Abstract: A centrifugal pump has a casing with an impeller cavity in which a shrouded impeller is mounted and with front and rear labyrinth seals associated one with each of the front and rear shrouds of the impeller and located near the inner ends of the shrouds. An additional seal is positioned inwardly of the rear labyrinth seal to substantially seal a space behind the innermost part of the rear shroud and a pump structure is mounted on the impeller to the rear of the rear shroud for pumping fluid from the substantially sealed space to the entrance of a volute surrounding the impeller.

Abstract: This invention relates to a fully modulatable centrifugal pump capable of handling a fluid containing solid contaminant particles and minimizing the temperature rise of the pumped fluid. The pump is of the type that includes an impeller to propel the fluid through a radial outlet to a diffuser which includes a plurality of diffuser passages. The improvement is comprised of the following cooperative combination which includes rotatably mounted valve elements passing, in part, through the diffuser and across the diffuser passages. Each of the valve elements have a port therethrough to variably selectively allow fluid passage therethrough upon rotation of the valve element. A driving arrangement is coupled to each of the valve elements to thereby affect a yieldable rotation of the valve elements in one direction to progressively reduce the opening of the valve element port to the diffuser passage.

Abstract: A fluid delivery system and, more particularly, a system for delivering fuel to an aircraft engine. A positive displacement pump delivers fuel to the engine and is supplied by an ejector boost pump connected to a fuel tank and having a nozzle supplied with fuel delivered by the fuel pump for drawing fuel from the tank and increasing the pressure of the fuel prior to delivery through interstage components to the inlet of the fuel pump. Valve means responsive to the pressure differential across the nozzle of the ejector boost pump operates to maintain a uniform rate of fuel flow through the nozzle. In certain embodiments of the fluid delivery system, the fuel pump is provided with auxiliary inlets for delivery of fuel to pumping chambers out of communication with the main inlet of the pump for improved operation of the fuel pump and avoidance of problems encountered from the presence of vapor in the fuel.