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Research Papers: Multiphase Flows

Comparison of Local Interfacial Structures Around 90 and 45-Degree Elbows in Horizontal Bubbly Flows

[+] Author and Article Information
Mohan Yadav

Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, 230 Reber Building, University Park, State College, PA 16802msy117@psu.edu

Justin D. Talley

Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, 230 Reber Building, University Park, State College, PA 16802jdt195@psu.edu

Seungjin Kim

Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, 230 Reber Building, University Park, State College, PA 16802skim@psu.edu

J. Fluids Eng 132(11), 111302 (Nov 17, 2010) (12 pages) doi:10.1115/1.4002872 History: Received September 28, 2009; Revised October 12, 2010; Published November 17, 2010; Online November 17, 2010

This study presents a comparison of the geometric effects of 90 deg and 45 deg elbows in horizontal two-phase air-water bubbly flow. Two separate experiments were performed in the horizontal test section made out of 50.3 mm inner diameter glass tubes. The first set of data was collected with a 90 deg elbow installed, and then a 45 deg elbow was added to the existing facility to acquire the second set of data. A total of 15 different flow conditions, all within the bubbly flow regime, were identified for the 90 deg experiment, and very similar flow conditions were extended to the 45 deg experiment. A double-sensor conductivity probe was employed to acquire the local data at seven different axial positions along the test section, out of which four measurement locations are associated with the 90 deg experiment and three with the 45 deg experiment. The data show that the elbows have a significant effect on the development of interfacial structures as well as the bubble interaction mechanisms. Furthermore, there are characteristic similarities and differences between the effects of the two elbows. While the effect of the 45 deg elbow is evident immediately after the elbow, the 90 deg elbow effect tends to propagate further downstream of the elbow rather than immediately after the elbow. Moreover, it is shown that both elbows induce spatial oscillations in the interfacial structures and two-phase flow parameters, but the degree and the nature of oscillations differ. The effects of the elbows are also compared for the axial transport of the two-phase flow parameters.

Copyright © 2010 by American Society of Mechanical Engineers
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Figures

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Figure 1

A schematic of the top view of the test facility (11)

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Figure 2

A schematic of the two-phase mixing chamber (12)

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Figure 3

Flow conditions at different measurement locations for (a) 90 deg experiment and (b) 45 deg experiment shown on the horizontal flow regime map by Mandhane (15) and Taitel and Dukler (16)

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Figure 4

Comparison of the local superficial gas velocity, jg,loc, measured by the flow meter with ⟨αug⟩ acquired by the conductivity probe; dotted lines represent ±10%

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Figure 5

Change in the local gauge pressure measured along the axial direction of the flow (vertical line shows the position of the elbows)

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Figure 6

Comparison of local horizontal α and ai profiles for 45 deg and 90 deg elbows at jg,atm=0.124 m/s and jf=4.3 m/s

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Figure 7

Comparison of local horizontal α and ai profiles for 45 deg and 90 deg elbows for different gas flow rates and constant jf=4.0 m/s immediately downstream of the elbows

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Figure 8

Local horizontal α and ai profiles for the 90 deg elbow for different gas flow rates and constant jf=4.0 m/s at L/D=250

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Figure 9

Comparison of the local horizontal profiles of bubble velocity vg for 45 deg and 90 deg elbows at measurement location immediately downstream of the elbow for different gas flow rates and constant jf=4.0 m/s

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Figure 10

Comparison of the local horizontal profiles of bubble Sauter mean diameter, dsm, for 45 deg and 90 deg elbows at measurement location immediately downstream of the elbow for different gas flow rates and constant jf=4.0 m/s

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Figure 11

Comparison of the local vertical α and ai profiles for the 45 deg and 90 deg elbows at different development lengths for jg,atm=0.320 m/s and jf=4.0 m/s

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Figure 12

Comparison of the local vertical α and ai profiles for the 45 deg and 90 deg elbows at different gas flow rates and constant jf=4.0 m/s immediately downstream of the elbows

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Figure 13

Comparison of the local vertical profiles of bubble velocity vg for the 45 deg and 90 deg elbows at different gas flow rates and constant jf=4.0 m/s at measurement location immediately downstream of the elbows

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Figure 14

Comparison of the local vertical profiles of bubble Sauter mean diameter, dsm, for the 45 deg and 90 deg elbows at different gas flow rates and constant jf=4.0 m/s at measurement location immediately downstream of the elbows

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Figure 15

Comparison of the one-dimensional transport of ⟨α⟩ and ⟨ai⟩ across the elbows for two characteristic flow conditions with constant jf=4.3 m/s

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Figure 16

Comparison of the one-dimensional transport of Sauter mean diameter, ⟨dsm⟩, across the elbows for two characteristic flow conditions with constant jf=4.3 m/s

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Figure 17

Axial development of one-dimensional void-weighted bubble velocity in two characteristic flow conditions at constant jf=4.0 m/s

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