Evolution of the structure of a gas–liquid two-phase flow in a large vertical pipe
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2007-09
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Conference Paper
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Abstract
The evolution of the structure of a gas–liquid flow in a large vertical pipe of 195 mm inner diameter was investigated at the TOPFLOW test facility in Rossendorf. Wire-mesh sensors were used to measure sequences of two-dimensional distributions of local instantaneous gas fraction within the complete pipe cross-section. The sensors own a resolution of 3 mm at a frequency of 2500 Hz. Superficial velocities were varied in a range covering flow regimes from bubbly to churn-turbulent flow. The distance between the gas injection and the sensor position was changed using a so-called variable gas injection system. It consists of six gas injection units, each equipped with three rings of injection orifices in the pipe wall (orifice diameter: 1 and 4 mm), which are fed from ring chambers. The gas flow towards these distributor chambers is individually controlled by valves. Measured bubble-size resolved radial gas fraction profiles reveal differences in the lateral migration of bubbles of different size starting from the injection at the wall. The evolution of bubble-size distributions allows to study bubble coalescence and break-up. The influence of the physical properties of the fluid was studied by comparing cold air–water experiments with steam–water tests at 65 bar.
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published
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Volume
237 (15-17)
Pages / Article No.
1848 - 1861
Publisher
North Holland
Event
11th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-11)
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03725 - Prasser, Horst-Michael (emeritus) / Prasser, Horst-Michael (emeritus)
03282 - Merkle, Hans Peter (emeritus)
03484 - Mazzotti, Marco (emeritus) / Mazzotti, Marco (emeritus)