The relation between internal flow and loss mechanism of unshrouded runners

Shunsuke Nagata*, Tatsuya Irie, Kazuyoshi Miyagawa

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review


High efficiency, low-cost, and reliable hydraulic turbines are in high demand for hydroelectric power generation, especially in medium and small-scale power plants. The authors' laboratory has been developing unshrouded, i.e., band-opened runners of turbines to meet the demand. Those runners feature highly efficient performance and less expensive manufacturing costs produced by cutting, not by casting. For the sake of developing further improved unshrouded runners, it is necessary to understand their loss mechanism in detail. Therefore, in this study, the internal flow and the loss mechanism are investigated experimentally and computationally, with two different specific speed hydro turbine runners. First, Euler's theoretical head on each runner is discussed to identify if they are influenced by the distinct specific speed. It demonstrated that the low specific speed turbine consumes greater potential energy in centrifugal force. Secondary, the loss mechanism in the unshrouded runners is investigated. The result showed that the dominant loss is caused by a tip leakage vortex developed by the collision of a leakage flow at the tip clearance and a secondary flow.

Original languageEnglish
Article number012064
JournalJournal of Physics: Conference Series
Issue number1
Publication statusPublished - 2022 May 6
Event16th Asian International Conference on Fluid Machinery, AICFM 2021 - Virtual, Online
Duration: 2021 Sept 132021 Sept 15

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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