Francis-type runner for a turbine, and energy conversion plant comprising such a runner

Abstract

This Francis-type runner for a turbine comprises a crown (3), a band (4) and blades (2A, 2B) the number of which is not a prime number. These blades are made as one piece and extend between the crown and the band and between a leading edge (6A, 6B) and a trailing edge (7A, 7B), each trailing edge having its concave face facing upstream over its entire length. In addition, first blades (2A) are uniformly distributed about a central axis (X1) of the runner in a number equal to a divisor of the total number of blades (2A, 2B). Each of these first blades has a point (PA) of attachment of its trailing edge (7A) to the crown that is lowered by comparison with the point (PB) of attachment of the trailing edge (7B) to the crown of second blades (2B), which are likewise part of the runner. Moreover, the ratio between, on the one hand, the radius (RPA) of a circle centered on the central axis of the runner, perpendicular to this axis and passing through the point of attachment of the trailing edge of a first blade to the crown and, on the other hand, the radius (RQ) of a circle centered on the central axis of the runner perpendicular to this axis and passing through the point (QA) of attachment of the trailing edge of the same blade to the band (4) is less 0.15.

Description

[0001] This application is a PCT patent application PCT / EP2013 / 077302 that entered the Chinese national phase on June 19, 2015 (the international filing date is December 19, 2013, the Chinese patent application number is 201380066888.2, and the title of the invention is "for turbine Francis-type runners and energy conversion devices including such runners"). technical field [0002] The present invention relates to a Francis-type wheel for a turbine and to an energy conversion device comprising such a wheel. Background technique [0003] Francis type runners can be fitted to various types of hydraulic machines such as turbines, pumps or turbopumps. They consist of blades distributed around a central axis of rotation and between them define tubes for the flow of water. The geometry of the blades of these runners is defined such that the water flow imparts a rotational torque to the runners when they are used in turbine mode. [0004] A constant focus on Francis-type runners...

AI Technical Summary

Problems solved by technology

The geometry of this blade makes it possible to reduce the mechanical stress on the runner, but leads to a discontinuity in the flow downstream of the runner

Furthermore, this blade structure can present problems fitting all blades on the crown of the runner, since the attachment points of the trailing edges of all blades to the crown are concentrated into a small area

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