Abstract: A method of checking refuelling of an aircraft comprising a gas turbine engine and a fuel tank arranged to provide fuel to the gas turbine engine comprises: receiving an input of calorific value data for fuel provided to the aircraft on refuelling; independently determining at least one of: (i) the calorific value of fuel supplied to the gas turbine engine in use; and (ii) the calorific value of the fuel provided to the aircraft on refuelling; and providing an alert if the determined calorific value is inconsistent with the calorific value data input received.

Abstract: A dispatch advisor for operating a power plant having at least one gas turbine with flexibility is described. The dispatch advisor can generate a representation of a flexible base load map for operating the power plant. The representation can include an aggregation of a primary base load operating space and an expanded portion of the base load operating space. The representation offers a range of operating values for operational parameters of the power plant during base load at various base load settings at predetermined ambient conditions and corresponding power output and efficiency values that are attained while operating the power plant at the range of operating values. This offers an operator of the power plant with flexibility in controlling the plant during base load.

Abstract: As for a control device for a turbocharger including a turbine, disposed in an exhaust passage of an internal combustion engine, and a compressor, disposed in an intake passage of the internal combustion engine and driven by the turbine, the control device includes a control unit configured to control the turbine such that a boost pressure of the turbocharger in the intake passage becomes equal to or lower than an allowable value, a first calculation unit configured to calculate a decrease amount of a compressor efficiency of the compressor, and a second calculation unit configured to calculate the allowable value based on an intake air amount in the intake passage, in accordance with the decrease amount.

Abstract: A method is provided for operating a system of an aircraft. During this method, rotation of a propulsor rotor is driven using mechanical power output by a powerplant. The powerplant includes a first drive device and a second drive device. The first drive device generates a first portion of the mechanical power. The second drive device generates a second portion of the mechanical power. A ratio between the first portion of the mechanical power and the second portion of the mechanical power is adjusted to control vibrations of the powerplant.

Abstract: Methods and system for operating a gas turbine engine are described. The method comprises determining an actual engine output power based on a torque of the gas turbine engine, comparing the actual engine output power to an estimated engine output power to obtain an error, obtaining an actual engine speed and biasing the actual engine speed using the error to produce a biased engine speed, determining the estimated engine output power using a model-based estimator having the biased engine speed as input, detecting a torque-related fault based on the error and a first threshold, and accommodating the torque-related fault in response to detecting the torque-related fault.

Abstract: Various embodiments described herein relate to providing asset behavior modeling. In this regard, a request to obtain one or more asset insights with respect to an asset is received. In response to the request, a model is executed based on sensor data associated with the asset and asset scenario data associated with different operation scenarios for the asset. The model represents predicted asset behavior of the asset to provide the one or more asset insights. Furthermore, in response to the request, one or more actions are performed based on the one or more asset insights.

Abstract: A gas turbine engine fuel supply system can include a fuel delivery system, a thermal management system, a fuel manifold, and one or more sensors that identify one or more fuel parameters. A fuel control system adjusts parameters of the fuel based on data received from the sensors.

Abstract: A method for forecasting aircraft engine deterioration includes creating a first fused data set corresponding to a first actual aircraft engine. The first fused data set includes at least one as manufactured parameter of the actual aircraft engine, expected operating parameters of the first actual aircraft engine, and actual operating parameters of the actual aircraft engine. The actual operating parameters of the actual aircraft engine include internal aircraft sensor data, and external flight tracking data. The method further includes predicting an expected engine deterioration of the first actual engine based on the expected operating parameters and the actual operating parameters of the first actual aircraft engine by applying the first fused data set to a forecasting model. The forecasting model is a recurrent neural network based algorithm, and the recurrent neural network based algorithm is trained via a plurality of second fused data sets corresponding to actual aircraft engines.

Abstract: A turbine fracturing system and a controlling method thereof, a controlling apparatus and a storage medium are provided. The turbine fracturing system includes: N turbine fracturing apparatuses, wherein each of the N turbine fracturing apparatuses comprises a turbine engine, and N is an integer greater than or equal to 2; a fuel gas supply apparatus connected to the N turbine engines, wherein the fuel gas supply apparatus is configured to supply fuel gas and distribute the fuel gas to the N turbine engines as gaseous fuel; and a fuel liquid supply apparatus connected to at least one of the N turbine engines and configured to supply liquid fuel to at least one of the N turbine engines in a case that at least one of a flow rate and a pressure of the fuel gas decreases.

Abstract: Hybrid electric propulsion systems are described. The systems include a gas turbine engine having low and high speed spools, each spool having a respective compressor and turbine. A mechanical power transmission is configured to at least one of extract power from and supply power to at least one of the low speed spool and the high speed spool, an electric machine is configured to augment rotational power of at least one of the spools, and a controller is operable to determine a rotational speed of the low speed spool, determine a rotational speed of the high speed spool, determine if a predetermined operational zone of operation based on the determined rotational speeds is present, and when a predetermined operational zone is determined, control a power augmentation of at least one spool to limit dwell operation of the gas turbine engine within the predetermined operational zone.

Abstract: A gas turbine engine is provided. The gas turbine engine includes: a turbomachine having a compressor section, a combustion section, and a turbine section arranged in serial flow order, the compressor section having a high pressure compressor defining a high pressure compressor exit area (AHPCExit) in square inches; wherein the gas turbine engine defines a redline exhaust gas temperature (EGT) in degrees Celsius, a total sea level static thrust output (FnTotal) in pounds, and a corrected specific thrust, wherein the corrected specific thrust is greater than or equal to 42 and less than or equal to 90, the corrected specific determined as follows: FnTotal×EGT/(AHPCExit2×1000).

Abstract: In some aspects, a method includes obtaining feature importance data associated with an alert and indicating relative importance of each of multiple sensor devices and of one or more simulated features. The method includes identifying a group of the sensor devices that have greater relative importance than a highest relative importance of any of the one or more simulated features. In some aspects, a method includes obtaining a reference list of alerts that are similar to a reference alert and a list of alerts predicted to be similar to the reference alert and ranked by predicted similarity to the reference alert. The method includes determining a score indicating similarity of the list to the reference list. A contribution of each alert in the list to the score is determined based on whether that alert appears in the reference list and the rank of that alert in the list.

Abstract: A method of generating a maintenance schedule for an aircraft including one or more gas turbine engines powered by an aviation fuel. The method includes: determining one or more fuel characteristics of the fuel; and generating a maintenance schedule according to the one or more fuel characteristics. Also disclosed is a method of maintaining an aircraft, a maintenance schedule generation system and an aircraft.

Abstract: Methods and systems for capturing and processing audio data of a vehicle engine. In one aspect, a vehicle audio capture system includes a mobile device configured to capture vehicle engine sounds in an audio file and to associate tags identifying one or more vehicle conditions observed during audio capture and reflected in the audio file, and a server configured to process the audio file and expose an application programming interface (API) to provide access to the audio file to one or more data consumer devices. In some instances, a condition report server is configured to access the application programming interface to retrieve a version of the audio file and include data describing the audio file within a vehicle condition report. Additionally, tags may be added to the audio file based on detected engine conditions. Detection of engine conditions may be based on use of trained models.

Abstract: A propulsion system for an aircraft includes an engine, a plurality of sensors, and a controller. The engine includes an air intake. The plurality of sensors includes an outside air temperature (OAT) sensor and an air intake sensor. The OAT sensor is disposed outside the engine and configured to measure an OAT. The air intake sensor is disposed inside the air intake and configured to measure an air intake temperature (T1). The controller is configured to: calculate an actual charge heating value (CHactual), compare the CHactual to a charge heating threshold value (CHthresh) to identify the CHactual is greater than or less than the CHthresh, identify a presence or an absence of an unusual engine performance condition for the engine, and identify a presence or an absence of a blockage condition of the air intake based on the CHactual greater than the CHthresh and the presence of the unusual engine performance condition.

Abstract: A multi-mode microwave waveguide blade sensing system includes a transceiver, a waveguide, and a probe sensor. The transceiver generates a microwave energy signal having a first waveguide mode and a different second waveguide mode. The waveguide includes a first end that receives the microwave energy signal. The probe sensor includes a proximate end that receives the microwave energy signal from the transceiver and a distal end including an aperture that outputs the microwave energy signal. The probe sensor directs the microwave energy signal at a first direction based on the first waveguide mode and a different second direction different based on the second waveguide mode. The probe sensor receives different levels of reflected microwave energy based at least in part on a location at which the at least one microwave energy signal is reflected from the machine.

Abstract: The reliability of path planning calculation can be evaluated with low load without using multiplexing of calculation or an additional sensor.

Abstract: A fuel temperature control system and a method of controlling a fuel temperature for a turbine engine including supplying an aviation fuel to a fuel nozzle fluidly coupled to a combustion chamber. A fuel temperature sensor for determining at least one input parameter to define an inlet fuel temperature of the aviation fuel in the fuel nozzle. A controller for receiving the at least one input parameter and for calculating a calculated flow number in the fuel nozzle. The controller capable of comparing the calculated flow number and a reference flow number associated with a threshold during a steady state condition to determine if the aviation fuel is boiling inside the fuel nozzle.

Abstract: Systems and methods for high bandwidth control of thrust response for turbofan or turboprop engines are provided. Such systems and methods include an engine control system that processes a rate command and a feedback signal from an engine to generate separate fuel and electric machine control signals that respectively control fuel and electric machine dynamics of the engine to produce engine dynamics that result in desired thrust response.

Abstract: In accordance with at least one aspect of this disclosure, a fluid system of an aircraft includes a primary fluid conduit that conveys a primary fluid, and a leak detection system disposed around at least a portion of the primary fluid conduit and forming one or more detection volumes. The leak detection system determines whether there is a primary fluid leak into the one or more detection volumes by sensing a pressure change in the one or more detection volumes.

Abstract: Method for controlling a clearance between the tips of the blades of a rotor of an aircraft engine turbine and a turbine ring, comprising the estimation of the clearance to be controlled and the control of a valve delivering an air stream directed towards the turbine ring based on the thus estimated clearance, this method comprising: the detection of a transient acceleration phase based on at least one parameter representative of the engine; the receipt of a data relating to the altitude of the aircraft; the determination of data representative of the temperature of the rotor during the transient acceleration phase and in steady speed and the calculation of a relative temperature deviation.

Abstract: An aircraft that includes a hybrid-electric propulsion system is provided. In one aspect, the hybrid-electric propulsion system includes at least one propulsor that includes a gas turbine engine and an electric machine mechanically coupled with a spool of the gas turbine engine. When idle operation is commanded, electrical power is provided to the electric machine to cause the electric machine to apply torque to the spool and fuel provided to the engine can be reduced. Thus, the electric machine is controlled to provide a power assist to maintain the engine at the commanded idle speed whilst reducing fuel consumption.

Abstract: An output corrector is provided with an adjustment coefficient creating unit which creates an adjustment coefficient, an output adjusting unit which adjusts a control output using the adjustment coefficient, and an output accepting unit which accepts an output from an output meter for detecting the output of a gas turbine. The adjustment coefficient creating unit includes a first coefficient element calculating unit which calculates a first coefficient element, a second coefficient element calculating unit which calculates a second coefficient element, and an adjustment coefficient calculating unit which calculates the adjustment coefficient using the first and second coefficient elements. The first coefficient element is the ratio of an immediately preceding output in an immediately preceding time period, to a reference output at a reference time point in the past. The second coefficient element is the ratio of the current output in the current time period, to the immediately preceding output.

Abstract: A method is provided for a gas turbine engine. During this method, a first lubricant parameter is determined during a first period of an engine operating cycle. The first lubricant parameter is indicative of a first quantity of lubricant within a reservoir of the gas turbine engine. A second lubricant parameter is determined during a second period of the engine operating cycle. The second lubricant parameter is indicative of a second quantity of the lubricant within the reservoir. The first lubricant parameter and the second lubricant parameter are compared to determine a lubricant consumption parameter. The lubricant consumption parameter is indicative of a quantity of the lubricant consumed by the gas turbine engine during the engine operating cycle.

Abstract: A wireless sensor system of a gas turbine engine of an aircraft can include a plurality of wireless sensors distributed within an engine core of the gas turbine engine and an energy harvesting system including one or more energy harvesting devices configured to convert mechanical or thermal energy within the gas turbine engine into electric power and provide the electric power to the wireless sensors. The wireless sensor system can also include a data concentrator coupled to the gas turbine engine. The data concentrator can be configured to receive a plurality of wireless sensor data from the wireless sensors and transmit the wireless sensor data to a communication adapter of the gas turbine engine.

Abstract: A computer-implemented system and process of producing a metric quality grade profile for use during inspection of DPM symbol marked on parts may include storing average metrics measured in a controlled environment for a “golden” sample. Measurements of the DPM symbol of the “golden” sample may be performed. Measurements of the metrics of the “golden” sample in an uncontrolled environment may be performed. Average metrics from the uncontrolled environment may be calculated. The averaged metrics from the controlled and uncontrolled environment may be compared. The user may be enabled to set an acceptable grade for the individual metrics. The acceptable grades for the individual metrics as a profile of the DPM symbol in memory.

Abstract: A method of determining an inlet total air pressure includes determining a first parameter indicative of a first inlet total air pressure. The method includes executing a sequence that includes: determining a mass air flow passing through the air inlet based on the first parameter, determining a Mach number of air passing through the air inlet based on the mass air flow, determining a static air pressure at the air inlet, determining an air pressure ratio based on the Mach number, generating a subsequent parameter indicative of the revised inlet total air pressure based on the air pressure ratio and the static air pressure, and substituting the subsequent parameter for the first parameter. The method includes executing at least one additional instance of the sequence with the subsequent parameter, and outputting the subsequent parameter as the inlet total air pressure.

Abstract: An electronic controller for an engine and a propeller, a control system and related methods are described herein. The control system comprises the controller having a first channel and a second channel independent from and redundant to the first channel. Each channel comprises a control processor configured to receive first engine and propeller parameters and to output, based on the first engine and propeller parameters, at least one engine control command and at least one propeller control command. Each channel also comprises a protection processor configured to receive second engine and propeller parameters and to output, based on the second engine and propeller parameters, at least one engine protection command and at least one propeller protection command. The control system comprises sensors for measuring the parameters of the engine and/or the propeller and effectors configured to control the engine and the propeller.

Abstract: A method of operating an aircraft including a gas turbine engine and a plurality of fuel tanks arranged to provide fuel to the gas turbine engine, where at least two of the fuel tanks contain fuels with different fuel characteristics. The method includes obtaining a flight profile for a flight of the aircraft; and determining a fuelling schedule for the flight based on the flight profile and the fuel characteristics. The fuelling schedule governs the variation with time of how much fuel is drawn from each tank. Fuel input to the gas turbine engine may then be controlled in operation in accordance with the fuelling schedule.

Abstract: A gas turbine engine includes a fuel cell assembly including a fuel cell stack and defining a fuel cell assembly operating parameter, a fuel source, and a turbomachine. The turbomachine includes a compressor section, a combustor, and a turbine section arranged in serial flow order. The combustor is configured to receive a flow of fuel from the fuel source and further configured to receive output products from the fuel cell stack. A controller is configured to perform operations including receiving data indicative of system operation conditions, determining a set of fuel cell operating conditions to move the system emission output into or maintain the system emission output within an emissions range, and controlling the fuel cell assembly operating parameter according to the determined set of fuel cell operating conditions.

Abstract: A propulsion system for an aircraft comprises a gas turbine engine; a plurality of fuel tanks arranged to contain different fuels to be used to power the gas turbine engine, wherein the fuels have different calorific values; and a fuel manager. The fuel manager is arranged to store information on the fuel contained in each fuel tank and to control fuel input to the gas turbine engine in operation by selection of a specific fuel or fuel combination from one or more of the plurality of fuel tanks based on thrust demand of the gas turbine engine such that a fuel with a lower calorific value is supplied to the gas turbine engine at lower thrust demand.

Abstract: A method and system for cleaning a fuel nozzle during engine operation is provided. Operations include operating the compressor section to provide the flow of oxidizer at a first oxidizer flow condition to the combustion chamber, wherein the first oxidizer flow condition comprises an environmental parameter; operating the fuel system at a first fuel flow condition to produce a fuel-oxidizer ratio at the combustion chamber; comparing the environmental parameter to a first environmental parameter threshold; and transitioning the fuel system to a second fuel flow condition corresponding to a cleaning condition at the fuel nozzle if the environmental parameter is equal to or greater than the first environmental threshold.

Abstract: A control system of a gas turbine engine is provided. The engine has a fuel flow metering valve which regulates a fuel flow to the engine, and one or more variable geometry components which are movable between different set points to vary an operating configuration of the engine. The control system has an engine fuel control sub-system which provides a fuel flow demand signal for controlling the fuel flow metering valve. The control system further has a variable geometry control sub-system which determines current set points to be adopted by the variable geometry components given the current engine operating condition in order to comply with one or more engine constraints. The control system further has an optimiser that receives the current set points and determines adjusted values of the set points which optimise, while complying with the engine constraints, an objective function modelling a performance characteristic of the engine, the objective function adapting to change in engine performance with time.

Abstract: A redundant control system includes a plurality of channels each including a processing system configured to execute a control application for a controlled system. The redundant control system also includes a switchover artificial intelligence control operable to evaluate a state of the channels of the redundant control system, monitor a plurality of input/output data and communication data of the channels, and apply a fault model to determine one or more component faults and system faults of the channels based on the state, the input/output data, and the communication data. The switchover artificial intelligence control is further operable to command a switchover of a control function from one of the channels having a lower health status to one of the channels having a higher health status based on the component faults and system faults of the channels.

Abstract: Methods for monitoring engine health of an aircraft having a first engine and a second engine are provided. In one example, the method includes obtaining a first turbine gas temperature of the first engine and a second engine turbine gas temperature of the second engine from a first flight. The first turbine gas temperature and the second turbine gas temperature are related to each other to define a first value. The first value is compared to a data set for monitoring the engine health.

Abstract: Herein provided are methods and systems for producing reverse thrust in a multi-engine propeller aircraft, comprising: obtaining, at a first engine controller of a first engine of the aircraft, a first power request for the first engine for producing reverse thrust; determining, at the first engine controller, a first blade angle for a first propeller coupled to the first engine; obtaining, at the first engine controller and from a second engine controller of a second engine of the aircraft, a second power request for the second engine and a second blade angle for a second propeller coupled to the second engine; and when the second power request is indicative of a request for producing reverse thrust and when the first and second blade angles are beyond a predetermined threshold, commanding, via the first engine controller, the first engine to produce reverse thrust based on the first power request.

Abstract: Systems and methods for configuring operation of an engine are described herein. A computer-readable label associate with the engine is read by a mobile device to obtain label information having at least one trim value for the engine encoded therein. The at least one trim value is extracted from the label information on the mobile device. The at least one trim value is wirelessly transmitted from the mobile device to a data transmission unit of the engine. The data transmission unit is configured for instructing an electronic engine controller to trim the engine with the at least one trim value during operation of the engine.

Abstract: A method for controlling a clearance control valve of a turbomachine wherein, during a maneuver to increase engine speed in cruise phase, a command to reduce the opening of the clearance control valve is actuated by a Full Authority Digital Engine Control based on a change in the state of a step-climb signal provided by a flight management system in order to increase clearances at the tips of the turbomachine blades and an increase in the opening of the clearance control valve follows its reduction, at the expiry of either of the following two time limits: a first time limit starting at the change in the state of the step-climb signal and determined not to penalize the performance of the engine for too long and a second time limit starting at the end of the maneuver and determined as a function of a thermal time constant of the casing.

Abstract: This application provides a temperature gradient control system for a double wall casing of a compressor. The double wall casing may include an inner casing and an outer casing such that a flow of air is pulled through the double wall casing. The temperature gradient control system may include upper discharge piping with an upper modulation valve and a lower discharge piping with a lower modulation valve. The upper modulation valve and/or the lower modulation valve modulate the flow air pulled through the double wall casing to reduce a temperature gradient across the outer casing.

Abstract: A distributed control system for a turbomachine and method of operating the distributed control system are provided. In one aspect, a distributed control system includes a central controller and a distributed controller communicatively coupled thereto. The distributed controller has one or more associated local actuators and one or more associated local sensors. The actuators and the sensors are communicatively coupled with the distributed controller. If a communication link between the central controller and the distributed controller becomes faulty, the distributed controller enters an autonomous safety mode. In this mode, the distributed controller uses a combination of its own associated local sensors and past commands received from the central controller to autonomously govern its associated local actuators to maintain safe operation of the turbomachine.

Abstract: Disclosed is a method for compiling an equivalent acceleration spectrum of creep under variable temperatures and loads. The method includes following steps: respectively carrying out a material high-temperature tensile test, material high-temperature creep tests and creep tests under two-stage variable temperatures and loads, and calculating values of a parameter p in a creep damage accumulation model under two-stage variable temperatures and loads; based on a nonlinear damage accumulation model under multi-stage variable temperatures and loads, calculating a damage D caused by a multi-stage variable temperatures and loads creep load spectrum by utilizing values of parameter p; based on the principle of consistency of damage D, transforming the multi-stage variable temperatures and loads creep load spectrum into an equivalent acceleration spectrum of a first-order maximum creep load, and finally compiling the equivalent acceleration spectrum of creep under variable temperatures and loads.

Abstract: A control device controls a magnetic field generated by a magnetic field generator, and includes a magnetic field controller that controls the magnetic field generator based on a detected value by a magnetic field sensor. The magnetic field controller receives a command value generated by the magnetic field generator, and the detected value. The magnetic field controller generates an error signal based on an error between the command value and the detected value and outputs to the magnetic field generator a control signal amplified by a control gain against the error. The control gain includes: a first gain that becomes smaller as a frequency of the error signal gets higher; and a second gain that gets larger as an amplitude of the error signal gets larger.

Abstract: A method of identifying a fuel contained in a fuel tank of an aircraft and arranged to power a gas turbine engine of the aircraft is performed by processing circuitry of the aircraft and includes: obtaining at least one fuel characteristic of any fuel already present in the fuel tank prior to refuelling; determining at least one fuel characteristic of a fuel added to the fuel tank on refuelling; and calculating at least one fuel characteristic of the resultant fuel in the fuel tank after refuelling. The method may further controlling the propulsion system of the aircraft based on the calculated at least one fuel characteristic of the resultant fuel in the fuel tank after refuelling.

Abstract: Systems, program products, and methods for detecting thermal stability within gas turbine systems are disclosed. The systems may include a computing device(s) in communication with a gas turbine system, and a plurality of sensors positioned within or adjacent the gas turbine system. The sensor(s) may measure operational characteristics of the gas turbine system. The computing device(s) may be configured to detect thermal stability within the gas turbine system by performing processes including calculating a lag output for each of the plurality of measured operational characteristics. The calculated lag output may be based on a difference between a calculated lag for the measured operational characteristics and the measured operational characteristic itself. The calculated lag output may be also be based on a time constant for the measured operational characteristics. The computing device(s) may also determine when each of the calculated lag outputs are below a predetermined threshold.

Abstract: An assistance method for assisting a pilot of a single-engined rotary-wing aircraft during a flight phase in autorotation, the aircraft including a hybrid power plant provided with a main engine, with an electric machine, with a main gearbox, and with an electrical energy storage device. The aircraft also includes a main rotor driven by the hybrid power plant. In the method, during a flight, operation of the main engine is monitored in order to detect a failure, in particular by means of a drop in power on the main rotor, then, when a failure of the main engine is detected, the electric machine is controlled to deliver auxiliary power We to the main rotor, making it possible to assist a pilot of the aircraft in performing the flight phase in autorotation following the failure.

Abstract: A system, apparatus, and method for controlling an engine system can provide fuel reactivity compensation control for an engine of the engine system. Pilot fuel quantity supplied to the engine can be controlled using a nitrous oxide (NOx) error. Likewise, air-to-fuel ratio (AFR) for the engine can be controlled using the NOx error. Each of a pilot fuel offset and an AFR control trim can be generated using the NOx error. The pilot fuel offset and the AFR control trim can be used to control the pilot fuel quantity and the AFR, respectively.

Abstract: A method for checking the maximum available power of a turbine engine of an aircraft equipped with two turbine engines configured to operate in parallel and together to supply a necessary power to the aircraft during a flight phase includes: placing one of the turbine engines in a maximum take-off power regime, and adjusting a power supplied by the other turbine engine, such that the turbine engines continue to supply the necessary power to the aircraft during the flight phase; determining a power supplied by the turbine engine placed in the maximum take-off power regime, and processing the supplied power determined in this way, in order to deduce a piece of information relating to the maximum available power.

Abstract: The present disclosure relates to a novel method to detect an imminent compressor stall by using nonlinear feature extraction algorithms. The present disclosure focuses on the small nonlinear disturbances prior to deep surge and introduces a novel approach to identify these disturbances using nonlinear feature extraction algorithms including phase-reconstruction of time-serial signals and evaluation of a parameter called approximate entropy. The technique is applied to stall data sets from a high-speed centrifugal compressor that unexpectedly entered rotating stall during a speed transient and a multi-stage axial compressor with both modal- and spike-type stall inception. In both cases, nonlinear disturbances appear, in terms of spikes in approximate entropy, prior to surge. The presence of these pre-surge spikes indicates imminent compressor stall.

Abstract: A system and method for operating a combustion system comprising a fuel nozzle defining at least one main fuel circuit and at least one pilot fuel circuit is generally provided. The method includes determining an overall flow of fuel, the overall flow of fuel defining a sum total fuel through the main fuel circuit and the pilot fuel circuit; determining a plurality of ranges of ratios of main fuel flow through the main fuel circuit versus pilot fuel flow through the pilot circuit from the overall flow of fuel, wherein each range of ratios is based on a combustion criterion different from one another; determining a resultant range of ratios of main fuel flow versus pilot fuel flow based on a hierarchy of combustion criteria, wherein the hierarchy of combustion criteria provides a priority ranking of the combustion criterion; and flowing the overall flow of fuel to the main fuel circuit and the pilot fuel circuit based on the resultant range of ratios of main fuel flow versus pilot fuel flow.

Abstract: A method of managing a gas turbine engine includes the steps of detecting an airspeed and detecting a fan speed. A parameter relationship is referenced related to a desired variable area fan nozzle position based upon at least airspeed and fan speed. The detected airspeed and detected fan speed is compared to the parameter relationship to determine a target variable area fan nozzle position. An actual variable area fan nozzle position is adjusted in response to the determination of the target area fan nozzle position and at least one threshold.