A method of preventing surge in a dynamic compressor is disclosed. The method includes providing an anti-surge valve having an adjustable opening for increasing the flow through a dynamic compressor. The next step is sensing process conditions in the dynamic control to determine a compressor load variable. A control system estimates a process disturbance model using the compressor load variable. The control system then adjusts a safety margin using a rate limited response and initiates a closed loop response using process feedback based on the process disturbance model. The control system adjusts the opening of the anti-surge valve according to the safety margin and closed loop response.

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 through a casing to an impeller of a compressor, and during first conditions, actuating an actuator to adjust a movable sleeve surrounding the casing from a first position to a second position and flowing intake air through a second chamber to the impeller, the movable sleeve adjusted in both a radial direction and an axial direction via a single actuating motion of the actuator. In this way, compressor surge may be mitigated without reducing compressor efficiency at higher air flow rates.

An apparatus for use in a gas turbine engine is disclosed comprising a bleed valve and an intermediate valve. In use the bleed valve is exposed to a source of pressurised air, and the bleed valve is movable between an open position, in which the bleed valve permits a flow of the pressurised air through the bleed valve and a closed position, in which the bleed valve does not permit a flow of the pressurised air through the bleed valve. The intermediate valve is operatively connected to the bleed valve and configured to selectively open and close the bleed valve, wherein the intermediate valve is configured in a mode of operation to close the bleed valve based on the pressurised air within the bleed valve exceeding a predetermined threshold.

In an aircraft gas turbine engine equipped with a bleed-off valve that bleeds intake air compressed by a compressor exterior and an electric actuator that drives the valve when current is supplied, a required valve opening r and a current value Ia corresponding thereto are calculated and Ia is supplied to the actuator to bring valve opening to the required opening r. Then Ia is compared with a current value Ib and if Ia exceeds 1b, the valve is estimated to have failed and another current value Ic is calculated and Ic is supplied to enlarge valve opening toward wide-opening w. Then a current value Id is calculated and supplied to decrease valve opening toward r. Next, Id is compared with Ib and the valve is determined normal when Id is equal to or smaller than 1b. If not, it is determined to be faulty.

A controller for an inline valve includes a manifold seating a set screw and has a reference fluid port, a control fluid port, and an actuator fluid port. A selector is movable within the manifold between a first position and a second position, the reference fluid port in fluid communication with the actuator fluid port in the first position, the control fluid port in fluid communication with the actuator fluid port in the second position. A biasing member is arranged between the selector and the set screw and urges the selector towards the first position. The set screw extends through an exterior of the manifold for adjustment of differential in pressures at the reference fluid port and the control fluid port responsive to which the selector moves between the first position and the second position. Inline valves and methods of controlling fluid flow through inline valves are also described.

A pneumatic controller for an inline valve includes a manifold with a set screw seated within it, a selector, and a biasing member. The manifold has a low pressure port, a high pressure port, and an actuator port. The selector is movable within the manifold between a first position and a second position, the low pressure port in fluid communication with the actuator port in the first position, the high pressure port in fluid communication with the actuator port in the second position. The biasing member urges the selector towards the first position with a biasing force and is spaced apart from the selector to limit eccentric force exerted on the selector. Inline valves and methods of controlling fluid flow through inline valves are also described.

A method of operating a gas turbine engine having a bleed air system with a switching valve, operable to switch between multiple air sources depending on an operating mode of the gas turbine engine (e.g. a motive powered mode or a standby mode), is described. The method includes operating the switching valve to provide pressurized air from a selected one or more of the multiple air sources to a cavity of the gas turbine engine having seals, and testing the switching valve to determine if the switching valve is functioning normally or abnormally. The switching valve is functioning normally when operable to switch between the multiple air sources and is functioning abnormally when switching between the multiple air sources is not possible. If the switching valve is determined to be functioning abnormally, the gas turbine engine is controlled to prevent a change of the operating mode.

Methods and systems are provided for a compressor having a variable inlet device and an active casing treatment. In one arrangement, a system for a compressor may include a casing forming a recirculation passage surrounding an inlet passage, an active casing treatment surrounding the inlet passage and configured to selectively control gas flow through the recirculation passage, an impeller, and a variable inlet device positioned in the inlet passage upstream of the impeller and configured to selectively reduce an effective size of the impeller. The variable inlet device and the active casing treatment may be adjusted based on operating conditions in order to increase a flow range of the compressor while providing high compressor efficiency.

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.

A method for monitoring a surge in a fluid device and a refrigeration system. A fluid device is disposed in an operating unit. The method includes providing and displaying a surge line of the fluid device, where the surge line is at least related to a characteristic between fluid pressure and a flow rate of the fluid device; based on preset time intervals, sequentially providing and displaying operating points, of the fluid device in a current operation condition, in a coordinate system to which the surge line belongs, and when a quantity of the provided operating points exceeds a preset value, removing the first provided operating point therein, so that a quantity of the remaining operating points is the preset value; and monitoring a surge status of the fluid device according to relative position relationships between the displayed operating points and the surge line.