Aeroengine rotating stall acoustic fingerprint monitoring method, system, medium and equipment

Abstract

Aero-engine compressor rotating stall acoustic fingerprint monitoring method, system, medium and equipment, in the method, the microphone array layout is determined through the compressor model parameters of the aero-engine, the multi-channel sound pressure time domain signal of the aero-engine compressor is synchronously collected through the microphone array; the multi-channel sound pressure time domain signal is arranged in sequence to construct a time domain signal matrix; the sound pressure time domain signal is analyzed by using fast Fourier transform algorithm, the frequency spectrum diagram of each channel sound pressure time domain signal is obtained, whether the abnormal single tone frequency peak lower than 1 times rotation frequency appears is monitored through the frequency spectrum diagram, the acoustic mode spectrum diagram of abnormal single tone frequency peak is obtained through single frequency acoustic mode decomposition method, whether the compressor rotating stall characteristic appears in the acoustic mode spectrum diagram is monitored to judge whether the compressor rotating stall appears.

Description

Technical Field

[0001] This invention relates to the field of aircraft engine noise testing technology, and in particular to a method, system, medium, and equipment for monitoring the acoustic signature of an aircraft engine compressor rotating stall. Background Technology

[0002] To improve performance, large aero-engines often increase the single-stage pressure ratio of the compressor while reducing the number of compressor stages. However, this increase in single-stage pressure ratio and reduction in the number of stages inevitably requires increased compressor blade load, leading to flow separation and causing flow instability issues within the compressor, such as rotating stall and surge. The occurrence of airflow path failures like rotating stall and surge severely impacts the stability and safety of aero-engine operation, often resulting in catastrophic consequences.

[0003] Rotating stall can generally be divided into two categories: progressive stall and abrupt stall. When a compressor experiences progressive stall, the pressure ratio gradually decreases without a sudden drop; when a compressor experiences abrupt stall, the pressure in the acoustic field drops abruptly, reflecting a discontinuity in the pressure ratio curve. When airflow stripping occurs at the compressor blade tips, forming a stall air mass at the blade tips, rotating stall will occur and gradually develop along the circumferential and radial directions. The compressor outlet pressure will decrease, and periodic oscillations with higher frequency and lower amplitude will form. When these oscillations develop throughout the entire compressor, they will trigger surge failure.

[0004] Rotating stall not only degrades the performance of aero engines and limits their operating range, but also, once it occurs, the engine is highly likely to shut down immediately, damaging critical engine components. Therefore, accurately identifying and analyzing its fault characteristics is crucial for the maintenance and repair of aero engines. Traditional fault detection methods mainly rely on visual inspection, non-destructive testing techniques, and vibration analysis; however, these methods often have limitations when dealing with compressor rotating stall faults.

[0005] The information disclosed in the background section is only for enhancing the understanding of the background of this invention, and therefore may contain information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] This invention provides a method, system, medium, and equipment for monitoring the acoustic signature of aero-engine compressor rotating stall. It employs a ring acoustic array to measure acoustic signals and uses a spectrum analysis module and an acoustic mode decomposition module to convert the acoustic signal from the time domain to the wavenumber domain, obtaining a more effective acoustic signature for rotating stall detection. This achieves the conversion of the sound field signal from the time domain to the frequency domain to the wavenumber domain, fully extracting the acoustic signal fault characteristics when a rotating stall fault occurs for identification.

[0007] A method for monitoring the acoustic signature of rotating stall in an aero-engine compressor includes:

[0008] In the first step, the microphone array layout is determined using the compressor model parameters of the aero-engine, based on the number of compressor rotor blades. With the number of stator blades Calculate the order of the transition-to-static interference mode of compressor single-tone noise Based on the order of the static interference mode The maximum modal order determines the acoustic modal monitoring range and the number of microphones. and the circumferential mounting angle of the microphone ;

[0009] In the second step, through the number of microphones and the installation angle of the microphone Construct a microphone array; synchronously acquire the multi-channel sound pressure time-domain signals of the aero-engine compressor using the microphone array; construct a time-domain signal matrix by arranging the multi-channel sound pressure time-domain signals in sequence;

[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 of the sound pressure time domain signal of each channel. By monitoring the spectrum, it is found that there are abnormal single-tone frequency peaks below 1 times the frequency. If there are no abnormal single-tone frequency peaks, it means that the compressor is in normal working condition. If there are abnormal single-tone frequency peaks, it will proceed to the fourth step.

[0011] In the fourth step, the acoustic mode spectrum of the abnormal single-tone frequency peak is obtained by the single-frequency acoustic mode decomposition method. The presence of compressor rotating stall characteristics in the acoustic mode spectrum is monitored to determine whether the compressor is experiencing rotating stall. When the compressor experiences rotating stall characteristics under supersonic conditions, the rotating stall characteristic frequency with a frequency component lower than 1 times the rotational frequency and an acoustic mode order of 1 appears in the wavenumber domain.

[0012] The aforementioned method for monitoring the acoustic signature of rotating stall in an aero-engine compressor also includes,

[0013] In the fifth step, the spectrum of the sound pressure time-domain signal is obtained through continuous broadband acoustic mode decomposition. The horizontal axis of the spectrum represents the frequency analysis range, the vertical axis represents the acoustic mode monitoring range, and the color intensity represents the amplitude. The darker the color, the larger the amplitude. By monitoring whether the compressor rotating stall characteristics appear in the spectrum, it can be further determined whether the compressor is experiencing rotating stall. When the compressor experiences rotating stall under supersonic conditions, the abnormal sound source of rotating stall and its harmonics appear in the spectrum, and they are all non-integer multiples of the rotational frequency. At the same time, there are oblique bright band components of the acoustic mode starting from the modal order of 1, corresponding to the rotating stall characteristic frequency and its harmonics.

[0014] In the aforementioned method for monitoring the acoustic signature of aero-engine compressor rotating stall, in the first step, the order of the compressor's rotating-to-static interference modes... for, ,in, This indicates the order of pressure pulsations caused by unsteady aerodynamic forces resulting from compressor static interference. Represents an integer, determining the number of microphones in the microphone array. And in the microphone installation angle,

[0015] When using a uniform acoustic array layout, calculate the number of sensors required for modal detection based on the Nyquist sampling theorem. Its order with the static interference mode The relationship is: When using a non-uniform acoustic array layout with few measurement points, in a virtually uniform layout... Randomly selected from the positions Install sensors at various locations. ;

[0016] When using a uniform acoustic array layout scheme, A circular acoustic array is composed of several sensors, with a spacing between the sensors being [missing information]. The microphone is installed at an angle of 100°. ,in , , And so on; when using a non-uniform acoustic array layout with few measurement points, the microphone installation angle... Random selection .

[0017] In the aforementioned method for monitoring the acoustic signature of aero-engine compressor rotating stall, the second step includes the following steps:

[0018] S201. The sound pressure signal of the aero-engine compressor is measured using a ring acoustic array. The measured sound pressure time-domain signal is: The length of the time-domain signal sequence measured by a single microphone is [length missing]. subscript These are microphones positioned at corresponding installation angles;

[0019] S202. Based on the sound pressure time-domain signals measured by the microphones at different installation angles, construct a time-domain signal matrix. , of which elements express The first measurement obtained by the microphone at the corresponding installation angle position Signal,

[0020] 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 .

[0021] In the aforementioned method for monitoring the acoustic signature of rotating stall in an aero-engine compressor, the third step includes:

[0022] S301, Measure the time-domain signal matrix of the circular acoustic array. The frequency domain matrix is ​​obtained by performing a Fourier transform on each column. , of which elements express The signal measured by the microphone at the corresponding installation angle position is in Amplitude at frequency, The length is According to the Nyquist sampling theorem, ,

[0023] In a uniform acoustic array layout, the frequency domain matrix The size is In a non-uniform acoustic array layout, the frequency domain matrix The size is ,

[0024] S302, According to the frequency domain matrix Plot the spectrum of signals measured by sensors at different installation angles and observe whether there are frequencies other than those of the passing blades. Abnormal single-tone frequency peaks outside the rotation frequency are rotating stall characteristic frequencies with frequencies lower than the rotation frequency and amplitudes more than twice the amplitude of the current blade passing frequency, as well as their second and third harmonics.

[0025] In the aforementioned method for monitoring the acoustic signature of rotating stall in an aero-engine compressor, the fourth step includes:

[0026] S401, When using a uniform acoustic array layout, the subscript The microphone at the corresponding installation angle position at the predetermined frequency Frequency domain signal at It can be viewed as a linear superposition of different circumferential acoustic modes, i.e. Construct the transformation matrix The format is as follows:

[0027] ,

[0028] When using a non-uniform acoustic array layout with few measurement points, an observation matrix is ​​constructed based on randomly selected sensor installation angles. Observation matrix Size is ,

[0029] ,

[0030] S402. When using a uniform acoustic array layout, the frequency domain matrix... Perform a spatial Fourier transform to obtain the wavenumber domain matrix. , ,in Frequency domain matrix The transpose of the matrix, ,in Represents the transformation matrix The false rebellion,

[0031] When using a non-uniform acoustic array layout with few measurement points, the compressed sensing model is: sparse dictionary Composed of orthogonal Fourier transform bases, For the sensing matrix, sparsely reconstruct the wavenumber domain matrix based on the compressed sensing model. ;

[0032] S403. Based on the obtained wavenumber domain matrix Plot the acoustic modal spectrum; under supersonic conditions, observe whether the rotating stall characteristic frequency and its harmonics appear. The rotating stall characteristic frequency is lower than 1 times the rotational frequency and the modal order is 1.

[0033] In the aforementioned method for monitoring the acoustic signature of rotating stall in an aero-engine compressor, the fifth step includes:

[0034] S501, the wavenumber domain matrix Extending to the full frequency domain, wavenumber domain matrix Size expansion to , of which elements Indicates frequency First The amplitude of the step sound mode,

[0035] ,

[0036] S502, According to the wavenumber domain matrix Plot the spectrum. Under supersonic conditions, observe whether there is a rotating stall anomalous sound source and its harmonics that are not integer multiples of the rotational frequency, as well as the corresponding rotating stall characteristic frequencies and their harmonics, and the oblique bright band components of the acoustic modes starting from mode order 1. The mathematical expression of the oblique bright band components of the acoustic modes is as follows:

[0037]

[0038] In the formula, The characteristic frequency of rotational stall. The harmonics representing the characteristic frequency. It is a non-negative integer. The circumferential acoustic mode order is represented by the characteristic frequency of rotating stall in the spectrum, the corresponding mode order at the characteristic frequency in the acoustic mode spectrum, the abnormal sound source in the wave spectrum and the oblique bright band component of the acoustic mode. Based on this, it is determined whether the compressor has experienced rotating stall.

[0039] A monitoring system for implementing the method includes:

[0040] The sound field measurement module includes a sound array measurement submodule and a data acquisition submodule, which are used to measure the sound field information that propagates in the pipeline to the sound array installation position when the compressor is working;

[0041] The spectrum analysis module is used to transform the time-domain sound field signal at the location of the acoustic array to the frequency domain to detect whether there are abnormal frequencies outside the blade passing frequency and the switching frequency;

[0042] The acoustic mode decomposition module is used to perform single-tone acoustic mode decomposition and continuous broadband acoustic mode decomposition, transforming the sound field information from the frequency domain to the wavenumber domain, and detecting whether compressor rotating stall characteristics appear in the acoustic mode spectrum and wave number spectrum.

[0043] A computer storage medium including computer instructions that, when run on a computer, cause the computer to perform the method.

[0044] An electronic device, the electronic device comprising:

[0045] Memory, processor, and computer programs stored in memory and executable on the processor, wherein,

[0046] The processor implements the method when executing the program.

[0047] Compared with existing technologies, this invention has the following advantages: This invention utilizes acoustic information to monitor compressor rotating stall faults, offering higher sensitivity and greater adaptability compared to traditional methods that rely on vibration signals and interstage pressure signals. This invention obtains the compressor rotating stall characteristics in the frequency domain through Fast Fourier Transform, resulting in clear features and a simple process. It also obtains the compressor rotating stall characteristics in the wavenumber domain through Spatial Fourier Transform, offering high sensitivity and adaptability to different engine speeds. Even with limited testing resources, a non-uniform layout scheme can be used to extract the acoustic signature features of aero-engine compressor rotating stall. Defining the abnormal components in the acoustic signal's spectrum, modal spectrum, and wave spectrum as the acoustic signature features of compressor rotating stall improves monitoring accuracy. Attached Figure Description

[0048] 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 for illustrative purposes only and are not intended to limit the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0049] In the attached diagram:

[0050] Figure 1 This is the flowchart of this disclosure;

[0051] Figure 2 This is a schematic diagram of a compressor rotating stall monitoring method and detection device based on acoustic signature features, provided in one embodiment of this disclosure.

[0052] Figures 3(a) to 3(c) This disclosure provides a spectrum diagram of the compressor without rotating stall and a spectrum diagram of the compressor at different speeds under supersonic operation, provided in one embodiment. Figure 3(a) is the spectrum diagram of the compressor without rotating stall, Figure 3(b) is the spectrum diagram of the compressor at higher speeds with rotating stall, and Figure 3(c) is the spectrum diagram of the compressor at lower speeds with rotating stall.

[0053] Figures 4(a) to 4(b) Figure 4(a) shows the acoustic modal spectrum at the characteristic frequency of compressor rotational stall and at the blade passage frequency, respectively, provided in one embodiment of this disclosure.

[0054] Figures 5(a) to 5(c) Figure 5(a) shows the spectrum of rotating stall when no fault occurs and at different speeds under supersonic compressor operation, provided in one embodiment of this disclosure. Figure 5(b) shows the spectrum of rotating stall when no fault occurs, Figure 5(c) shows the spectrum of rotating stall when the compressor operates at a higher speed, and Figure 5(c) shows the spectrum of rotating stall when the compressor operates at a lower speed.

[0055] The present invention will be further explained below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0056] Specific embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While specific embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0057] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0058] To facilitate understanding of the embodiments of the present invention, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0059] like Figures 1 to 5(c) As shown, the method for monitoring the acoustic signature of aero-engine compressor rotating stall includes the following steps:

[0060] In the first step S1, the microphone array layout is determined using the compressor model parameters of the aero-engine, based on the number of compressor rotor blades. With the number of stator blades Calculate the order of the transition-to-static interference mode of compressor single-tone noise Based on the order of the static interference mode The maximum modal order determines the acoustic modal monitoring range and the number of microphones. and the circumferential mounting angle of the microphone ;

[0061] In the second step S2, through the number of microphones and the installation angle of the microphone Construct a microphone array; synchronously acquire the multi-channel sound pressure time-domain signals of the aero-engine compressor using the microphone array; construct a time-domain signal matrix by arranging the multi-channel sound pressure time-domain signals in sequence;

[0062] In the third step S3, the fast Fourier transform algorithm is used to perform spectral analysis on the sound pressure time domain signal to obtain the spectrum of the sound pressure time domain signal of each channel. By monitoring the spectrum, it is found that there is an abnormal single-tone frequency peak below 1 times the frequency. If there is no abnormal single-tone frequency peak, it means that the compressor is in normal working condition. If there is, proceed to the fourth step S4.

[0063] In the fourth step S4, the acoustic mode spectrum of the abnormal single-tone frequency peak is obtained by the single-frequency acoustic mode decomposition method. The presence of compressor rotating stall characteristics in the acoustic mode spectrum is monitored to determine whether the compressor is experiencing rotating stall. When the compressor experiences rotating stall characteristics under supersonic conditions, the rotating stall characteristic frequency with a frequency component lower than 1 times the rotational frequency and an acoustic mode order of 1 appears in the wavenumber domain.

[0064] In a preferred embodiment of the aforementioned method for monitoring the acoustic signature of aero-engine compressor rotating stall, it further includes,

[0065] In step S5, the spectrum of the sound pressure time-domain signal is obtained through continuous broadband acoustic mode decomposition. The horizontal axis of the spectrum represents the frequency analysis range, the vertical axis represents the acoustic mode monitoring range, and the color intensity represents the amplitude. The darker the color, the larger the amplitude. By monitoring whether the compressor rotating stall characteristics appear in the spectrum, it can be further determined whether the compressor is experiencing rotating stall. When the compressor experiences rotating stall under supersonic conditions, the abnormal sound source of rotating stall and its harmonics appear in the spectrum, and they are all non-integer multiples of the rotational frequency. At the same time, there are oblique bright band components of the acoustic mode starting from the modal order of 1, corresponding to the rotating stall characteristic frequency and its harmonics.

[0066] In a preferred embodiment of the method for monitoring the acoustic signature of aero-engine compressor rotating stall, in the first step S1, the order of the compressor's rotating-to-stationary interference modes... for, ,in, This indicates the order of pressure pulsations caused by unsteady aerodynamic forces resulting from compressor static interference. Represents an integer, determining the number of microphones in the microphone array. And in the microphone installation angle,

[0067] When using a uniform acoustic array layout, calculate the number of sensors required for modal detection based on the Nyquist sampling theorem. Its order with the static interference mode The relationship is: When using a non-uniform acoustic array layout with few measurement points, in a virtually uniform layout... Randomly selected from the positions Install sensors at various locations. ;

[0068] When using a uniform acoustic array layout scheme, A circular acoustic array is composed of several sensors, with a spacing between the sensors being [missing information]. The microphone is installed at an angle of 100°. ,in , , And so on; when using a non-uniform acoustic array layout with few measurement points, the microphone installation angle... Random selection .

[0069] In a preferred embodiment of the method for monitoring the acoustic signature of aero-engine compressor rotating stall, the second step S2 includes the following steps:

[0070] S201. The sound pressure signal of the aero-engine compressor is measured using a ring acoustic array. The measured sound pressure time-domain signal is: The length of the time-domain signal sequence measured by a single microphone is [length missing]. subscript These are microphones positioned at corresponding installation angles;

[0071] S202. Based on the sound pressure time-domain signals measured by the microphones at different installation angles, construct a time-domain signal matrix. , of which elements express The first measurement obtained by the microphone at the corresponding installation angle position Signal,

[0072] 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 .

[0073] In a preferred embodiment of the method for monitoring the acoustic signature of aero-engine compressor rotating stall, the third step S3 includes:

[0074] S301, Measure the time-domain signal matrix of the circular acoustic array. The frequency domain matrix is ​​obtained by performing a Fourier transform on each column. , of which elements express The signal measured by the microphone at the corresponding installation angle position is in Amplitude at frequency, The length is According to the Nyquist sampling theorem, ,

[0075] In a uniform acoustic array layout, the frequency domain matrix The size is In a non-uniform acoustic array layout, the frequency domain matrix The size is ,

[0076] S302, According to the frequency domain matrix Plot the spectrum of signals measured by sensors at different installation angles and observe whether there are frequencies other than those of the passing blades. Abnormal single-tone frequency peaks outside the rotation frequency are rotating stall characteristic frequencies with frequencies lower than the rotation frequency and amplitudes more than twice the amplitude of the current blade passing frequency, as well as their second and third harmonics.

[0077] In a preferred embodiment of the method for monitoring the acoustic signature of aero-engine compressor rotating stall, the fourth step S4 includes:

[0078] S401, When using a uniform acoustic array layout, the subscript The microphone at the corresponding installation angle position at the predetermined frequency Frequency domain signal at It can be viewed as a linear superposition of different circumferential acoustic modes, i.e. Construct the transformation matrix The format is as follows:

[0079] ,

[0080] When using a non-uniform acoustic array layout with few measurement points, an observation matrix is ​​constructed based on randomly selected sensor installation angles. Observation matrix Size is ,

[0081] ,

[0082] S402. When using a uniform acoustic array layout, the frequency domain matrix... Perform a spatial Fourier transform to obtain the wavenumber domain matrix. , ,in Frequency domain matrix The transpose of the matrix, ,in Represents the transformation matrix The false rebellion,

[0083] When using a non-uniform acoustic array layout with few measurement points, the compressed sensing model is: sparse dictionary Composed of orthogonal Fourier transform bases, For the sensing matrix, sparsely reconstruct the wavenumber domain matrix based on the compressed sensing model. ;

[0084] S403. Based on the obtained wavenumber domain matrix Plot the acoustic modal spectrum; under supersonic conditions, observe whether the rotating stall characteristic frequency and its harmonics appear. The rotating stall characteristic frequency is lower than 1 times the rotational frequency and the modal order is 1.

[0085] In a preferred embodiment of the method for monitoring the acoustic signature of aero-engine compressor rotating stall, the fifth step S5 includes:

[0086] S501, the wavenumber domain matrix Extending to the full frequency domain, wavenumber domain matrix Size expansion to , of which elements Indicates frequency First The amplitude of the step sound mode,

[0087] ,

[0088] S502, According to the wavenumber domain matrix Plot the spectrum. Under supersonic conditions, observe whether there is a rotating stall anomalous sound source and its harmonics that are not integer multiples of the rotational frequency, as well as the corresponding rotating stall characteristic frequencies and their harmonics, and the oblique bright band components of the acoustic modes starting from mode order 1. The mathematical expression of the oblique bright band components of the acoustic modes is as follows:

[0089]

[0090] In the formula, The characteristic frequency of rotational stall. The harmonics representing the characteristic frequency. It is a non-negative integer. The circumferential acoustic mode order is represented by the characteristic frequency of rotating stall in the spectrum, the corresponding mode order at the characteristic frequency in the acoustic mode spectrum, the abnormal sound source in the wave spectrum and the oblique bright band component of the acoustic mode. Based on this, it is determined whether the compressor has experienced rotating stall.

[0091] A monitoring system for implementing the method includes:

[0092] The sound field measurement module includes a sound array measurement submodule and a data acquisition submodule, which are used to measure the sound field information that propagates in the pipeline to the sound array installation position when the compressor is working;

[0093] The spectrum analysis module is used to transform the time-domain sound field signal at the location of the acoustic array to the frequency domain to detect whether there are abnormal frequencies outside the blade passing frequency and the switching frequency;

[0094] The acoustic mode decomposition module is used to perform single-tone acoustic mode decomposition and continuous broadband acoustic mode decomposition, transforming the sound field information from the frequency domain to the wavenumber domain, and detecting whether compressor rotating stall characteristics appear in the acoustic mode spectrum and wave number spectrum.

[0095] A computer storage medium including computer instructions that, when run on a computer, cause the computer to perform the method.

[0096] An electronic device, the electronic device comprising:

[0097] Memory, processor, and computer programs stored in memory and executable on the processor, wherein,

[0098] The processor implements the method when executing the program.

[0099] In one embodiment, the method for monitoring the acoustic signature of aero-engine compressor rotating stall includes the following steps:

[0100] In the first step S1, based on the number of rotor blades of the aero-engine compressor... With the number of stator blades Calculate the order of the transition-to-static interference mode of compressor single-tone noise In the selected implementation case, a uniform acoustic array layout is adopted. Based on the aforementioned acoustic mode order... The maximum modal order determines the acoustic modal monitoring range, according to the Nyquist sampling theorem: Determine the number of microphones and the installation angle of the microphone ;

[0101] In the second step S2, through the number of microphones and the installation angle of the microphone Construct a microphone array; synchronously acquire the multi-channel sound pressure of the aero-engine compressor using the microphone array; arrange the time-domain sound pressure signals of the multi-channel sound pressure in sequence to construct a time-domain signal matrix;

[0102] In the third step S3, the Fast Fourier Transform algorithm is used to perform spectral analysis on the acoustic array signal to obtain the spectrum of the acoustic signal in each channel. The normal working chamber spectrum of the compressor only contains the blade passage frequency (and rotational frequency). The signal spectrum is monitored to check for any abnormal single-tone frequency peaks below 1 times the rotational frequency. If none are found, it indicates that the compressor is in normal working condition; if so, further analysis is required.

[0103] In step S4, based on the constructed transformation matrix, the acoustic modal spectrum of the abnormal single-tone frequency peak is obtained using the single-frequency acoustic modal decomposition method. The presence of compressor rotating stall characteristics in the acoustic modal spectrum is monitored to determine if the compressor is experiencing rotating stall. When the compressor exhibits rotating stall characteristics under supersonic conditions, the main components in the spectrum are rotating stall characteristic frequencies below one times the rotational frequency. In the wavenumber domain, rotating stall characteristic frequencies with frequency components below one times the rotational frequency and a modal order of 1 appear. To more fully illustrate the compressor's rotating stall fault at this time, the acoustic array signal is further analyzed.

[0104] In step S5, the spectrum of the array signal is obtained through continuous broadband acoustic mode decomposition. By monitoring whether compressor rotating stall characteristics appear in the spectrum, it is further determined whether the compressor is experiencing rotating stall. When the compressor experiences rotating stall under supersonic conditions, the spectrum shows an abnormal rotating stall sound source and its harmonics, all of which are non-integer multiples of the rotational frequency. Simultaneously, a bright band component of the acoustic mode starting from mode order 1 appears, corresponding to the rotating stall characteristic frequency and its harmonics.

[0105] In a preferred embodiment, in the first step S1, the number of rotor blades of the aero-engine compressor is determined. With the number of stator blades Calculate the modal order of compressor single-tone noise : ,in, This indicates the order of pressure pulsations caused by unsteady aerodynamic forces resulting from compressor static interference. Represents an integer. Determining the number and mounting angle of sensors in a microphone array involves the following steps:

[0106] S101. Calculate the number of sensors required for modal detection based on the Nyquist sampling theorem. Its relationship with the order of acoustic modes The relationship is: ;

[0107] S102, Several sensors are arranged in a uniform circular acoustic array, with a spacing between the sensors being [missing information]. The microphone is installed at an angle of 100°. ,in , , And so on;

[0108] In a preferred embodiment, the second step S2 involves conducting a compressor stall test on an aero-engine, acquiring sound field information within the compressor duct using a microphone array, and establishing a time-domain signal matrix, which includes the following steps:

[0109] S201. The sound pressure signal of the aero-engine compressor is measured using a ring acoustic array. The measured sound pressure signal is: , representing the length of the time-domain signal sequence measured by a single microphone. subscript These are microphones at corresponding angular positions;

[0110] S202. Based on the time-domain signals measured by the microphones at different angular positions, construct a time-domain signal matrix. , of which elements express The first angular position measured by the microphone Signal.

[0111]

[0112] In a preferred embodiment, in the third step S3, a spectrum is obtained by fast Fourier transform to observe whether there are any abnormal single-tone components with significant energy in the spectrum, and whether there is no integer relationship with the blade rotation frequency.

[0113] S301, Measure the time-domain signal matrix of the circular acoustic array. The frequency domain matrix is ​​obtained by performing a Fourier transform on each column. , of which elements express The signal measured by the microphone at the corresponding angular position Amplitude at a given frequency. The length is According to the Nyquist sampling theorem, .

[0114]

[0115] S302. Based on the obtained frequency domain matrix Plot the spectrum of signals measured by sensors at different angles and positions, and observe whether there are frequencies other than those of the blades passing by. Abnormal single-tone frequency peaks outside the rotational frequency. Specifically, this manifests as a large value of the rotating stall characteristic frequency and its harmonics, which is less than 1 times the rotational frequency.

[0116] In a preferred embodiment, in the fourth step S4, single-frequency acoustic mode decomposition is performed to obtain an acoustic mode spectrum, and the presence or absence of compressor rotating stall characteristics is observed.

[0117] S401, Subscript A microphone at a corresponding angular position at a specific frequency acoustic signal at the location It can be viewed as a linear superposition of different circumferential acoustic modes, i.e. Therefore, a transformation matrix can be constructed. Its specific form is as follows:

[0118]

[0119] S402, Regarding the frequency domain matrix Perform a spatial Fourier transform to obtain the wavenumber domain matrix. According to S401, ,in Frequency domain matrix The transpose of the matrix, therefore we have ,in Represents the transformation matrix The false rebellion.

[0120] S403. Based on the obtained wavenumber domain matrix Plot the acoustic modal spectrum; under supersonic conditions, observe whether there is an obvious rotating stall characteristic frequency and its harmonics, the rotating stall characteristic frequency is less than 1 times the rotational frequency and the modal order is 1.

[0121] In a preferred embodiment, in the fifth step S5, continuous broadband acoustic mode decomposition is performed to obtain a spectrogram, and the presence or absence of compressor rotating stall characteristics is observed:

[0122] S501. Perform continuous broadband acoustic mode decomposition across the entire frequency domain, then the wavenumber domain matrix... Size expansion to , of which elements Indicates frequency First The amplitude of the step sound mode.

[0123]

[0124] S502, Based on the obtained wavenumber domain matrix Plot the spectrum; under supersonic conditions, observe whether there is a rotating stall anomalous sound source and its harmonics that are not integer multiples of the rotational frequency, and the corresponding rotating stall characteristic frequencies and their harmonics, with oblique bright band components of the acoustic modes starting from mode order 1. The mathematical expression of this oblique bright band is as follows:

[0125]

[0126] The above features are defined as the acoustic signature of compressor rotational stall monitoring, which is used to determine whether the compressor has experienced rotational stall.

[0127] In a preferred embodiment, the sound field information is measured by a microphone array to obtain a time-domain signal matrix. , of which elements express The first angular position measured by the microphone Signal.

[0128] Figure 1 This is a flowchart of the rotating stall monitoring method for aero-engine compressors based on acoustic signature features, as completed in this invention. The method uses a compressor model of the aero-engine to calculate the order of the rotating-to-stationary interference modes in the compressor's single-tone noise. Based on the maximum order of the mode of interest, it determines the acoustic mode monitoring range, the number of microphones, the axial mounting position, and the circumferential mounting angle. A fast Fourier transform is performed on the acoustic array signal to obtain the frequency domain signal matrix. Output the spectrum and observe whether there are any frequencies other than the blade passage frequency. The abnormal peak values ​​outside the rotation frequency are observed. Based on the constructed transformation matrix, the acoustic mode spectrum of the abnormal single-tone frequency peaks is obtained through single-frequency acoustic mode decomposition. It is then observed whether there are rotating stall characteristic frequencies with frequency components lower than 1 times the rotation frequency and a mode order of 1. The spectrum of the array signal is obtained through continuous broadband acoustic mode decomposition. It is then observed whether there are rotating stall abnormal sound sources and their harmonics that are not integer multiples of the rotation frequency, as well as the corresponding rotating stall characteristic frequencies and their harmonics, with oblique bright band components of the acoustic modes starting from mode order 1. The specific steps are as follows:

[0129] 1) Assume the number of rotor blades of the aero-engine compressor With the number of stator blades According to the formula for calculating the modal order of compressor single-tone noise, , usually take The order of the pressure pulsation caused by the unsteady aerodynamic forces resulting from the compressor's static interference is 1. In this case, we take... Representing the first-order acoustic mode, the calculation yields... ,Pick Representing the second-order acoustic mode, the calculation yields... According to the Nyquist sampling theorem: The required number of sensors Therefore, the number of sensors is selected as follows: ;

[0130] 2) Several sensors are arranged in a uniform circular acoustic array, with a sampling frequency set to 20000 Hz and a spacing between the sensors of [missing information]. The microphone is installed at an angle of 100°. ,in , , And so on;

[0131] 3) The sound pressure signal of the aero-engine compressor was measured using a ring acoustic array, with each channel measured as follows: The constructed time-domain signal matrix consists of 1 data point. The size is The time-domain signal matrix measured for the circular acoustic array Perform a Fourier transform on each column to transform the signal from the time domain to the frequency domain, obtaining the frequency domain matrix. Frequency domain matrix The size is According to the Nyquist sampling theorem, .

[0132] 4) Based on the obtained frequency domain matrix Plot the spectrum of signals measured by the sensor at different angles, with the installation position as the baseline. Taking the microphone signal as an example, in Figure 3(a) when there is no rotating stall, the main components of the spectrum are the rotation frequency and its harmonics. In Figures 3(b) and 3(c) when there is rotating stall, the spectrum contains only the blade passing frequency. With frequency conversion, abnormal peak values ​​appear at frequencies less than 1 times the frequency conversion.

[0133] 5) Elements in the frequency domain matrix Indicates subscript A microphone at a corresponding angular position at a specific frequency The acoustic signal at that location can be considered as a linear superposition of different circumferential acoustic modes, i.e. Therefore, the constructed transformation matrix Size is .

[0134] 6) Single-frequency acoustic mode decomposition at the abnormal peak frequency yields a value of... wavenumber domain matrix And the acoustic modal spectrum was plotted. When rotational stall occurs, the acoustic mode observed in the acoustic modal spectrum at the rotational stall characteristic frequency in Figure 4(a) is as follows: Figure 4(b) shows the acoustic mode observed in the acoustic mode spectrum at the passing frequency of the blade as follows: and .

[0135] 7) For the frequency domain matrix Performing continuous broadband acoustic mode decomposition yields a value of wavenumber domain matrix wavenumber domain matrix Middle elements Indicates frequency First The amplitude of the order acoustic mode. Based on the obtained wavenumber domain matrix. Spectral diagrams were plotted. Under supersonic conditions, in Figure 5(a) when there is no rotating stall, the main sound source in the spectral diagram is the blade passage frequency. In Figures 5(b) and 5(c) when rotating stall occurs, abnormal rotating stall sound sources and their harmonics appear in the spectral diagrams, all of which are non-integer multiples of the rotational frequency; at the same time, oblique bright band components of the acoustic mode starting from the modal order 1 appear, corresponding to the rotating stall characteristic frequency and its harmonics.

[0136] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art can make many other forms based on the guidance of this specification and without departing from the scope of protection of the claims of the present invention, and all of these are within the scope of protection of the present invention.

Claims

1. A method of monitoring the sound signature of rotating stall in an aircraft engine compressor, characterized by, The method comprises the following steps: In the first step (S1), the microphone array layout is determined by the compressor model parameters of the aero-engine, according to the number of rotor blades of the compressor and the number of stator blades , the rotor-stator interaction modal order of the compressor single-tone noise is calculated , the maximum modal order based on the rotor-stator interaction modal order is determined to determine the sound modal monitoring range, the number of microphones and the circumferential installation angle of the microphone ; In the second step (S2), the number of microphones is determined by the number of microphones and the circumferential installation angle of the microphones The microphone array is constructed; the multi-channel sound pressure time domain signals of the aero-engine compressor are synchronously collected by the microphone array; and the multi-channel sound pressure time domain signals are sequentially arranged 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 graph of the sound pressure time domain signal of each channel, and it is monitored whether an abnormal single-tone frequency peak lower than 1 times the rotating frequency appears in the spectrum graph. If not, it indicates that the compressor is in a normal working state, and if yes, it enters the fourth step (S4); In the fourth step (S4), an abnormal single-tone frequency peak is obtained through a single-frequency sound mode decomposition method, and it is monitored whether a compressor rotating stall characteristic appears in the sound mode spectrum graph to determine whether the compressor has a rotating stall. When the compressor has a rotating stall under a supersonic working condition, a rotating stall characteristic frequency with a frequency component lower than 1 times the rotating frequency and a sound mode order of 1 appears in the wave number domain; In the fifth step (S5), a wave spectrum graph of the sound pressure time domain signal is obtained through continuous wideband sound mode decomposition. The abscissa of the wave spectrum graph represents a frequency analysis range, the ordinate represents the sound mode monitoring range, and the color depth represents the amplitude. The deeper the color, the greater the amplitude. It is monitored whether a compressor rotating stall characteristic appears in the wave spectrum graph to further indicate whether the compressor has a rotating stall. When the compressor has a rotating stall under a supersonic working condition, the rotating stall abnormal sound source and its frequency doubling in the wave spectrum graph are in a non-integer multiple relationship with the rotating frequency, and a sound mode oblique bright band component with a mode order of 1 appears. The rotating stall characteristic frequency appearing in the spectrum, the corresponding mode order appearing at the rotating stall characteristic frequency in the sound mode spectrum graph, the abnormal sound source and the sound mode oblique bright band component in the wave spectrum graph are defined as compressor rotating stall monitoring voiceprint characteristics, and the compressor rotating stall is judged according to the voiceprint characteristics.

2. A method of monitoring the sound signature of a rotating stall in an aircraft engine compressor according to claim 1, wherein, In the first step (S1), the rotor-stator interaction mode order of the compressor is, wherein, denotes the pressure pulsation order caused by the unsteady aerodynamic forces due to the rotor-stator interaction of the compressor, denotes an integer; When using a uniform acoustic array layout, calculate the number of microphones required for modal detection based on the Nyquist sampling theorem. Its order with the static interference mode The relationship is: When using a non-uniform acoustic array layout with few measurement points, in a virtually uniform layout... Randomly selected from the positions Install a microphone in one location. ; When the uniform sound array layout scheme is adopted, a plurality of microphones are arranged to form a ring-shaped sound array, the interval between the microphones is , and the circumferential installation angle of the microphones is , wherein , , and so on; when the few-measurement-point non-uniform sound array layout scheme is adopted, the circumferential installation angle of the microphones is randomly selected, .

3. A method of monitoring the sound signature of a rotating stall in an aircraft engine compressor according to claim 1, wherein, The second step (S2) comprises the following steps: S201、using a ring-shaped acoustic array to measure the sound pressure signal of the compressor of an aero-engine, and the measured sound pressure time-domain signal is , wherein the length of the time-domain signal sequence measured by a single microphone is , and the subscript is a microphone corresponding to the circumferential installation angle position. S202, according to the sound pressure time domain signals measured by the microphones at different circumferential installation angle positions, a time domain signal matrix is established wherein the elements represent the first signal measured by the microphone corresponding to the circumferential installation angle position, When a uniform acoustic array layout is adopted, the size of the time-domain signal matrix is ; when a few-measurement-point non-uniform acoustic array layout scheme is adopted, the size of the time-domain signal matrix is .

4. A method of monitoring the sound signature of a rotating stall in an aircraft engine compressor according to claim 3, wherein, The third step (S3) comprises, S301, Measure the time-domain signal matrix of the circular acoustic array. The frequency domain matrix is ​​obtained by performing a Fourier transform on each column. , of which elements express The signal measured by the microphone at the corresponding circumferential installation angle position is Amplitude at frequency, The length is According to the Nyquist sampling theorem, , In the uniform acoustic array layout, the size of the frequency-domain matrix is ; in the non-uniform acoustic array layout, the size of the frequency-domain matrix is , S302、According to the frequency domain matrix Draw the spectrum of the signals measured by the different circumferential installation angle position microphones, and observe the blade passing frequency In addition to the rotating frequency, there are abnormal single frequency peaks, which are rotating stall characteristic frequencies with a frequency lower than the rotating frequency and an amplitude twice or more than the amplitude of the current blade passing frequency, and their second and third harmonics.

5. A method of monitoring the sound signature of a rotating stall in an aircraft engine compressor according to claim 4, wherein, The fourth step (S4) comprises, S401、In the case of uniform acoustic array layout, subscript The microphone corresponding to the circumferential installation angle position constructs the frequency domain signal at the predetermined frequency The linear superposition of different circumferential acoustic modes, that is, , the conversion matrix is constructed The form is as follows:​ ， In the case of a few-measurement-point non-uniform acoustic array layout, an observation matrix is constructed according to a circumferentially installed angle of randomly selected microphones , the observation matrix has a size of , ， S402、in the case of adopting a uniform acoustic array layout, performing spatial Fourier transform on the frequency domain matrix to obtain a wave number domain matrix , wherein is a transpose matrix of the frequency domain matrix , wherein denotes a pseudo-inverse of the conversion matrix , In the case of using a non-uniform acoustic array with few measurement points, the compressed sensing model is , the sparse dictionary is composed of the orthogonal Fourier transform basis, is a sensing matrix, and the sparse reconstructed wave number domain matrix is based on the compressed sensing model. S403、According to the obtained wave number domain matrix , draw the acoustic modal spectrum; under the supersonic working condition, observe whether the rotating stall characteristic frequency and its multiple appear, the rotating stall characteristic frequency is lower than 1 times the rotating frequency and the modal order is 1.

6. A method of monitoring the sound signature of a rotating stall in an aircraft engine compressor according to claim 5, wherein, The fifth step (S5) comprises, S501, the wavenumber domain matrix Extending to the full frequency domain, wavenumber domain matrix Size expansion to , of which elements Indicates frequency First The amplitude of the step sound mode, ， S502、According to the wave number domain matrix , draw the spectrum diagram, under the supersonic working condition, observe whether the rotating stall abnormal sound source and its multiple frequency appear in the non-integer multiple relationship with the rotation frequency, and the sound mode oblique bright band component from the mode order 1 corresponding to the rotating stall characteristic frequency and its multiple frequency, the mathematical expression of the sound mode oblique bright band component is ， wherein is a rotational stall characteristic frequency, is a multiple of the rotational stall characteristic frequency, is a non-negative integer, denotes a circumferential acoustic mode order.

7. A monitoring system implementing the method of any one of claims 1-6, characterized by It comprises: The sound field measurement module comprises a sound array measurement sub-module and a data acquisition sub-module, and is used to measure the sound field information propagating to the sound array installation position in the pipeline when the compressor is working; The spectrum analysis module is used to transform the time domain sound field signal at the sound array position to the frequency domain, and detect whether there is an abnormal frequency outside the blade passing frequency and the rotating frequency; The sound mode decomposition module is used to perform single-tone sound mode decomposition and continuous wideband sound mode decomposition, transform the sound field information from the frequency domain to the wave number domain, and detect whether the compressor rotating stall characteristic appears in the sound mode spectrum graph and the wave spectrum graph.

8. A computer storage medium, characterized in that The storage medium comprises computer instructions which, when executed on a computer, cause the computer to perform the method of any one of claims 1-6.

9. An electronic device, comprising: The electronic device comprises: A memory, a processor, and a computer program stored on the memory and executable on the processor, wherein The processor implements the method of any one of claims 1-6 when executing the program.

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