Flow Field Characterization at the Onset of Gas Entrainment in a Single Downward Discharge Using Particle Image Velocimetry

2007 ◽  
Vol 129 (12) ◽  
pp. 1565-1576 ◽  
Author(s):  
R. C. Bowden ◽  
I. G. Hassan

The incipience of two-phase flow in discharging branches from a stratified gas-liquid region has major implications in industrial applications where safety is of concern. An experimental investigation of the liquid side flow field at the onset of gas entrainment, in a single downward oriented discharging branch, was presented. Particle image velocimetry was used to measure the liquid side flow field in horizontal and vertical planes. Averaged velocity profiles were presented and demonstrated a highly radial flow. The particle image velocimetry data were validated using continuity and showed that the mass flow rate to be in the range of 10–25% of the expected value. Further, the vortex-free flow field assumption, used previously in the development of analytical and empirical models, was found to be reasonable.

Author(s):  
Wael Fairouz Saleh ◽  
Ibrahim Galal Hassan

The discharge of two-phase flow from a stratified region through single or multiple branches is an important process in many industrial applications including the pumping of fluid from storage tanks, shell-and-tube heat exchangers, and the fluid flow through small breaks in cooling channels of nuclear reactors during loss-of-coolant accidents (LOCA). Knowledge of the flow phenomena involved along with the quality and mass flow rate of the discharging stream(s) is necessary to adequately predict the different phenomena associated with the process. Particle Image Velocimetry (PIV) in three dimension was used to provide detailed measurements of the flow patterns involving distributions of mean velocity, vorticity field, and flow structure. The experimental investigation was carried out to simulate two phase discharge from a stratified region through branches located on a semi-circular wall configuration during LOCA scenarios. The semi-circular test section is in close dimensional resemblance with that of a CANDU header-feeder system, with branches mounted at orientation angles of zero, 45 and 90 degrees from the horizontal. The experimental data for the phase development (mean velocity, flow structure, etc.) was done during single discharge through the bottom branch from an air/water stratified region over a three selected Froude numbers. These measurements were used to describe the effect of outlet flow conditions on phase redistribution in headers and understand the entrainment phenomena.


Author(s):  
R. C. Bowden ◽  
I. G. Hassan

The incipience of two-phase flow in discharging branches, from a stratified gas-liquid region, has major implications in industrial applications where safety is of primary concern. The transition from single phase liquid to a two phase gas-liquid mixture is termed the onset of gas entrainment, and may be formed by either vortex or vortex-free mechanisms. The two phase flow quality in the discharging branch is greatly impacted by vortex-free gas entrainment, as compared with gas entrainment due to vortex formation. Presented is a preliminary experimental investigation to demonstrate quantitative measurements of the liquid flow field at the onset of gas entrainment in a single discharging bottom branch. The three dimensional flow field is resolved into three horizontal planes and a single vertical plane. Results indicate a strong dependency of the flow field on the radial component, directed toward the branch center, and where a solid wall is present a larger tangential component.


2002 ◽  
Vol 33 (6) ◽  
pp. 794-800 ◽  
Author(s):  
U. Dierksheide ◽  
P. Meyer ◽  
T. Hovestadt ◽  
W. Hentschel

2010 ◽  
Vol 43 (6) ◽  
pp. 1039-1047 ◽  
Author(s):  
Emily J. Berg ◽  
Jessica L. Weisman ◽  
Michael J. Oldham ◽  
Risa J. Robinson

AIAA Journal ◽  
2019 ◽  
Vol 57 (2) ◽  
pp. 735-748 ◽  
Author(s):  
D. J. Tan ◽  
D. Honnery ◽  
A. Kalyan ◽  
V. Gryazev ◽  
S. A. Karabasov ◽  
...  

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