Abstract: An underwater vehicle such as a torpedo has a jet pump propulsion system. A high speed pump is located inside a rigid cylindrical housing of the torpedo near an end thereof. A water inlet communicates with the pump as does a water outlet provided at the aft end of the rigid housing via a water passage. A high speed electrical motor, on the order of 10,000 rpm, is provided inside an inner cylindrical housing disposed within the outer cylindrical housing. The electric motor is provided aft of the pump and the electric motor shaft is directly coupled to the pump rotor. Only one bearing and one water seal is provided between the electric motor and pump rotor. A water exit passage is provided between the inner cylindrical housing containing the high speed motor and the rigid outer cylindrical housing. Water passing through the exit passage cools the electric motor by dissipating heat therefrom.

Abstract: The subject compressor is of the centrifugal type having a rotatable impeller with hub and shroud sides and a diffuser surrounding the impeller, the diffuser having spaced side walls with vanes spaced around the impeller to provide passages for receiving fluid discharged from the impeller, the diffuser also having chambers formed on the hub and shroud sides and restricted openings along lines of static pressure in the diffuser passages establishing communication between the chambers and the diffuser passages near the inlet ends thereof whereby the pressures at such passage inlet ends will be equalized during the operation of the compressor and the tendency of the compressor to stall prematurely thereby reduced. Suitable communication between the chambers on the hub and shroud sides may be provided.