Abstract: Systems and methods are described for operating a turbocharger. A current exhaust manifold pressure is determined based on an engine operating condition. A current operating condition of the turbocharger is determined. A surge correction factor is determined based on the current operating condition of the turbocharger. The current exhaust manifold pressure is adjusted based on the surge correction factor.

Abstract: 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.

Abstract: Systems and methods are described for operating a turbocharger. A current exhaust manifold pressure is determined based on an engine operating condition. A current operating condition of the turbocharger is determined. A surge correction factor is determined based on the current operating condition of the turbocharger. The current exhaust manifold pressure is adjusted based on the surge correction factor.

Abstract: A control device configured to control an inflow adjusting unit that quantitatively adjusts an inflow of a gas into a compressor and to control a valve provided in a second flow passage branching from a first flow passage from the compressor to a compressed gas supply destination includes: a command calculating unit that is configured to calculate a command value for at least any one of the inflow adjusting unit and the valve; and a correction value calculating unit that is configured to calculate a correction value with respect to a command value for at least any one of the inflow adjusting unit and the valve.

Abstract: A centrifugal pump for delivering a medium comprising solid admixtures includes a blade-free space arranged in front of an impeller. The centrifugal pump has a suction-side arrangement that permits variable sizing of the blade-free space. The suction-side arrangement permits the efficiency of the centrifugal pump to be increased while avoiding blockages.

Abstract: A compressor system includes an inlet in which fluid flows, an inlet temperature measuring part configured to measure an inlet temperature (T_in) of the fluid at the inlet, an inlet guide vane (IGV) configured to change opening degree (IGV_position) to control a flow rate of the fluid through the inlet, a compressor to compress the fluid passing through the inlet guide vane, a motor connected to the compressor to drive the compressor, and configured to change rotating speed, a discharge pressure measuring part to measure a discharge pressure (P_disch) of the fluid passed the compressor, an outlet to discharge the compressed fluid, and a check valve installed at the outlet to prevent backflow of the fluid.

Abstract: Provided is a swing-back preventing apparatus capable of preventing a hydraulic actuator in a stop state from operating by undesired load. The swing-back preventing apparatus includes a housing, a piston, and a pair of biasing members. First and second spaces are formed between the piston and the housing, and the piston includes a pair of communication passages that are communicable with first and second spaces. When the piston is located at a first offset position, the first space is blocked from a first port. When the piston separates from the first offset position, the first space is connected to the first port. When the piston is located at a second offset position, the second space is blocked from a second port. When the piston separates from the second offset position, the second space is connected to the second port. When the piston is located at a position on the first offset position side of a neutral position, a first communication passage is connected to the first space.

Abstract: A recirculation valve configured to open or close a recirculation line connected to a front stage of a compressor from a rear stage of the compressor on an intake line of an engine is provided. The valve includes a recirculation valve adaptor that has an inlet into which gas is introduced formed in a bottom thereof, having an outlet from which the gas is discharged formed in a first side of a side surface thereof, and having an inner space connected to the inlet and the outlet and in which the gas flows. A plug is configured to open or close the inlet and the outlet. The inner space has an asymmetric shape in which a width in a horizontal direction is increased in a direction from the other side of an inside surface to one side thereof.

Abstract: In order for charge air to be conducted with the lowest possible losses in pressure in a turbocharger including a blow-off valve, a flow-guiding element in an inlet region is designed such that neutral zones are formed at the flow openings. The flow openings recirculate charge air from the pressure side to the suction side when the blow-off valve is opened. The flow-guiding element avoids vortices and therefore losses in pressure in the region of the flow openings.

Abstract: A gas turbine system includes a compressor protection subsystem; a hibernation mode subsystem; and a control subsystem that controls the compressor subsystem and the hibernation subsystem. At partial loads on the turbine system, the compressor protection subsystem maintains an air flow through a compressor at an airflow coefficient for the partial load above a minimum flow rate coefficient where aeromechanical stresses occur in the compressor. The air fuel ratio in a combustor is maintained where exhaust gas emission components from the turbine are maintained below a predetermined component emission level while operating at partial loads.

Abstract: The invention relates to a method of operating a gas turbine assembly, which includes a compressor, a combustor and a gas turbine. The method includes operating the gas turbine assembly at a partial load with respect to a base load of the gas turbine assembly; bypassing a portion of blow-off air from the compressor; and introducing the portion of blow-off air into an exhaust gas duct after the gas turbine. The gas turbine assembly, when operating at partial load, can maintain the air-to-fuel ratio approximately constant and hence to control the combustion flame temperature at a level where emissions are kept below the permission limit.

Abstract: An axial compressor of a fluid-flow machine includes a flow path disposed between a rotor shaft and a relatively stationary housing wall. The flow path extends in an axial direction of the rotor shaft concentrically with the rotor shaft and the housing wall. A plurality of compressor stages are axially arranged in sequence along the flow path in the axial direction. Each of the compressor stages includes a rotor blades row and a guide vane row disposed after the rotor blades row in the axial direction. The flow path and the compressor stages operating therein are penetrable by a mass flow of a fluid to be compressed in a flow direction during operation of the compressor. A return is configured to return a part of the mass flow from a compressor discharge.

Abstract: Auxiliary power units and methods and systems for activation and deactivation of a load compressor therein are provided. Auxiliary power unit includes the load compressor having an impeller, APU engine, coupling member, pre-spinning means, and APU controller. APU engine is adapted to be mechanically engaged to load compressor to drive load compressor to provide pneumatic power and to be disengaged when the need for pneumatic power ceases. Coupling member couples load compressor and APU engine and is configured to be controllably moved between an engaged position in which the APU engine is mechanically engaged with the load compressor, and a disengaged position, in which the APU engine is disengaged from the load compressor. APU controller is operably coupled to load compressor, APU engine, coupling member, and pre-spinning means and adapted to receive and be responsive to rotational speed signals for controlling movement of coupling member between engaged and disengaged positions.

Abstract: Disclosed is a system for suppressing vibration and noise mitigation in structures such as blades in turbomachinery. The system includes flexible piezoelectric patches which are secured on or imbedded in turbomachinery blades which, in one embodiment, comprises eight (8) fan blades. The system further includes a capacitor plate coupler and a power transfer apparatus, which may both be arranged into one assembly, that respectively transfer data and power. Each of the capacitive plate coupler and power transfer apparatus is configured so that one part is attached to a fixed member while another part is attached to a rotatable member with an air gap therebetween. The system still further includes a processor that has 16 channels, eight of which serve as sensor channels, and the remaining eight, serving as actuation channels. The processor collects and analyzes the sensor signals and, in turn, outputs corrective signals for vibration/noise suppression of the turbine blades.

Abstract: A method for preventing a surge event prior to a first surge event occurring in an engine system including a turbocharger and a diesel engine operable at a plurality of discrete speeds, the method comprising sensing an operating parameter of the engine system that determines a surge margin, determining whether a change in the sensed operating parameter may result in exceeding the surge margin, and controlling an operating input to the engine system to prevent the surge event from occurring.

Abstract: A bi-modal bleed valve assembly is provided. In one embodiment, the bi-modal bleed valve assembly includes a housing assembly having a bleed inlet, a bleed outlet, a control servo port, and a control chamber therein. A main flow control valve is fluidly coupled to the control chamber and configured to move between an open position and a closed position to regulate fluid flow from the bleed inlet to the bleed outlet. The main flow control valve is configured to move from an open position to a closed position when the pressure within the control chamber surpasses a predetermined threshold. A switching valve is fluidly coupled between the bleed inlet, the servo control port, and the control chamber. The switching valve is configured to route fluid flow into the control chamber from: (i) the bleed inlet in an autonomous mode, and (ii) the servo control port in a servo-controlled mode.

Abstract: A turbo-compressor being driven by an electric motor has an inlet guide vane and a blow-off valve. The surge limit line of the compressor is amended depending upon seasonal changes of temperature and pressure of a working gas to be sucked into the compressor. Upon the basis of the surge limit line amended, the minimum opening of the inlet guide vale is altered, thereby reducing the driving power or force of the compressor.

Abstract: A system and method of surge limit control for turbo compressors including a turbo compressor having an inlet and an outlet, an anti-surge valve, a variable speed drive to operate the compressor, a rotational speed transmitter, an inlet temperature transmitter, an inlet pressure transmitter, an outlet pressure transmitter and/or guide vanes, and a controller, the controller including a PID control module wherein the computer uses information from the transmitters to continuously calculate a pressure ratio of the compressor at the compressor's current operational speed and compare it to the compressor's calculated pressure ratio at surge limit conditions. A computer generates a control signal for determining when to open the anti-surge valve if the pressure ratio of the compressor at the compressor's current operational speed guide vanes are within a user defined safety margin to the calculated pressure ratio at surge limit conditions.

Abstract: A gas compressor control device and a gas turbine plant control mechanism are disclosed. A fuel gas pressurized by a gas compressor is supplied to a gas turbine via fuel gas piping. A gas turbine control device adjusts the flow rate of the fuel gas into the gas turbine by exercising opening and closing control of a pressure control valve and a flow control valve. The gas compressor control device controls a fuel gas pressure at the outlet of the gas compressor by effecting opening and closing control of a recycle valve and an IGV. If load rejection or load loss occurs, the gas compressor control device opens the recycle valve in a preceding manner and closes the IGV in a preceding manner. Thus, elevation of the fuel gas pressure at the gas compressor outlet can be prevented, and elevation of a fuel gas pressure at an inlet of the gas turbine can be suppressed, thereby ensuring stable operation.

Abstract: To protect a turbocompressor (3) with a downstream process from operation in the unstable working range, a machine controller is used, which optionally contains—besides a surge limit controller (15)—an intake pressure controller (11), an end pressure controller (20) and a bypass controller (9). A control matrix is determined from the position of a control unit (fuel gas control valve 6) determining the flow to the process, optionally taking into account additional influencing variables such as the compressor intake pressure and the compressor discharge pressure.

Abstract: Gas turbine starting method is improved to start operation with bleed valves being first throttled, then fully opened on the way and then fully closed at 90% speed, thereby fluid unstableness phenomenon is suppressed and starter motor power is reduced. While inlet guide vane (11) and variable stator vanes (C1 to C5) are set to predetermined opening from starting to rated speed, bleed valves (1, 2, 3) are set to predetermined opening until 52% speed for the bleed valve (1) and until 51% speed each for the bleed valves (2, 3), then the bleed valves (1, 2, 3) are fully opened until the speed exceeds 90%, when they are fully closed for rated operation. In the prior art, starting operation is done with bleed valves being first fully opened until the speed is elevated to 90% and then fully closed, but in the present invention, air discharged into ambient air in vain can be reduced and thereby starter motor power can be also reduced.

Abstract: An air bleed tube is attached to a single-stage centrifugal pump, which has an impeller and a liquid suction tube whose inlet is at a center of the impeller. The air bleed tube is attached with its air inlet at an exposed eye of the impeller to bleed air from the pump and thereby reduce the likelihood that the pump will lose its prime. A light-touch check valve at an air outlet of the air bleed tube allows air at the impeller eye to be discharged from the pump and at the same time prevents air from being sucked by venturi vacuum pressure in the pump back into the air bleed tube and the pump.

Abstract: A pressure sensor (12) is located in the compressor stage of a gas turbine engine (10) to provide a pressure signal (PR1) that shows the compressor flow characteristics. The pressure signal (PR1) is applied to a bandpass filter (16) with roll-offs above and below N2. The difference between the filter output and a stored value for the pressure signal is integrated, and compressor bleed valves (18) are opened if the integral exceeds a stored threshold. The health of a compressor stage is determined by analyzing the magnitude of compressor pressure variations at N2 while accelerating the engine and by comparing the magnitude with values obtained from a compressor with a known stall margin.

Abstract: The present invention is for an evacuation system which preferrably in its entirety is connected to and operates at the outlet side of a pump. The evacuation system is connected to the socket 5 by the connector 9 and one of the valves 15 or 16. In the evacuation system there is a compressor 19 and a pressurized air ejector 18. Air from the ejector exits through a pipe 24.

Abstract: The stroking speed of an antisurge control valve is impeded by the combined damping effects of signal dead time and the inherent lag of ancillary pneumatic components within a primary control loop. Furthermore, as control valve actuator size increases, the negative influence of these two impediments (dead time and lag) is amplified. As a result, control valve response times are adversely affected; and the possibilities of surge-induced compressor damage and process upsets are heightened. For these reasons, this disclosure relates to a method for protecting turbocompressors from impending surge, and for preventing subsequent process upsets, by improving antisurge control. But more specifically, it describes a technique for decreasing damping effects by evacuating control valve actuators (diaphragm or piston) through restrictions having a lower resistance to compressible-fluid flow rather than through volume boosters--consequently, increasing a control valve's opening speed to that of an emergency shutdown.

Abstract: A technique for controlling compressor stall and surge is disclosed. In a gas turbine engine, static pressure asymmetry is sensed at a plurality of locations along the circumference of the compressor inlet. Time rate of change of the mass flow in the compressor is also estimated using pressure measurements in the compressor. A signal processor uses these signals to modulate a compressor bleed valve responsive to the level of flow property asymmetry, the time rate of change of the annulus average flow to enhance operability of the compressor.

Abstract: A process and a device for avoiding regulator instabilities in surge limit regulators for protecting a turbocompressor from surging if a high proportional gain is selected for the surge limit regulator by a blow-off via a blow-off valve. The control of the velocity of closing of the blow-off valve over time is performed by a gradient limiter of asymmetric design, wherein no velocity limitation acts in the opening direction, but a freely parameterizable velocity limitation of the closing process of the blow-off valve is provided in the closing direction. The gradient limiter is inserted between the surge limit regulator, which receives the control signals on the actual value of flow and the desired value of flow from a subtracter, and the control line for a pneumatic or hydraulic operating device of the blow-off valve.

Abstract: A process and to a device for protecting a turbocompressor from operating in the unstable working range by means of a blow-off device, wherein a control parameter is determined from measured values for the compressor flow, the compressor final pressure and the temperature measurement, as well as from preset or presettable desired values, and controlled opening of the blow-off fittings is performed by a pump surge limiter by means of a pneumatic actuating device each on the basis of the said control parameter. The measured values for the temperature, flow and pressure entered into the pump surge limiter are coupled with a dynamic blow-off line. The blow-off fittings are operated in sequence, and the control signals for the quick opening of the blow-off fittings are first sent to a small blow-off fitting, and then to a large blow-off fitting after the opening of the small blow-off fitting. In cooperation with the dynamic blow-off line, the pump surge limiter provides for continuous control, i.e.

Abstract: A method of, and a system for, detecting an occurrence of a surge in a gas turbine engine. The method includes steps, executed during consecutively occurring time periods, of: obtaining filtered derivatives of first and second engine operating characteristics; comparing the filtered derivatives of the first and the second engine operating characteristics to first and second threshold values, respectively; and incrementing a count only if both of the filtered derivatives exceed their respective threshold values. Otherwise, a next step decrements the count if one or both of the filtered derivatives do not exceed their respective threshold values. The method further includes a step of indicating a surge condition only if the count is equal to a predetermined value that is greater than unity. In a presently preferred embodiment of this invention the engine is a turbofan engine, the first engine operating characteristic is fan speed, and the second engine operating characteristic is exhaust gas temperature.

Abstract: A control system prevents recurrence of surge in a dynamic compressor. An anti-surge valve bypasses flow and is operated by the control system between a low limit and a full open position. The low limit is initially established to be zero, or a fully closed anti-surge valve. In the event of a compressor surge, the system detects a position of the anti-surge valve at the onset of surge, and stores a position related to the detected position as a new low limit. The stored position is preferably the detected position plus a small increment in order to prevent recurrence of the surge event.

Abstract: In an aircraft gas turbine engine, stator vane deflection and compressor bleed are controlled to alter the compressor airflow vs. compressor pressure relationship map when stall conditions are detected based on compressor speed and compressor temperature, a change that means that less change in pressure required to nudge the compressor from of a stall, accelerating stall recovery. Once the stall has ceased, the stator deflection and bleed are restored to pre-recovery values.

Abstract: A method and apparatus for controlling working fluid surge in a centrifugal compressor include preventing surge by using a variable-speed prime-mover to achieve a minimum desired surge margin. Surge prevention is also accomplished by continuously modulating a blowoff valve to maintain an actual compressor pressure ratio at a predetermined target maximum value. Surge detection is accomplished by monitoring the time rate of change of the final stage discharge pressure.

Abstract: A method of operating a multistage turbocompressor or of monitoring the pump limit thereof, whereby the pump limit function is stored in the control unit in the form Y=m.F+b and the coefficients m and b are determined by the linear relationshipsm=m.sub.0 +m.sub.1.dT.sub.s +.SIGMA.m.sub.2i.dT.sub.rib=b.sub.0 +b.sub.1.dT.sub.s +.SIGMA.b.sub.2i.dT.sub.riwhere T.sub.s and T.sub.ri represent the intake temperature and the backcooling temperatures following coolers after each turbocompressor and dT.sub.s and T.sub.ri and reference temperatures T.sub.ref. The system automatically compensates for the shift of the pump limit with temperature and allows operation closer to the pump limit or boundary for stable aerodynamic operation.

Abstract: An anti-surge valve (11) equipped with a servomotor and connected between the outlet of the compressor (12) and its inlet, the servomotor being controlled from a regulating system (13) which receives at the input a parameter (m) representing the flow of the compressor and a nominal value (c) determined from the inlet pressure and outlet pressure of the latter, for the purpose of injecting some of the outlet flow of the compressor at the inlet of this, in order to keep it above its breakaway point. The device comprises a quick-emptying solenoid valve (16) of the servomotor of the anti-surge valve and means (17, 18) for controlling this as a function of the amount of deviation between the parameter and the nominal value.

Abstract: In a control system for a turbine engine having a variable geometry air compressor, a valve arrangement responsive to a first operational pressure differential created between a discharge fluid pressure produced by the air compressor and an environmental fluid pressure for controlling the communication of a first fluid pressure to an actuator assembly which responds to a second operational pressure differential created across a piston between the first fluid pressure and a second fluid pressure produced through a modification of the discharge fluid pressure. The second fluid pressure being developed by compressor discharge fluid pressure flowing from a blind bore in a shaft through a variable opening to one side if the piston while at the same time fluid pressure flows through a restriction to the surrounding environment.

Abstract: Method and apparatus for operating a compressor to avoid surge conditions. The compressor is controlled by determining a surge line for the compressor as a function of compression ratio and the flow coefficient (M.sqroot.RTZ)/P.sub.s ; measuring the differential head, h, across a flow element, the suction pressure, P.sub.s, and the discharge pressure, P.sub.d ; generating a process signal that is a function of P.sub.d /P.sub.s and .sqroot.h/P.sub.s and comparing the process signal with a set point signal to control recycling of discharge flow to the inlet flow to prevent operation of the compressor in surge conditions.

Abstract: In compression systems, a portion of the compressor outlet flow (28) is extracted and introduced through a surge nozzle (52) into a plenum (48) upstream of the compressor (14). The surge nozzle (52) is oriented so as to introduce in the fluid in the plenum (48) a vortex having the same axis and direction of rotation as the compressor rotor (54).

Abstract: An air flow system includes a supercharger, a bypass passageway connected between an intake side and a discharge side of the supercharger, a compression machine and an air bypass valve in the bypass passageway. An intake port of the compression machine is connected with the bypass passageway such that supercharged air is delivered to the intake port of the compression machine at least during high supercharging conditions, thereby increasing the volumetric efficiency of the compressor at high engine speeds.

Abstract: A control system actively controls at least one troublesome mode of an unsteady motion phenomenon in turbomachinery in order to enable an increase in the operating range of the turbomachinery. For example, rotor blade flutter or rotating stall may be controlled in a turbocompressor. The control system has a control bandwidth which is at least partly coextensive with the bandwidth of the unsteady motion phenomenon and operates by passing sensor signals related to the unsteady motion phenomenon from a sensor array in the turbomachine to a mode filter which produces a signal or signals which are related to the troublesome mode or modes. The selected mode signals are amplified and phase-shifted by time-variable amounts so as to produce control signals having controlled amplitude and phase relationship to the troublesome mode.

Abstract: An anti-surge control of a turbocompressor includes a controller which controls the progressive opening or closing of a blow-off valve as a function of the working point location relative to a blow-off line defined in the characteristic field. A quick opening of the blow-off valve upon the occurrence of a close approach to surge is effective by applying a correction signal to the integral section of the controller.

Abstract: A method for preventing surges in a turbocompressor which supplies downstream processor with a gaseous medium by regulating a blow-off valve. The compressor volumetric intake flow is continuously measured, as is the compressor outlet pressure. A first minimum is designated to the compressor volumetric intake flow, and this minimum is dependent on the compressor outlet pressure. The blow-off valve is opened to ensure that the volumetric intake flow of the compressor remains above a surge limit when the intake flow drops to or below the first minimum and to a value that is still permissible and above the surge limit. The flow to the processor downstream is measured separately and in vicinity of the processor intake. The blow-off valve is also opened when the flow to the processor drops below a permissible second mininum value. The compressor intake flow is measured in vicinity of the compressor intake, whereas the flow to the processor is measured separately in vicinity of the processor intake.

Abstract: A regulating method for preventing surges in turbo-compressors, in which the compressor flow and forwarding pressure are continuously measured. The compressor operating point is defined by the compressor flow and the forwarding pressure. Surges are prevented by regulating the opening of at least one blow-off valve by a regulator with an adjustment parameter when the operating point has arrived at a blow-off curve that parallels a surge limit, but before the operating point arrives at the surge limit. The adjustment parameter is returned to an actual state of the blow-off valve by a readjustment circuit when a difference exceeding a predetermined threshold occurs betwen the actual state of the blow-off valve and the adjustment parameter of the regulator.

Abstract: In the surge limit control for turbo compressors the amplification factor of the control device producing the control signal for a blow-off valve is varied according to the ascending gradient of the compressor's characteristic corresponding to the respective working point.

Abstract: A method for reliably operating turbocompressors in which flow and forwarding pressure defining the operating point of a compressor are continuously measured. At least one blow-off valve or blow-around valve is opened by a blow-off regulating system to prevent surging once the operating point of the compressor has attained a blow-off curve that parallels a surge limit, but before the operating point can attain the surge limit so that the flow will attain a minimum level depending on the forwarding pressure. The speed at which the operating point moves relative to the blow-off curve or surge limit is determined continuously to obtain the opening of either one of the valves ahead of time. The blow-off valve or blow-around valve is opened at maximum speed by a procedure that supercedes a normal blow-off regulation system when the operating point has arrived at or beyond a rapid valve-opening curve representing a speed-dependent minimum distance of the operating point from the blow-off curve.

Abstract: A regulating method for preventing surges in a turbocompressor by initiating blow-off when necessary during operation. Flow to the turbocompressor and the compressor outlet pressure are measured continuously, and a first regulating difference is calculated from these measurements. This first regulating difference is then applied as an input parameter to a regulator which has a limited response rate. The output of this regulator is then used as a regulating parameter for a blow-off valve. The blow-off valve is opened rapidly by safety controls under malfunctioning conditions that tend to stress the limited response rate of the regulator. A second regulating difference is calculated from the preceding measurements or from the first regulating difference to indicate the need to open rapidly the blow-off valve.

Abstract: An arrangement for protecting a turbocompressor against surges by blowing off through a blow-off valve, in which at least the flow-through of the compressor and the compressor outlet pressure are measured. A regulating parameter is determined from the measured results, as well as from predetermined reference values. A blow-off valve is adjusted dependent on the regulating parameter, by a surge-limit regulator through activating device with a downstream state regulator and a compressed medium. The blow-off valve is shifted in opening direction at a maximum rate of adjustment by safety controls when the regulating parameter exceeds a safe threshold. The compressed medium that activates the blow-off valve bypasses the state regulator and escapes directly when the safety controls engage. The compressed medium is prevented from escaping, on the other hand, when the safety controls disengage, and regulation is resumed only by the surge-limit regulator and the downstream state regulator.

Abstract: In a compressor station for boosting the pressure of gas stream being transported in a pipeline wherein the act of recompressing the gas stream to a desired pressure results in a gas temperature sufficiently high to stimulate cracking activity in the pipeline when the compressed stream gas is reinjected into the pipeline, method and apparatus are disclosed for cooling a portion of the warm compressed gas to form a cool gas stream and then controlling a division of the cooled stream to supply both a cooled recycle stream for anti-surge control and a cooled stream for mixing with the warm compressed gas for temperature control.

Abstract: A surge control system (16) is provided for a compressor (14) which anticipates the actual surge condition and initiates anti-surge protection in proportion to the magnitude of the anticipated surge condition. This is done by providing a feed foward signal (20) to a summing station (48) along with a normally generated surge control line point (44) to offset this point (44) by an amount determined by the feed forward signal (20). This offset point (50) is used as an input to a controller for controlling the bypass valve (28) in a bypass loop (30) around the compressor (14).

Abstract: Single shaft, air breathing auxiliary power units having a single stage centrifugal load compressor driven by a gas turbine engine. The latter has a single stage centrifugal compressor and a single stage radial inflow turbine mounted in back-to-back relationship on the same shaft as the load compressor. Control systems for these auxiliary power units feature turbine exhaust gas temperature and turbine speed responsive fuel flow control; a bypass valve control which causes air to be dumped overboard when the pneumatic load demand drops to prevent load compressor surge; and an inlet guide vane control.

Abstract: Apparatus for controlling bleed gas in the bleed gas system of a compressor for gas turbine engine wherein a valve disposed in the bleed conduit of a compressor is moved from closed to open position in a selectively controlled manner in accordance with a preselected bleed gas pressure sensed in the bleed gas system of the compressor.