MULTISTAGE CENTRIFUGAL PUMP Russian patent published in 2000 - IPC

FIELD: hydraulic machinery; pumping liquids; oil extraction from wells. SUBSTANCE: centrifugal pump has outlet device mounting at least one impeller built up of hub, main and cover disks, and blades between them. Impeller disks are provided with auxiliary enclosed ducts whose inlet and outlet holes are arranged at different radii relative to impeller axis of revolution. Ratio of maximum distance between adjacent blades to blade height at impeller outlet is lower than 2; auxiliary ducts at outlet radius are tilted relative to direction of peripheral velocity through acute angle. EFFECT: improved pump pressure at low flowrate including that as low as zero; improved reliability and reduced size of pump. 2 dwg