Design optimization of medium specific speed Francis turbines with unshrouded runners

W. Takahashi, M. Shinji, Z. H. Liu, Kazuyoshi Miyagawa, Y. Hayashi

Research output: Contribution to journalConference articlepeer-review

3 Citations (Scopus)


In present, many undeveloped locations of small hydropower generation exist in Japan. To promote the use of small hydropower generation it is required to reduce costs and increase efficiency. Unshrouded runners are proposed to simplify the manufacturing process and also to reduce the manufacturing costs. In this paper, the computation results of optimized unshrouded runners are presented. This research was conducted to minimize the shroud tip leakage loss, which is the main loss of unshrouded runners. In the author's laboratory, medium specific speed (160 [m-kW]) Francis turbines was developed. For this 160 [m-kW] Francis turbines, investigation of internal flow and loss mechanism were done by computation. Using this loss mechanism which was revealed by rothalpy, the design of the same specific speed Francis turbines with unshrouded runners was optimized. For the new runners, shroud tip clearance and the pressure distribution of vane surfaces was changed. Due to this, shroud tip leakage flow has weakened. In the simulation of whole domain, 2.45% of improvement was confirmed on the design point.

Original languageEnglish
Article number022060
JournalIOP Conference Series: Earth and Environmental Science
Issue number2
Publication statusPublished - 2019 Mar 28
Event29th IAHR Symposium on Hydraulic Machinery and Systems, IAHR 2018 - Kyoto, Japan
Duration: 2018 Sept 162018 Sept 21

ASJC Scopus subject areas

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


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