Modal decomposition method, device, equipment and storage medium for fan-shaped pipeline

Abstract

The present application proposes a modal decomposition method and device, equipment and storage medium for a fan-shaped duct, the method comprising: determining a first sound pressure limit condition based on a predetermined physical equation, a sound pressure relationship and an initial sound pressure algorithm; determining a second sound pressure limit condition for each microphone based on the first sound pressure limit condition and the position information of each microphone in the fan-shaped duct; performing an even function expansion process and a Fourier transform process on the second sound pressure limit condition to obtain a modal coefficient corresponding to the fan-shaped duct; determining the complex amplitude of the sound pressure of each sensor based on the sound pressure signal and the modal coefficient of each sensor; determining the modal decomposition result of the fan-shaped duct based on the modal coefficient and the complex amplitude of the sound pressure of each sensor. The technical solution of the present application makes up for the defect of the lack of modal decomposition method for fan-shaped ducts in aircraft engines in the related art, and can be applied to the fan-shaped ducts in aircraft engines to reduce noise and improve stability.

Description

[Technical field]

[0001] The present application relates to the field of aviation technology, and in particular to a modal decomposition method and device, equipment and storage medium for a fan-shaped duct. [Background technology]

[0002] At the rear end of the aircraft engine, a fan-shaped duct is formed due to the use of a support plate. The circumferential mode inside the fan-shaped duct is restricted by the partitions on both sides. Through this structure, it can be known that measuring and exploring the acoustic mode in the form of the fan-shaped duct plays a great role in reducing noise and improving stability.

[0003] At present, there have been studies on fan-shaped closed cavities. Through the form of room acoustics, the characteristic function of the Helmholtz equation related to the partition angle is obtained, and the Green function is further derived to construct the sound field in the cavity.

[0004] However, there are certain differences between the fan-shaped closed cavity and the fan-shaped pipe. Compared with the fan-shaped closed cavity, the fan-shaped pipe has no axial restrictions. Due to this difference, the research results of the fan-shaped closed cavity cannot be directly applied to the fan-shaped pipe.

[0005] Therefore, how to perform reliable modal decomposition of the fan-shaped ducts in aircraft engines has become a technical problem that needs to be solved urgently. [Summary of the invention]

[0006] The embodiments of the present application provide a modal decomposition method and apparatus, equipment and storage medium for a fan-shaped duct, aiming to solve the technical problem that the related art lacks a modal decomposition method for fan-shaped ducts in aircraft engines.

[0007] In a first aspect, an embodiment of the present application provides a modal decomposition method for a fan-shaped duct, comprising: determining a sound pressure relationship based on the boundary conditions of the fan-shaped duct; determining a first sound pressure limitation condition based on a predetermined physical equation, the sound pressure relationship and an initial sound pressure algorithm; determining a second sound pressure limitation condition for each microphone based on the first sound pressure limitation condition and the position information of each microphone of the fan-shaped duct; performing even function expansion processing and Fourier transform processing on the second sound pressure limitation condition to obtain a modal coefficient corresponding to the fan-shaped duct; determining the complex amplitude of the sound pressure of each sensor based on the sound pressure signal of each sensor and the modal coefficient; determining the modal decomposition result of the fan-shaped duct based on the modal coefficient and the complex amplitude of the sound pressure of each sensor.

[0008] In the above embodiment of the present application, optionally, it also includes: determining the sensor arrangement matrix of the fan-shaped pipeline based on a preset maximum propagable modal order and the number of the sensors.

[0009] In the above embodiment of the present application, optionally, determining the sound pressure relationship based on the boundary conditions of the fan-shaped pipe includes: performing variable separation processing on the characteristic function of the fan-shaped pipe according to predetermined boundary conditions to obtain the sound pressure relationship.

[0010] In the above-mentioned embodiment of the present application, optionally, the first sound pressure limitation condition is determined based on the predetermined physical equation, the sound pressure relationship and the initial sound pressure algorithm, including: substituting the sound pressure relationship into the predetermined physical equation to obtain the first decomposition condition and the second decomposition condition; based on the first decomposition condition, determining the axial parameter value of the predetermined axis and the target axial propagation wave number, and based on the second decomposition condition, determining the baffle azimuth angle limitation condition of the fan-shaped pipe; based on the axial parameter value of the predetermined axis, the axial propagation wave number and the baffle azimuth angle limitation condition, determine the first sound pressure limitation condition.

[0011] In the above embodiment of the present application, optionally, determining the target axial propagation wave number based on the first decomposition condition includes: determining the relationship between the axial propagation wave number and the sound pressure based on the first decomposition condition; and determining an analytical expression of the target axial propagation wave number based on a predetermined fluid flow mode under the predetermined axial direction.

[0012] In the above embodiment of the present application, optionally, before determining the second sound pressure limit condition of each microphone, it also includes: arranging each microphone of the fan-shaped duct at the same axial position.

[0013] In the above embodiment of the present application, optionally, the second sound pressure constraint condition is subjected to even function expansion processing and Fourier transform processing to obtain modal coefficients corresponding to the fan-shaped duct, including: according to a specified expansion interval, the second sound pressure constraint condition is subjected to even function expansion processing to obtain an even function expansion result; the even function expansion result is subjected to Fourier transform processing to obtain a Fourier transform result; based on the Fourier transform result, the modal coefficients corresponding to the fan-shaped duct are determined; based on the modal coefficients and the complex amplitude of the sound pressure of each sensor, the modal decomposition results of the fan-shaped duct are determined, including: discretizing the Fourier transform result to obtain a discrete constraint condition; based on the discrete constraint condition, the modal decomposition results of the fan-shaped duct are determined.

[0014] In a second aspect, an embodiment of the present application provides a modal decomposition device for a fan-shaped duct, comprising: a sound pressure relationship determination unit, used to determine the sound pressure relationship based on the boundary conditions of the fan-shaped duct; a first sound pressure limitation condition determination unit, used to determine the first sound pressure limitation condition based on a predetermined physical equation, the sound pressure relationship and an initial sound pressure algorithm; a second sound pressure limitation condition determination unit, used to determine the second sound pressure limitation condition of each microphone based on the first sound pressure limitation condition and the position information of each microphone of the fan-shaped duct; a modal coefficient determination unit, used to perform even function expansion processing and Fourier transform processing on the second sound pressure limitation condition to obtain the modal coefficient corresponding to the fan-shaped duct; a sound pressure complex amplitude determination unit, used to determine the sound pressure complex amplitude of each sensor based on the sound pressure signal of each sensor and the modal coefficient; a modal decomposition unit, used to determine the modal decomposition result of the fan-shaped duct based on the modal coefficient and the sound pressure complex amplitude of each sensor.

[0015] In the above embodiment of the present application, optionally, it further includes: a sensor arrangement unit, which is used to determine the sensor arrangement matrix of the fan-shaped pipeline based on a preset maximum propagable modal order and the number of the sensors.

[0016] In the above embodiment of the present application, optionally, the sound pressure relationship determination unit is used to: perform variable separation processing on the characteristic function of the fan-shaped duct according to predetermined boundary conditions to obtain the sound pressure relationship.

[0017] In the above embodiment of the present application, optionally, the first sound pressure limitation condition determination unit is used to: substitute the sound pressure relationship into the predetermined physical equation to obtain a first decomposition condition and a second decomposition condition; based on the first decomposition condition, determine the axial parameter value of the predetermined axis and the target axial propagation wave number, and based on the second decomposition condition, determine the baffle azimuth angle limitation condition of the fan-shaped pipe; based on the axial parameter value of the predetermined axis, the axial propagation wave number and the baffle azimuth angle limitation condition, determine the first sound pressure limitation condition.

[0018] In the above embodiment of the present application, optionally, the first sound pressure limitation condition determination unit is used to: determine the relationship between the axial propagation wave number and the sound pressure based on the first decomposition condition; and determine the analytical expression of the target axial propagation wave number based on the predetermined fluid flow mode under the predetermined axial direction.

[0019] In the above embodiment of the present application, optionally, it also includes: an axial setting unit, which is used to set each microphone of the fan-shaped duct to be arranged at the same axial position before the second sound pressure limit condition determination unit determines the second sound pressure limit condition of each microphone.

[0020] In the above embodiment of the present application, optionally, the modal coefficient determination unit is used to: perform an even function expansion process on the second sound pressure restriction condition according to a specified expansion interval to obtain an even function expansion result; perform Fourier transform process on the even function expansion result to obtain a Fourier transform result; based on the Fourier transform result, determine the modal coefficient corresponding to the fan-shaped duct; the modal decomposition unit is used to: discretize the Fourier transform result to obtain a discrete restriction condition; based on the discrete restriction condition, determine the modal decomposition result of the fan-shaped duct.

[0021] In a third aspect, an embodiment of the present application provides a device comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are configured to execute any of the methods described in the first aspect above.

[0022] In a fourth aspect, an embodiment of the present application provides a storage medium storing computer-executable instructions, wherein the computer-executable instructions are used to execute the method flow described in any one of the first aspects above.

[0023] The above technical scheme, in response to the technical problem that the related technology lacks a modal decomposition method for fan-shaped ducts in aircraft engines, provides a specific modal decomposition method for fan-shaped ducts in aircraft engines, making up for the defect that the related technology lacks a modal decomposition method for fan-shaped ducts in aircraft engines, and can meet the requirements of reducing noise and improving stability of fan-shaped ducts in aircraft engines.

Brief Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A flow chart of a modal decomposition method for a fan-shaped duct according to an embodiment of the present application is shown;

[0026] Figure 2 A schematic diagram of a fan-shaped pipeline according to an embodiment of the present application is shown;

[0027] Figure 3 A schematic diagram of a fan-shaped pipeline according to another embodiment of the present application is shown;

[0028] Figure 4A block diagram of a modal decomposition device for a fan-shaped pipe according to an embodiment of the present application is shown;

[0029] Figure 5 A block diagram of a device according to an embodiment of the present application is shown. [Specific implementation method]

[0030] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0031] Figure 1 A flow chart of a modal decomposition method for a fan-shaped duct according to an embodiment of the present application is shown.

[0032] like Figure 1 As shown, a modal decomposition method for a fan-shaped pipe according to an embodiment of the present application includes:

[0033] Step 102, determining a sound pressure relationship based on the boundary conditions of the fan-shaped duct.

[0034] Among them, the front view and side view of the fan-shaped pipe are as follows Figure 2 As shown, step 102 specifically includes: performing variable separation processing on the characteristic function of the fan-shaped pipe according to predetermined boundary conditions to obtain the sound pressure relationship.

[0035] The boundary conditions of the fan-shaped pipe are:

[0036]

[0037] Among them, Ψ is The characteristic function of . Represents the coordinate system. y1 and y2 are used to represent the radial direction and circumferential direction on the cross section of the fan-shaped pipe. The predetermined axial direction is the axial direction of the fan-shaped pipe, which can be represented by y3. The boundary conditions of the fan-shaped pipe do not have any restrictions in the axial direction, i.e., the y3 direction. By separating the variables of the characteristic function of the fan-shaped pipe, the sound pressure relationship can be obtained as follows:

[0038]

[0039] Step 104: determining a first sound pressure limiting condition based on a predetermined physical equation, the sound pressure relationship and an initial sound pressure algorithm.

[0040] Specifically, first, the sound pressure relationship can be substituted into the predetermined physical equation to obtain a first decomposition condition and a second decomposition condition; based on the first decomposition condition, the axial parameter value of the predetermined axis and the target axial propagation wave number are determined. The predetermined physical equation can be expressed as the Helmholtz equation:

[0041]

[0042] Where Ψ and k0 are the characteristic function and characteristic value of the Helmholtz equation respectively. Substituting the sound pressure relationship into equation (3) yields:

[0043]

[0044] Furthermore, formula (4) can be organized as:

[0045]

[0046] Based on formula (5), the first decomposition condition (6) and the second decomposition condition (7) can be decomposed into:

[0047]

[0048]

[0049] Among them, k r represents a constant that is independent of y3, and the solution of the second-order ordinary differential equation (6) can be obtained by characteristic decomposition, that is, the axial parameter value of the predetermined axis:

[0050]

[0051] Where A is an arbitrary constant, It represents the axial propagation wave number, with a negative sign for backward propagation and a positive sign for forward propagation.

[0052] Furthermore, in combination with a predetermined fluid flow mode under a predetermined axis, the above axial propagation wave number can be rewritten as an analytical expression of the axial propagation wave number under the corresponding fluid flow mode. Specifically, the relationship between the axial propagation wave number and the sound pressure can be determined based on the first decomposition condition; and the analytical expression of the target axial propagation wave number can be determined based on the predetermined fluid flow mode under the predetermined axis.

[0053] Under different flow conditions, the derivation process changes, resulting in The analytical expression of changes. On this basis, when there is a predetermined fluid flow mode of uniform flow along the predetermined axial direction y3 (also denoted as z), the target axial propagation wave number is:

[0054]

[0055] Among them, M a is the flow Mach number in the y3 direction,

[0056] Next, based on the second decomposition condition, the partition azimuth angle restriction condition of the fan-shaped pipeline is determined.

[0057] The second decomposition condition (7) can be written in cylindrical coordinates as:

[0058]

[0059] in, are the inner and outer radius of the pipe, θ A、 θ B are the azimuth angles of the partitions respectively. Next, the separation variables are substituted into equation (10), where the separation variables are:

[0060] φ(r,θ)=Φ(θ)ψ(r) (11)

[0061] After substituting the separation variables into equation (10), we can get

[0062]

[0063] In formula (12), the two ends of the equal sign are different variables. If the equal sign holds, then the two ends are equal to constants:

[0064]

[0065] and

[0066]

[0067] The solution of formula (13) is

[0068] Φ(θ)=Acosλ(θ-θ1),

[0069] Where A is an arbitrary constant.

[0070] The solution of equation (14) is the λ-order Bessel function, which can be expressed as:

[0071] ψ λ (k λn r)=AJ λ (k λn r)+BN λ (k λn r)(16)

[0072] Among them, J λ and N λ are the first and second Bessel functions respectively. According to the boundary conditions, a series of k r The value of k λn ,n indicates the order of these values.

[0073] Substituting equations (15) and (16) into equation (11), we obtain the diaphragm azimuth angle restriction condition:

[0074]

[0075] Then, based on the axial parameter value of the predetermined axial direction, the axial propagation wave number and the partition azimuth angle restriction condition, the first sound pressure restriction condition is determined. Specifically, equations (8) and (17) are substituted into equation (2), and the result is then substituted into the initial sound pressure expression: In the equation, we get the first sound pressure limitation condition:

[0076]

[0077] Step 106: Determine a second sound pressure limiting condition for each microphone based on the first sound pressure limiting condition and the position information of each microphone of the fan-shaped duct.

[0078] For the fan-shaped duct, the biggest difference between it and the circular / annular duct lies in the expression of its circumferential angle θ. Restricted by the baffles on both sides, the amplitude of the sound pressure in the fan-shaped duct varies with the position in the circumferential direction, with the same phase, and exists in the form of standing waves, which is different from the spiral propagation in the circular / annular duct, while the axial and radial expressions are similar to those of the circular / annular duct.

[0079] In a possible design, before determining the second sound pressure limit condition of each microphone, it also includes: arranging each microphone of the fan-shaped duct at the same axial position. Specifically, when only forward wave or backward wave exists, it is only necessary to place the microphones at the same axial position and arrange a row of microphones to perform modal decomposition. Based on this, according to formula (18), it can be known that the second sound pressure limit condition of the sound pressure measured by the microphones at each position is:

[0080]

[0081] Among them, θ j represents the position of the jth microphone.

[0082] In one possible design, according to equation (15), we know that λ(θ j -θ A )=mπ(θ j -θ A ) / (θ B -θ A ), and π(θ j -θ A ) / (θ B -θ A )∈(0,π), so any sector section can be equivalent to a Figure 3 The 180-degree semicircle / ring shown is treated as such, so that equation (19) can be described in a more general form:

[0083]

[0084] Step 108, performing an even function expansion process and a Fourier transform process on the second sound pressure limit condition to obtain the modal coefficients corresponding to the fan-shaped duct. Specifically, performing an even function expansion process on the second sound pressure limit condition according to a specified expansion interval to obtain an even function expansion result; performing a Fourier transform process on the even function expansion result to obtain a Fourier transform result; and determining the modal coefficients corresponding to the fan-shaped duct based on the Fourier transform result.

[0085] The specific method of even function expansion is to let Extending formula (20) to an even function, we get:

[0086]

[0087] The specific method of Fourier transform processing is to perform Fourier transform on equation (21) based on the numerical integration method to obtain:

[0088]

[0089] For the right side of equation (22), the integral value is not 0 only when m = M, thus we can get the modal coefficient B mω ,Right now

[0090]

[0091] Step 110: Determine the complex amplitude of the sound pressure of each sensor based on the sound pressure signal of each sensor and the modal coefficient.

[0092] Step 112: Determine a modal decomposition result of the sector duct based on the modal coefficients and the complex amplitude of the sound pressure of each sensor.

[0093] Specifically, the Fourier transform result is discretized to obtain discrete restriction conditions; based on the discrete restriction conditions, the modal decomposition result of the fan-shaped pipe is determined.

[0094] In reality, it is impossible to arrange an infinite number of microphones with infinite density to obtain a complete curve of the circumferential sound pressure. For a fan-shaped duct, an array of K+1 microphones can be evenly distributed in the circumference, with the first microphone arranged at one side of the partition and the last one at the other side of the partition, marked as j=0,1,…,K. The sound pressure signal measured by the jth microphone is:

[0095] χ j (t) = x j (sΔt), s=1,2,…,S (24)

[0096] Where S is the number of samples. The complex amplitude of the sound pressure can be obtained by fast Fourier transform of the sound pressure signal, that is,

[0097]

[0098] at this time, It has been extended to an even function on the specified expansion interval (-π,π). On this basis, equation (22) is discretized to obtain the discrete restriction condition:

[0099]

[0100]

[0101] When m≠±M±2nK, n=0,1,2,…, we have:

[0102]

[0103] On the contrary, when m=±M±2nK,n=0,1,2,…, we have

[0104]

[0105] The left side of equation (26) is denoted as B Mω

[0106]

[0107] This is the M-mode decomposition result obtained by modal decomposition.

[0108] It should be added that after obtaining the modal decomposition results, the influence of modal aliasing should be eliminated, that is, the aliased mode should appear in the cut-off mode, so it is necessary to know the maximum propagable mode and the number of sensors. Next, the sensor arrangement matrix of the fan-shaped pipeline can be determined based on the preset maximum propagable mode order and the number of sensors.

[0109] Specifically, substituting equations (27) and (28) into (26) yields

[0110]

[0111] This shows that the solution B Mω Actually all B ±M±2nK,ω Therefore, when measuring, it is necessary to consider the number of propagable modes and select an appropriate number of microphones.

[0112] In actual situations, the arrangement of microphones may not meet the requirements of equidistant distribution, and the modal coefficients cannot be solved by numerical integration. In this case, the modal coefficients can be solved by solving algebraic equations. Assuming that for a fan-shaped pipe, under given conditions, its maximum propagable modal order is determined, let's assume it is circumferential K order, temporarily ignoring the radial mode, and arranging a circle of K+1 microphones along the circumference of the pipe. When there are only forward waves or backward waves, the K+1 microphones are respectively:

[0113]

[0114] The subscript p represents the number of microphones at different positions. To identify K+1 modes, at least K+1 microphones are required. Equation (31) is rewritten in matrix form, i.e., the sensor arrangement matrix:

[0115] P=LG (32)

[0116]

[0117] The modal decomposition when there are only backward propagation waves or forward propagation waves is given above. When there are both forward and backward propagation waves in the pipeline, the sound pressure in the pipeline is expressed as:

[0118]

[0119] Among them A m , B m It can be seen that in order to obtain the forward and backward modal amplitudes of the K+1 propagable modes in the pipeline, at least 2 (K+1) microphones are required and arranged in at least two rows to decompose the forward and backward sound waves.

[0120] Furthermore, the 2(K+1) microphones are:

[0121]

[0122] Similarly, formula (34) can be rewritten in matrix form, that is, the sensor layout matrix:

[0123] P=LG (35)

[0124]

[0125] So far, the above technical solution obtains the characteristic function of the pipeline by solving the Helmholtz equation in the fan-shaped pipeline, and further obtains the sound pressure expression in the fan-shaped pipeline. Through the sound pressure expression, the expression of the sound pressure measured by the microphone at a specific position can be known, so as to derive the modal coefficient, obtain the modal decomposition result, and give the corresponding microphone arrangement scheme on this basis. Therefore, this technical solution gives a specific modal decomposition method for the fan-shaped pipeline in the aircraft engine, which makes up for the lack of modal decomposition methods for the fan-shaped pipeline in the aircraft engine in the related technology, and can be applicable to the fan-shaped pipeline in the aircraft engine. Reduce noise and improve stability requirements.

[0126] Figure 4 A block diagram of a modal decomposition device for a fan-shaped duct according to an embodiment of the present application is shown.

[0127] like Figure 4 As shown, an embodiment of the present application provides a modal decomposition device 400 for a fan-shaped duct, including: a sound pressure relationship determination unit 402, used to determine the sound pressure relationship based on the boundary conditions of the fan-shaped duct; a first sound pressure limitation condition determination unit 404, used to determine the first sound pressure limitation condition based on a predetermined physical equation, the sound pressure relationship and an initial sound pressure algorithm; a second sound pressure limitation condition determination unit 406, used to determine the second sound pressure limitation condition of each microphone based on the first sound pressure limitation condition and the position information of each microphone of the fan-shaped duct; a modal coefficient determination unit 408, used to perform even function expansion processing and Fourier transform processing on the second sound pressure limitation condition to obtain the modal coefficient corresponding to the fan-shaped duct; a sound pressure complex amplitude determination unit 410, used to determine the sound pressure complex amplitude of each sensor based on the sound pressure signal of each sensor and the modal coefficient; a modal decomposition unit 412, used to determine the modal decomposition result of the fan-shaped duct based on the modal coefficient and the sound pressure complex amplitude of each sensor.

[0128] In the above embodiment of the present application, optionally, it further includes: a sensor arrangement unit, which is used to determine the sensor arrangement matrix of the fan-shaped pipeline based on a preset maximum propagable modal order and the number of the sensors.

[0129] In the above embodiment of the present application, optionally, the sound pressure relationship determination unit 402 is used to: perform variable separation processing on the characteristic function of the fan-shaped duct according to predetermined boundary conditions to obtain the sound pressure relationship.

[0130] In the above embodiment of the present application, optionally, the first sound pressure limitation condition determination unit 404 is used to: substitute the sound pressure relationship into the predetermined physical equation to obtain a first decomposition condition and a second decomposition condition; based on the first decomposition condition, determine the axial parameter value of the predetermined axis and the target axial propagation wave number, and based on the second decomposition condition, determine the baffle azimuth angle limitation condition of the fan-shaped pipe; based on the axial parameter value of the predetermined axis, the axial propagation wave number and the baffle azimuth angle limitation condition, determine the first sound pressure limitation condition.

[0131] In the above embodiment of the present application, optionally, the first sound pressure limitation condition determination unit 404 is used to: determine the relationship between the axial propagation wave number and the sound pressure based on the first decomposition condition; and determine the analytical expression of the target axial propagation wave number based on the predetermined fluid flow mode under the predetermined axial direction.

[0132] In the above embodiment of the present application, optionally, it also includes: an axial setting unit, which is used to set each microphone of the fan-shaped duct to be arranged at the same axial position before the second sound pressure limit condition determination unit 406 determines the second sound pressure limit condition of each microphone.

[0133] In the above embodiment of the present application, optionally, the modal coefficient determination unit 410 is used to: perform an even function expansion process on the second sound pressure restriction condition according to a specified expansion interval to obtain an even function expansion result; perform Fourier transform process on the even function expansion result to obtain a Fourier transform result; based on the Fourier transform result, determine the modal coefficient corresponding to the fan-shaped duct; the modal decomposition unit 412 is used to: discretize the Fourier transform result to obtain a discrete restriction condition; based on the discrete restriction condition, determine the modal decomposition result of the fan-shaped duct.

[0134] The modal decomposition device 400 of the fan-shaped pipe uses any of the solutions described in the above embodiments, and therefore has all the above technical effects, which will not be repeated here.

[0135] Figure 5 A block diagram of a device according to an embodiment of the present application is shown.

[0136] like Figure 5 As shown, a device 500 of an embodiment of the present application includes at least one memory 502; and a processor 504 in communication with the at least one memory 502; wherein the memory stores instructions executable by the at least one processor 504, and the instructions are configured to execute the solution described in any of the above embodiments. Therefore, the device 500 has the same technical effect as any of the above embodiments, and will not be described in detail here.

[0137] The devices of the embodiments of the present application exist in various forms, including but not limited to:

[0138] (1) Mobile communication devices: These devices are characterized by their mobile communication functions and their main purpose is to provide voice and data communications. These terminals include: smart phones (such as iPhone), multimedia phones, functional phones, and low-end phones.

[0139] (2) Ultra-mobile personal computer devices: These devices fall into the category of personal computers, have computing and processing capabilities, and generally also have mobile Internet access features. These terminals include: PDA, MID and UMPC devices, such as iPad.

[0140] (3) Portable entertainment devices: These devices can display and play multimedia content. They include audio and video players (such as iPods), handheld game consoles, e-books, as well as smart toys and portable car navigation devices.

[0141] (4) Server: A device that provides computing services. The server consists of a processor, hard disk, memory, system bus, etc. The server is similar to a general computer architecture, but because it needs to provide highly reliable services, it has higher requirements in terms of processing power, stability, reliability, security, scalability, and manageability.

[0142] (5) Other electronic devices with data interaction functions.

[0143] In addition, an embodiment of the present application provides a storage medium storing computer executable instructions, wherein the computer executable instructions are used to execute the method flow described in any of the above embodiments.

[0144] The technical solution of the present application is described in detail above in combination with the accompanying drawings. Through the technical solution of the present application, a specific modal decomposition method of the fan-shaped duct in the aircraft engine is given, which makes up for the defect of the related technology that there is a lack of modal decomposition method for the fan-shaped duct in the aircraft engine, and can be suitable for the fan-shaped duct in the aircraft engine to reduce noise and improve stability requirements.

[0145] It should be understood that, although the terms first, second, etc. may be used to describe the decomposition conditions in the embodiments of the present application, these decomposition conditions should not be limited to these terms. These terms are only used to distinguish the decomposition conditions from each other. For example, without departing from the scope of the embodiments of the present application, the first decomposition condition may also be referred to as the second decomposition condition, and similarly, the second decomposition condition may also be referred to as the first decomposition condition.

[0146] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0147] The word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0148] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0149] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0150] The above-mentioned integrated unit implemented in the form of a software functional unit can be stored in a computer-readable storage medium. The above-mentioned software functional unit is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor (Processor) to perform some steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), disk or optical disk and other media that can store program codes.

[0151] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A modal decomposition method for a fan-shaped pipe, characterized in that: include: Based on the boundary conditions of the fan-shaped duct, the sound pressure relationship is determined; Substituting the sound pressure relationship into a predetermined physical equation to obtain a first decomposition condition and a second decomposition condition; wherein the predetermined physical equation is a Helmholtz equation; Based on the first decomposition condition, determining an axial parameter value of a predetermined axial direction and a target axial propagation wave number, and based on the second decomposition condition, determining a partition azimuth angle restriction condition of the fan-shaped pipeline; Determining a first sound pressure limiting condition based on the axial parameter value of the predetermined axial direction, the axial propagation wave number and the diaphragm azimuth limiting condition; Determining a second sound pressure limiting condition for each microphone based on the first sound pressure limiting condition and the position information of each microphone of the fan-shaped duct; Performing even function expansion processing and Fourier transform processing on the second sound pressure limit condition to obtain modal coefficients corresponding to the fan-shaped duct; Determining the complex amplitude of the sound pressure of each microphone based on the sound pressure signal of each microphone and the modal coefficient; Determining a modal decomposition result of the fan-shaped duct based on the modal coefficients and the complex amplitude of the sound pressure of each microphone; The boundary conditions of the fan-shaped pipeline are: in, For The characteristic function of represents the coordinate system, Indicates the radial direction on the cross section of the fan-shaped pipe. Indicates the circumferential direction of the fan-shaped pipe, Indicates the axial direction of the fan-shaped pipe; The sound pressure relationship is: The first decomposition condition is: The second decomposition condition is: in, is the eigenvalue of the Helmholtz equation, Representation and Unrelated constants.

2. The modal decomposition method of the fan-shaped pipeline according to claim 1, characterized in that: Also includes: The microphone arrangement matrix of the fan-shaped duct is determined based on the preset maximum transmissible mode order and the number of the microphones.

3. The modal decomposition method of a fan-shaped pipeline according to claim 1 or 2, characterized in that: The sound pressure relationship is determined based on the boundary conditions of the fan-shaped pipe, including: The characteristic function of the fan-shaped duct is subjected to variable separation processing according to predetermined boundary conditions to obtain the sound pressure relationship.

4. The modal decomposition method of a fan-shaped pipeline according to claim 1, characterized in that: The step of determining a target axial propagation wave number based on the first decomposition condition comprises: Based on the first decomposition condition, determining a relationship between the axial propagation wave number and the sound pressure; Based on the predetermined fluid flow mode under the predetermined axial direction, an analytical expression of the target axial propagation wave number is determined.

5. The modal decomposition method of a fan-shaped pipeline according to claim 1 or 2, characterized in that: Before determining the second sound pressure limiting condition of each microphone, the method further includes: Each microphone of the fan-shaped duct is arranged at the same axial position.

6. The modal decomposition method of a fan-shaped pipeline according to claim 1 or 2, characterized in that: The second sound pressure limit condition is subjected to an even function expansion process and a Fourier transform process to obtain a modal coefficient corresponding to the fan-shaped duct, including: According to the specified expansion interval, performing an even function expansion process on the second sound pressure limit condition to obtain an even function expansion result; Performing Fourier transform processing on the even function expansion result to obtain a Fourier transform result; Based on the Fourier transform result, determining the modal coefficients corresponding to the fan-shaped pipe; The determining of the modal decomposition result of the fan-shaped duct based on the modal coefficients and the complex amplitude of the sound pressure of each microphone comprises: Discretizing the Fourier transform result to obtain a discrete constraint condition; Based on the discrete restriction condition, a modal decomposition result of the fan-shaped pipeline is determined.

7. A modal decomposition device for a fan-shaped pipeline, characterized in that: include: A sound pressure relationship determination unit, used for determining the sound pressure relationship based on the boundary conditions of the fan-shaped duct; A first sound pressure limit condition determination unit is used to substitute the sound pressure relationship into a predetermined physical equation to obtain a first decomposition condition and a second decomposition condition; wherein the predetermined physical equation is the Helmholtz equation; based on the first decomposition condition, determine the axial parameter value of the predetermined axial direction and the target axial propagation wave number, and based on the second decomposition condition, determine the baffle azimuth angle limit condition of the fan-shaped duct; based on the axial parameter value of the predetermined axial direction, the axial propagation wave number and the baffle azimuth angle limit condition, determine the first sound pressure limit condition; a second sound pressure limiting condition determining unit, configured to determine a second sound pressure limiting condition of each microphone based on the first sound pressure limiting condition and position information of each microphone of the sector-shaped duct; A modal coefficient determination unit, configured to perform an even function expansion process and a Fourier transform process on the second sound pressure restriction condition to obtain a modal coefficient corresponding to the fan-shaped duct; a sound pressure complex amplitude determining unit, configured to determine the sound pressure complex amplitude of each microphone based on the sound pressure signal of each microphone and the modal coefficient; A modal decomposition unit, configured to determine a modal decomposition result of the fan-shaped duct based on the modal coefficients and the complex amplitude of the sound pressure of each microphone; The boundary conditions of the fan-shaped pipeline are: in, For The characteristic function of represents the coordinate system, Indicates the radial direction on the cross section of the fan-shaped pipe. Indicates the circumferential direction of the fan-shaped pipe, Indicates the axial direction of the fan-shaped pipe; The sound pressure relationship is: The first decomposition condition is: The second decomposition condition is: in, is the eigenvalue of the Helmholtz equation, Representation and Unrelated constants.

8. A device, characterized in that include: at least one processor; and, a memory communicatively coupled to the at least one processor; The memory stores instructions executable by the at least one processor, wherein the instructions are configured to execute the method according to any one of claims 1 to 6.

9. A storage medium, characterized in that: Computer executable instructions are stored, and the computer executable instructions are used to execute the method process according to any one of claims 1 to 6.

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