Effects of 90° vertical elbows on two-phase flow parameters

S. Qiao, D. Mena, S. Kim

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

    Abstract

    This study investigates two-phase flow from vertical-upward to horizontal and horizontal to vertical-downward direction through 90° vertical elbows. Specifically, effects of 90° vertical elbows on two-phase pressure drop, development of bubble distribution, and one-dimensional transport of bubble velocity are studied. Pressure measurements are obtained along the test section over a wide range of flow conditions. The two-phase pressure drops across the elbows are modeled using the modified Lockhart-Martinelli correlation which accounts for the minor loss effect. It is demonstrated that the modified Lockhart-Martinelli correlation can predict the pressure loss across elbows with different orientations and angles by varying the minor loss coefficient. A database is established by measuring two-phase flow parameters across 90° vertical elbows using a four-sensor conductivity probe. It is found that immediately downstream of the 90° vertical-upward elbow, the bubbles have a bimodal distribution along the horizontal radius of the pipe cross-section causing a dual-peak in the profiles of local void fraction and interfacial area concentration. As the flow develops, the bimodal bubble distribution dissipates and develops to a single-peaked bubble distribution near the top of the pipe. Immediately downstream of the 90° vertical-downward elbow, a bimodal bubble distribution is also observed near the inner curvature of the elbow. As the flow develops, the bimodal bubble distribution migrates to the pipe center and finally develops to a characteristic center-peaked bubble distribution. For the area averaged void-weighted bubble velocity, it varies significantly in the elbow regions due to the changes in local velocity profile and bubble distribution caused by the elbow effects.

    Original languageEnglish (US)
    Title of host publicationInternational Topical Meeting on Advances in Thermal Hydraulics 2016, ATH 2016
    PublisherAmerican Nuclear Society
    Pages291-304
    Number of pages14
    ISBN (Electronic)9780894487330
    StatePublished - Jan 1 2016
    Event3rd International Topical Meeting on Advances in Thermal Hydraulics 2016, ATH 2016 - New Orleans, United States
    Duration: Jun 12 2016Jun 16 2016

    Publication series

    NameInternational Topical Meeting on Advances in Thermal Hydraulics 2016, ATH 2016

    Other

    Other3rd International Topical Meeting on Advances in Thermal Hydraulics 2016, ATH 2016
    CountryUnited States
    CityNew Orleans
    Period6/12/166/16/16

    All Science Journal Classification (ASJC) codes

    • Nuclear Energy and Engineering
    • Geotechnical Engineering and Engineering Geology
    • Nuclear and High Energy Physics

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