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
    CountryUnited States
    CityChicago
    Period8/30/159/4/15

    All Science Journal Classification (ASJC) codes

    • Instrumentation
    • Nuclear Energy and Engineering

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