Francis-type hydraulic turbine wheel equipped with a tip-forming member, and method of reducing fluctuations using such a wheel

摘要

This wheel comprises a plurality of vanes (2) arranged on a crown (3) and is equipped with a tip-forming member (10) attached to a central region (32) of the crown or hub of the wheel (1), radially inside the vanes (2), the crown defining a wet surface (31) for guiding a flow (E) passing between the vanes. The tip-forming member (10) is provided with at least one opening (121) for diverting a fraction (E1) of the flow towards the internal volume (V10) of this member. This member comprises a frustoconical annular skirt (11) and at least one fin (15) arranged in its internal volume (V10) and able to modify the path of the flow fraction (E1) entering this volume through the opening (121). This fin (15) extends as far as the edge (112) of the skirt (11) which defines an outlet opening (14) of the member (10) for the flow fraction (E1).

主权项

1. A Francis wheel for a turbine or a hydraulic turbine pump, the wheel comprising:
a plurality of vanes arranged on a crown and having a tip-forming member attached to a central region of the crown radially inside the vanes, the crown defining a wet surface for guiding a flow passing between the vanes, the tip-forming member having a radial wall defining an internal volume, the radial wall being provided with at least one opening for diverting a fraction of the flow passing between the vanes towards the internal volume of the tip-forming member, the tip-forming member including a frustoconical annular skirt which encloses the internal volume of the tip-forming member and towards which the fraction of the flow is diverted, and in that at least one fin is arranged inside the internal volume of the tip-forming member and extends as far as an edge of the skirt delimiting an outlet opening from the tip-forming member for the fraction of the flow that is diverted towards the internal volume, the at least one fin modifies a flow path of the fraction of the flow within the internal volume to direct the fraction of the flow through the outlet opening; a plurality of spaced openings in the tip-forming member for diverting a fraction of the flow and wherein a sum of areas of entrance regions into the plurality of openings for diverting the flow is greater than or equal to 25% of an area of an external surface of the tip-forming member; and wherein the at least one fin is provided with a trailing edge that extends from the edge of the skirt delimiting the outlet opening in a direction of an axis of rotation of the wheel and which is perpendicular to the axis of rotation.