Radial flow runner for a hydraulic machine

Abstract

A runner of the Francis type including a crown, a plurality of blades, each blade being defined by a pressure surface, a suction surface, an edge adjoining the high pressure side and a spaced apart edge adjoining the low pressure side. The crown includes a seal to seal the space above the crown against water from the high pressure side. The further runner includes at least one passage being capable to drain high pressure leakage water to the low pressure side. The passage includes an inlet aperture located in a portion of the crown which is exposed to high pressure leakage water. The passage is located within a blade and leads from the inlet aperture to the edge of the same blade adjoining to the low pressure side. The passage is shaped to form a continuous opening in the same edge adjoining to the low pressure side.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This is a continuation of PCT application No. PCT / EP2017 / 081659, entitled “RADIAL FLOW RUNNER FOR A HYDRAULIC MACHINE”, filed Dec. 6, 2017, which is incorporated herein by reference.BACKGROUND OF THE INVENTION1. Field of the Invention[0002]The present invention relates generally to hydroelectric turbine or pump installations with a radial flow runner of the Francis type.2. Description of the Related Art[0003]Hydraulic machines including a radial flow runner of the Francis type are suffering from axial thrust applied to the runner of the hydraulic machine. Since the sealing between the runner and the high pressure side of the water passage cannot be made perfectly tight, water can get in the space between the head cover of the hydraulic machine and the runner crown resulting in a high axial thrust. To reduce the axial thrust prior art has proposed several concepts. One concept comprises balancing pipes draining the water passing the seals ...

AI Technical Summary

Benefits of technology

[0006]The axial thrust can be reduced by a runner that includes at least one passage leading from the runner crown to the trailing edge of at least one of the

Problems solved by technology

Hydraulic machines including a radial flow runner of the Francis type are suffering from axial thrust applied to the runner of the hydraulic machine.

Since the sealing between the runner and the high pressure side of the water passage cannot be made perfectly tight, water can get in the space between the head cover of the hydraulic machine and the runner crown resulting in a high axial thrust.

Balancing pipes are generally expensive.

The effectiveness of the prior art balancing holes depends on the revolution speed of the runner and the blade geometry and therefore leading not always to satisfactory results concerning thrust reduction.

Especially in the case of modernization projects when an existing runner relying on balancing holes has to be replaced by a new runn

Images