Study on characteristics of void fraction in vertical countercurrent two-phase flow by neutron radiography
- Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
In order to make clear the flow mechanism and characteristics of falling water limitation under the countercurrent two-phase flow, that is, the countercurrent flow limitation (CCFL), in a vertical channel, a technique of neutron radiography (NRG) provided in the Research Nuclear Reactor JRR-3M was applied to an air-water system of vertical rectangular channels of 50 and 782 mm in length with 66 mm in channel width and 2.3 mm in channel gap under atmospheric pressure. The neutron radiography facility used in this study has a high thermal neutron flux that is suitable for visualization of fluid phenomena. A real-time electronic imaging method was used for capturing two-phase flow images in a vertical channel. It was found the technique applied was very potential to clarify the characteristics of instantaneous, local and average void fractions which were important to understand flow mechanism of the phenomena, while the measurements of void fraction had not been applied fully effectively to understanding of the flow mechanism of CCFL, because the differential pressure for determining void fraction is, in general, too small along the tested channel and is fluctuating too frequently to be measured accurately enough. From the void fraction measured by NRG as well as through direct flow observation, it was revealed that the shorter side walls of rectangular channel tested were predominantly wetted by water falling down with the longer side walls being rather dry by ascending air flow. It was strongly suggested that the analytical flow model thus obtained and proposed for the CCFL based on the flow observation was most effective.
- OSTI ID:
- 271906
- Report Number(s):
- CONF-960306-; ISBN 0-7918-1226-X; TRN: 96:017214
- Resource Relation:
- Conference: ICONE 4: ASME/JSME international conference on nuclear engineering, New Orleans, LA (United States), 10-13 Mar 1996; Other Information: PBD: 1996; Related Information: Is Part Of ICONE-4: Proceedings. Volume 1 -- Part B: Basic technological advances; Rao, A.S. [ed.] [General Electric Nuclear Energy, San Jose, CA (United States)]; Duffey, R.B. [ed.] [Brookhaven National Lab., Upton, NY (United States)]; Elias, D. [ed.] [Commonwealth Edison, Downers Grove, IL (United States)]; PB: 564 p.
- Country of Publication:
- United States
- Language:
- English
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