Study on flow instability and countermeasure in a draft tube with swirling flow

T. Nakashima, R. Matsuzaka, Kazuyoshi Miyagawa, K. Yonezawa, Y. Tsujimoto

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

    Abstract

    The swirling flow in the draft tube of a Francis turbine can cause the flow instability and the cavitation surge and has a larger influence on hydraulic power operating system. In this paper, the cavitating flow with swirling flow in the diffuser was studied by the draft tube component experiment, the model Francis turbine experiment and the numerical simulation. In the component experiment, several types of fluctuations were observed, including the cavitation surge and the vortex rope behaviour by the swirling flow. While the cavitation surge and the vortex rope behaviour were suppressed by the aeration into the diffuser, the loss coefficient in the diffuser increased by the aeration. In the model turbine test the aeration decreased the efficiency of the model turbine by several percent. In the numerical simulation, the cavitating flow was studied using Scale-Adaptive Simulation (SAS) with particular emphasis on understanding the unsteady characteristics of the vortex rope structure. The generation and evolution of the vortex rope structures have been investigated throughout the diffuser using the iso-surface of vapor volume fraction. The pressure fluctuation in the diffuser by numerical simulation confirmed the cavitation surge observed in the experiment. Finally, this pressure fluctuation of the cavitation surge was examined and interpreted by CFD.

    Original languageEnglish
    Title of host publicationIOP Conference Series: Earth and Environmental Science
    PublisherInstitute of Physics Publishing
    Volume22
    DOIs
    Publication statusPublished - 2014
    Event27th IAHR Symposium on Hydraulic Machinery and Systems, IAHR 2014 - Montreal, Canada
    Duration: 2014 Sep 222014 Sep 26

    Other

    Other27th IAHR Symposium on Hydraulic Machinery and Systems, IAHR 2014
    CountryCanada
    CityMontreal
    Period14/9/2214/9/26

    Fingerprint

    cavitation
    turbine
    vortex
    aeration
    simulation
    experiment
    hydraulics

    ASJC Scopus subject areas

    • Earth and Planetary Sciences(all)
    • Environmental Science(all)

    Cite this

    Nakashima, T., Matsuzaka, R., Miyagawa, K., Yonezawa, K., & Tsujimoto, Y. (2014). Study on flow instability and countermeasure in a draft tube with swirling flow. In IOP Conference Series: Earth and Environmental Science (Vol. 22). [032007] Institute of Physics Publishing. https://doi.org/10.1088/1755-1315/22/3/032007

    Study on flow instability and countermeasure in a draft tube with swirling flow. / Nakashima, T.; Matsuzaka, R.; Miyagawa, Kazuyoshi; Yonezawa, K.; Tsujimoto, Y.

    IOP Conference Series: Earth and Environmental Science. Vol. 22 Institute of Physics Publishing, 2014. 032007.

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

    Nakashima, T, Matsuzaka, R, Miyagawa, K, Yonezawa, K & Tsujimoto, Y 2014, Study on flow instability and countermeasure in a draft tube with swirling flow. in IOP Conference Series: Earth and Environmental Science. vol. 22, 032007, Institute of Physics Publishing, 27th IAHR Symposium on Hydraulic Machinery and Systems, IAHR 2014, Montreal, Canada, 14/9/22. https://doi.org/10.1088/1755-1315/22/3/032007
    Nakashima T, Matsuzaka R, Miyagawa K, Yonezawa K, Tsujimoto Y. Study on flow instability and countermeasure in a draft tube with swirling flow. In IOP Conference Series: Earth and Environmental Science. Vol. 22. Institute of Physics Publishing. 2014. 032007 https://doi.org/10.1088/1755-1315/22/3/032007
    Nakashima, T. ; Matsuzaka, R. ; Miyagawa, Kazuyoshi ; Yonezawa, K. ; Tsujimoto, Y. / Study on flow instability and countermeasure in a draft tube with swirling flow. IOP Conference Series: Earth and Environmental Science. Vol. 22 Institute of Physics Publishing, 2014.
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