A technique for controlling a rotating stall in a compressor of a gas turbine engine. In the technique a flow injection is introduced into an axial air flow path of the compressor via a flow-injection opening located at a pressure side of a guide vane in the compressor and directed towards a leading edge of a compressor rotor blade located adjacently downstream of the guide vane. The flow injection is introduced when the rotating stall is detected and/or when the compressor is being operated at a speed lower than full load speed. The flow injection reduces an angle of incidence of compressor air on the leading edge of the downstream rotor blade and hence the rotor sees a more favorable velocity. The favorable velocity results into an increase in the operating range of the rotor and hence of the compressor by mitigating and/or reducing the rotating stalls.

Methods and apparatuses are provided for a compressor. The compressor includes a first stage having a first rotor and a first stator, and a second stage downstream from the first stage in a direction of a fluid flow. The compressor also includes a secondary flow system that directs fluid from the second stage into the first stator to improve at least one of a performance and a stability of the compressor.

A bleed valve system comprises a duct, featuring a central longitudinal axis and allowing a main flow of fluid to pass from a first environment at a first static pressure to a second environment at a second static pressure along a bleed direction, a valve comprising a valve member arranged within the duct between the first and second environments and movable to partially obstruct the duct and deviate the main flow of fluid to direct at least a part of it towards a portion of an internal wall of the duct; and an ejector, arranged within the duct, downstream of the valve member and offset from the central longitudinal axis in correspondence of said portion of the internal wall, adapted to supply an additional flow of fluid within the duct to accelerate the main flow of fluid and reduce the second static pressure.

A compressed vaporous discharge stream is de-superheated in a de-superheater system. The de-superheater system comprises a de-superheater heat exchanger configured to bring at least a portion of the compressed vaporous discharge stream in indirect heat exchanging contact with an ambient stream. A de-superheater bypass line comprising an temperature-controlled valve is configured to selectively bypass the de-superheater heat exchanger. A combiner is configured downstream of the de-superheater heat exchanger for rejoining the bypass portion with the portion of the compressed vaporous discharge stream that has passed through the de-superheater heat exchanger. A mixer is configured downstream of said combiner, to receive and mix the rejoined stream, and discharge the rejoined stream into a de-superheater discharge conduit as a de-superheated stream.

A vapor compression system comprising a centrifugal compressor (22) having: an inlet (24); an outlet (26); a first impeller stage (28); a second impeller stage (30); and a motor (34) coupled to the first impeller stage and second impeller stage. A first heat exchanger (38) is downstream of the outlet along a refrigerant flowpath. An expansion device (56) and a second heat exchanger (64) are upstream of the inlet along the refrigerant flowpath. A bypass flowpath (120; 320) is positioned to deliver refrigerant from the compressor bypassing the first heat exchanger. A valve (128) is positioned to control flow through the bypass flowpath, wherein: the bypass flowpath extends from a first location (140) intermediate the inlet and outlet to a second location (142; 342) downstream of the first heat exchanger along the refrigerant flowpath.

A centrifugal compressor for a chiller system includes a casing having an inlet portion and an outlet portion, a recirculation structure including a recirculation path and a recirculation discharge cavity, an impeller disposed downstream of the recirculation discharge cavity, the impeller being attached to a shaft rotatable about a shaft rotation axis, a motor arranged to rotate the shaft in order to rotate the impeller, and a diffuser disposed in the outlet portion downstream of the impeller. The recirculation structure is configured and arranged to impart a swirl to a flow of refrigerant into the inlet portion, with a velocity of a recirculation flow caused by the swirl being higher than a velocity of the flow of the refrigerant in the inlet portion.

A turbocharger (1) with an axial flow turbine stage (2) includes a compressor stage (4) using active casing treatment (50) for choke flow improvement. With switchable slots (52, 54), one of the slots (52) may be between the compressor's full and splitter blades (27, 23) and one of the slots (54) can be located downstream of the compressor's splitter blades (23) to maximize choke flow capacity. In turbochargers with a wastegate assembly, a pneumatic actuator (32) may control both a wastegate control valve (30) and an active casing treatment slot selection valve (56).

According to the present invention, the impeller inlet of a turbocharger compressor receives intake air from an inner channel and an outer channel. The outer channel is pressurized with an electrically powered secondary compressor. The pressurized air in the outer channel flows into the impeller near the outer wall of the impeller inlet. The pressurized air next to the outer wall of the impeller inlet prevents backflow of air out of the impeller and thereby prevents surge and enables the compressor to produce high boost pressures under small mass flow settings. Only a portion of the intake air is pressurized with the electrically powered secondary compressor, and the boost pressure of the electrical compressor is only a fraction of the turbocharger compressor's overall pressure ratio. Consequently, only a small amount of electrical power is required to drive the secondary compressor, thereby enabling conventional 12 volt batteries to be used to power the electrical compressor for almost all automotive applications.

Provided is a compressor arrangement in an air line supplying charged air to a combustion engine. The compressor arrangement comprises a compressor unit comprising a housing including an air intake passage, a compressor wheel arranged in said air intake passage, and an additional air passage allowing recirculation of air from the air intake passage in a position radially outwardly of a part of the compressor wheel. The additional air passage is configured to allow recirculation of air to an air conduit delivering an air flow to the air intake passage of the compressor unit.

To solve the problems of compressor wheel blade flow separation causing surge type noises when an exhaust gas recirculation (EGR) duct introduces into the compressor exhaust gases to be returned to the engine, the exhaust gas is fed into an annular volume, defined between inner and outer walls or an annular transition cavity shaped as a radially expanded, axially flattened cylindrical space in the compressor inlet, so that the generally unidirectional radial flow from an EGR duct is re-directed and organized as it is turned from generally radial to generally axial, merging with the general inlet flow and presenting the compressor wheel with airflow of circumferentially uniform flow velocity.