Abstract: A compressor includes a diffuser, a recirculation duct, and a flow control valve. The recirculation duct has an inlet in fluid communication with the air outlet of the diffuser, and an outlet in fluid communication with the air inlet of the diffuser. The flow control valve is selectively moveable between open and closed positions, to thereby fluidly couple and isolate, respectively, the recirculation duct inlet and outlets. During operation of the compressor, the flow control valve may be opened, which circulates a portion of the compressed air discharged from the diffuser air outlet back to the diffuser air inlet. The air that is circulated back to the diffuser air inlet reduces the effective area of the diffuser air inlet, thereby increasing the surge margin of the compressor.

Abstract: To prevent surge in a compressor, the flow therethrough is automatically altered when the static pressure differential taken laterally across one of its diffuser vanes approaches a magnitude indicative of a surge condition.

Abstract: A crossover duct assembly for providing flow communication between multiple stages of centrifugal compressors and the like. The duct assembly includes inner and outer wall sections forming a continuous annular flow path between compressor stages for turning radially outward gas flow to a radially inward direction. The duct includes a thin vane diffuser section, a vaneless turning bend having an elongated wall geometry, and a deswirl vane section for enhancing smooth gas flow with minimum pressure loss.

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.