Three-dimensional flow pattern visualization and bubble size distributions in stationary and transient upward flashing flow
Metadata only
Date
2006-08Type
- Journal Article
ETH Bibliography
yes
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Abstract
For the first time, an experimental three-dimensional reconstruction and visualization of stationary and transient flashing flow in a vertical pipe (47 mm diameter) is presented. The measurements have been performed by means of wire-mesh sensors. This type of sensor delivers two-dimensional void-fraction distributions in the pipe cross-section where it is mounted with a maximum sampling rate of 10,000 frames per second. A sampling rate of 1200 frames per second has been used in this work. Steam bubbles have been identified from the wire-mesh data and their complete three-dimensional reconstruction has been performed by taking into account the steam bubble velocity. For the estimation of the bubble velocity, two wire-mesh sensors positioned at a small axial distance from each other have been used. The velocity has been determined by cross-correlation of the two wire-mesh signals, by direct identification of the traveling time of the steam bubbles between the two sensors and by means of a drift-flux model. A comparison between the three methods of bubbles velocity measurement is reported. Stationary and time-dependent bubble size distributions have been derived. The stationary radial void-fraction profiles have been decomposed according to bubble size classes and compared with the results obtained with an equilibrium model. Show more
Publication status
publishedExternal links
Journal / series
International Journal of Multiphase FlowVolume
Pages / Article No.
Publisher
ElsevierSubject
Flashing; Two-phase flow; Three-dimensional visualization; Bubble sizeOrganisational unit
03725 - Prasser, Horst-Michael (emeritus) / Prasser, Horst-Michael (emeritus)
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ETH Bibliography
yes
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