Patent ID: 8720054

Claim:
A method of setting a performance characteristic of a pump, the pump including an impeller that takes in fluid from a suction port and that sends out the fluid toward a discharge port, and a diffuser provided in a flow passage between the impeller and the discharge port, the method comprising: providing the diffuser with a hub arranged in a central portion of the flow passage, a shroud arranged around the hub, and a plurality of diffuser vanes radially arranged from an outer peripheral surface of the hub toward an inner peripheral surface of the shroud; and setting a mounting position of each of the diffuser vanes to be mounted on the hub according to a performance characteristic of the pump in a direction perpendicular to a radial direction extending from the hub toward the shroud, wherein the setting includes: setting an efficiency η of the pump such that the efficiency η becomes equal to a maximum efficiency η max based on a designed discharged fluid volume Q 1 ; deriving an average inlet angle β based on the efficiency η; setting an offset amount with respect to a preset basic mounting position from an offset amount corresponding to the average inlet angle β based on the average inlet angle β, and setting the mounting position of the diffuser vane to be deviated from the basic mounting position in an X direction by the offset amount, where the X direction is a tangent direction to an outer peripheral surface of the hub at an intersection N of a base end of a radially-intermediate portion of the diffuser vane with the outer peripheral surface of the hub.