Effects of the vortex rope dynamic characteristics on the swirling flow in the draft tube cone

Yang, Jing; Hu, Qingjuan; Ding, Jinghuan; Kong, F B; Han, W. F.; Xiao, Wang; Wang, Z W

doi:10.1088/1755-1315/163/1/012003

Cited by 2 publications

(2 citation statements)

References 3 publications

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“…In some special occasions, the pressure fluctuations resulted from the vortex rope in the draft tube might lead to intense shock, even the collapses of workshop building. 2…”

Section: Introductionmentioning

confidence: 99%

“…In some special occasions, the pressure fluctuations resulted from the vortex rope in the draft tube might lead to intense shock, even the collapses of workshop building. 2 These days, more and more scholars begin to pay attention to the formation mechanism of vortex rope in draft tube 3 and serious of experimental studies have been conducted with the help of advanced technique. Skripkin et al 4 studied the evolution process of helices with the help of high-speed visualization and he observed that several coils which originated at draft tube inlet and the size of these coils show clear increase trend in downstream direction.…”

Section: Introductionmentioning

confidence: 99%

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Runner cone drilling and slotting to reduce vortex rope - induced pressure fluctuations in a Francis turbine

Qin

Zhang

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part A:

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Pressure fluctuations caused by helical vortex rope in the draft tube is one of the main reasons for the instability of Francis turbines. Previous studies showed that drilling holes on runner cone can reduce the amplitude of pressure fluctuation. In this study, based on the runner cone which has been drilled one hole, two kinds of new runner cones are designed by means of drilling two more holes (2 holes runner cone) and drilling a slot (2 holes and 1 slot runner cone). Pressure fluctuation and flow pattern observation experiments as well as numerical simulations at partial load operation condition in a Francis turbine were carried out for the three types of runner cones. Analyses were performed to reveal the generation mechanism of the low frequency pressure fluctuations. The results showed that low frequency fluctuations are related to the cyclical rotation of helical vortex rope. Holes and slots on the runner cone have little impact on the efficiency of the Francis turbine. Slotting on the runner cone can reduce the amplitude of pressure fluctuation induced by vortex rope to a maximum of 29.41%. Hence, proper slotting on the runner cone can effectively reduce the low-frequency fluctuation caused by vortex rope in Francis turbines. These findings provide a new idea to improve the hydraulic instability of Francis turbines induced by vortex rope.

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“…In some special occasions, the pressure fluctuations resulted from the vortex rope in the draft tube might lead to intense shock, even the collapses of workshop building. 2…”

Section: Introductionmentioning

confidence: 99%