The length of the entrance edge of each blade on the side of the crown ring is made longer than that on the side of the shroud ring; and the runner satisfies the following three conditions: 15.degree..ltoreq..theta..ltoreq.35.degree. .gamma..sub.1 c.ltoreq..gamma..sub.1 s D.sub.1 c.ltoreq. D.sub.1 s Where .theta. = an angle between the centerline of the runner and a line connecting the points at which the entrance edge of the blade contacts with the crown and shroud rings respectively; .gamma..sub.1 c = an angle between the line passing through the center of the runner and a point at which the entrance edge of the blade contacts with the crown ring and the normal to the tangent at said contact point to the curved surface of the blade; .gamma..sub.1 s = an angle between the line passing through the center of the runner and a point at which the entrance edge of the blade contacts with the shroud ring and the normal to the tangent at said contact point to the curved surface of the blade; D.sub.1 c = an outer diameter of the blade at a point where the blade contacts with the crown ring; and D.sub.1 s = an outer diameter of the blade at a point where the blade contacts with the shroud ring.
A Francis-type runner for pump-turbines comprising a crown ring, a shroud ring and a plurality of runner blades interconnected therebetween, each of said blades satisfying the following relations where 0.09.ltoreq.B/D.ltoreq.0.30: D = a diameter of a circle circumscribing the outer ends of the respective runner blades; B = a height of the outer end of the runner blade between the crown ring and the shroud ring; .gamma. = an angle between the tangent at the outer end of the runner blade to the curved surface thereof and the tangent at the outer end of the runner blade to the circle circumscribing the outer ends of the respective runner blades, both tangents being in a horizontal plane close to the crown ring; and .theta. = an angle which the outer edge of the runner blade forms relative to a vertical plane passing through the center axis of the runner; whereby dual characteristics of operation showing a double efficiency curve are eliminated.
An improved Francis-type turbine runner permitting a significant reduction in cavitation is provided by shaping the runners extending between the ring and crown in such a fashion that at least a portion of the area of the streamlined suction face side of each blade is (when used as a turbine) exposed when viewed in the axial direction looking away from the crown.
Rotor blades of a hydraulic machine rotor are shaped such that the inlet edge and outlet edge of two adjacent rotor blades have varying profiles in different sections.
Disclosed is a runner for a Francis-type hydraulic turbine, comprising a ring, a hub, and a number of blades all having a curved shape and being attached to the ring and hub. Each blade has an inlet edge and an outlet edge. The blades are characterized in that, in the direction of turbine rotation, the junction point of each blade inlet edge at the ring is located forwardly of the inlet edge attachment point for that blade at the hub, and the junction point of each blade outlet edge at the hub is located forwardly of the outlet edge attachment point for that blade at the ring.
In a single stage, single suction, high speed centrifugal pump utilizing a closed Francis-vane impeller, operating noise is reduced by encasing a single-step helical gear drive arrangement in a common bearing housing with the impeller's shaft. The operating noise is further reduced by forming the driven helical gear directly on the impeller's shaft to improve dynamic balance, and by mounting a plurality of fins on the bearing housing of the pump to absorb some of the high frequency sound wave energy of the pump, and to translate a further portion of the high frequency sound wave energy into low frequency mechanical vibrations of the fins. Operating noise is further reduced by encasing the fins within a shroud and by providing a fan to blow ambient air by the fins to further disrupt the sound wave patterns emanating from the bearing housing. Operating noise is still further reduced by maintaining the impeller's shaft under tension whereby vibration of the shaft is reduced, as is the noise produced thereby.
