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Steam-water experiments at high pressure to study the structure of the gas-liquid interface in a large vertical pipe

Prasser, H.-M.; Beyer, M.; Carl, H.; Pietruske, H.; Schütz, P.; Weiß, F.-P.

In the frame of the TOPFLOW project, vertical pipe flow is experimentally studied in order to develop and validate models for bubble forces as well as for bubble coalescence and fragmentation in a gas-liquid two-phase flow. The advantage of TOPFLOW consists in the combination of (1) a large scale of the test channel with (2) a wide operational range both in terms of the superficial velocities and the system pressure and finally (3) the availability of an instrumentation that is ca-pable in resolving structures of the gas-liquid interface, namely the wire-mesh sensors. Results are presented for tests with steam-water mixture at a saturation pressure of up to 6.5 MPa. The measured radial gas fraction profiles and bubble size distributions show in detail the influence of the fluid properties to the flow structure and its evolution along the flow path when compared to earlier results obtained at identical superficial velocities in an air-water flow. The results from the high-pressure tests are of particular interest for the validation of CFD codes for an application in the field of nuclear reactor safety. A significant influence of the physical properties to the flow structure was found: the steam-water flow at high pressure compared to the air water flow under ambient conditions shows less tendency to develop large bubbles and a bimodal bubble size distribution but is characterised by larger bubble sizes in the region of the small bubble peak.

Keywords: two-phase flow; steam-water flow; wire-mesh sensor; flow pattern

  • Contribution to proceedings
    Annual Meeting on Nuclear Technology, 10.-12.05.2005, Nürnberg, Germany, 98-101

Permalink: https://www.hzdr.de/publications/Publ-8005
Publ.-Id: 8005