Design optimization of medium specific speed Francis turbines with unshrouded runners

29th IAHR Symposium on Hydraulic Machinery and Systems

Takahashi, W.^1 ; Shinji, M.^1 ; Liu, Z.H.^1 ; Miyagawa, K.^2 ; Hayashi, Y.^3

Department of Applied Mechanics, Waseda University, Tokyo

1698555, Japan^1

Department of Applied Mechanics and Aerospace Engineering, Waseda University, Tokyo

1698555, Japan^2

Research and Development Dept., Chigasaki Research Institute, Kanagawa

2530041, Japan^3

关键词: Design optimization;    Internal flows;    Loss mechanisms;    Manufacturing cost;    Manufacturing process;    Small hydro power;    Specific speed;    Tip leakage flow;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/240/2/022060/pdf
DOI  :  10.1088/1755-1315/240/2/022060

来源: IOP

【 摘 要 】

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.