Patent Description:
When ice forms on the fan blades of turbine engines, damage to the turbine engine may occur. For example, the ice releasing from individual fan blades may cause the fan to become unbalanced. The unbalanced rotation of the fan causes the fan to become uncentered within a fan casing. When the fan becomes uncentered, the fan blades may contact the inside of the fan casing and wear away liner material from the interior of the fan casing. The worn away material increases a gap between the tip of the fan blade and the interior surface of the fan casing. The increase in the gap may reduce engine performance and/or cause other difficulties with flight of an aircraft powered by the turbine engine.

Conventional systems for detecting these "rubout" events rely on monitoring a magnitude of vibration of the turbine engine at the rotational frequency of the rotor in the turbine engine. These conventional systems may not detect all rubout events and may falsely indicate a rubout event has occurred. Accordingly, some conventional systems indicate that the turbine engine should be inspected after every flight through known icing conditions. Such inspection requires manual measurement of the gaps between the fan blades and fan casing. The time and manpower requirement for such manual inspections may cause delays and additional costs to the operators of an aircraft that includes the turbine engine. <CIT> relates to managing vibrations in gas turbine engines. <CIT> relates to an apparatus to monitor and control fan blade motion caused by harmonic modes. <CIT> relates to control of flutter of fan blades of turbine engines.

In a first example, an aircraft includes a turbine engine according to claim <NUM>.

In a second example, a device for damage monitoring of a turbine engine having a fan case with a fan case liner according to claim <NUM>.

In a third example, a method for determining whether damage to the fan case liner of a turbine engine has occurred due to icing conditions, according to claim <NUM>.

Advantages of the systems and methods described herein will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:.

As used herein, the term module refers to any hardware, software, firmware, electronic control component, processing logic, and/or processor device, individually or in any combination, including without limitation: application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.

In addition, those skilled in the art will appreciate that embodiments of the present disclosure may be practiced in conjunction with any number of systems, and that the systems described herein are merely exemplary embodiments of the present disclosure.

It is further noted that the systems and methods may be implemented on various types of data processor environments (e.g., on one or more data processors) which execute instructions (e.g., software instructions) to perform operations disclosed herein. Non-limiting examples include implementation on a single general purpose computer or workstation, or on a networked system, or in a client-server configuration, or in an application service provider configuration. For example, the methods and systems described herein may be implemented on many different types of processing devices by program code comprising program instructions that are executable by the device processing subsystem. The software program instructions may include source code, object code, machine code, or any other stored data that is operable to cause a processing system to perform the methods and operations described herein. Other implementations may also be used, however, such as firmware or even appropriately designed hardware configured to carry out the methods and systems described herein. For example, a computer can be programmed with instructions to perform the various steps of the flowcharts described herein.

The systems' and methods' data (e.g., associations, mappings, data input, data output, intermediate data results, final data results, etc.) may be stored and implemented in one or more different types of computer-implemented data stores, such as different types of storage devices and programming constructs (e.g., memory, RAM, ROM, Flash memory, flat files, databases, programming data structures, programming variables, IF-THEN (or similar type) statement constructs, etc.). It is noted that data structures describe formats for use in organizing and storing data in databases, programs, memory, or other computer-readable media for use by a computer program.

The systems and methods may be provided on many different types of computer-readable storage media including computer storage mechanisms (e.g., non-transitory media, such as CD-ROM, diskette, RAM, flash memory, computer's hard drive, etc.) that contain instructions (e.g., software) for use in execution by a processor to perform the methods' operations and implement the systems described herein.

The computer components, software modules, functions, data stores and data structures described herein may be connected directly or indirectly to each other in order to allow the flow of data needed for their operations. It is also noted that a module or processor includes but is not limited to a unit of code that performs a software operation, and can be implemented for example as a subroutine unit of code, or as a software function unit of code, or as an object (as in an object-oriented paradigm), or as an applet, or in a computer script language, or as another type of computer code. The software components and/or functionality may be located on a single computer or distributed across multiple computers depending upon the situation at hand.

Various embodiments disclosed herein describe methods and systems for detecting damage to housings of rotating components. Specifically, the methods and systems may be used for near real time identification of damage done to a turbine engine fan case liner resulting in increased fan tip clearances and loss of thrust. The methodology uses a tracked vibration filter that has been shown to correlate the presence of engine fan case liner rub out damage to the presence of vibration from the engine's higher orders/harmonics.

Referring now to <FIG>, an example of an aircraft <NUM> flying into icy conditions <NUM> is illustrated in accordance with some embodiments. Aircraft <NUM> includes a turbine engine <NUM>, monitor system <NUM>, and a sensor system <NUM>, among other systems. Although aircraft <NUM> is described in this description as an airplane, it should be appreciated that monitor system <NUM> may be utilized in other aircraft, land vehicles, water vehicles, space vehicles, or other machinery that utilizes rotating components contained within a case or housing without departing from the scope of the present disclosure. For example, monitor system <NUM> may be utilized in submarines, helicopters, airships, spacecraft, or automobiles.

Monitor system <NUM> is configured to monitor systems on aircraft <NUM> and to perform the methods described below. In the example provided, monitor system <NUM> is an external device coupled for electronic communication with a vibration sensor or engine controller of aircraft <NUM>. For example, monitor system <NUM> may have its own housing and input port to communicate with the sensor or engine controller and has built-in capability to process the engine vibration transducer signal(s) and decode engine tachometer signal(s) in near real time. Furthermore, monitor system <NUM> is configured to conduct spectral analysis to extract the spectral content from the vibration sensor signal and to calculate the inspection metrics. Accordingly, monitor system <NUM> may be used/plugged in only when aircraft <NUM> is expected to fly through icing conditions, or may be plugged in seasonally, all the time, or at any other time it may be desirable to monitor engine <NUM> for fan case liner damage. In some embodiments, monitor system <NUM> is integrated with an engine controller of aircraft <NUM>. For example, the method described below may be programmed directly into the engine controller.

In some embodiments, monitor system <NUM> is configured to vary a voltage input to interface with different engines or engine controllers according to the engine and/or aircraft make and model. In some embodiments, monitor system <NUM> is configured to provide power to vibration sensor <NUM> if needed. Monitor system <NUM> may be powered through the connection with aircraft <NUM> or externally without departing from the scope of the present disclosure.

Monitor system <NUM> includes at least one processor <NUM> and a non-transitory computer readable storage device or medium <NUM>. Non-transitory computer readable storage device or medium <NUM> is storage device for storing instructions for performing the method described below. At least one processor <NUM> is one or more data processors configured to execute the instructions to perform the method described below. The processor may be any custom made or commercially available processor, a central processing unit (CPU), a graphics processing unit (GPU), an auxiliary processor among several processors associated with monitor system <NUM>, a semiconductor based microprocessor (in the form of a microchip or chip set), a macroprocessor, any combination thereof, or generally any device for executing instructions. The computer readable storage device or medium may include volatile and nonvolatile storage in read-only memory (ROM), random-access memory (RAM), and keep-alive memory (KAM), for example. The computer-readable storage device or medium may be implemented using any of a number of known memory devices such as PROMs (programmable read-only memory), EPROMs (electrically PROM), EEPROMs (electrically erasable PROM), flash memory, or any other electric, magnetic, optical, or combination memory devices capable of storing data, some of which represent executable instructions, used by monitor system <NUM> in controlling aircraft <NUM>.

Although only one monitor system <NUM> is shown in <FIG>, embodiments of aircraft <NUM> may include any number of monitor systems <NUM> that communicate over any suitable communication medium or a combination of communication media and that cooperate to process the sensor signals, perform logic, calculations, methods, and/or algorithms. In various embodiments, one or more instructions of monitor system <NUM>, when executed by the processor, performs the methods described below.

Sensor system <NUM> includes one or more sensing devices that sense observable conditions of the exterior environment, the interior environment of aircraft <NUM>, or operational conditions and status of aircraft <NUM>. For example, sensor system <NUM> may include accelerometers, gyroscopes, RADARs, LIDARs, global positioning systems, optical cameras, thermal cameras, ultrasonic sensors, and/or other sensors. In the example provided, sensor system <NUM> includes a vibration sensor <NUM> physically coupled with turbine engine <NUM> to measure vibration of turbine engine <NUM>. Vibration sensor <NUM> may be any sensor configured to obtain vibration information for turbine engine <NUM>, such as an accelerometer or a velocimeter. Vibration sensor <NUM> outputs vibration sensor data that may be used to extract acceleration, velocity, and displacement data describing turbine engine <NUM>.

Referring now to <FIG>, and with continued reference to <FIG>, a method <NUM> for determining whether turbine engine damage has occurred is illustrated in accordance with some embodiments. In the example provided, monitor system <NUM> performs the tasks of method <NUM>. For example, instructions may be stored on storage device <NUM> and one or more processors <NUM> may be configured to execute the instructions. Other systems may be utilized to perform method <NUM> without departing from the scope of the present disclosure. In the example provided, method <NUM> is utilized to detect fan case liner damage in turbine engine <NUM>.

Task <NUM> retrieves a rotor rotation frequency of a turbine engine. For example, monitor system <NUM> may retrieve the rotor rotation frequency from sensor system <NUM>.

Task <NUM> forms a harmonic indicator based on at least one harmonic frequency of the rotor rotation frequency. As used herein, the term "harmonic frequency" includes all higher order integer and non-integer harmonic frequencies, but specifically excludes the fundamental frequency N1 that is sometimes called the first harmonic. An integer harmonic frequency is an integer multiple of the rotor rotation frequency. For example, monitor system <NUM> may form the harmonic indicator based on the harmonic frequencies n=<NUM>, <NUM>, <NUM>, <NUM>,. <NUM>, etc. as illustrated in <FIG>. The harmonic indicator may be a single harmonic frequency, multiple harmonic frequencies individually evaluated against a threshold, or may be a mathematical combination of a plurality of harmonic frequencies of the at least one harmonic frequencies. For example, multiple harmonic frequencies may be added, subtracted, multiplied, and otherwise combined with each other using any vector magnitude or aggregate magnitude methods to form the harmonic indicator. The actual numerical values used for the harmonic frequencies used may vary from those illustrated and will vary by engine and aircraft model. In some embodiments, the harmonic frequencies used to form the harmonic indicator are non-sequential. The harmonic indicator may indicate vibration caused from individual blades contacting the casing of turbine engine <NUM>.

Task <NUM> measures a broadband acceleration of the turbine engine. In the example provided, vibration sensor <NUM> is an accelerometer and the vibration sensor output from vibration sensor <NUM> measures the broadband acceleration. In some embodiments, mathematical operations may be performed on the vibration sensor output to result in a velocity, a displacement, or a jerk of the turbine engine.

Task <NUM> extracts a vibration amplitude at the at least one harmonic frequency. For example, monitor system <NUM> may extract the vibration amplitude from the vibration sensor signal using any suitable techniques for extracting frequency information from a broadband signal. The vibration amplitude is illustrated on the vertical axis of <FIG>.

Task <NUM> determines whether the harmonic indicator or the broadband acceleration indicate vibrations are present. For example, monitor system <NUM> may determine that vibrations are present when the harmonic indicator and/or the broadband acceleration exceed a first threshold. Monitor system <NUM> may determine whether the vibration amplitude of any individual harmonic frequency or of the aggregate magnitude is above a predetermined threshold that is based on noise and environmental effects to determine that there are vibrations present.

When vibrations are present, method <NUM> proceeds to task <NUM>. Task <NUM> indicates damage may have and/or has occurred. For example, monitor system <NUM> may indicate that turbine engine <NUM> may have taken damage in a Crew Alerting System (CAS) message presented to the flight crew of aircraft <NUM>. In the example provided, monitor system <NUM> causes aircraft <NUM> to generate a caution CAS message.

When vibrations are not present, method <NUM> proceeds to task <NUM>. Task <NUM> determines whether the harmonic indicator has reached a second threshold. For example, monitor system <NUM> may determine that the harmonic indicator exceeds a predetermined value that has been shown to correlate with damage to the specific turbine engine make and model or specific aircraft make and model.

When the harmonic indicator has not reached the second threshold, method <NUM> proceeds to task <NUM>. When the harmonic indicator has reached the second threshold, method <NUM> proceeds to task <NUM>.

Task <NUM> indicates that no damage has occurred. For example, monitor system <NUM> may continue operating without generating any CAS messages or other flight crew indications that damage has occurred. Method <NUM> ends after task <NUM>, but may be repeated for the entire duration of a flight or only when icy conditions <NUM> are detected.

Task <NUM> indicates that damage has occurred and indicates that manual inspection of the engine should be performed. For example, monitor system <NUM> may generate a warning CAS message to indicate that manual inspection of the fan casing of the turbine engine <NUM> should be performed.

The various embodiments described herein provide a solution to a technical problem. Specifically, the harmonics-based evaluation is more accurate than conventional methods and systems to detect damage to a fan case liner due to unbalanced rotation of a fan within a turbine engine. Additionally, the broadband acceleration-based evaluation is more accurate than conventional methods and systems to detect damage due to ice shedding from fan rotor blades in aircraft. The increased accuracy results in fewer manual inspections when no damage has occurred, resulting in fewer delays and reduced costs for aircraft operators.

Referring now to <FIG>, and with continued reference to <FIG>, a data flow <NUM> for a flow of data related to the method of <FIG> is illustrated in accordance with some embodiments. Task <NUM> represents a turbine engine operating in an aircraft. For example, turbine engine <NUM> may be operating in aircraft <NUM> during a flight that may encounter icing conditions <NUM>.

Turbine engine <NUM> generates a fan rotor speed signal <NUM>, a broadband engine vibration signal <NUM>, and various other data to be processed by aircraft computer <NUM>. It should be appreciated that aircraft computer <NUM> may be an engine controller on aircraft <NUM> or may be an external device that is connected to a data bus or other communication port for receiving vibration sensor data from vibration sensor <NUM>.

The aircraft computer converts <NUM> the fan rotor speed into a fan rotor frequency. For example, the fan rotor frequency may be expressed in cycles per second. The aircraft computer multiplies the fan rotor rotation frequency by an integer greater than one at <NUM>. In some embodiments, a non-integer value is used to calculate a non-integer harmonic at <NUM>. Tasks <NUM> and <NUM> are repeated for other integers greater than one for integer harmonics and/or for other non-integer numbers greater than one at <NUM>.

When vibration levels or a combination of levels determined at <NUM> surpass a pre-determined threshold, the appropriate aircraft systems are alerted to the possibility of fan case liner rub out damage at <NUM>. For example, aircraft <NUM> may generate a CAS message indicating that the fan case liner should be examined for potential damage.

Claim 1:
An aircraft (<NUM>), comprising:
a turbine engine (<NUM>) having a fan case with a fan case liner;
a vibration sensor (<NUM>) attached to the turbine engine and configured to output a vibration sensor signal that indicates broadband acceleration of the turbine engine; and
a processor (<NUM>) programmed to:
determine whether the broadband acceleration of the turbine engine indicates that damage to the fan case liner has occurred due to icing conditions as a result of unbalanced rotation of the fan; and
indicate that inspection of the fan case should be conducted in response to the broadband acceleration of the turbine engine indicating that damage to the fan case liner has occurred.