Abstract: Fluid release apparatus (26) for the release of fluid from the interior of a rotating and/or pressurised body (16;18;102;104), the apparatus comprising a core member (28) having a chamber wall (44) disposed thereabout so as to define an open chamber (30) about said core member. The apparatus further comprises a chamber closure (48) mounted about said core member (28), said closure being resiliently deformable between an at rest state in which the closure contacts the chamber wall (44) and an actuated state in which the closure is spaced there-from, wherein the chamber has an aperture (32;35;55) for receiving liquid phase fluid from the interior of said rotating body. Upon build up of sufficient liquid in said chamber (30) the closure (48) moves to said actuated state so as to release liquid from the interior of the body.

Abstract: A gas turbine has a rear bearing chamber 2 including a bearing arrangement 1. A vent valve 14 vents the bearing chamber 2 as a function of relative pressure of the bearing chamber.

Abstract: A kinetic hydropower generation system has a turbine and a generator coupled to the turbine. An underwater intake nozzle assembly is fluidly coupled to the turbine. For one embodiment, an underwater tower nozzle may be fluidly coupled between the turbine and the underwater intake nozzle assembly. The underwater intake nozzle assembly may include a collector and a converging nozzle.

Abstract: A turbine system includes a turbine positioned so that its blades are exposed during at least part of their rotation to a region of fluid flow accelerated by a columnar structure, such as a building or a bridge pylon. A protective casing moves to isolate the turbine blades from the fluid flow, thereby protecting the turbine from overpowering conditions. Upwind and downwind fairings may be used when retrofitting pre-existing buildings. Turbines may be positioned on opposing sides of a building. Multiple turbine modules may be positioned in line along peripheries of a building. Turbines may be mounted on in-water structures, such as buoys.

Abstract: Smooth, preferably variable-sweep fluid collection device surfaces disposed into opposition with wind, river, surf, ocean or tidal currents generate enhanced velocity fluid flows at length driven into onboard work-extracting disc turbines at advantageous angles of attack. Keyed to shafts turning freely through optionally extendable volutes, disc turbines comprising a dense population of smooth, axially fixed or adjustably spaced discs conducting preferably laminar flow between adjacent elements develop significant torque through boundary layer adhesion and viscous shear-stress between fluid layers. Exhaust of disc turbine throughput into divergent channels drafting into external currents of initially higher than ambient velocity and lower pressure may reduce turbine discharge backpressure, rapidly clear system throughput, and allow normally disadvantageous drag to be utilized to develop greater work generation.

Abstract: A system for measuring clearance between a first object and a second object is provided. The system includes a sensor configuration to generate a first signal representative of a first sensed parameter and a second signal representative of a second sensed parameter. The system also includes a clearance measurement unit configured to process the first and second signals based upon a ratiometric technique to calculate clearance between the first and second objects.

Abstract: A pump system (1) is provided for the pumping of multiphase mixtures which includes a pumping apparatus (3) for multiphase mixtures with at least one liquid phase and at least one gaseous phase. The pumping apparatus (3) contains one or more axial compression stages with one respective axial impeller each and one or more pumping stages with a respective one radial impeller each which are arranged adjoining the axial compression stage or stages, wherein the pump system (1) additionally includes a separator (2) at the inlet side of the pumping apparatus (3) to separate a portion of the gaseous phase and wherein the pumping apparatus (3) is configured for delivery heads larger than 50 m.

Abstract: A ducted water turbine is configured to be installed in a subsea environment to generate hydroelectric power and broadly includes a turbine housing, a turbine rotor, and a generator. The turbine rotor includes a peripheral rim and a plurality of rotor blades mounted to and extending radially inwardly from the rim. The turbine housing includes a duct that permits water to flow through the housing. The peripheral rim is rotatably mounted in the duct, with the water flow causing the turbine rotor to spin. The turbine rotor is drivingly connected to the generator and powers the generator when the turbine rotor is spun by the water flow.

Abstract: A compression system is disclosed, the compression system comprising a rotor having a plurality of blades arranged around a centerline axis, each blade having a blade airfoil and a blade tip, and at least one plasma actuator located on a blade. Exemplary embodiments of a detection system for detecting an instability in a compression system rotor and a mitigation system comprising at least one plasma actuator mounted on a blade to facilitate the improvement of the stability of the rotor are disclosed.

Abstract: A system for cooling a high pressure section of a turbomachine includes a conduit configured to carry cooling steam from a boiler to a space upstream of a first stage nozzle of the turobmachine. The conduit extends through a housing of the turbomachine and a nozzle diaphragm of the first stage nozzle. The system further includes a control valve in the conduit configured to regulate the flow of cooling steam. A turbomachine includes a housing; a turbine shaft rotatably supported in the housing; and a plurality of turbine stages located along the turbine shaft and contained within the housing. Each turbine stage includes a diaphragm attached to the housing. The diaphragm comprises a plurality of nozzles. A hole is provided in the diaphragm upstream of a first stage of the plurality of stages for the introduction of cooling steam. A method of cooling a high pressure section of a turbomachine includes introducing cooling steam into the turbomachine through the at least one hole.

Abstract: The present disclosure is directed to a method for power management in a machine. The method for power management may include sensing a parameter indicative of a torque applied to a torque consuming device rotatably driven by a power source. The method may further include modifying a quantity of fuel supplied to the power source as a function of the sensed parameter.

Abstract: A gas turbine engine system includes a fan (14) and a fan bypass passage (30) downstream of the fan (14) for conveying a bypass airflow from the fan. A nozzle (40) associated with the fan bypass passage (30) includes a plurality of different positions that influence the bypass air flow. One or more sensors (54) near the fan (14) produce a signal representative of a foreign object F near the fan (14). A controller (44) commands the nozzle (40) to move to a desired one of the plurality of different positions in response to the signal from the sensor (54) to change a pressure ratio across the fan (14) to thereby reduce a mechanical stress on the fan (14).

Abstract: The invention concerns a turbo engine, especially a gas turbine, with a stator and a rotor, wherein the rotor has rotating blades and the stator has a housing (11) and guide blades (12), wherein the rotating blades at the rotor side form at least one rotating blade ring, and the rotating blade ring or each rotating blade ring at one radially outward lying end adjoins an inner ring or casing ring (17) of the housing at the stator side, by which it is surrounded and with which it bounds a gap, wherein the particular casing ring (17) is connected to a support ring (20) via curved walls (19), which together with the casing ring (17) and the support ring (20) bound a cavity (22) and form a bellows-like structure (21), and wherein by changing the pressure prevailing in the cavity (22) of the respective bellows-like structure (21) the gap between the casing ring (17) and the radially outward lying ends of the respective rotating blade ring can be pneumatically adjusted.

Abstract: Systems and methods of detecting and correcting the undesirable operation of a turbine by monitoring one or more sensor devices, where each sensor device monitors one or more operating parameter values associated with various turbine components. If any of the sensor devices detects that a particular operating parameter associated with one or more turbine components is operating in a range of unacceptable risk, then corrective action is taken which may include opening and or closing one or more of the steam valves associated with an inlet pipe until that particular operating parameter of the turbine is no longer operating in a range of unacceptable risk.

Abstract: Methods and systems for monitoring particulate in a flow of gases are provided. A particulate monitor system includes an emitter coupled to an exhaust duct and downstream from a turbine engine. The emitter emits light at a predetermined intensity through a flow of gases discharged from the turbine engine into the exhaust duct. A receiver is coupled to the exhaust duct and oriented to receive at least a portion of the light emitted from the emitter. The receiver generates a first signal indicative of an intensity of the emitted light received. A controller is coupled in communication with the receiver. The controller is configured to generate, based on the first signal, an output signal corresponding to a variation in intensity of the portion of the emitted light received. A monitor in communication with the controller receives the output signal from the controller.

Abstract: (A1) A turbofan engine control system is provided for managing a fan operating line. The engine (10) includes a spool having a turbine housed in a core nacelle (12). A turbofan (20) is coupled to the spool (14). A fan nacelle (34) surrounds the turbofan and core nacelle and provides a bypass flow path having a nozzle exit area (40). A controller (50) is programmed to effectively change the nozzle exit area in response to an undesired turbofan stability margin which may result in a stall or flutter condition. In one example, the physical nozzle exit area is increased at the undesired stability condition in which the airflow into the engine creates a destabilizing pressure gradient at the inlet side of the turbofan. A turbofan pressure ratio, turbofan pressure gradient, low spool speed and throttle position are monitored to determine the undesired turbofan stability margin.

Abstract: Many variables in processes such as those using turbocompressors and turbines must be limited or constrained. Limit control loops are provided for the purpose of limiting these variables. By using a combination of closed loop and open loop limit control schemes, excursions into unfavorable operation can be more effectively avoided. Transition between open loop and closed loop may be enhanced by testing the direction and magnitude of the rate at which the limit variable is changing. If the rate of change indicates recovery is imminent, control is passed back to the closed loop limit control function.

Abstract: The present invention relates to a fluid compressor having an aerostatic bearing, to a control system of a fluid compressor having an aerostatic bearing as well as to a method of controlling a compressor, wherein the aerostatic bearing is fed by a compressed fluid accumulator (5) which is charged during the operation of the compressor (100) and discharged at the respective start to prevent damage to the bearings.

Abstract: A turbofan engine includes a core nacelle housing a spool having a turbine. A turbofan is arranged upstream from the core nacelle and is coupled to the spool. A fan nacelle surrounds the turbofan and core nacelle. A bifurcation supports the core nacelle relative to the fan nacelle and extends radially between the nacelles. The core and fan nacelles provide a bypass flow path receiving bypass flow from the turbofan. In the example, the nacelles provide a fixed nozzle exit area. The bifurcation includes an inlet that is in communication with a passage. The passage is selectively opened and closed by a valve to provide air from the inlet to a vent opening near the nozzle exit area. By opening the valve, the nozzle exit area is effectively increased to provide increased bypass flow through the turbine engine.

Abstract: A compressor rotor 6a and a turbine rotor 7a are respectively attached at either end of the main shaft 13 so that the compressor rotor 6a is driven by the power generated by the turbine rotor 7a. The main shaft 13 is supported by rolling contact bearings 15 and 16 relative to the radial direction. The thrust force applied to the main shaft 13 is supported by electromagnets 17. A sensor 18 is provided to detect the thrust force which affects the main shaft 13 through air within the compressor 6 and the expansion turbine 7. In the sensor 18, sensor elements having the properties changeable in accordance with a pressing force and capable to electrically detect the change in the properties are arranged in a circumferential direction of the main shaft. The sensor 18 detects the thrust force from the output of the sensor elements.

Abstract: A method and device for maintaining air boost system performance is provided. One or more stages of the air boost system can be connected by tubing to a cleaning system that includes a fluid reservoir (135, 235) containing cleaning fluid and a means of conveying the cleaning fluid into at least one stage of the air boost system. The air boost system can also include a means for detecting (150, 250) at least one fouling parameter of said air boost system. Mien the fouling parameter meets a pre-determined condition, a control means (155, 255) can trigger the cleaning means and inject cleaning fluid into the stage or stages to be cleaned.

Abstract: A windfarm including a plurality of wind turbines, an ice detection sensor adapted to detect an icing condition of at least one of said plurality of wind turbines, and a main controller connected to said ice detection sensor and to at least two of said wind turbines, wherein the main controller is adapted to control the operation of said at least two wind turbines based on an icing condition detected by said ice detection sensor. A method for controlling the wind farm is also disclosed.

Abstract: Interruption in supervisory position control signals can cause problems with respect to actuators which upon loss of such control signals for the actuator will generally slew to a fixed idle position. In such circumstances a machine such as a gas turbine engine in which an actuator is associated will not sustain performance even though there is continued local power supply to the actuator. By utilising a local controller which stores actuator response profiles for certain machine status stages through perturbation or marginal activation of the actuator an appropriate actuator response profile can be chosen and therefore sustaining control signals presented to the actuator to maintain machine operation.

Abstract: A hydroelectric turbine generator and control system is provided that optimizes the maximum possible power output at all times by strictly monitoring power output from the generator unit and modulating the wicket gate angle and the runner blade pitch independently of one another. The hydroelectric turbine generator includes a means for separately controlling wicket gate angle and runner blade pitch. The wicket gate angle control mechanism controls the flow into the system, pre conditions flow for maximum power and maintains reservoir level. The runner blade pitch control mechanism continuously monitors the system power output based on actual power produced, and adjusts system parameters in order to achieve maximum power output.

Abstract: A gas turbine engine system includes a nacelle, a fan casing within the nacelle, a variable area fan nozzle, a sensor and a controller. The sensor detects an airfoil flutter condition. The controller communicates with the sensor and is operable to move the variable area fan nozzle to influence a discharge airflow area in response to the detection of the airfoil flutter condition.

Abstract: A stability control algorithm is provided for a centrifugal compressor. The stability control algorithm is used to control a variable geometry diffuser and a hot gas bypass valve (when provided) in response to the detection of compressor instabilities. The stability control algorithm can adjust the position of a diffuser ring in the variable geometry diffuser in response to the detection of a surge condition or a stall condition. The diffuser ring in the variable geometry diffuser can be adjusted to determine an optimal position of the diffuser ring. The stability control algorithm can also be used to open a hot gas bypass valve in response to the detection of continued surge conditions.

Abstract: A valve tester system is disclosed that comprises a valve tester assembly for rotating a valve stem of a valve. The valve tester assembly may include a support, a rotation element mounted on the support for rotating a valve during a rotation event, a control element for controlling aspects of the rotation event of the valve by the rotation element, and an element for detecting a location of the valve tester assembly during the rotation event of the valve. In some embodiments of the invention, the element for detecting the location of the valve tester assembly includes a Global Positioning Satellite (GPS) receiver. In some embodiments, the GPS receiver is integral with the control element.

Abstract: A method for determining an approximate value for a parameter characteristic of the fatigue state of a component as a result of a time-varying stress to which it is subjected by means of a number of load cycles should, itself, during comparatively lengthy stress cycles, enable a prognosis concerning the current fatigue state of the component, this prognosis being, in particular, adapted to the needs and suited for the real-time determination of maintenance intervals. To this end, in addition to optionally already fully completed load cycles, a first partially completed load cycle is also taken into consideration during the determination of the parameter, whereby temporary stress values for phases that have not yet been run through of the partially completed load cycle are, together with a predetermined fixed value, taken into consideration.

Abstract: A computer system is capable of operating with various types of fans from the same manufacturer or from different manufacturers and is capable identifying the type of fan which is presently installed in the system. The system includes a fan of the type which includes an integral optical sensor and detectable indicia such as, by way of example, a bar code label or imprint. Fan identification has a variety of uses including, for instance, adjusting system parameters to properly execute the computer system's cooling functions based on the type of fan presently installed, and reporting fan type and/or serial number to an administrator or central inventory server for quality control purposes. Particular embodiments include the derivation of tachometric information from the detectable indicia. The computer system may include an inventory program which maintains fan ID data for a plurality of fans.

Abstract: A gas turbine engine plasma blade tip clearance control system includes an annular shroud surrounding rotatable blade tips and an annular plasma generator spaced radially outwardly and apart from the blade tips. An exemplary embodiment of the annular plasma generator is mounted to the annular shroud and includes radially inner and outer electrodes separated by a dielectric material disposed within an annular groove in a radially inwardly facing surface of the annular shroud. The plasma generator is operable for producing an annular plasma between the annular shroud and blade tips and an effective clearance produced by the annular plasma between the annular shroud and blade tips that is smaller than a clearance between the annular shroud and blade tips.

Abstract: A device and method for conversion of the energy of medium flows are provided. The proposed device and method ensure suppression of the vortex streams in the flow on the leg of its motion along the radially converging trajectories and concentration of the flow energy, which is expressed by the increase of its velocity and decrease of the summary area of the cross section of the converging trajectories. As the flow runs along the first system of helical trajectories the following takes place: the harmful secondary vortex jets continue attenuating, the degree of concentration of the flow energy increases and velocity components form in the flow, which correspond to natural vortex streams, for instance, tornadoes, whirlpools.

Abstract: Systems and methods of detecting and correcting the undesirable operation of a turbine by monitoring one or more sensor devices, where each sensor device monitors one or more operating parameter values associated with various turbine components. If any of the sensor devices detects that a particular operating parameter associated with one or more turbine components is operating in a range of unacceptable risk, then corrective action is taken which may include opening and or closing one or more of the steam values associated with an inlet pipe until that particular operating parameter of the turbine is no longer operating in a range of unacceptable risk.

Abstract: For setting the position of a control element, a controller and method according to the invention provide for impressing a required temporal characteristic of the actuating signal onto a should-be value then using said should-be value as a time-variable signal for forming the actuating signal.

Abstract: A rotor system is provided whereby a rotary assembly such as a fan blade combination in a jet engine is brought into rub contact with a casing such that sensors detect vibration. The casing is then retreated in order to open the gap to a desired value for engine performance. In such circumstances, the rub contact position is defined as a base datum reference from which distance the casing is displaced in order to provide the specified gap for engine performance and efficiency.

Abstract: An axial fan has a blade support wheel coupled to a drive shaft. A disk is positioned about the drive shaft adjacent the wheel. A torsion spring is coupled to the wheel and to the disk. When the torsion spring is in tension, the disk is poised for a relative rotation about the drive shaft. A lock couples the disk to the wheel when the torsion spring is in tension. Fan blades are supported by the wheel, and are coupled to the disk. Rotation of the drive shaft rotates the fan blades generating a specific flow direction. To reverse the flow direction, a release mechanism uncouples the lock from the disk and wheel causing the disk to experience rotation about the drive shaft as tension in the torsion spring is released. The disk's relative rotation re-positions the fan blades reversing the flow direction as the drive shaft continues to rotate.

Abstract: Many variables in processes such as those using turbocompressors and turbines must be limited or constrained. Limit control loops are provided for the purpose of limiting these variables. By using a combination of closed loop and open loop limit control schemes, excursions into unfavorable operation can be more effectively avoided. Transition between open loop and closed loop may be enhanced by testing the direction and magnitude of the rate at which the limit variable is changing. If the rate of change indicates recovery is imminent, control is passed back to the closed loop limit control function.

Abstract: Methods, devices, and/or systems for controlling vibration and/or acoustic noise. An exemplary method senses noise and/or, for example, rotational speed of a rotating shaft, determines control parameters and actuates one or more actuators. An exemplary device includes a controller configured to receive information, determine control parameters and actuate one or more actuators. An exemplary system includes one or more sensors, a processor and one or more actuators. Various exemplary methods, devices, and/or systems are optionally suitable for use with turbochargers and/or other boost systems.

Abstract: A wind energy machine has four rotor chambers formed by perpendicular walls. Each rotor chamber has an intake portion, a reversal portion, a parallel portion, and an exhaust portion. Air flow is reversed in each chamber for every 90 degrees of rotation, such that the intake portion becomes an exhaust and the exhaust portion becomes and inlet.

Abstract: A fan regulation circuit configuration includes an input receiving an input voltage (proportional to fan current and forms a first comparison voltage), a low-pass filter (filters input voltage and a filter output voltage is tapped off as second comparison voltage), a first comparison device for commutation identification (outputs signal indicating a commutation if value of one of the comparison voltages multiplied by first factor is greater than the other comparison voltage), and a regulator (outputs a control voltage dependent upon identified commutation pulses). The circuit has self-adjusting sensitivity adaptation and a second comparison device outputting a signal if the value of one of the comparison voltages multiplied by a second factor is greater than the other comparison voltage, the second factor being less than the first factor.

Abstract: In a method of controlling steam flow through a steam turbine having a turbine rotor, a maximum heat transfer rate is determined based on thermal stress calculations in the turbine rotor. A maximum steam flow rate can be calculated based on the maximum heat transfer rate. An actual steam flow rate through the steam turbine is determined, and a turbine inlet valve is controlled based on a difference between the actual steam flow rate and the maximum steam flow rate. In this manner, steam flow can be controlled to the steam turbine in such a way as to limit thermal stress to an acceptable level while minimizing start times and maximizing operability.

Abstract: Wind power installations using more modern technology have long been known. Such wind power installations have rotors comprising at least one or more rotor blades. The rotors and accordingly the rotor blades carried thereby of wind power installations are subjected to a particular degree to the ambient environmental influences such as for example rain, snow, hail or also insects. In particular the leading edges of the rotor blades are heavily loaded in that respect. In that situation it can happen that the rotor blades and in particular the leading edges thereof, after some time, suffer from (mechanical) damage, for which cost-intensive repair is necessary, especially as a crane is frequently required for that purpose and the entire wind power installation is also stopped for a prolonged period due to the repair and under some circumstances even individual rotor blades have to be transported away to the repair location.

Abstract: A control unit for driving a regulating transistor (2) of a fan arrangement, in which the regulating transistor (2) is connected in series with an electronically commutated fan (1), having control means (5, 6, R1, R2) for the analog driving of the regulating transistor (2) with a control signal (Ucontrol) in a manner dependent on a control input voltage (Uin). The control unit comprises compensation means (R3, R4) for influencing the control signal (Ucontrol) in a manner dependent on an AC voltage component (UAC) of an operating voltage (UB) of the fan arrangement, so that the AC voltage component (UAC) of the operating voltage (UB) is completely or partially compensated for in a voltage across the fan (1).

Abstract: A fan regulation circuit configuration includes an input receiving an input voltage (proportional to fan current and forms a first comparison voltage), a low-pass filter (filters input voltage and a filter output voltage is tapped off as second comparison voltage), a first comparison device for commutation identification (outputs signal indicating a commutation if value of one of the comparison voltages multiplied by first factor is greater than the other comparison voltage), and a regulator (outputs a control voltage dependent upon identified commutation pulses). The circuit has self-adjusting sensitivity adaptation and a second comparison device outputting a signal if the value of one of the comparison voltages multiplied by a second factor is greater than the other comparison voltage, the second factor being less than the first factor.

Abstract: A method for determining whether a centrifugal pump is operating within its normal flow operating range includes the steps: of determining a motor torque/TDH relationship over a range of speeds for a minimum flow rate in order to obtain a minimum flow operating range for the centrifugal pump; determining a motor torque/TDH relationship over a range of speeds for a maximum flow rate in order to obtain a maximum flow operating range for the centrifugal pump; determining the actual operating motor torque and TDH of the centrifugal pump at a given operating point; and determining whether the actual operating motor torque and TDH of the centrifugal pump fall within the minimum flow and maximum flow operating ranges of the centrifugal pump.

Abstract: An apparatus having a pressure control system that balances the natural gas flow rate passing through a multi-stage, axial-flow, impulse turbogenerator to produce an electrical power output is provided. The pressure control system includes a primary bypass conduit circuit; pressure regulator valves; modulating valves; and flow sensors. The pressure control system is operatively connected to the multi-stage, axial-flow, impulse turbogenerator. The turbogenerator is operatively connected to both a microprocessor based governor control and a generator for producing electrical output and is preferably contained within a section of bypass conduit that is directly connected to an existing gas distribution pipeline. As the electrical load on the generator and downstream customer demand for gas fluctuate, the pressure control system can provide the proper amount of gas flow through the primary by-pass and turbine that is required to produce a predetermined, steady state electrical output.

Abstract: A system (10) controlling operation of a steam turbine (T). Sensors (12) measure dynamic pressure level variations in a stage (S1-Sn) of the turbine. A signal (Ps) from a sensor is converted to a frequency based signal (Fs). A comparator (16) compares the pressure levels at various frequencies as represented by the frequency based signal (Fs) to a matrix of limiting values including both alarm and trip signal limits. The control system provides an alarm to an operator of the steam turbine if the comparison indicates that an alarm limit has been exceeded, or takes the steam turbine off line, if a trip signal limit has been exceeded. This is done to prevent damage to the steam turbine. However, the control system maintains the steam turbine in operation if no aeromechanical disturbances or instabilities, as sensed by the sensors, has occurred.

Abstract: The invention pertains to an electromagnetical radial lamella clutch (10) for an electromechanical actuator (30), in particular for a valve (50). The clutch (10) comprises a rotor element (11) having an axis (12) of rotation and a circumferential outer surface area (13) with at least one recess (17). The rotor element (11) is surrounded by a cylindrical element (14), whereby at least one lamella element (15) is fastened to said cylindrical element (14). The lamella element (15) has an insertion portion (16) for being placed in said recess (17), whereby an electrical coil (21) holds said lamella element (15) in said recess (17). The invention further relates to an electromechanical actuator (30) and to a turbine having a valve (50) operated by said electromechanical actuator (30).

Abstract: A system and method is provided for detecting and controlling rotating stall in the diffuser region of a centrifugal compressor. The process begins with the detection or sensing of acoustic energy associated with the onset of rotating stall. A pressure transducer is placed in the gas flow path downstream of the impeller, preferably in the compressor discharge passage or the diffuser, to measure the sound or acoustic pressure phenomenon. Next, the signal from the pressure transducer is processed either using analog or digital techniques to determine the presence of rotating stall. Rotating stall is detected by comparing the detected energy amount, which detected energy amount is based on the measured acoustic pressure, with a predetermined threshold amount corresponding to the presence of rotating stall. Finally, an appropriate corrective action is taken to change the operation of the centrifugal compressor in response to the detection of rotating stall.

Abstract: A method for controlling fan operation that includes detecting a stopped fan and attempting to start the stopped fan. The method includes attempting to start the stopped fan again after at least one first time interval when the fan does not start. The method includes attempting to start the stopped fan again after at least one second time interval when the fan does not start after a predetermined number of first time intervals, where the at least one second time interval is longer than the first time interval.

Abstract: The invention relates to a fluid operated reversible volumetric machine comprising a receiving housing (C), at least two pairs of gear elements (I) mounted for rotation in the receiving housing (C) so that each gear element (I) is in meshing engagement with two adjoining gear elements (I) equal to it, an outer peripheral sequence, with respect to the gear elements, of suction openings or inlets (E alternating with as many delivery openings or outlet (U) formed in the receiving housing (C), an inner peripheral sequence, with respect to the gear elements, of delivery openings or outlets (U), alternating with as many suction openings or inlets (E) formed in the receiving housing (E), each outer and inner sequence comprising a number of inlets (E) or outlets (U) equal o the number of gear elements (I).