| 摘要 |
A Francis turbine with a improved shape of blades to reduce the secondary flow around the blades and improve the hydraulic efficiency is provided. A Francis turbine comprises a rotating shaft, a crown, a plurality of blades and a band. The band is coaxially coupled with the crown by the blades and the rotating shaft, the crown, the blades, and the band as a whole are driven by water and rotate toward a turbine direction during a turbine operation. On a leading edge of at least one of the blades, a local maximum point exists between the crown and the band. The leading edge leans toward the turbine direction from the band connecting point, where the band and the leading edge are connected. And, a circumferential distance in the rotating direction between the band connecting point and the leading edge is the largest at the local maximum point.
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