Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
  • F01D21/04—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for responsive to undesired position of rotor relative to stator or to breaking-off of a part of the rotor, e.g. indicating such position
  • F01D21/045—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for responsive to undesired position of rotor relative to stator or to breaking-off of a part of the rotor, e.g. indicating such position special arrangements in stators or in rotors dealing with breaking-off of part of rotor
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
  • F01D21/003—Arrangements for testing or measuring

Definitions

• the present invention relates to a device and method for detecting an impact on a blade of a gas turbine engine, in particular on a fan blade.
• a gas turbine engine when mounted on an aircraft is susceptible to damage by objects being sucked up by the engine during use. These objects can come in various forms, for example, birds, stones or ice.
• Patent application FR2840358 A1 of SNECMA discloses a system for detecting rotor damage of an aircraft engine comprising means for measuring vibration and rotor speed during a given flight.
• a system for detecting rotor damage of an aircraft engine comprising means for measuring vibration and rotor speed during a given flight.
• such a system does not have the precision required to detect the ingestion of a foreign body.
• ROLLS-ROYCE patent application EP 1312766 A2 discloses an impact detection method on a rotor blade in which the speed drop of the rotor is measured to emit an alarm. Such detection has the disadvantage of being poorly discriminating. Indeed, in case of pumping the motor, the rotor speed drops and an alarm is issued when no body has been ingested. To eliminate this drawback, patent application EP 1312766 A2 teaches adding sensors to measure the torsion angle of the motor and thus improve the accuracy of the method. Such a method, with many sensors, is not satisfactory and does not allow to accurately and reliably detect ingestion of a foreign body.
• the invention relates to a method for automatically detecting the ingestion of at least one foreign body by a gas turbine engine comprising a rotor, a method according to which:
• the rotor speed signal is filtered so as to separate its static component from its dynamic component
• the filtered dynamic component is compared with a standard resonant wave of the rotor in order to obtain an ingestion indicator; standard resonance corresponding to the vibratory impulse response of a rotor;
• the ingestion indicator obtained is compared with a detection threshold
• a signal for detecting ingestion of a foreign body is emitted when the ingestion indicator is greater than the detection threshold.
• the vibratory response of a rotor constitutes its signature following an impact, that is to say, following a pulse.
• standard resonant wave is meant the vibratory impulse response measured on a rotor following the ingestion of a body by said rotor.
• the transient dynamic component of the rotor speed is compared to its signature to detect ingestion.
• the method according to the invention is more discriminating than the method according to the prior art based solely on amplitude thresholding of the dynamic component of the rotor speed (t), a dynamic component of high amplitude may have several causes.
• the invention it is possible to ignore vibrations of large amplitude (eg pumping) when the shape of the dynamic component of the rotor speed R (t) does not correspond to that of a standard resonant wave.
• this method is implemented without adding a sensor and without any structural modification.
• the standard resonant wave of the rotor corresponds to the impulse response of the first mode of torsion of the rotor.
• the search in the filtered dynamic component of the impulse response of the first mode of torsion of the rotor, whose characteristics are known elsewhere, makes it possible to obtain an ingestion rate which makes it possible to qualify a vibration.
• the impulse response of the first mode of torsion is present only after a transient excitation in torsion of the rotor, which is typical of an ingestion of foreign body. In this way, ingestion is detected reliably and accurately.
• a convolution product is made between the filtered dynamic component and the standard resonant wave to obtain the ingestion indicator.
• the standard resonant wave is measured directly on the rotor of the engine on which the detection method is implemented.
• the standard resonance wave is theoretically defined as a function of the characteristics of the impulse response of the first mode of torsion of the rotor (frequency, damping, etc.).
• the rotor is a low pressure rotor of a gas turbine engine
• the filtered dynamic component is compared to a standard resonant wave of the low pressure rotor to obtain an ingestion indicator, the resonance wave standard corresponding to the vibratory impulse response of a low pressure rotor.
• FIG. 2 represents the dynamic component of the low-pressure rotor speed of FIG. 1;
• FIG. 3 represents a standard resonance wave of the low-pressure rotor
• FIG. 4 represents the ingestion indicator corresponding to a measurement of resemblance between the dynamic component of the rotor speed and a standard resonant wave of said rotor.
• the invention relates to a method for accurately detecting ingestion of a foreign body by a dual-body gas turbine engine comprising a low-pressure rotor shaft and a high-pressure rotor shaft, a fan being secured to the low rotor. pressure.
• the rotational speed (t) of the low-pressure rotor is measured over time by means of a voice wheel, known as such to those skilled in the art, arranged to measure the angular velocity of the low pressure rotor shaft. It goes without saying that the low-pressure rotor speed could also be measured by other means, in particular by accelerometers arranged in the engine.
• the low-pressure rotor R (t) regime measured by the phonic wheel has a static component Rs and a dynamic component Rd (t) and decomposes in the following form:
• the low pressure rotor R (t) regime is filtered to retain only the dynamic component Rd (t) of the signal, for example, by means of bandpass filtering centered on the frequency of the standard resonance wave.
• the Applicant has noticed that when a body strikes the blower after ingestion, the low pressure rotor, connected to the blower, responds by vibrating in its first mode of torsion, in the manner of a bell, by emitting a resonance wave whose frequency and shape is specific to the rotor.
• This vibratory response following a brief shock is the impulse response of the first mode of torsion of the low pressure rotor. Thanks to this characteristic response, it is possible to discriminate the vibratory disturbances resulting from the body ingestions of disturbances resulting from noise or external phenomena, and this, well, that their influences on the low-pressure rotor regime (t) are almost identical from a total point of view.
• the dynamic component Rd (t) of the low pressure rotor speed signal R (t) is thus generally in the following form:
• C (t) .cos (w x (t) * t + ⁇ I>) is the perturbation due to the vibratory response of the low-pressure rotor following ingestion. This perturbation depends on an amplitude parameter C (t), a phase parameter ⁇ and a pulse parameter w T corresponding to the first torsion mode of the low pressure rotor.
• the low pressure rotor has several low frequency twist modes. When ingesting foreign bodies, only the first mode of torsion will respond significantly. The impulse response of the latter will therefore be a signature characteristic of ingestion. Following ingestion, C (t) will vary strongly in one form:
• C (t) C.exp (-t / x T ) This is the amplitude of the disturbance and is a function of the "severity" of the ingestion, the amplitude of the disturbance being very small compared to the value of the static regime Rs.
• the damping parameter ⁇ ⁇ is a function of the damping of the first mode of torsion of the low pressure rotor and the natural frequency of this mode.
• the dynamic component Rd (t) of the low-pressure rotor strongly resembles the impulse response of the first torsion mode e (t) of the low-pressure rotor, shown in FIG. Figure 3.
• the impulse response of the first rotor twist mode e (t) is compared with the dynamic response Rd (t) of the low-pressure rotor R (t) to determine whether a body has been ingested by the engine.
• the filtered dynamic component is compared with a standard resonance wave e (t) of the low-pressure rotor in order to obtain an ingestion indicator T ING corresponding to a measurement of resemblance between the standard resonant wave e (t) and the dynamic component Rd (t) of the measured speed signal.
• T ING an ingestion indicator
• this wave corresponds to the impulse response of the first mode of torsion of the rotor.
• the first mode of torsion of the rotor is a "specific" mode, the characteristics (frequency, damping) of the first mode of torsion being measured directly on the low pressure rotor on which will be implemented the detection of ingestion, the detection being then carried out "Custom-made” with the standard resonance wave the vibratory impulse response first mode of torsion of the rotor.
• the setting of the detection method with a specific mode makes it possible to implement an accurate detection adapted to said low pressure rotor. Indeed, each rotor has an impulse response of its first mode of torsion of its own. In other words, different rotor models have different impulse responses.
• the impulse response of the first mode of torsion of the rotor is determined analytically by calculation.
• the standard resonance wave e (t) corresponds to the sum of a plurality of torsion modes of the same low-pressure rotor, preferably the first 2 or 3 modes of torsion of a low rotor. pressure.
• a standard resonant wave e (t) comprising several torsion modes makes it possible to increase the reliability of the detection and its accuracy.
• a convolution product is produced between the dynamic response of the low pressure rotor d (t) and the standard wave e (t) to obtain a ingestion indicator T ING .
• the comparison algorithms are set to take into account distortions of the standard resonance wave (delay, noise, etc.).
• the ingestion indicator T ING shown in FIG. 4, makes it possible to qualify the suspicious oscillation 2 detected in the measurement of the low-pressure rotor R (t) regime. The more the dynamic response of the low pressure rotor Rd (t) resembles the theoretical impulse response characteristic of a shock response (here, ingestion of a foreign body), plus the value of the ingestion indicator T ING will be high.
• the value of the detection S is determined so as not to generate an alarm for T ING indicator values corresponding to the normal operation of the engine and which can be described as noise.
• This detection threshold is thus obtained by applying a margin to the average level of the "noise” Sb.
• This margin is a function of the characteristics of the signal "noise” as well as the desired level of detection reliability. With reference to FIG. 4, a margin of 70% separates the detection threshold from the average noise level.
• This method is very selective because the ingestion indicator T ING for a noise signal (excluding ingestion) is low since, in the absence of ingestion, the impulse response of the first mode of torsion is not present. in the signal.
• the noise signal does not resemble the impulse response of the first mode of torsion.
• the alarm generated can be directed directly to the pilot of the aircraft, on which the engine is mounted, to be consulted in real time, or stored in a memory to be consulted. subsequently, for example, for an inspection of the engine, be transmitted in real time to the maintenance services of the airline to allow it to anticipate and organize, at the next stopover, a detailed inspection impacted engine and all necessary maintenance actions.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
• Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
• Testing Of Engines (AREA)

Applications Claiming Priority (2)

Publications (2)

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• 2010
  • 2010-02-08 FR FR1050870A patent/FR2956159B1/fr not_active Expired - Fee Related
• 2011
  • 2011-02-02 EP EP11707886.5A patent/EP2534341B1/de active Active
  • 2011-02-02 CN CN201180008788.5A patent/CN103026006B/zh not_active Expired - Fee Related
  • 2011-02-02 JP JP2012551665A patent/JP5698766B2/ja not_active Expired - Fee Related
  • 2011-02-02 US US13/577,455 patent/US9366154B2/en active Active
  • 2011-02-02 CA CA2788901A patent/CA2788901C/fr active Active
  • 2011-02-02 WO PCT/FR2011/050205 patent/WO2011095737A1/fr active Application Filing
  • 2011-02-02 BR BR112012019559A patent/BR112012019559A2/pt not_active IP Right Cessation
  • 2011-02-02 RU RU2012138447/06A patent/RU2551252C2/ru not_active IP Right Cessation

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