GB1267023A - - Google Patents

Abstract

1,267,023. Centrifugal and axial-flow pumps. WORTHINGTON CORP. July 28, 1970 [July 31, 1969], No.36457/70. Heading F1C. A centrifugal or axial-flow pump comprises an inducer 24 coaxial with and preceding the impeller 13, means being provided to exert a fluid-dynamic action in at least one peripheral zone of the pump casing coincident with or adjacent the suction side of the inducer so as to act on the main flow and on the return flow pre-set in the zone in such manner as to stabilize the position of the return flow under substantially all operation conditions. The means comprises a slot 25 through which liquid is injected at an angle so as to overcome the tendency for the return flow zone to extend upstream of the leading edges of the inducer blades at low delivery rates. The liquid comes from a collecting chamber 26 which is kept at a pressure substantially equal to the pump suction pressure by means of ports 29, 30 and is supplied with liquid from the delivery side 19 leaking past wear rings 17 into at least one channel 28 opening into the collecting chamber and also with liquid from the discharge zone 21 of the inducer leaking past a clearance 22 into the channel. In order to balance end thrust, a chamber 23 receiving liquid leaking from the delivery side 19 past wear rings 18 is kept at the suction pressure, e.g., by being connected via a pipe 31 with the chamber 26. If the suction pressure is materially higher than the atmospheric pressure, a regulating valve may be provided in the pipe 31 to afford a compensatory increase in the pressure in the chamber 23.