A method of operation for a gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, reducing a rotational speed of a fan relative to a shaft through a gear train, driving the shaft with a low pressure turbine, driving a high pressure compressor with a high pressure turbine, communicating airflow from the fan through a bypass passage defined by a nacelle, the nacelle extending along an engine axis and surrounding the fan, discharging the airflow through a variable area fan nozzle defining a discharge airflow area, detecting an airfoil flutter condition associated with adjacent airfoils of the fan, and moving the variable area fan nozzle to vary the discharge airflow area and mitigate the airfoil flutter condition.

An infrared imaging device includes a case, a plurality of electronic components, and a heat transfer structure. The plurality of electronic components is configured to collect data and have a predetermined temperature parameter. The plurality of electronic components is disposed within the case. The heat transfer structure is disposed within the case. The heat transfer structure is configured to conduct heat away from the plurality of electronic components. The heat transfer structure is further configured to regulate a temperature of the electronic components below the predetermined temperature parameter.

The invention relates to a measuring device for an aircraft engine, characterized by at least one probe device for measuring a physical and/or chemical state in at least one measuring space within the aircraft engine, wherein the at least one measuring space is fluidically connected to a cavity, and at least one air-conducting device, which is fluidically coupled to the cavity in such a manner that a fluid flow, in particular a gas flow, can be removed from the at least one cavity to a pressure sink. The invention also relates to an aircraft engine and to a measuring method.

The invention relates to a measuring device for an aircraft engine, characterized by at least one probe device for measuring a physical and/or chemical state in at least one measuring space within the aircraft engine, wherein the at least one measuring space is fluidically connected to a cavity, and at least one air-conducting device, which is fluidically coupled to the cavity in such a manner that a fluid flow, in particular a gas flow, can be removed from the at least one cavity to a pressure sink. The invention also relates to an aircraft engine and to a measuring method.

A method and system for monitoring a temperature of a gas turbine engine are described. The method comprises obtaining individual sensor readings from functioning temperature sensors of a sensor array, where a number of the functioning temperature sensors is less than a total number of temperature sensors in the sensor array; applying correction factors to the individual sensor readings of the functioning temperature sensors based on deviations of the individual sensor readings from a total average temperature of all the temperature sensors in the array, to obtain corrected individual sensor readings; and determining a corrected total average temperature as a sum of the corrected individual sensor readings divided by the number of functioning temperature sensors.

A non-transitory computer readable medium with instructions stored thereon, the instructions executable by one or more processors for calculating base swirl in a gas turbine; and calculating relative swirl in the gas turbine. Also, a method for gas turbine maintenance, comprising identifying a combustor in need of repair or replacement within a gas turbine; and repairing or replacing the combustor; wherein said identifying comprises calculating base swirl of the gas turbine and calculating relative swirl of the gas turbine in order to associate a gas path from a thermocouple to the combustor in need of repair or replacement.

A method to monitor rotor blade vibration using unsteady casing pressure. The method applies a non-intrusive blade vibration monitoring technique by using an array of unsteady pressure sensors which may be flush-mounted in the casing of a compressor. The method comprises using spinning mode theory and temporal-spatial analysis to obtain frequency and nodal diameter information of spinning pressure waves associated with the rotor blade vibration. An example of the compressor can be a multistage axial compressor.

A method to monitor rotor blade vibration using unsteady casing pressure. The method applies a non-intrusive blade vibration monitoring technique by using an array of unsteady pressure sensors which may be flush-mounted in the casing of a compressor. The method comprises using spinning mode theory and temporal-spatial analysis to obtain frequency and nodal diameter information of spinning pressure waves associated with the rotor blade vibration. An example of the compressor can be a multistage axial compressor.

A method of estimating a parameter of a fluid flowing in a passage includes: having a plurality of instruments operable to measure one or more fluid properties flowing in the passage, the plurality of instruments being disposed in the passage and arranged within a common measurement plane; assigning a stream tube to each instrument, each stream tube represents a region of space in the common measurement plane within the passage and each stream tube surrounds one of the plurality of instruments, the stream tubes together correspond to the cross-sectional shape and area of the passage in the common measurement plane; measuring the one or more fluid properties using the instruments to obtain one or more measured values for each stream tube; using the measured value(s) for each stream tube to calculate a derived value for each stream tube; and summing the derived values across all of the stream tubes.

An environmental condition may be measured with a sensor (10) including a wire (20) having an ultrasonic signal transmission characteristic that varies in response to the environmental condition by sensing ultrasonic energy propagated through the wire using multiple types of propagation, and separating an effect of temperature on the wire from an effect of strain on the wire using the sensed ultrasonic energy propagated through the wire using the multiple types of propagation. A positive feedback loop may be used to excite the wire such that strain in the wire is based upon a sensed resonant frequency, while a square wave with a controlled duty cycle may be used to excite the wire at multiple excitation frequencies. A phase matched cone (200, 210) may be used to couple ultrasonic energy between a waveguide wire (202, 212) and a transducer (204, 214).