FULID MACHINE OF THE FRANCIS TURBINE TYPE WITH A SEALING PORTION FEATURING A GROOVE WITH A DEFINED CROSS SECTIONAL SHAPE

摘要

Disclosed is a Francis Turbine type fluid machine. The machine includes a sealing portion which is formed of an annular minute gap formed between a runner band of a runner configuring a rotating portion and a sealing liner which is a stationary portion and arranged in opposition to the runner band. The machine has a groove having a quadrangular cross-sectional shape which is formed circumferentially on a surface of the sealing liner configuring the sealing portion. In a cross section perpendicular to a groove forming direction of the groove, an angle, which is formed between a side of the groove on the most upstream side with respect to the flowing direction of the leakage flow, and a side of the groove which is on an extended line of the surface of the sealing liner, is determined to be between 15 degree and 40 degree .