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.

A combustor includes fuel nozzles that extend in an axial direction of a combustor main body and are capable of injecting fuel from injection holes on a combustion chamber side. The combustor includes a phase adjusting unit which partially changes a flow path cross-sectional area of at least one of the fuel nozzles in the axial direction such that phases of flow rate fluctuation of fuel do not match with respect to at least two of the fuel nozzles.

The present disclosure provides a centrifugal blower assembly that includes a centrifugal fan and a scroll casing housing the centrifugal fan. The scroll casing includes a scroll starting position, a scroll ending position and an air passage extending between the scroll starting and ending positions. The scroll ending position is downstream from the scroll starting position relative to airflow through the scroll casing. The centrifugal blower assembly further includes an air outlet extending from the scroll ending position and a plurality of resonators mounted on an exterior surface of the air outlet. Each of the plurality of tuned resonators has respective cavities in fluid communication with inside of the air outlet. Each of the cavities has respective different volumes, heights, widths, and/or lengths from each other.

An aircraft propulsion system comprises first and second thrust producing gas turbine engines. The system comprises a controller configured to determine a required overall propulsion system thrust level, and determine an engine core power level contribution from each aircraft gas turbine engine such that the overall propulsion system produces a minimum overall noise level and meets the required overall propulsion system thrust level. In meeting the minimum overall noise level, at least the first and second gas turbine engines are operated at different engine core power settings.

Methods, apparatus, systems and articles of manufacture are disclosed for closed loop control of a gas turbine. An example apparatus includes a frequency band splitter to separate a combustion pulsation signal into a plurality of frequency bands. The example apparatus includes a plurality of subcontrollers, each subcontroller corresponding to one of the frequency bands. Each subcontroller is to be activated at an amplitude threshold associated with the normal operating set point of the frequency band and to generate a correction value while the corresponding frequency band is operating beyond the amplitude threshold. The example apparatus includes a net correction output calculator to aggregate the correction values to generate an aggregated correction value. The example apparatus includes a subcontroller limiter having a maximum limit and/or a minimum limit to inhibit subcontroller(s) from increasing their respective correction values when aggregated correction value is to exceed the maximum limit and/or minimum limit.

Methods and systems for processing a signal indicative of at least one operating condition of a gas turbine engine to remove noise associated therewith are provided. The method and systems receive a signal from one or more sensors operably coupled to a gas turbine engine, retrieves one or more known system parameters and a previously determined average signal, and processes the signal using the system parameter and the previously determined average signal to remove noise therefrom. In some of the described methods and systems, the processed signal is then compared to predetermined upper and lower limits, and, if the processed signal exceeds the limits, at least one component of the gas turbine engine, such as a fuel-flow split, is adjusted in an effort to bring the signal back within the limits.

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 may include at least one of a fan inlet case and a bypass duct case. Additionally, the gas turbine engine may include a variable volume acoustic damper coupled to the at least one of the fan inlet case and the bypass duct case, wherein the variable volume acoustic damper is configured to damp acoustic energy. The variable volume acoustic damper may include a case and a diaphragm movably coupled within the case. An acoustic volume may be defined by a position of the diaphragm relative to the case and the acoustic volume may correspond to and may be configured to damp acoustic energy of a gas turbine engine.

A system for identifying timeframes for borescope inspections for a gas turbine engine, having: monitoring systems monitor engine conditions, derive engine condition information and communicate such information to processors; feature interpreter module electronically communicates (i) with processors to process engine condition information, and (ii) feature interpreter information to processors, such information defines a probability of a FOD event; accumulator module electronically communicates (i) with processors to processes feature interpreter information, stored information since a last borescope inspection, and (ii) accumulator information to processors, such information defines an accumulated probability of a FOD event; and predictor and inspection planner module electronically communicates (i) with processors to processes accumulator information and stored information defines a threshold limits for a probability of a FOD event, and (ii) predictor and inspection planner information to processors, such information identifies a timeframe for a next borescope inspections predicted to occur before a FOD event.

A rotating machine includes a rotating part rotatably supported by a bearing disposed between a first stationary part and a second stationary part. A rubbing position identification device determines, when rubbing occurs on the rotating machine, whether the occurrence position of the rubbing is a first unit including the first stationary part or a second unit including the second stationary part, based on an AE signal detected by a pair of first AE sensors attached to the first stationary part and the second stationary part, respectively.