Runner for a hydraulic turbine or pump and method of manufacturing

A runner for a hydraulic turbine or pump, the runner comprising:

• a plurality of blades, each blade defined by a pressure side surface, an oppositely facing suction side surface, a leading edge and a spaced apart trailing edge;
• at least one of said blades having a device for supplying a flow of oxygen containing gas to said trailing edge of said at least one blade, said device including a gas inlet aperture, a gas passage and at least one opening in said trailing edge to admit gas out of said gas passage to a passing fluid during operation of the runner;
• said suction side surface of said at least one blade having a concave profile along a cross section through a point P1 and a point P2, said point P1 being located on said suction side surface of said trailing edge at said at least one opening, said point P2 being spaced apart from said point P1 by less than 3% of a runner outlet diameter D and said point P2 being located upstream of said point P1 on a line perpendicular to said trailing edge starting at said point P1.