Fluid operated multi-stage machine

1,039,473. Centrifugal pumps; turbines. G. & J. WEIR Ltd. April 13, 1965 [June 4, 1961], No. 23120/64. Headings F1C and FIT. In a multi-stage pump or turbine, the fluid passes radially through several adjacent bladed passages of the rotor, and is then directed by stationary passages to pass again and again through the rotor. In the centrifugal pump shown, fluid entering a central inlet 16 passes radially outwards through several adjacent bladed passages of the impeller 10 and into a first diffuser passage 14 and thence through a first return passage 15 which communicates with the inner ends of a further set of bladed passages of the impeller, the outer ends of which communicate with a second diffuser passage 14. The fluid passes five times through the impeller in this manner and finally passes via the fifth diffuser passage 14 to an outlet 17. Labyrinth packing 22 is provided between the first and fifth diffuser passages. An axial-flow impeller is provided upstream of the inlet 16. The machine may be operated as an inward-flow turbine.