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Research Papers: Multiphase Flows

# Incipience of Liquid Entrainment From a Stratified Gas-Liquid Region in Multiple Discharging Branches

[+] Author and Article Information
R. C. Bowden

Department of Mechanical and Industrial Engineering,  Concordia University, Montreal, QC, H3G 2W1, Canada

I. G. Hassan1

Department of Mechanical and Industrial Engineering,  Concordia University, Montreal, QC, H3G 2W1, Canadaibrahimh@alcor.concordia.ca

1

Corresponding author.

J. Fluids Eng 130(1), 011301 (Dec 19, 2007) (10 pages) doi:10.1115/1.2813138 History: Received December 29, 2005; Revised July 17, 2007; Published December 19, 2007

## Abstract

The onset of liquid entrainment in discharging branches, from a stratified gas-liquid region, has implications in industrial applications where safety is of concern. The onset criterion was characterized by the critical height, the vertical distance from the discharge inlet to the gas-liquid interface, and was shown to be a function of the Froude number. The critical height signified a transition in the discharging flow quality from a single phase gas to a two-phase gas-liquid mixture. The onset of liquid entrainment with multiple discharging branches, and a stratified gas-liquid region, was experimentally investigated using air and water. A test section with a semicircular cross section and three discharging branches at $0deg$, $45deg$, and $90deg$ was used. The critical height was recorded using both increasing and decreasing liquid level methods, thereby demonstrating surface tension and wetness effects. A total of eight cases were investigated for single, dual, and triple discharges, with onset occurring in the branch closest to and above the gas-liquid interface. Wall curvature effects were discussed through comparison with previous flat wall studies. Agreement between previously developed analytical models and the decreasing liquid level results was found.

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Topics: Bifurcation

## Figures

Figure 1

(a) Modeled geometry and parameters and (b) test section installed in the two-phase reservoir

Figure 2

Experimental test facility schematic

Figure 3

The OLE using the ILL method

Figure 4

OLE in side branch with comparison to Hassan (5) for (a) ILL method, (b) DLL method, and (c) Maier (9) for ILL method. Analytical models by (d) Maier (11), (e) Armstrong (6), and (f) Yonomoto and Tasaka (3).

Figure 5

OLE in side Branch B with comparison to (a) Hassan (12) (DLL) and (b) flat wall analytical model by Hassan (10)

Figure 6

OLE in Branch A with secondary Branch C. Comparison with single discharge cases demonstrating the effect of varying FrC.

Figure 7

OLE in side Branch A and secondary Branch B. Comparison with single discharge cases demonstrating the effect of varying FrB.

Figure 8

OLE in a side Branch B with secondary Branch C. Comparison with single discharge cases demonstrating the effect of varying FrC.

Figure 9

OLE in a side Branch B with secondary Branch A. Comparison with single discharge cases demonstrating the effect of varying FrA.

Figure 10

Comparison between present results and Hassan (10); (a) experimental data for a flat vertical wall using DLL, (b) finite branch model, and (c) point-sink model by Armstrong (6)

Figure 11

Comparison between present results with (a) the experimental results (DLL) of Hassan (12) and (b) finite branch model by Hassan (10)

Figure 12

OLE in side Branch A with secondary Branches B and C. Effect of l∕d, FrB, and FrC on ∣H∣∕d by comparison with single and dual discharge cases.

Figure 13

OLE in Branch B with secondary Branches A and C. Effect of l∕d and FrA by comparison with single discharge and dual discharge cases.

Figure 14

OLE in Branch B with secondary Branches A and C. Effect of l∕d and FrC by comparison with single discharge and dual discharge cases.

Figure 15

Image of dual discharge with Branches A and C active, demonstrating simultaneous liquid and gas entrainment

Figure 16

Image captured of triple discharge with simultaneous gas entrainment in Branches B and C, and liquid entrainment in Branch A

Figure 17

Sketch of the ILL method when Fr>1

Figure 18

Sketch of the ILL method when Fr<1

Figure 19

Sketch of the DLL method when Fr>0

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