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EP-4321735-B1 - DETECTION OF GAS TURBINE ENGINE BLADE ABNORMALITIES BASED ON LIGHT REFLECTIONS

EP4321735B1EP 4321735 B1EP4321735 B1EP 4321735B1EP-4321735-B1

Inventors

  • LEE, JEREMIAH C.
  • McMENAMIN, Daniel
  • SHAW, Janet

Dates

Publication Date
20260506
Application Date
20230803

Claims (15)

  1. A method of inspecting blades (43) of a gas turbine engine (20) for abnormalities, comprising: projecting light from a light source (60) into an illumination area (64); utilizing a sensor (66) to record data of at least one reflection of the projected light (162; 262) from a blade that is part of a gas turbine engine (20) and is disposed in the illumination area (64); determining, based on the recorded data, whether the blade is abnormal; and based on the determining indicating that the blade is abnormal, providing a blade abnormality notification, characterised in that said projecting light includes projecting the light through at least one cylindrical lens (78) disposed between the light source (60) and the illumination area (64), and wherein said projecting light includes utilizing the at least one cylindrical lens (78) to arrange the projected light (162; 262) into a generally planar light sheet (84) in the illumination area (64) which forms a line or curve of a surface of the blade.
  2. The method of claim 1, wherein: the blade is one of a plurality of blades (43) that extend radially outwards from a hub (90); said projecting is performed while the plurality of blades rotate about a longitudinal axis (A) during operation of the gas turbine engine (20), such that the light source (60) projects light onto each of the plurality of blades as they pass through the illumination area (64); and said utilizing a sensor (66) and said determining are performed for reflections of the projected light (162; 262) from each of the plurality of blades.
  3. The method of claim 2, wherein said operation of the gas turbine engine (20) corresponds to a flight, and said projecting, utilizing, determining, and providing are performed during the flight.
  4. The method of claim 2 or 3, wherein based on a rotational speed of the hub (90), the notification is provided in a manner that indicates at least one of: a quantity of blades that are determined to be abnormal; or which one or more particular ones of the plurality of blades are abnormal.
  5. The method of any preceding claim, wherein: the light source (60) includes a laser; the at least one cylindrical lens includes a first cylindrical lens (76) and a second cylindrical lens (78); the first cylindrical lens (76) is concave, is disposed between the light source (60) and illumination area (64), and provides a decollimating feature that causes the projected light (162; 262) to diverge into a first light sheet (83) as the projected light (162; 262) approaches the second cylindrical lens (78); and the second cylindrical lens (78) is convex, is disposed between the first cylindrical lens (76) and the illumination area (64), and provides a collimating feature that causes the diverged projected light (162; 262) to become a second light sheet (84) that is more collimated than the first light sheet (83) as the projected light (162; 262) approaches the illumination areas.
  6. The method of claim 5, wherein: the first cylindrical lens (76) extends along a first longitudinal axis; the at least one cylindrical lens includes a third cylindrical lens that is concave, is disposed between the second cylindrical lens (78) and the illumination area (64), and extends along a second longitudinal axis; and the second longitudinal axis is rotated approximately 90° with respect to the first longitudinal axis.
  7. The method of any preceding claim, wherein: the light source (60) includes a plurality of light-emitting diodes; and the at least one cylindrical lens includes a convex cylindrical lens that causes the projected light (162; 262) to converge as it approaches the illumination area (64).
  8. The method of any preceding claim, wherein said utilizing a sensor (66) to record data of at least one reflection of the projected light (162; 262) comprises utilizing at least one photodiode to record the data.
  9. The method of any preceding claim, wherein: said utilizing the sensor (66) to record data includes recording a time trace of sensor data; and said determining, based on the recorded data, whether the blade is abnormal includes utilizing a neural network to analyze the time trace and determine whether the blade is abnormal, wherein the neural network is trained with historical data of reflections of projected light (162; 262) from blades of one or more gas turbine engines.
  10. A gas turbine engine (20), comprising: a light source (60) configured to project light into an illumination area (64); a hub (90) and a plurality of blades that extend radially outward from the hub (90) and are configured to rotate about a longitudinal axis through the illumination area (64); a sensor (66) configured to record data of at least one reflection of the projected light (162; 262) from one of the plurality of blades disposed in the illumination area (64); and processing circuitry configured to: determine, based on the recorded data, whether the blade is abnormal; and based on the determination indicating that the blade is abnormal, provide a blade abnormality notification, characterised in that the gas turbine engine (20) includes at least one cylindrical lens disposed between the light source (60) and the illumination area (64); and wherein the light source (60) is configured to project the light into the illumination area through the at least one cylindrical lens, and wherein the at least one cylindrical lens is configured to arrange the projected light (162; 262) into in a generally planar light sheet in the illumination area (64) that forms a line or curve on a surface of the blade.
  11. The gas turbine engine (20) of claim 10, wherein: the sensor (66) is configured to measure reflections of the projected light (162; 262) as the blades rotate through the illumination area (64); and the processing circuitry is configured to: based on a rotational speed of the hub (90), determine at least one of a quantity of blades that are abnormal or which one or more particular ones of the plurality of blades are abnormal; and provide the notification in a manner that indicates said at least one of the quantity of blades that are abnormal or which one or more particular ones of the plurality of blades are abnormal, and/or wherein the blades are fan blades in a fan section of the gas turbine engine (20).
  12. The gas turbine engine (20) of claim 10 or 11, wherein the sensor (66) includes at least one photodiode.
  13. The gas turbine engine (20) of claim 11 or 12, wherein: the light source (60) includes a laser; the at least one cylindrical lens includes a first cylindrical lens (76) and a second cylindrical lens (78); the first cylindrical lens (76) is concave, is disposed between the light source (60) and illumination area (64), and provides a decollimating feature that causes the projected light (162; 262) to diverge into a first light sheet (83) as the projected light (162; 262) approaches the second cylindrical lens (78); and the second cylindrical lens (78) is convex, is disposed between the first cylindrical lens (76) and the illumination area (64), and provides a collimating feature that causes the projected light (162; 262) to become a second light sheet (84) that is more collimated than the first light sheet (83) as the projected light (162; 262) approaches the illumination area (64),
  14. The gas turbine engine (20) of claim 13, wherein: the first cylindrical lens (76) extends along a first longitudinal axis (X1); the at least one cylindrical lens includes a third cylindrical lens (80) that is concave, is disposed between the second cylindrical lens (78) and the illumination area (64), and extends along a second longitudinal axis (X4); and the second longitudinal axis (X4) is rotated approximately 90° with respect to the first longitudinal axis.
  15. The gas turbine engine (20) of claim 13 or 14, wherein: the light source (60) includes a plurality of light-emitting diodes; the at least one cylindrical lens includes a convex cylindrical lens (82) that causes the projected light (162; 262) to converge as it approaches the illumination area (64).

Description

TECHNICAL FIELD This invention relates to detecting abnormalities in blades of a gas turbine engine, and more particularly to detecting abnormalities in the blades based on reflections of light projected onto the blades. BACKGROUND A gas turbine engine typically includes a fan section, a compressor section, a combustor section and a turbine section. Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-pressure and temperature exhaust gas flow. The high-pressure and temperature exhaust gas flow expands through the turbine section to drive the compressor and the fan section. The compressor section may include low and high pressure compressors, and the turbine section may also include low and high pressure turbines. It is known to manually inspect blades of a gas turbine engine, such as fan blades, for wear to determine if the blades should be replaced or serviced. However such inspections can typically only happen when a gas turbine engine is not operating and sometimes, the engine has been removed from the aircraft. Inlet debris monitoring systems are known that can detect debris entering a gas turbine engine during engine operation, but they can only detect debris that enters the engine and they do not detect abnormalities, such as damage, on fan blades of the gas turbine engine at all regardless of whether the engine is in operation. US 20060078193 A1 describes an optical inspection system for visually inspecting the blades of a turbine at turning gear operation. US 11268881 B2 describes a system for component inspection comprising at least one sensor configured to capture sensor data of the component; and a processor coupled to the at least one sensor, the processor comprising at least one model configured to separate the sensor data into a normal category and an abnormal category. SUMMARY From a first aspect of the present invention, there is provided a method of inspecting blades of a gas turbine engine for abnormalities as recited in claim 1. In a further embodiment of the foregoing embodiment, the blade is one of a plurality of blades that extend radially outwards from a hub; said projecting is performed while the plurality of blades rotate about a longitudinal axis during operation of the gas turbine engine, such that the light source projects light onto each of the plurality of blades as they pass through the illumination area; and said utilizing a sensor and said determining are performed for reflections of the projected light from each of the plurality of blades. In a further embodiment of any of the foregoing embodiments, said operation of the gas turbine engine corresponds to a flight, and said projecting, utilizing, determining, and providing are performed during the flight. In a further embodiment of any of the foregoing embodiments, based on a rotational speed of the hub, the notification is provided in a manner that indicates at least one of: a quantity of blades that are determined to be abnormal; or which one or more particular ones of the plurality of blades are abnormal. In a further embodiment of any of the foregoing embodiments, the light source includes a laser and the at least one cylindrical lens includes a first cylindrical lens and a second cylindrical lens. The first cylindrical lens is concave, is disposed between the light source and illumination area, and provides a decollimating feature that causes the projected light to diverge into a first light sheet as the projected light approaches the second cylindrical lens. The second cylindrical lens is convex, is disposed between the first cylindrical lens and the illumination area, and provides a collimating feature that causes the diverged projected light to become a second light sheet that is more collimated than the first light sheet as the projected light approaches the illumination areas. In a further embodiment of any of the foregoing embodiments, the first cylindrical lens extends along a first longitudinal axis; the at least one cylindrical lens includes a third cylindrical lens that is concave, is disposed between the second cylindrical lens and the illumination area, and extends along a second longitudinal axis; and the second longitudinal axis is rotated approximately 90° with respect to the first longitudinal axis. In a further embodiment of any of the foregoing embodiments, the light source includes a plurality of light-emitting diodes and the at least one cylindrical lens includes a convex cylindrical lens that causes the projected light to converge as it approaches the illumination area. In a further embodiment of any of the foregoing embodiments, said utilizing a sensor to record data of at least one reflection of the projected light comprises utilizing at least one photodiode to record the data. In a further embodiment of any of the foregoing embodiments, said utilizing the sensor to record data includes recording a ti