Blade configurations for Francis-type turbine runners

A Francis-type hydraulic turbine runner rotatable about an axis of rotation and having a crown forming the upper axial end thereof when said axis of rotation is substantially vertical, a band concentric with said crown on said axis of rotation and an array of blades between said band and said crown, said runner terminating at its lower end in an outlet end, each of said blades having a suction face and a pressure face trailing said suction face in the direction of rotation, said suction and pressure faces meeting between said band and said crown at the outer periphery of each of said blades in a flow dividing edge, said faces providing substantially smooth streamlined surfaces to define flow paths between adjacent of said blades in said array, each of said flow dividing edges meeting with and terminating at said band adjacent an upper edge of said band at a junction, a first portion of said suction surface of each blade located immediately adjacent to said junction and said flow dividing edge being exposed when viewed in an axial direction looking toward said outlet end so that said first portion of said suction face extending from said band toward said crown is sloped rearwardly in the direction of rotation of said runner, a second portion of each of said suction surfaces located spaced from said first portion, said second portions being exposed when viewed in an axial direction looking from said outlet and being located below said junctions.