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A comparison of the mixing characteristics in single- and two-phase grid-generated turbulent flow systems

Moghaddas, Jafar Sadegh LU ; Trägårdh, Christian LU ; Östergren, Karin LU and Revstedt, Johan LU (2004) In Chemical Engineering & Technology 27(6). p.662-670
Abstract
The mixing process is studied in grid-generated turbulent flow for single- and bubbly two-phase flow systems. Concentration and mixing characteristics in the liquid phase are measured with the aid of a PLIF/PLIF arrangement. A nearly isotropic turbulent flow field is generated at the center of the vertical pipe by using a honeycomb, three grids and a contraction. In two-phase flow experiments, air bubbles were injected into the flow from a rectangular grid, with mesh size M = 6 mm, which is placed midway between two circular grids each with a mesh size of M = 2 mm. For single-phase flow, the normalized mean concentration cross-stream profiles have rather similar Gaussian shapes, and the cross-stream profiles of the normalized... (More)
The mixing process is studied in grid-generated turbulent flow for single- and bubbly two-phase flow systems. Concentration and mixing characteristics in the liquid phase are measured with the aid of a PLIF/PLIF arrangement. A nearly isotropic turbulent flow field is generated at the center of the vertical pipe by using a honeycomb, three grids and a contraction. In two-phase flow experiments, air bubbles were injected into the flow from a rectangular grid, with mesh size M = 6 mm, which is placed midway between two circular grids each with a mesh size of M = 2 mm. For single-phase flow, the normalized mean concentration cross-stream profiles have rather similar Gaussian shapes, and the cross-stream profiles of the normalized root-mean-square (RMS) values of concentration were found to be quite similar. Cross-stream profiles of the mean concentration, for bubbly two-phase flow, were also found to be quite similar, but they did not have the Gaussian shape of the profiles for single-phase flow. Almost self-similar behavior was also found for the RMS values of the concentration in two-phase systems. The turbulent diffusion coefficient in the liquid phase was also calculated. At the center of the plume, the flow was found to have a periodic coherent structure, probably of vortex shedding character. Observations showed that the period of oscillation is higher in the case of two-phase flow than in single-phase flow. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Chemical Engineering & Technology
volume
27
issue
6
pages
662 - 670
publisher
John Wiley & Sons
external identifiers
  • wos:000222129500008
  • scopus:3042698243
ISSN
1521-4125
DOI
10.1002/ceat.200401986
language
English
LU publication?
yes
id
8ffc1ee0-c3e0-4ae2-8127-d7f50894307c (old id 139193)
date added to LUP
2007-07-04 09:51:08
date last changed
2017-01-01 05:13:00
@article{8ffc1ee0-c3e0-4ae2-8127-d7f50894307c,
  abstract     = {The mixing process is studied in grid-generated turbulent flow for single- and bubbly two-phase flow systems. Concentration and mixing characteristics in the liquid phase are measured with the aid of a PLIF/PLIF arrangement. A nearly isotropic turbulent flow field is generated at the center of the vertical pipe by using a honeycomb, three grids and a contraction. In two-phase flow experiments, air bubbles were injected into the flow from a rectangular grid, with mesh size M = 6 mm, which is placed midway between two circular grids each with a mesh size of M = 2 mm. For single-phase flow, the normalized mean concentration cross-stream profiles have rather similar Gaussian shapes, and the cross-stream profiles of the normalized root-mean-square (RMS) values of concentration were found to be quite similar. Cross-stream profiles of the mean concentration, for bubbly two-phase flow, were also found to be quite similar, but they did not have the Gaussian shape of the profiles for single-phase flow. Almost self-similar behavior was also found for the RMS values of the concentration in two-phase systems. The turbulent diffusion coefficient in the liquid phase was also calculated. At the center of the plume, the flow was found to have a periodic coherent structure, probably of vortex shedding character. Observations showed that the period of oscillation is higher in the case of two-phase flow than in single-phase flow.},
  author       = {Moghaddas, Jafar Sadegh and Trägårdh, Christian and Östergren, Karin and Revstedt, Johan},
  issn         = {1521-4125},
  language     = {eng},
  number       = {6},
  pages        = {662--670},
  publisher    = {John Wiley & Sons},
  series       = {Chemical Engineering & Technology},
  title        = {A comparison of the mixing characteristics in single- and two-phase grid-generated turbulent flow systems},
  url          = {http://dx.doi.org/10.1002/ceat.200401986},
  volume       = {27},
  year         = {2004},
}