Inlet effects on vertical-downward air-water two-phase flow

S. Qiao, D. Mena, Seungjin Kim

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    2 Scopus citations

    Abstract

    This paper focuses on investigating the geometric effects of inlets on global and local two-phase flow parameters in vertical-downward air-water two-phase flow. Flow visualization, frictional pressure loss analysis, and local experiments are performed in a test facility constructed from 50.8 mm inner diameter acrylic pipes. Three types of inlets of interest are studied: (1) two-phase flow injector without a flow straightener (Type A), (2) two-phase flow injector with a flow straightener (Type B), and (3) injection through a horizontal-to-vertical-downward 90° vertical elbow (Type C). A detailed flow visualization study is performed to characterize flow regimes including bubbly, slug, churn-turbulent, and annular flow. Flow regime maps for each inlet are developed and compared to identify the effects of each inlet. Frictional pressure loss analysis shows that the Lockhart-Martinelli method is capable of correlating the frictional loss data acquired for Type B and Type C inlets with a coefficient value of C=25, but additional data may be needed to model the Type A inlet. Local two-phase flow parameters measured by a four- sensor conductivity probe in four bubbly and near bubbly flow conditions are analyzed. It is observed that vertical-downward two-phase flow has a characteristic center-peaked void profile as opposed to a wall- peaked profile as seen in vertical-upward flow. Furthermore, it is shown that the Type A inlet results in the most pronounced center-peaked void fraction profile, due to the coring phenomenon. Type B and Type C inlets provide a more uniform distribution of the void fraction profile with a reduced coring effect.

    Original languageEnglish (US)
    Title of host publicationInternational Topical Meeting on Nuclear Reactor Thermal Hydraulics 2015, NURETH 2015
    PublisherAmerican Nuclear Society
    Pages5587-5600
    Number of pages14
    ISBN (Electronic)9781510811843
    StatePublished - Jan 1 2015
    Event16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2015 - Chicago, United States
    Duration: Aug 30 2015Sep 4 2015

    Publication series

    NameInternational Topical Meeting on Nuclear Reactor Thermal Hydraulics 2015, NURETH 2015
    Volume7

    Other

    Other16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2015
    Country/TerritoryUnited States
    CityChicago
    Period8/30/159/4/15

    All Science Journal Classification (ASJC) codes

    • Instrumentation
    • Nuclear Energy and Engineering

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