Patent ID: 8894366

Claim:
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.