Study on Flow Instability and Countermeasure in a Draft tube with Swirling flow

Nakashima, Takahiro; Matsuzaka, Ryo; Miyagawa, Kazuyoshi; Yonezawa, Koichi; Tsujimoto, Yoshinobu

doi:http://dx.doi.org/10.5293/IJFMS.2015.8.4.230

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자료유형: 학술저널

저자정보: Nakashima, Takahiro Matsuzaka, Ryo Miyagawa, Kazuyoshi Yonezawa, Koichi Tsujimoto, Yoshinobu

저널정보: 한국유체기계학회 International Journal of Fluid Machinery and Systems International Journal of Fluid Machinery and Systems Vol.8 No.4

발행연도: 2015.12

수록면: 230 - 239 (10page)

DOI: http://dx.doi.org/10.5293/IJFMS.2015.8.4.230

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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.

#Draft tube #Hydro turbine #Vortrex rope #Cavitation #Aeration

참고문헌 (9)

참고문헌 신청

[학술지(정기간행물)] - Michihiro Nishi / 2013 / An Outlook on the Draft-Tube-Surge Study / International Journal of Fluid Machinery and Systems 6 (1) : 33 ~ 48

[학술지(정기간행물)] - Ji, B. / 2013 / Numerical analysis of unsteady cavitating turbulent flow and shedding horse-shoe vortex structure around a twisted hydrofoil / International Journal of Multiphase Flow 51 : 33 ~ 43

[학술지(정기간행물)] - Ji, B. / 2013 / Three-dimensional large eddy simulation and vorticity analysis of unsteady cavitating flow around a twisted hydrofoil / Journal of Hydrodynamics 25 (4) : 510 ~

[학술대회논문] - Nakashima, T. / 2014 / Flow instability in the draft tube of the hydro turbine and effects on the efficiency by the suppression / Proceedings of the Turbomachinery Society of Japan Conference

[학술대회논문] - Ji, B / 2013 / Numerical analysis of cavitation surge in a diffuser with swirling flow / Proceedings of the Turbomachinery Society of Japan Conference

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