Acoustic identification method and system for synchronous vibration of aircraft fan blades, medium and equipment

Abstract

The invention discloses an aero-generator fan blade synchronous vibration acoustic identification method and system, a medium and equipment, and the method comprises the steps: determining a microphone array layout through parameters of a fan model; sound pressure time domain signals of multiple channels of the fan are synchronously collected through a microphone array; arranging the multi-channel sound pressure time-domain signals in sequence to construct a time-domain signal matrix; performing spectral analysis on the sound pressure time-domain signal by adopting a fast Fourier transform algorithm to obtain a spectrogram of the sound pressure time-domain signal of each channel, and monitoring whether a broadband noise component of which the blade passing frequency amplitude of the fan exceeds a first preset value and the frequency band distribution is greater than a preset range appears by monitoring the spectrogram; if not, it is indicated that the fan is in a normal working state, when the fan blades vibrate synchronously, the vibration of the blades is reflected through the frequency and the frequency doubling acoustic mode of the frequency, and the vibration pitch diameter and the frequency of the fan blade disc are output through the frequency passing acoustic mode of the blades on the basis of the frequency coupling relation.

Description

Technical Field

[0001] The present invention relates to the technical field of fan noise testing, and in particular to a method, system, medium and equipment for acoustic identification of synchronous vibration of aircraft engine fan blades. Background Art

[0002] The fan is a typical highly coupled multi-physics system, with internal blades subjected to the combined effects of structural elastic forces, rotational inertia, and unsteady flow excitation. When the fan operates under abnormal conditions, the critical thin-walled structures within it induce abnormal vibrations due to the interaction of high centrifugal loads, alternating vibration loads, and aerodynamic excitation loads. On the one hand, certain unsteady flow excitations can cause the blade vibration amplitude to grow exponentially, forcing it to undergo high-cycle fatigue failure, form cracks, and even induce fatigue fracture of the blades; on the other hand, abnormal fan vibrations can change the internal flow field structure, threatening the aerodynamic stability of the compression system; on the other hand, abnormal vibrations of the critical thin-walled structures can create new sources of aerodynamic noise. Under certain low Mach number conditions, sound waves may act on the structure, affecting the vibration state.

[0003] Currently, strain gauges are typically installed on rotating blades to monitor fan blade vibration. This is a costly and invasive method that interferes with the fan flow field. Acoustic sensors offer high sensitivity, a short transmission path, and are non-invasive, eliminating interference with the fan flow field. Modal decomposition of acoustic array signals fully captures key information such as blade vibration frequency and pitch diameter. This acoustic signature-driven fan blade vibration monitoring method improves the diagnostic accuracy of typical abnormal conditions and provides new insights into aircraft engine fan condition monitoring.

[0004] Large-amplitude synchronous vibration of fan blades not only increases fan noise but can also cause severe fatigue failure or even blade fracture, seriously threatening the safe and stable operation of high-performance aircraft engine fans. Therefore, accurately identifying and analyzing fault characteristics is crucial for aircraft engine maintenance and repair. Traditional fault detection methods rely primarily on visual inspection, nondestructive testing techniques, and vibration analysis. However, these methods often have limitations when dealing with synchronous vibration faults in fan blades.

[0005] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the Invention

[0006] The present invention provides a method, system, medium and equipment for acoustic identification of synchronous vibration of aircraft engine fan blades, which measures acoustic signals and realizes the conversion of sound field signals in time domain, frequency domain and wavenumber domain through signal processing means, thereby obtaining a more effective soundprint image of fan blade synchronous vibration detection indicators and identifying the fault characteristics of acoustic signals in fan blade synchronous vibration.

[0007] A method for identifying synchronous vibration acoustics of an aero-engine fan blade includes:

[0008] In the first step, the microphone array layout is determined by the parameters of the fan model;

[0009] In the second step, the number of microphones and the microphone installation angle Constructing a microphone array; synchronously collecting multi-channel sound pressure time domain signals of the fan through the microphone array; arranging the multi-channel sound pressure time domain signals in sequence to construct a time domain signal matrix;

[0010] In the third step, the fast Fourier transform algorithm is used to perform spectral analysis on the sound pressure time domain signal to obtain the spectrum diagram of the sound pressure time domain signal of each channel. The spectrum diagram is monitored to see whether the increase in the frequency amplitude of the fan blade passing through exceeds the first predetermined value and whether a broadband noise component with a frequency band distribution greater than a predetermined range appears. If no broadband noise component exists, it indicates that the fan is in normal working condition.

[0011] In the method for identifying synchronous vibration acoustics of aero-engine fan blades, if the increase in the amplitude of the fan blade passing frequency exceeds a first predetermined value and a broadband noise component with a frequency distribution greater than a predetermined range occurs, the fourth step is entered;

[0012] In the fourth step, an acoustic modal spectrum at the blade passing frequency is obtained by a single-frequency acoustic modal decomposition method. Whether the fan blades are experiencing synchronous vibration is determined by monitoring the spectrum for the presence of synchronous vibration characteristics of the fan blades. When synchronous vibration occurs, a change in the amplitude of the rotational-static interference mode in the acoustic modal spectrum at the blade passing frequency exceeds a second predetermined value.

[0013] In the fifth step, a spectrogram of the sound pressure time domain signal is obtained by continuous broadband acoustic modal decomposition. The horizontal axis of the spectrogram represents the frequency analysis range, the vertical axis represents the acoustic modal monitoring range, and the depth of the color represents the amplitude. The darker the color, the larger the amplitude. Whether the fan blade synchronous vibration feature appears in the spectrogram is monitored. When the fan blades experience synchronous vibration, the amplitude increase of the broadband noise mode in the spectrogram exceeds the third predetermined value, and the change in the amplitude of the rotation-static interference mode at the blade passing frequency exceeds the second predetermined value and propagates to the surrounding frequencies, combining with the blade passing frequency sound source to form a cross bright band phenomenon.

[0014] In the sixth step, when the fan blades vibrate synchronously, the acoustic modes of the blade pass frequency and its multiples reflect the vibration of the blades. At this time, the vibration frequency of the blade disk is coupled with the blade pass frequency, and the vibration pitch diameter and frequency of the fan blade disk are output through the acoustic mode of the blade pass frequency based on the frequency coupling relationship.

[0015] In the method for identifying synchronous vibration and acoustics of aero-engine fan blades, the second step includes the following steps:

[0016] S201, using a circular acoustic array to measure the sound pressure signal of the fan, the measured sound pressure time domain signal is , where the length of the time domain signal sequence measured by a single microphone is , subscript They are microphones at corresponding installation angle positions respectively;

[0017] S202. Build a time domain signal matrix based on the sound pressure time domain signals measured by the microphones at different installation angles. , where the elements express The first measurement of the microphone at the corresponding installation angle position Signal,

[0018] , when using a uniform acoustic array layout, the time domain signal matrix The size of ; When using a non-uniform acoustic array layout with few measurement points, the time domain signal matrix The size of .

[0019] In the method for identifying synchronous vibration and acoustics of aero-engine fan blades, the third step (S3) includes:

[0020] S301, time domain signal matrix Perform Fourier transform on each column to obtain the frequency domain matrix , where the elements express The signal measured by the microphone at the corresponding installation angle position is The amplitude at the frequency, The length is , according to Nyquist sampling theorem, ,

[0021] , in a uniform acoustic array layout, the frequency domain matrix The size of ; Frequency domain matrix in non-uniform acoustic array layout The size of ,

[0022] S302, according to the frequency domain matrix Draw the spectrum of the signal measured by the sensor at different installation angles, and the fan blade passing frequency The increase in amplitude exceeds a first predetermined value and a broadband noise component with a frequency distribution greater than a predetermined range appears.

[0023] In the method for synchronous vibration and acoustic identification of aero-engine fan blades, the fourth step (S4) includes:

[0024] S401, when using uniform acoustic array layout, subscript The microphone at the corresponding installation angle position is at the predetermined frequency The frequency domain signal at It can be regarded as the linear superposition of different circumferential acoustic modes, that is, , construct the transformation matrix The form is as follows:

[0025] ,

[0026] When using a non-uniform acoustic array layout with few measurement points, the observation matrix is constructed based on the randomly selected sensor installation angles. , the observation matrix Size ,

[0027] ,

[0028] S402, when using a uniform acoustic array layout, the frequency domain matrix Perform spatial Fourier transform to obtain the wave number domain matrix , ,in is the frequency domain matrix The transposed matrix of ,in Represents the transformation matrix The pseudo-rebellion,

[0029] When a non-uniform acoustic array layout with few measurement points is used, the compressed sensing model is , sparse dictionary It is composed of an orthogonal Fourier transform basis, For the perception matrix, the wave number domain matrix is sparsely reconstructed based on the compressed sensing model ;

[0030] S403, according to the obtained wave number domain matrix , draw an acoustic modal spectrum; when the fan blades vibrate synchronously, the sound source excitation frequency is coupled with the blade vibration frequency, and the change in the rotation-static interference mode amplitude in the acoustic modal spectrum of the blade passing frequency exceeds a second predetermined value.

[0031] In the method for identifying synchronous vibration and acoustics of aero-engine fan blades, the fifth step (S5) includes:

[0032] S501, the wave number domain matrix Expanded to full frequency domain, wave number domain matrix Size expanded to , where the elements Indicates the frequency Place The amplitude of the order acoustic mode,

[0033] ,

[0034] S502, according to the wave number domain matrix , draw a spectrum diagram, observe that the amplitude increase of the broadband noise mode in the spectrum diagram exceeds the third predetermined value, and the change of the amplitude of the rotation-static interference mode at the blade passing frequency exceeds the second predetermined value and propagates to the surrounding frequencies, which is combined with the blade passing frequency sound source to form a cross bright band phenomenon, which is defined as the identification feature of the synchronous vibration soundprint of the fan blade, and based on this, it is judged whether the fan blades are vibrating synchronously.

[0035] In the aforementioned method for acoustic identification of synchronous vibration of aero-engine fan blades, in the sixth step (S6), when the fan blades vibrate synchronously, the fan blade disc vibration pitch diameter and frequency are output.

[0036] S601, when the fan blades vibrate synchronously, the vibration frequency of the blade disk is coupled with the blade frequency, and the acoustic mode order is equal to the blade pitch number. At this time, the sound source excitation frequency and blade vibration frequency of satisfaction,

[0037] , where Indicates the rotor speed frequency,

[0038] S602: Calculate the blade vibration frequency and vibration node diameter according to the excitation frequency and modal order of the sound source in the spectrum diagram and output them.

[0039] A fan blade synchronous vibration identification system for implementing the method includes:

[0040] The sound field measurement module includes a sound array measurement submodule and a data acquisition submodule, and is used to measure the sound field information propagated in the duct to the sound array installation position when the fan is working;

[0041] The spectrum analysis module is used to transform the time domain sound field signal at the acoustic array position into the frequency domain to detect whether there are abnormal changes in the blade passing frequency and abnormal frequency components;

[0042] The acoustic modal decomposition module is used to perform single-tone acoustic mode decomposition and continuous broadband acoustic mode decomposition, transform the sound field information from the frequency domain to the wavenumber domain, and detect whether the synchronous vibration characteristics of the fan blades appear in the acoustic modal spectrogram and wave spectrogram;

[0043] The synchronous vibration calculation module is used to determine whether the fan blades have synchronous vibration and output the fan blade vibration pitch diameter and frequency.

[0044] A computer storage medium includes computer instructions, which, when executed on a computer, cause the computer to execute the method described above.

[0045] An electronic device, comprising:

[0046] A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein:

[0047] When the processor executes the program, the method described is implemented.

[0048] Compared with the existing technology, the present invention has the following advantages: the present invention uses acoustic information to identify the synchronous vibration of fan blades, which is more sensitive and adaptable than the traditional method using vibration signals and interstage pressure signals; the characteristics of the synchronous vibration of fan blades in the frequency domain of the acoustic signal are obtained by fast Fourier transform, which has obvious characteristics and a simple process; the characteristics of the synchronous vibration of fan blades in the wavenumber domain of the acoustic signal are obtained by spatial Fourier transform, which has high sensitivity and adaptability to different speeds. When testing resources are limited, the extraction of soundprint features of synchronous vibration of aircraft engine fan blades can be achieved by adopting a non-uniform layout scheme. The abnormal components in the spectrum, acoustic modal spectrum, and wave spectrum of the acoustic signal are defined as the soundprint features of the synchronous vibration of fan blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are intended only to illustrate preferred embodiments and are not to be construed as limiting the present invention. It should be understood that the drawings described below are merely examples of the present invention, and that those skilled in the art will be able to derive other drawings from these drawings without inventive effort. Throughout the drawings, identical reference numerals are used to denote identical components.

[0050] In the attached figure:

[0051] Figure 1 is a flow chart of the present disclosure;

[0052] Figure 2This is a schematic diagram of a detection device for a method of identifying synchronous vibration of fan blades based on voiceprint features provided by an embodiment of the present disclosure;

[0053] Figure 3(a) to Figure 3(b) 3(a) is a spectrum diagram of a fan in normal working state and blade synchronous vibration state, provided by one embodiment of the present disclosure; FIG3(b) is a spectrum diagram of a fan in normal working state, and FIG3(a) is a spectrum diagram of a fan in blade synchronous vibration state;

[0054] Figure 4(a) to Figure 4(b) Figure 4(a) is an acoustic modal spectrum diagram of the fan blades at the pass-through frequency in a normal working state and a synchronous vibration state, provided by one embodiment of the present disclosure; Figure 4(b) is an acoustic modal spectrum diagram of the fan blades at the pass-through frequency in a synchronous vibration state;

[0055] Figure 5(a) to Figure 5(b) It is a spectrum diagram of the fan in normal working state and blade synchronous vibration under subsonic working condition provided by an embodiment of the present invention; among them, Figure 5(a) is the spectrum diagram when blade synchronous vibration does not occur, and Figure 5(b) is the spectrum diagram when blade synchronous vibration occurs under subsonic working condition of the fan.

[0056] The present invention will be further explained below with reference to the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0057] Specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0058] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the invention. The scope of protection of the present invention shall be as defined in the attached claims.

[0059] To facilitate understanding of the embodiments of the present invention, further explanation will be given below using specific embodiments as examples in conjunction with the accompanying drawings, and the accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0060] like Figures 1 to 5(b) As shown, the synchronous vibration acoustic identification method of aero-engine fan blades includes the following steps:

[0061] In the first step (S1), the microphone array layout is determined by the parameters of the fan model, wherein the number of rotor blades of the fan is Number of stator blades Calculating the Rotor-Station Interference Modal Order of a Fan's Single-Tone Noise , based on the modal order of the rotation-static interference The maximum modal order determines the acoustic mode monitoring range and the number of microphones and the circumferential installation angle of the microphone ;

[0062] In the second step (S2), the number of microphones is and the microphone installation angle Constructing a microphone array; synchronously collecting multi-channel sound pressure time domain signals of the fan through the microphone array; arranging the multi-channel sound pressure time domain signals in sequence to construct a time domain signal matrix;

[0063] In the third step (S3), a fast Fourier transform algorithm is used to perform spectrum analysis on the sound pressure time domain signal to obtain a spectrum diagram of the sound pressure time domain signal of each channel. The spectrum diagram is monitored to determine whether there is a broadband noise component with a frequency amplitude exceeding a first predetermined value and a frequency band distribution greater than a predetermined range when the fan blade passes through. If no broadband noise component exists, it indicates that the fan is in normal working condition. If no broadband noise component exists, the process proceeds to the fourth step (S4).

[0064] In the fourth step (S4), an acoustic modal spectrum at the blade passing frequency is obtained by a single-frequency acoustic modal decomposition method. Whether the fan blades are experiencing synchronous vibration is determined by monitoring the spectrum for the presence of a synchronous vibration characteristic of the fan blades. When synchronous vibration occurs, a change in the amplitude of the rotational-static interference mode in the acoustic modal spectrum at the blade passing frequency exceeds a second predetermined value.

[0065] In the fifth step (S5), a spectrogram of the sound pressure time domain signal is obtained by continuous broadband acoustic mode decomposition, wherein the horizontal axis of the spectrogram represents the frequency analysis range, the vertical axis represents the acoustic mode monitoring range, the depth of the color represents the amplitude, and the darker the color, the larger the amplitude. Whether the fan blade synchronous vibration feature appears in the spectrogram is monitored. When the fan blades vibrate synchronously, the amplitude increase of the broadband noise mode in the spectrogram exceeds the third predetermined value, and the change of the rotation-static interference mode amplitude at the blade passing frequency exceeds the second predetermined value and propagates to the surrounding frequencies, and forms a cross bright band phenomenon in combination with the blade passing frequency sound source;

[0066] In the sixth step (S6), when the fan blades vibrate synchronously, the acoustic modes of the blade pass frequency and its multiples reflect the vibration of the blades. At this time, the vibration frequency of the blade disk is coupled with the blade pass frequency, and the vibration pitch diameter and frequency of the fan blade disk are output through the acoustic mode of the blade pass frequency based on the frequency coupling relationship.

[0067] In a preferred embodiment of the method for identifying synchronous vibration and acoustics of an aero-engine fan blade, in the first step (S1), the rotation-static interference mode order of the fan is for, ,in, represents the pressure pulsation order caused by the unsteady aerodynamic force caused by the fan's rotation-stationary interference. Represents an integer that determines the number of microphones in the microphone array and the microphone installation angle,

[0068] Calculate the number of sensors required for modal detection based on Nyquist sampling when using a uniform acoustic array layout , which has the same modal order as the rotation-static interference modal The relationship is: When using a non-uniform acoustic array layout with a few measurement points, the virtual uniform layout Randomly select from Install sensors at different locations. ;

[0069] When using a uniform acoustic array layout solution, The sensors form a circular acoustic array, and the spacing between the sensors is , the microphone is installed at an angle of ,in 、 、 , and so on; when using a non-uniform acoustic array layout with few measurement points, the microphone installation angle Randomly selected, .

[0070] In a preferred embodiment of the method for synchronous vibration and acoustic identification of aero-engine fan blades, the second step (S2) includes the following steps:

[0071] S201, using a circular acoustic array to measure the sound pressure signal of the fan, the measured sound pressure time domain signal is , where the length of the time domain signal sequence measured by a single microphone is , subscript They are microphones at corresponding installation angle positions respectively;

[0072] S202: Build a time domain signal matrix based on the sound pressure time domain signals measured by the microphones at different installation angles. , where the elements express The first measurement of the microphone at the corresponding installation angle position Signal,

[0073] , when using a uniform acoustic array layout, the time domain signal matrix The size of ; When using a non-uniform acoustic array layout with few measurement points, the time domain signal matrix The size of .

[0074] In a preferred embodiment of the method for identifying synchronous vibration and acoustics of aero-engine fan blades, the third step (S3) includes:

[0075] S301, time domain signal matrix Perform Fourier transform on each column to obtain the frequency domain matrix , where the elements express The signal measured by the microphone at the corresponding installation angle position is The amplitude at the frequency, The length is , according to Nyquist sampling theorem, ,

[0076] , in a uniform acoustic array layout, the frequency domain matrix The size of ; Frequency domain matrix in non-uniform acoustic array layout The size of ,

[0077] S302, according to the frequency domain matrix Draw the spectrum of the signal measured by the sensor at different installation angles, and the fan blade passing frequency The increase in amplitude exceeds a first predetermined value and a broadband noise component with a frequency distribution greater than a predetermined range appears.

[0078] In a preferred embodiment of the method for synchronous vibration and acoustic identification of aero-engine fan blades, the fourth step (S4) includes:

[0079] S401, when using uniform acoustic array layout, subscript The microphone at the corresponding installation angle position is at the predetermined frequency The frequency domain signal at It can be regarded as the linear superposition of different circumferential acoustic modes, that is, , construct the transformation matrix The form is as follows:

[0080] ,

[0081] When using a non-uniform acoustic array layout with few measurement points, the observation matrix is constructed based on the randomly selected sensor installation angles. , the observation matrix Size ,

[0082] ,

[0083] S402, when using a uniform acoustic array layout, the frequency domain matrix Perform spatial Fourier transform to obtain the wave number domain matrix , ,in is the frequency domain matrix The transposed matrix of ,in Represents the transformation matrix The pseudo-rebellion,

[0084] When a non-uniform acoustic array layout with few measurement points is used, the compressed sensing model is , sparse dictionary It is composed of an orthogonal Fourier transform basis, For the perception matrix, the wave number domain matrix is sparsely reconstructed based on the compressed sensing model ;

[0085] S403, according to the obtained wave number domain matrix , draw an acoustic modal spectrum; when the fan blades vibrate synchronously, the sound source excitation frequency is coupled with the blade vibration frequency, and the change in the rotation-static interference mode amplitude in the acoustic modal spectrum of the blade passing frequency exceeds a second predetermined value.

[0086] In a preferred embodiment of the method for identifying synchronous vibration and acoustics of aero-engine fan blades, the fifth step (S5) includes:

[0087] S501, the wave number domain matrix Expanded to full frequency domain, wave number domain matrix Size expanded to , where the elements Indicates the frequency Place The amplitude of the order acoustic mode,

[0088] ,

[0089] S502, according to the wave number domain matrix , draw a spectrum diagram, observe that the amplitude increase of the broadband noise mode in the spectrum diagram exceeds the third predetermined value, and the change of the amplitude of the rotation-static interference mode at the blade passing frequency exceeds the second predetermined value and propagates to the surrounding frequencies, which is combined with the blade passing frequency sound source to form a cross bright band phenomenon, which is defined as the identification feature of the synchronous vibration soundprint of the fan blade, and based on this, it is judged whether the fan blades are vibrating synchronously.

[0090] In a preferred embodiment of the method for identifying synchronous vibration of an aero-engine fan blade, in the sixth step (S6), when the fan blades vibrate synchronously, the fan blade disk vibration pitch diameter and frequency are output.

[0091] S601, when the fan blades vibrate synchronously, the vibration frequency of the blade disk is coupled with the blade frequency, and the acoustic mode order is equal to the blade pitch number. At this time, the sound source excitation frequency and blade vibration frequency of satisfaction,

[0092] , where Indicates the rotor speed frequency,

[0093] S602: Calculate the blade vibration frequency and vibration node diameter according to the excitation frequency and modal order of the sound source in the spectrum diagram and output them.

[0094] A fan blade synchronous vibration identification system for implementing the method includes:

[0095] The sound field measurement module includes a sound array measurement submodule and a data acquisition submodule, and is used to measure the sound field information propagated in the duct to the sound array installation position when the fan is working;

[0096] The spectrum analysis module is used to transform the time domain sound field signal at the acoustic array position into the frequency domain to detect whether there are abnormal changes in the blade passing frequency and abnormal frequency components;

[0097] The acoustic modal decomposition module is used to perform single-tone acoustic mode decomposition and continuous broadband acoustic mode decomposition, transform the sound field information from the frequency domain to the wavenumber domain, and detect whether the synchronous vibration characteristics of the fan blades appear in the acoustic modal spectrogram and wave spectrogram;

[0098] The synchronous vibration calculation module is used to determine whether the fan blades have synchronous vibration and output the fan blade vibration pitch diameter and frequency.

[0099] A computer storage medium includes computer instructions, which, when executed on a computer, cause the computer to execute the method described above.

[0100] An electronic device, comprising:

[0101] A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein:

[0102] When the processor executes the program, the method described is implemented.

[0103] In one embodiment, the first predetermined value is 1.5 times the sound pressure amplitude under normal operating conditions, and the predetermined range is 1.5 times the maximum sound pressure amplitude within the frequency band under normal operating conditions.

[0104] The second predetermined value is 1.5 times the modal amplitude under normal operating conditions, and the third predetermined value is 1.5 times the maximum modal amplitude within the frequency band under normal operating conditions.

[0105] In one embodiment, the fan is a fan of an aircraft engine.

[0106] In one embodiment, the sound field information is measured by a microphone array to obtain a time domain signal matrix , where the elements express The first value measured by the microphone at the corresponding angular position Signal.

[0107] In one embodiment, Figure 1 This is a flow chart of the method for synchronous vibration identification of aircraft engine fan blades based on soundprint features completed by the present invention. The method calculates the rotational-static interference modal order in the fan single-tone noise through the aircraft engine fan model, determines the acoustic mode monitoring range, the number of microphones, the axial installation position and the circumferential installation angle according to the maximum modal order of interest; performs fast Fourier transform on the acoustic array signal to obtain the frequency domain signal matrix And output the spectrum diagram to observe whether there is abnormal broadband noise component, blade passing frequency and its harmonic amplitude greatly increased; based on the constructed conversion matrix, the single-frequency acoustic mode decomposition method is used to obtain the acoustic mode spectrum of the blade passing frequency to observe whether there is a phenomenon of a significant increase in the amplitude of the rotation-static interference mode; the spectrum diagram of the array signal is obtained by continuous broadband acoustic mode decomposition to observe whether there is a significant increase in the amplitude of the broadband noise mode, and the rotation-static interference mode at the blade passing frequency is significantly enhanced and propagates to the surrounding frequencies, and is combined with the blade passing frequency sound source to form an obvious cross bright band phenomenon; if the fan blade vibrates synchronously, the vibration pitch diameter and frequency of the blade disk are output. The specific steps are as follows:

[0108] Assuming the number of rotor blades of the aircraft engine fan Number of stator blades , according to the calculation formula of the fan single-tone noise mode order , usually take The pressure pulsation order caused by the unsteady aerodynamic force caused by the fan's static interference is 1. Represents the first-order acoustic mode, and is calculated to be ,Pick Represents the second-order acoustic mode, and is calculated to be , according to Nyquist sampling theorem: , the number of sensors required , so the number of sensors is selected as ;

[0109] The sensors are evenly arranged to form a ring sound array, the sampling frequency is set to 20000hz, and the spacing between the sensors is , the microphone is installed at an angle of ,in 、 、 , and so on;

[0110] The sound pressure signal of the aircraft engine fan is measured using a circular acoustic array. data points, the constructed time domain signal matrix The size of The time domain signal matrix of the ring acoustic array is measured Perform Fourier transform on each column of to transform the signal from time domain to frequency domain and obtain the frequency domain matrix , the frequency domain matrix The size of According to Nyquist sampling theorem, ;

[0111] According to the obtained frequency domain matrix , draw the spectrum of the signal measured by the sensor at different angles, taking the installation position as Taking the microphone signal as an example, Figure 3(a) shows that when the fan blades do not vibrate synchronously, the main component of the spectrum is the blade passing frequency. And its amplitude is 195 Pa. When the fan blades vibrate synchronously in Figure 3(b), the blades pass the frequency The amplitude increases to 281Pa, and a broadband noise component with a large frequency distribution appears;

[0112] Elements in the frequency domain matrix Indicates subscript The microphone at the corresponding angular position is at a specific frequency The acoustic signal at can be regarded as the linear superposition of different circumferential acoustic modes, that is, , so the constructed transformation matrix Size .

[0113] The single-frequency acoustic modal decomposition at the abnormal peak frequency is Wavenumber domain matrix And draw the acoustic modal spectrum. Figure 4 (a) When the fan blades do not vibrate synchronously, the amplitude of the rotor-static interference mode is , Figure 4(b) shows the amplitude of the rotor-static interference mode when the fan blades vibrate synchronously The amplitude increases to ;

[0114] Frequency domain matrix Continuous broadband acoustic modal decomposition is performed to obtain a magnitude of The wavenumber domain matrix , the wavenumber domain matrix Chinese elements Indicates the frequency Place The amplitude of the order acoustic mode. According to the obtained wave number domain matrix , draw a spectrum. Figure 5(a) shows that when the fan blades are not vibrating synchronously, the overall color of the spectrum is lighter, and the main sound source is the sound source at the blade passing frequency. Figure 5(b) shows that when the fan blades are vibrating synchronously, the overall color of the spectrum is significantly darker, indicating that the amplitude of the broadband noise mode is significantly increased, and the rotation-static interference mode at the blade passing frequency is significantly enhanced and propagates to the surrounding frequencies, combining with the sound source at the blade passing frequency to form a clear cross bright band phenomenon.

[0115] It is determined that the fan blades are vibrating synchronously at this time. The fan blade vibration pitch diameter calculated based on the excitation frequency and modal order of the sound source in the spectrum is: , the vibration frequency is .

[0116] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments and application fields. The above-mentioned specific embodiments are merely illustrative and instructive, and are not restrictive. A person skilled in the art, guided by this specification and without departing from the scope of protection of the claims of the present invention, may also devise various forms, all of which fall within the scope of protection of the present invention.

Claims

1. A method for identifying synchronous vibration and acoustics of aircraft engine fan blades, characterized in that: The steps include: In the first step (S1), the microphone array layout is determined by the parameters of the fan model; In the second step (S2), the number of microphones and the microphone installation angle Constructing a microphone array; synchronously collecting multi-channel sound pressure time domain signals of the fan through the microphone array; arranging the multi-channel sound pressure time domain signals in sequence to construct a time domain signal matrix; In the third step (S3), a fast Fourier transform algorithm is used to perform spectrum analysis on the sound pressure time domain signal to obtain a spectrum diagram of the sound pressure time domain signal of each channel. The spectrum diagram is monitored to see whether the increase in the frequency amplitude of the fan blade passing through exceeds a first predetermined value and whether a broadband noise component with a frequency band distribution greater than a predetermined range appears. If no broadband noise component exists, it indicates that the fan is in normal working condition.

2. The method for synchronous vibration and acoustic identification of aero-engine fan blades according to claim 1, characterized in that: Preferably, if the increase in the frequency amplitude of the fan blades exceeds the first predetermined value and a broadband noise component with a frequency distribution greater than a predetermined range occurs, the fourth step (S4) is entered; In the fourth step (S4), an acoustic modal spectrum at the blade passing frequency is obtained by a single-frequency acoustic modal decomposition method. Whether the fan blades are experiencing synchronous vibration is determined by monitoring the spectrum for the presence of a synchronous vibration characteristic of the fan blades. When synchronous vibration occurs, a change in the amplitude of the rotational-static interference mode in the acoustic modal spectrum at the blade passing frequency exceeds a second predetermined value. In the fifth step (S5), a spectrogram of the sound pressure time domain signal is obtained by continuous broadband acoustic mode decomposition, wherein the horizontal axis of the spectrogram represents the frequency analysis range, the vertical axis represents the acoustic mode monitoring range, the depth of the color represents the amplitude, and the darker the color, the larger the amplitude. Whether the fan blade synchronous vibration feature appears in the spectrogram is monitored. When the fan blades vibrate synchronously, the amplitude increase of the broadband noise mode in the spectrogram exceeds the third predetermined value, and the change of the rotation-static interference mode amplitude at the blade passing frequency exceeds the second predetermined value and propagates to the surrounding frequencies, and forms a cross bright band phenomenon in combination with the blade passing frequency sound source; In the sixth step (S6), when the fan blades vibrate synchronously, the acoustic modes of the blade pass frequency and its multiples reflect the vibration of the blades. At this time, the vibration frequency of the blade disk is coupled with the blade pass frequency, and the vibration pitch diameter and frequency of the fan blade disk are output through the acoustic mode of the blade pass frequency based on the frequency coupling relationship.

3. The method for synchronous vibration and acoustic identification of aero-engine fan blades according to claim 1, characterized in that: The second step (S2) includes the following steps: S201, using a circular acoustic array to measure the sound pressure signal of the fan, the measured sound pressure time domain signal is , where the length of the time domain signal sequence measured by a single microphone is , subscript They are microphones at corresponding installation angle positions respectively; S202: Build a time domain signal matrix based on the sound pressure time domain signals measured by the microphones at different installation angles. , where the elements express The first measurement of the microphone at the corresponding installation angle position Signal, , when using a uniform acoustic array layout, the time domain signal matrix The size is ; When using a non-uniform acoustic array layout with few measurement points, the time domain signal matrix The size is .

4. The method for synchronous vibration and acoustic identification of aero-engine fan blades according to claim 3, characterized in that: The third step (S3) includes, S301, time domain signal matrix Perform Fourier transform on each column to obtain the frequency domain matrix , where the elements express The signal measured by the microphone at the corresponding installation angle position is The amplitude at the frequency, The length is , according to Nyquist sampling theorem, , , in a uniform acoustic array layout, the frequency domain matrix The size is ; Frequency domain matrix in non-uniform acoustic array layout The size is , S302, according to the frequency domain matrix Draw the spectrum of the signal measured by the sensor at different installation angles, and the fan blade passing frequency The increase in amplitude exceeds a first predetermined value and a broadband noise component with a frequency distribution greater than a predetermined range appears.

5. The method for synchronous vibration and acoustic identification of aero-engine fan blades according to claim 4, characterized in that: The fourth step (S4) comprises, S401, when using uniform acoustic array layout, subscript The microphone at the corresponding installation angle position is at the predetermined frequency The frequency domain signal at It can be regarded as the linear superposition of different circumferential acoustic modes, that is, , construct the transformation matrix The form is as follows: ， When using a non-uniform acoustic array layout with few measurement points, the observation matrix is constructed based on the randomly selected sensor installation angles. , the observation matrix Size , ， S402, when using a uniform acoustic array layout, the frequency domain matrix Perform spatial Fourier transform to obtain the wave number domain matrix , ,in is the frequency domain matrix The transposed matrix of ,in Represents the transformation matrix The pseudo-rebellion, When a non-uniform acoustic array layout with few measurement points is used, the compressed sensing model is , sparse dictionary It is composed of an orthogonal Fourier transform basis, For the perception matrix, the wave number domain matrix is sparsely reconstructed based on the compressed sensing model ; S403, according to the obtained wave number domain matrix , draw the acoustic modal spectrum; When the fan blades vibrate synchronously, the excitation frequency of the sound source is coupled with the vibration frequency of the blades, and a change in the amplitude of the rotational-static interference mode in the acoustic modal spectrum of the blade passing frequency exceeds a second predetermined value.

6. The method for synchronous vibration and acoustic identification of aero-engine fan blades according to claim 5, characterized in that: The fifth step (S5) comprises, S501, the wave number domain matrix Expanded to full frequency domain, wave number domain matrix Size expanded to , where the elements Indicates the frequency Place The amplitude of the order acoustic mode, ， S502, according to the wave number domain matrix , draw a spectrum diagram, observe that the amplitude increase of the broadband noise mode in the spectrum diagram exceeds the third predetermined value, and the change of the amplitude of the rotation-static interference mode at the blade passing frequency exceeds the second predetermined value and propagates to the surrounding frequencies, which is combined with the blade passing frequency sound source to form a cross bright band phenomenon, which is defined as the identification feature of the synchronous vibration soundprint of the fan blade, and based on this, it is judged whether the fan blades are vibrating synchronously.

7. The method for synchronous vibration and acoustic identification of aero-engine fan blades according to claim 1, characterized in that: In the sixth step (S6), when the fan blades vibrate synchronously, the fan blade disc vibration pitch diameter and frequency are output. S601, when the fan blades vibrate synchronously, the vibration frequency of the blade disk is coupled with the blade frequency, and the acoustic mode order is equal to the blade pitch number. At this time, the sound source excitation frequency and blade vibration frequency of satisfaction, , where Indicates the rotor speed frequency, S602: Calculate the blade vibration frequency and vibration node diameter according to the excitation frequency and modal order of the sound source in the spectrum diagram and output them.

8. A fan blade synchronous vibration identification system implementing the method according to any one of claims 1 to 7, characterized in that: It includes: The sound field measurement module includes a sound array measurement submodule and a data acquisition submodule, and is used to measure the sound field information propagated in the duct to the sound array installation position when the fan is working; The spectrum analysis module is used to transform the time domain sound field signal at the acoustic array position into the frequency domain to detect whether there are abnormal changes in the blade passing frequency and abnormal frequency components; The acoustic modal decomposition module is used to perform single-tone acoustic mode decomposition and continuous broadband acoustic mode decomposition, transform the sound field information from the frequency domain to the wavenumber domain, and detect whether the synchronous vibration characteristics of the fan blades appear in the acoustic modal spectrogram and wave spectrogram; The synchronous vibration calculation module is used to determine whether the fan blades have synchronous vibration and output the fan blade vibration pitch diameter and frequency.

9. A computer storage medium, characterized in that The storage medium includes computer instructions, which, when executed on a computer, enable the computer to perform the method according to any one of claims 1 to 7.

10. An electronic device, characterized in that: The electronic device comprises: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method according to any one of claims 1 to 7 is implemented.

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