Methods and systems are provided for a compressor adapted with a movable sleeve and an active casing treatment that form separate air flow chambers. In one example, a method includes flowing intake air in a first direction through a casing to an impeller of a compressor, selectively flowing intake air from the casing through a first chamber in an opposite, second direction, the first chamber circumferentially surrounding the casing, and selectively flowing intake air in the first direction through a second chamber to the impeller, the second chamber circumferentially surrounding the first chamber. In this way, compressor surge may be mitigated without reducing compressor efficiency at higher air flow rates.

A centrifugal compressor operable in a wide operation range under a condition accompanied with pulsations of a pressure and a flow rate. The centrifugal compressor has a casing including at least one recirculation channel that includes a first inlet slit connected to an air flow passage on a downstream side of a leading edge in an air flow direction of the air flow passage, a second inlet slit connected to the air flow passage on a downstream side of the first inlet slit in the air flow direction of the air flow passage, a first vane disposed on a downstream side of the first inlet slit or in the first inlet slit in the at least one recirculation channel, and a second vane disposed on a downstream side of the second inlet slit or in the second inlet slit in the at least one recirculation channel.

Method for controlling a compressor comprising a last stage (40) and a compressor load controller (90), a set point outlet pressure corresponding to the consumer needed pressure, being given in the load controller (90) comprising the steps of: a—measuring the temperature at the inlet of the last stage (40), b—measuring the ratio between the outlet and inlet pressure of the last stage (40), c—computing a coefficient (Ψ) based on the value of the inlet temperature (Tin) and on the pressure ratio (Pout/Pin), d—if the coefficient (Ψ) is in a predetermined range, changing the set point outlet pressure by a new greater set point outlet pressure until the coefficient (Ψ) computed with the new set point outlet pressure goes out of the predetermined range, and e—adapting the pressure of the fluid coming out of the compressor in a pressure regulator (100) to the consumer needed pressure.

Controller for controlling a bleed valve including a first body with an internal cavity connected to an air inlet port and an air outlet port, a second body including a chamber, a mobile member in the cavity and in the chamber, connecting the two bodies. The member is mobile between a position whereby the ports fluidly communicate and a position whereby the ports are isolated, the member further including two pistons housed in the chamber and defining in this chamber at least two spaces. The controller also includes a fluid supply for at least one of the spaces for the purpose of moving the pistons in the chamber.

A method for operating a pump, for conveying a fluid from a low-pressure side to a high-pressure side of the pump includes determining a current rate of change of pump vibrations and comparing the current rate of change with a limit for the rate of change or determining a current vibration of the pump and comparing the current vibration with a vibration amplitude limit for the vibration, storing the limit for the rate of change or the vibration amplitude limit in a surge controller, providing a control signal when the current rate of change reaches the limit or when the current vibration reaches the vibration amplitude limit, and changing a control variable of the pump by the control signal, such that the vibration is reduced and an unstable operating state of the pump is avoided.

A compressor system is described, including: at least a first compressor having a suction side and a delivery side; an anti-surge line; an anti-surge valve arranged along the anti-surge line and controlled for recirculating a gas flow from the delivery side back to the suction side of the compressor; a heat removal arrangement between the anti-surge valve and the suction side of the compressor.

A method for operating a pump, for conveying a fluid from a low-pressure side to a high-pressure side of the pump includes determining a current rate of change of pump vibrations and comparing the current rate of change with a limit for the rate of change or determining a current vibration of the pump and comparing the current vibration with a vibration amplitude limit for the vibration, storing the limit for the rate of change or the vibration amplitude limit in a surge controller, providing a control signal when the current rate of change reaches the limit or when the current vibration reaches the vibration amplitude limit, and changing a control variable of the pump by the control signal, such that the vibration is reduced and an unstable operating state of the pump is avoided.

A method of operating a gas turbine engine having a high pressure compressor and a secondary air system includes, when the gas turbine engine is operating in a first power range, providing a first bleed source for the secondary air system by bleeding air from a first bleed location, providing bleed air at a first pressure, proximate to an outlet of the high pressure compressor. When the gas turbine engine is operating in a second power range, higher than the first power range, the method includes providing a second bleed source by bleeding air from both a second bleed location and a third bleed location. The second and third bleed locations, respectively providing bleed air at second and third pressures, are both disposed upstream of the first bleed location within the gas turbine engine. The second and third pressures are different from the first pressure.

A bleed valve includes a housing with an inlet coupled to an outlet by a duct, a guide tube with an orifice fixed in the housing between the inlet and the outlet, a piston, and baffle. The piston is slideably supported on the guide tube and is movable between an open and a closed position, the duct fluidly coupling the inlet and outlet in the open position, the duct fluidly separating the inlet and outlet in the closed position. The orifice fluidly couples the inlet and outlet in the open and closed positions to move piston between the open and closed positions according to differential pressure between the bleed valve inlet and outlet. The baffle is slideably supported by the guide tube to set the differential pressure at which the piston moves between the open and closed positions. Gas turbines and differential pressure adjustment methods are also described.

Methods are provided for identifying degradation in components of a compressor recirculation valve (CRV). One method may include inferring degradation of the CRV based on adaptation of a compressor surge line outside an expected range.