FRANCIS TYPE HYDRAULIC MACHINE

摘要

PROBLEM TO BE SOLVED: To inhibit drop of axial thrust force reduction effect by employing a runner shape with which centrifugal force making fluid flow reversely to a back pressure chamber side does not act on the fluid in a balance hole even if the balance hole is applied to a small runner. SOLUTION: An opening part at a flowing water surface side of the balance hole 20 is set closer to a main shaft 2 side than a water outlet end of the runner 1 in the balance hole 20 providing communication between a back pressure chamber 8 side and the flowing water surface at a lower part of a runner crown 1b. A communication pipe 30 communicating to the opening part at the back pressure chamber 8 side of the balance hole 20 is disposed in parallel with a main shaft 2 toward the runner 1 from an upper surface of the balance hole 20 at an upper part of the balance hole 20. The communication pipe 30 communicates to the opening part at the back pressure chamber 8 side of the balance hole 20, having hole 30a of a prescribed shape provided on a main shaft flange part 2a of a main shaft flange part 2a in a view from a main shaft 2 direction with a prescribed interval in a circumference direction having the main shaft 2 as a reference as the opening part. COPYRIGHT: (C)2011,JPO&INPIT