise velocity in the outlet pipe of sharp edge tee for Re=32,000 and Q1∕Q3=50%: 엯—measurements in horizontal plane; ×—measurements in vertical plane (full and half profiles)

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Figure 12

Radial profiles of u′/U in the junction region of the sharp-edge tee for Re=32,000 and Q1∕Q3=50%, measured between the axis and the front wall

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Figure 13

Radial profiles of u′∕U and v′∕U in the outlet straight pipe of the sharp-edge tee for Re=32,000 and Q1∕Q3=50%. (a)u′∕U (◯: Horizontal cross-stream profile; ×: Vertical cross-stream profile); (b)v′∕U (vertical cross-stream profile).

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Figure 14

Radial profiles of v′∕U and u′∕U in the branch pipe of the sharp-edge tee for Re=32,000 and Q1∕Q3=50%. (a)v′∕U (엯—horizontal measurement; ×—vertical measurement); (b) u′∕U (vertical cross-stream profile).

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Figure 15

Variation of the local loss coefficient K31 in a rounded edge (R∕D=0.1)90deg tee: (a) Effect of Reynolds number and flow rate ratio; (b) comparison with literature

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Figure 16

Variation of the local loss coefficient K32 in a rounded edge (R∕D=0.1)90deg tee: (a) Effect of Reynolds number and flow rate ratio; (b) comparison with literature

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Figure 17

Comparison between the sharp and round corner tees in terms of total energy loss for Re≈31,000

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Figure 18

Radial profiles of mean axial velocity in the bifurcation region of the round tee for Re=32,000 and Q1∕Q3=50%: −1D (엯), −0.5D(▵); Vertical cross-stream profile at −1D (×)

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Figure 19

Vector plot of the mean velocity in the horizontal diametric plane x-y of the rounded corner tee junction for Re=32,000 and Q1∕Q3=50%. Vector scale corresponds to u∕U=1.

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Figure 20

Radial profiles of the longitudinal velocity in the branch pipe of the round edge tee flow for Re=32,000 and Q1∕Q3=50%

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Figure 21

Radial profiles of streamwise velocity in the outlet pipe of the round-edge tee for Re=32,000 and Q1∕Q3=50%: 엯—measurements in horizontal plane; ×—measurements in vertical plane

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Figure 22

Horizontal cross-stream profiles of u′∕U (엯) and v′∕U(×) velocities in the outlet pipe of the round-edge tee for Re=32,000 and Q1∕Q3=50%

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Figure 23

Radial profiles of v′∕U and u′∕U in the branch pipe of the round-edge tee for Re=32,000 and Q1∕Q3=50%. (a)v′∕U (엯—horizontal profile; ×—vertical profile); (b)u′∕U (vertical cross-stream profile).

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