An aircraft propulsion unit including two distinct fan spools, and including a first duct and a second duct extending downstream of the two fan spools, the propulsion unit including a control ring disposed on one of the ducts, downstream of one of the fan spools, with at least one annular internal wall extending in an interior space of the duct, the control unit of the control ring being configured to modify the shape of the internal wall, and to cause an air passage cross section in the duct to vary at the ring, a device for acquiring acoustic signals generated by acoustic waves propagating downstream of the fan spools, and a device for processing the acoustic signals, configured to measure a dephasing between the acoustic waves and to control the control ring depending on the dephasing.

Disclosed herein is a method of automatically determining an operating condition of at least part of a gas turbine engine 10 for an aircraft, the method comprising: measuring one or more gas pressure waves by a gas pressure detector 401, wherein the gas pressure detector 401 is located in the gas turbine engine 10; and automatically determining, by a computing system, an operating condition of at least part of a gas turbine engine 10 in dependence on an output signal of the gas pressure detector 401.

A monitoring system for monitoring behaviour of a rotating shaft is provided. The system includes a phonic wheel which is mounted coaxially to the shaft for rotation therewith, the phonic wheel having a number N of teeth in a circumferential row. The system further includes a first sensor configured to detect the passage of the teeth of the phonic wheel by generating a first alternating measurement signal which includes (i) a primary oscillatory component having a frequency of fN, where f is the rotational frequency of the shaft, and (ii) a secondary oscillatory component of frequency f when the phonic wheel precesses such that each revolution of the shaft a clearance between the phonic wheel and the first sensor cyclically varies between a maximum value and a minimum value. The system further includes a processor unit configured to determine the durations of successive first speed samples, each first speed sample being a block of integer n successive cycles of the primary oscillatory component of the first alternating measurement signal. The secondary oscillatory component of the first alternating measurement signal, when present, produces a cyclical variation of frequency fin the durations of the successive first speed samples. The processor unit is further configured to detect any such cyclical variation of the first speed samples and to compare a detected cyclical variation of the first speed samples against a threshold variation to determine therefrom if the phonic wheel is precessing.

A vibration detection device for detecting vibration of a cartridge including a bearing housing that accommodates a rotor coupling a wheel and a rotor shaft, and a bearing rotatably supporting the rotor, the bearing housing including a lubricant-oil passage port for allowing lubricant oil to pass through an interior of the bearing housing, includes: a sensor mount attached to an oil-flow-passage forming member configured to be capable of connecting to and separating from the bearing housing, the oil-flow-passage forming member including, inside thereof, an oil flow passage through which one of lubricant oil to be supplied to the interior of the bearing housing via the lubricant-oil passage port or lubricant oil discharged from the interior of the bearing housing via the lubricant-oil passage port flows; a vibration sensor disposed on the sensor mount; and a vibration transmission leg portion connected to the sensor mount and configured to be in contact with the bearing housing in a state where the oil-flow-passage forming member is connected to the bearing housing.

A gas turbine engine generates noise during use, and one particularly important flight condition for noise generation is take-off. A gas turbine engine that has high efficiency provides low noise, in particular from the fan and the turbine that drives the fan. Values are defined for a noise parameter NP that results in a gas turbine engine having reduced combined fan and turbine noise.

Health monitoring systems and associated methods for gas turbine engines are provided. A health monitoring method includes using a microphone to acquire operation data indicative of acoustic energy generated in a core gas path of the gas turbine engine. The operation data is compared to reference data indicative of an acoustic signature of fluid noise associated with a non-normal condition in the core gas path of the gas turbine engine. Based on the comparing of the operation data to the reference data, the non-normal condition is determined to exist within the core gas path of the gas turbine engine. A signal indicative of the existence of the non-normal condition within the core gas path of the gas turbine engine is output.

An apparatus externally detects the presence of a fault or malfunction in a gas turbine using the sound of air passing through vanes. The apparatus includes a sound sensor configured to sense a sound; a signal converter configured to convert the sensed sound into a digital signal; a data processor configured to perform a sound quality evaluation by analyzing a sound quality of the digital signal; and a display configured to display a result of the sound quality evaluation. The gas turbine includes a compressor housed in a compressor casing in which an inlet guide vane (IGV) assembly and a variable guide vane (VGV) assembly are installed. The sound sensor includes a plurality of microphones are installed outside the compressor casing at positions adjacent to at least one of a vane of the IGV assembly and a vane of the VGV assembly.

A gas turbine engine generates noise during use, and one particularly important flight condition for noise generation is take-off. A gas turbine engine that has high efficiency provides low noise, in particular from the fan and the turbine that drives the fan. Values are defined for a noise parameter NP that results in a gas turbine engine having reduced combined fan and turbine noise.

A health monitoring system including an array of microphones, a data collection system, and analytic software used to detect health status, pending malfunctions, or faults of several disparate, engine subsystems. The system can be used to monitor health of the main engines, the engine nacelles, and auxiliary power units (APU) on the aircraft.

A system for controlling an operation of a combustor in a gas turbine that includes: an acoustic sensor configured to periodically measure a pressure of the combustor and generate a raw data stream having the pressure data points resulting from the periodic measurements; and a blowout detection unit configured to receive the raw data stream from the acoustic sensor. The blowout detection unit may include a processor and a machine-readable storage medium on which is stored instructions that cause the processor to execute a procedure related to a detection of a blowout precursor. The procedure may include an ensemble approach in which the detection of the blowout precursor depends upon a outcomes generated respectively by separate detection analytics.