Pipeline flow-induced and sound-induced vibration detection and acoustic modal analysis experimental device and method

Abstract

The invention discloses a pipeline flow-induced and sound-induced vibration detection and acoustic modal analysis experimental device which comprises a main pipeline, one end of the main pipeline is connected with a gas source, the other end of the main pipeline is connected with a first silencer, the other end of the first silencer is connected with a replaceable experimental pipeline, and the other end of the replaceable experimental pipeline is connected with a second silencer. The main pipeline and the replaceable experiment pipeline are on the same straight line; a flow adjusting part is arranged on the main pipeline close to the gas source; a modal analysis part and a pressure detection part are sequentially arranged at the position, close to the second silencer, of the replaceable experiment pipeline in the airflow direction; the system further comprises an experimental data acquisition part which is connected with the flow regulation part, the pressure detection part and the modal analysis part. The invention further discloses a pipeline flow-induced and sound-induced vibration detection and sound modal analysis method. A pipeline vibration test result obtained through the experimental device is high in precision and high in reliability, and meanwhile, a test part is convenient to disassemble and replace.

Description

Technical Field

[0001] The present invention belongs to the technical field of pipeline flow-induced and acoustic-induced vibration experiments, and specifically relates to a pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis experimental device. The present invention also relates to a pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis method. Background Art

[0002] Valves and orifice plates are widely used in process pipeline systems in petroleum, chemical industry and energy, and are also used in air distribution systems in aircraft, automobile systems and buildings to control flow rate. The disturbance of fluid by valves and orifice plates will lead to local backflow and vortex, causing local pressure pulsation in the pipe and generating strong noise, which will cause vibration in the pipeline system. In severe cases, it will lead to structural cracking and fluid leakage. In order to fundamentally avoid pipeline damage, it is necessary to test the pipeline vibration to facilitate reasonable adjustment during design. The current pipeline vibration test methods are mainly theoretical analysis and numerical simulation. Many conditions will be simplified in theoretical analysis and numerical simulation, so the results obtained are not accurate and have low credibility. Therefore, theoretical analysis and numerical simulation have obvious limitations. Summary of the invention

[0003] The purpose of the present invention is to provide an experimental device for pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis. The pipeline vibration test results obtained by the experimental device have high accuracy and high credibility, and the test part is convenient to disassemble and replace.

[0004] The technical solution adopted by the present invention is a pipeline flow-induced and sound-induced vibration detection and acoustic modal analysis experimental device, which is characterized in that it includes a main pipeline, one end of the main pipeline is connected to an air source, the other end of the main pipeline is connected to a first muffler, the other end of the first muffler is connected to a replaceable experimental pipeline, and the other end of the replaceable experimental pipeline is connected to a second muffler; the main pipeline and the replaceable experimental pipeline are on the same straight line; a flow regulating part is arranged at the main pipeline near the air source; a modal analysis part and a pressure detection part are arranged in sequence along the airflow direction at the replaceable experimental pipeline near the second muffler; and it also includes an experimental data acquisition part, which is respectively connected to the flow regulating part, the pressure detection part and the modal analysis part.

[0005] The present invention is also characterized in that:

[0006] A flexible pipe is arranged between the main pipeline and the gas source.

[0007] The flow regulating part comprises a regulating ball valve and a gas mass flow meter which are sequentially arranged on the main pipe along the air flow direction, and the regulating ball valve and the gas mass flow meter are respectively connected to the experimental data acquisition part.

[0008] The pressure detection part comprises a pressure gauge and a vibration acceleration sensor which are sequentially arranged on a replaceable experimental pipeline along the air flow direction, and the pressure gauge and the vibration acceleration sensor are respectively connected to the experimental data acquisition part.

[0009] The modal analysis part includes several groups of microphone arrays and a signal amplifier. Each group of microphone arrays includes several microphones, and the several microphones are arranged at equal angles along the circumference of the replaceable experimental pipeline; the signal amplifier is connected to the several microphones; and the signal amplifier is connected to the experimental data acquisition part.

[0010] The air source is a centrifugal fan; the experimental data acquisition part is a computer.

[0011] Another technical solution adopted by the present invention is a pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis method, using a pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis experimental device, including a pipeline flow-induced and acoustic-induced vibration detection method and an acoustic modal analysis method;

[0012] The pipeline flow-induced and sound-induced vibration detection method specifically comprises the following steps:

[0013] Step 1: along the airflow direction, select two microphone groups, and the microphones at corresponding positions of the two microphone groups constitute a microphone pair;

[0014] Step 2: Start the gas source to fill the main pipeline with air flow, and at the same time start the flow adjustment part to adjust the air flow;

[0015] Step 3: Use different microphone spacings to measure the fluid excitation signal and the sound excitation signal, and use the cross-spectral density to characterize the flow-induced and sound-induced pressures;

[0016] Take the signals obtained from several microphones to calculate the average of the cross-spectral density. The formula is:

[0017]

[0018] Where X(ω) and Y(ω) are the frequency domain signals obtained by Fourier transform of the time domain pressure pulsation signals collected by microphones at two corresponding positions, X*(ω) is the conjugate complex number of X(ω), and N represents the number of sampling points; f s represents the sampling frequency in Hz; ω=2πf is the angular frequency in rad / s, and f represents the frequency in Hz;

[0019] Step 4: The vibration acceleration sensor collects the vibration signal on the pipeline surface;

[0020] The acoustic modal analysis method specifically includes the following steps:

[0021] Step 1: Place the component to be tested in the pipeline flow-induced, acoustic-induced vibration detection and acoustic modal analysis experimental device;

[0022] Step 2: When there is no flow in the pipeline, first set up speakers at several microphone measurement points upstream of the element to be tested, turn on the speaker at any microphone and collect the sound pressure signals of other microphones; then repeat the operation downstream of the element to be tested to obtain the incident sound wave modal pressure amplitude matrix a upstream and downstream of the element to be tested in (ω) and the reflected acoustic wave modal pressure amplitude matrix a out (ω), calculate the scattering matrix S(ω) between the incident sound wave and the reflected sound wave;

[0023] Step 3: Turn off the signal amplifier, start the centrifugal fan and adjust the flow control part to the appropriate opening. Select a section at the upstream and downstream of the replaceable experimental pipeline to form a section pair. Take two sections with different positions to measure the cross-spectral density respectively. The two terminals of the pipeline flow-induced, acoustic-induced vibration detection and acoustic modal analysis experimental device generate acoustic reflections. Calculate the terminal matrix R and the acoustic wave modal pressure amplitude matrix a generated by the element itself under the condition of no reflection. s (ω);

[0024] Step 4: Use the 2N-port method to analyze and calculate the acoustic modes.

[0025] Another technical solution of the present invention is also characterized in that:

[0026] In the acoustic modal analysis method, in step 2, loudspeakers are respectively set at several microphone measuring points upstream of the element to be tested, the loudspeaker at any microphone is turned on and the sound pressure signals of other microphones are collected. The pressure signals of multiple microphones at the measuring points are expressed as:

[0027]

[0028] In the formula, s l represents the first group of microphones, z represents the axial coordinate, e is the electrical signal of the signal amplifier, is the transfer function between the lth microphone and the electrical signal;

[0029] Repeat this operation downstream of the element to be tested to obtain the incident acoustic wave modal pressure amplitude matrix a upstream and downstream of the element to be tested in (ω) and the reflected acoustic wave modal pressure amplitude matrix a out (ω), there is no sound source in the tube, and the scattering matrix S(ω) between the incident sound wave and the reflected sound wave is:

[0030] s(ω)=a out (ω)[a in (ω)] -1

[0031] In the formula, [] -1 represents the pseudo-inverse matrix.

[0032] Acoustic modal analysis method, in step 3, the terminal matrix R is:

[0033] R = a in (ω)[a out (ω)] -1

[0034] The acoustic wave modal pressure amplitude matrix a generated by the element itself under non-reflection conditions s (ω) is:

[0035] a s (ω)=[I 2N -S(ω)R]a out (ω)

[0036] In the formula, I 2N is the identity matrix of dimension 2N.

[0037] Acoustic modal analysis method, in step 4,

[0038] The element to be tested is placed in the experimental device for pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis. The pressure field in the pipeline satisfies the Helmholtz equation, and at point s1 = (s1, z1):

[0039]

[0040] Where, the center of the cross section of the main pipe inlet is taken as the coordinate origin, s1 is the circumferential and radial position of the measuring point, and z1 is the axial distance between the microphone and the main pipe inlet; p ac is the sound pressure, Ψ pq is the normalized pipeline mode, is the amplitude of the downstream propagating mode, The amplitude of the upstream propagation mode, i is an imaginary unit, ω is the angular frequency; is the axial wave number, expressed as:

[0041]

[0042] Where M is the Mach number, k is ⊥ is the circumferential wave number; k = ω / c is the wave number, c = 340 m / s is the speed of sound;

[0043] The 2N port method is used to analyze and calculate the acoustic modal. The formula of the 2N port method is as follows:

[0044] a out (ω)=S(ω)a in (ω)+a s (ω)

[0045] In the formula, a in(ω), a out (ω) are the modal pressure amplitude matrices of the incident and reflected acoustic waves at the upstream and downstream of the element under test, and is the vector of acoustic modal coefficients, a s (ω) is the acoustic wave modal pressure amplitude matrix generated by the element itself under non-reflection conditions, S(ω)∈c [2N×2N] is the scattering matrix between the incident sound wave and the reflected sound wave, I and II represent the upstream and downstream sides of the 2N port;

[0046] Calculate the cross-spectral density G s , expressed as:

[0047] G s =E[a s (ω)(a s (ω) c ]

[0048] In the formula, E[] represents expectation and c represents the conjugate transpose of the matrix.

[0049] The beneficial effects of the present invention are:

[0050] 1. The pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis experimental device of the present invention can simulate the flow-induced and acoustic-induced vibration and modal analysis experimental device under different working conditions, has high experimental reliability and accuracy, and can provide theoretical support for pipeline design. The device of the present invention can detect pipeline vibration and analyze the acoustic modal in the pipe at the same time.

[0051] 2. The pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis experimental device of the present invention has a detachable and replaceable test part, which can be replaced according to different test requirements to simulate different working conditions, and can also be replaced in time when fatigue damage occurs to the experimental equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a structural schematic diagram of the experimental device for pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis of the present invention;

[0053] Figure 2 It is a structural schematic diagram of the microphone array of the modal analysis part of the present invention.

[0054] In the figure, 1-1, main pipeline; 1-2, replaceable experimental pipeline; 2, gas source; 3, flow adjustment part; 3-1, regulating ball valve; 3-2, gas mass flow meter; 4-1, first muffler; 4-2, second muffler; 5, pressure detection part; 5-1, pressure gauge; 5-2, vibration acceleration sensor; 6, modal analysis part; 6-1, microphone; 7, experimental data acquisition part. DETAILED DESCRIPTION

[0055] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0056] Experimental device for pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis, such as Figure 1 As shown, it includes a main line 1-1, one end of which is connected to a gas source 2, which is a centrifuge and provides test gas for the main line 1-1. The gas source 2 is connected to the main line 1-1 through a flexible tube, and the flexible tube is used to isolate the vibration of the gas source 2 and the main line 1-1.

[0057] The other end of the main pipeline 1-1 is connected to a first muffler 4-1, and the other end of the first muffler 4-1 is connected to a replaceable experimental pipeline 1-2, which is used to simulate flow-induced and sound-induced vibrations of different pipeline components. The other end of the replaceable experimental pipeline 1-2 is connected to a second muffler 4-2; the main pipeline 1-1 and the replaceable experimental pipeline 1-2 are on the same straight line. The main pipeline 1-1 is provided with a flow regulating part 3 near the gas source 2, and the flow regulating part 3 is used to adjust the average flow in the pipeline. The first muffler 4-1 is used to reduce the noise generated by the gas source 2 and the flow regulating part 3; the air is discharged into the atmosphere through the second muffler 4-2 of the muffler part, and the second muffler 4-2 is used to reduce the sound returning to the pipeline from the exhaust port and reduce the noise discharged into the atmosphere.

[0058] The flow regulating part 3 comprises a regulating ball valve 3-1 and a gas mass flow meter 3-2 which are sequentially arranged on the main pipe 1-1 along the gas flow direction.

[0059] The replaceable experimental pipeline 1-2 is provided with a modal analysis part 6 and a pressure detection part 5 in sequence along the airflow direction near the second muffler 4-2. The pressure detection part 5 is used to detect the air pressure flowing through the replaceable experimental pipeline; the modal analysis part 6 is used to analyze the acoustic mode of the pipeline.

[0060] The pressure detection part 5 comprises a pressure gauge 5-1 and a vibration acceleration sensor 5-2 which are sequentially arranged on the replaceable experimental pipeline 1-2 along the air flow direction. The pressure detection part 5 is used to detect the air pressure flowing through the replaceable experimental pipeline 1-2.

[0061] The modal analysis part 6 includes several groups of microphone arrays and a signal amplifier. Each group of microphone arrays includes several microphones 6-1. The microphones 6-1 are arranged at equal angles along the circumference of the replaceable experimental pipeline 1-2. Figure 2 As shown, the signal amplifier is connected to a plurality of microphones 6-1. The modal analysis part 6 can distinguish between acoustic pressure and flow pressure, and measure the cross-spectral density at different distances through two groups of microphone arrays with different spacings located upstream and downstream respectively.

[0062] The experimental data acquisition part 7 is also included, and the experimental data acquisition part 7 is a computer. The experimental data acquisition part 7 is connected to the flow regulating part 3, the pressure detecting part 5, and the modal analysis part 6 respectively, and is used to collect data generated by the pressure detecting part and the modal analysis part. Specifically, the regulating ball valve 3-1, the gas mass flow meter 3-2, the pressure gauge 5-1, the vibration acceleration sensor 5-2, and the signal amplifier are connected to the experimental data acquisition part 7 respectively.

[0063] A pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis method uses a pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis experimental device, including a pipeline flow-induced and acoustic-induced vibration detection method and an acoustic modal analysis method.

[0064] The pipeline flow-induced and sound-induced vibration detection method specifically comprises the following steps:

[0065] Step 1: along the airflow direction, select two microphone groups, and the microphones 6 - 1 at corresponding positions of the two microphone groups constitute a microphone pair;

[0066] Step 2: Start the gas source 2 to fill the main pipeline with air flow, and start the flow regulating part 3 to regulate the air flow;

[0067] Step 3: Use different microphone spacings to measure the fluid excitation signal and the sound excitation signal, and use the cross-spectral density to characterize the flow-induced and sound-induced pressures;

[0068] Take the signals obtained from several microphones to calculate the average of the cross-spectral density. The formula is:

[0069]

[0070] Where X(ω) and Y(ω) are the frequency domain signals obtained by Fourier transform of the time domain pressure pulsation signals collected by microphones at two corresponding positions, X*(ω) is the conjugate complex number of X(ω), and N represents the number of sampling points; f s represents the sampling frequency in Hz; ω=2πf is the angular frequency in rad / s, and f represents the frequency in Hz;

[0071] Generally, the distance between microphones for measuring flow-induced pressure signals is smaller than the distance between microphones for measuring sound-induced pressure signals.

[0072] Step 4: The vibration acceleration sensor collects the vibration signal of the pipeline surface.

[0073] The acoustic modal analysis method specifically includes the following steps:

[0074] Step 1: Place the component to be tested in the pipeline flow-induced, acoustic-induced vibration detection and acoustic modal analysis experimental device;

[0075] Step 2: When there is no flow in the pipeline, first set up speakers at several microphone measurement points upstream of the element to be tested, turn on the speaker at any microphone and collect the sound pressure signals of other microphones;

[0076] The multiple microphone pressure signals at the measurement point are expressed as:

[0077]

[0078] In the formula, s l represents the first group of microphones, z represents the axial coordinate, e is the electrical signal of the signal amplifier, is the transfer function between the lth microphone and the electrical signal;

[0079] Repeat this operation downstream of the element to be tested to obtain the incident acoustic wave modal pressure amplitude matrix a upstream and downstream of the element to be tested in (ω) and the reflected acoustic wave modal pressure amplitude matrix a out (ω), there is no sound source in the tube at this time, calculate the scattering matrix S(ω) between the incident sound wave and the reflected sound wave:

[0080] S(ω)=a out (ω)[a in (ω)] -1

[0081] In the formula, [] -1 represents the pseudo-inverse matrix.

[0082] Step 3: Turn off the signal amplifier, start the centrifugal fan and adjust the flow regulating part 3 to the appropriate opening. Select a section to form a section pair at the upstream and downstream of the replaceable experimental pipeline 1-2. Take two sections with different positions to measure the cross-spectral density respectively. The two terminals of the pipeline flow-induced, acoustic-induced vibration detection and acoustic modal analysis experimental device generate acoustic reflections. Calculate the terminal matrix R and the acoustic wave modal pressure amplitude matrix a generated by the element itself under the condition of no reflection. s (ω);

[0083] The terminal matrix R is:

[0084] R = a in (ω)[a out (ω)] -1

[0085] The acoustic wave modal pressure amplitude matrix a generated by the element itself under non-reflection conditions s (ω) is:

[0086] a s (ω)=[I 2N -S(ω)R]a out (ω)

[0087] In the formula, I2N is the identity matrix of dimension 2N.

[0088] Step 4: Use the 2N-port method to analyze and calculate the acoustic modes.

[0089] The element to be tested is placed in the experimental device for pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis. The pressure field in the pipeline satisfies the Helmholtz equation, and at point s1 = (s1, z1):

[0090]

[0091] Where, the center of the cross section of the main pipe inlet is taken as the coordinate origin, s1 is the circumferential and radial position of the measuring point, and z1 is the axial distance between the microphone and the main pipe inlet; p ac is the sound pressure, ψ pq is the normalized pipeline mode, is the amplitude of the downstream propagating mode, The amplitude of the upstream propagation mode, i is an imaginary unit, ω is the angular frequency; is the axial wave number, expressed as:

[0092]

[0093] Where M is the Mach number, k is ⊥ is the circumferential wave number; k = ω / c is the wave number, c = 340m / s is the speed of sound. The purpose of the acoustic mode measurement in the tube is to obtain the amplitude of each high-order acoustic mode.

[0094] The 2N port method is used to analyze and calculate the acoustic modal. The formula of the 2N port method is as follows:

[0095] a out (ω)=S(ω)a in (ω)+a s (ω)

[0096] In the formula, a in (ω), a out (ω) are the modal pressure amplitude matrices of the incident and reflected acoustic waves at the upstream and downstream of the element under test, and is the vector of acoustic modal coefficients, a s (ω) is the acoustic wave modal pressure amplitude matrix generated by the element itself under non-reflection conditions, S(ω)∈c [2N×2N] is the scattering matrix between the incident sound wave and the reflected sound wave, I and II represent the upstream and downstream sides of the 2N port;

[0097] Calculate the cross-spectral density G s , expressed as:

[0098] G s =E[a s (ω)(a s (ω) c ]

[0099] In the formula, E[] represents expectation and c represents the conjugate transpose of the matrix.

[0100] Example 1

[0101] This embodiment provides a pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis experimental device, such as Figure 1 As shown, it includes a main line 1-1, one end of the main line 1-1 is connected to an air source 2, the other end of the main line 1-1 is connected to a first silencer 4-1, the other end of the first silencer 4-1 is connected to a replaceable experimental line 1-2, and the other end of the replaceable experimental line 1-2 is connected to a second silencer 4-2; the main line 1-1 and the replaceable experimental line 1-2 are on the same straight line; a flow regulating part 3 is provided at the main line 1-1 near the air source 2; a modal analysis part 6 and a pressure detection part 5 are provided in sequence along the airflow direction at the position of the replaceable experimental line 1-2 near the second silencer 4-2; and it also includes an experimental data acquisition part 7, which is respectively connected to the flow regulating part 3, the pressure detection part 5 and the modal analysis part 6.

[0102] Example 2

[0103] On the basis of Example 1, the gas source 2 is a centrifugal fan, and a flexible pipe is provided between the main pipeline 1-1 and the centrifugal fan. The experimental data acquisition part 7 is a computer.

[0104] Example 3

[0105] Based on Example 2, the flow regulating part 3 includes a regulating ball valve 3-1 and a gas mass flow meter 3-2 which are sequentially arranged on the main line 1-1 along the air flow direction, and the regulating ball valve 3-1 and the gas mass flow meter 3-2 are respectively connected to the experimental data acquisition part 7.

[0106] The pressure detection part 5 includes a pressure gauge 5-1 and a vibration acceleration sensor 5-2 which are sequentially arranged on the replaceable experimental pipeline 1-2 along the air flow direction. The pressure gauge 5-1 and the vibration acceleration sensor 5-2 are connected to the experimental data acquisition part 7 respectively.

[0107] The modal analysis part 6 includes several groups of microphone arrays and a signal amplifier, each group of microphone arrays includes several microphones 6-1, and the several microphones 6-1 are arranged at equal angles along the circumference of the replaceable experimental pipeline 1-2; the signal amplifier is connected to the several microphones 6-1; the signal amplifier is connected to the experimental data acquisition part 7.

[0108] Example 4

[0109] This embodiment provides a pipeline flow-induced and acoustic-induced vibration detection method, using the pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis experimental device provided in Example 3, specifically including the following steps:

[0110] Step 1: along the airflow direction, select two microphone groups, and the microphones 6 - 1 at corresponding positions of the two microphone groups constitute a microphone pair;

[0111] Step 2: Start the gas source 2 to fill the main pipeline 1-1 with air flow, and start the flow regulating part 3 to regulate the air flow;

[0112] Step 3: Use different microphone spacings to measure the fluid excitation signal and the sound excitation signal, and use the cross-spectral density to characterize the flow-induced and sound-induced pressures;

[0113] Take the signals obtained from several microphones to calculate the average of the cross-spectral density. The formula is:

[0114]

[0115] Where X(ω) and Y(ω) are the frequency domain signals obtained by Fourier transform of the time domain pressure pulsation signals collected by microphones at two corresponding positions, X*(ω) is the conjugate complex number of X(ω), and N represents the number of sampling points; f s represents the sampling frequency in Hz; ω=2πf is the angular frequency in rad / s, and f represents the frequency in Hz;

[0116] Step 4: The vibration acceleration sensor collects the vibration signal of the pipeline surface.

[0117] Example 5

[0118] This embodiment provides an acoustic modal analysis method, using the pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis experimental device provided in Embodiment 3, specifically comprising the following steps:

[0119] Step 1: Place the component to be tested in the pipeline flow-induced, acoustic-induced vibration detection and acoustic modal analysis experimental device;

[0120] Step 2: When there is no flow in the pipeline, speakers are first set at several microphone measuring points upstream of the element to be tested, and the speaker at any microphone is turned on to collect the sound pressure signals of other microphones; then the operation is repeated downstream of the element to be tested to obtain the modal pressure amplitude matrix of the incident sound wave and the reflected sound wave upstream and downstream of the element to be tested, and the scattering matrix S(ω) between the incident sound wave and the reflected sound wave is calculated;

[0121] Step 3: Turn off the signal amplifier, start the centrifugal fan and adjust the flow regulating part 3 to the appropriate opening. Select a section to form a section pair at the upstream and downstream of the replaceable experimental pipeline 1-2. Take two sections with different positions to measure the cross-spectral density respectively. The two terminals of the pipeline flow-induced, acoustic-induced vibration detection and acoustic modal analysis experimental device generate acoustic reflections. Calculate the terminal matrix R and the acoustic wave modal pressure amplitude matrix a generated by the element itself under the condition of no reflection. s (ω);

[0122] Step 4: Use the 2N-port method to analyze and calculate the acoustic modes.

[0123] Example 6

[0124] On the basis of Example 5, in step 2, loudspeakers are respectively set at several microphone measuring points upstream of the element to be measured, the loudspeaker at any microphone is turned on and the sound pressure signals of other microphones are collected. The pressure signals of multiple microphones at the measuring points are expressed as:

[0125]

[0126] In the formula, s l represents the first group of microphones, z represents the axial coordinate, e is the electrical signal of the signal amplifier, is the transfer function between the lth microphone and the electrical signal;

[0127] Repeat this operation downstream of the element to be tested to obtain the incident acoustic wave modal pressure amplitude matrix a upstream and downstream of the element to be tested in (ω) and the reflected acoustic wave modal pressure amplitude matrix a out (ω), there is no sound source in the tube, and the scattering matrix S(ω) between the incident sound wave and the reflected sound wave is:

[0128] S(ω)=a out (ω)[a in (ω)] -1

[0129] In the formula, [] -1 represents the pseudo-inverse matrix.

[0130] In step 3, the terminal matrix R is:

[0131] R = a in (ω)[a out (ω)] -1

[0132] The acoustic wave modal pressure amplitude matrix a generated by the element itself under non-reflection conditions s (ω) is:

[0133] a s (ω)=[I 2N-S(ω)R]a out (ω)

[0134] In the formula, I 2N is the identity matrix of dimension 2N.

[0135] In step 4,

[0136] The element to be tested is placed in the experimental device for pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis. The pressure field in the pipeline satisfies the Helmholtz equation, and at point s1 = (s1, z1):

[0137]

[0138] Where, the center of the cross section of the main pipe inlet is taken as the coordinate origin, s1 is the circumferential and radial position of the measuring point, and z1 is the axial distance between the microphone and the main pipe inlet; p ac is the sound pressure, ψ pq is the normalized pipeline mode, is the amplitude of the downstream propagating mode, The amplitude of the upstream propagation mode, i is an imaginary unit, ω is the angular frequency; is the axial wave number, expressed as:

[0139]

[0140] Where M is the Mach number, k is ⊥ is the circumferential wave number; k = ω / c is the wave number, c = 340 m / s is the speed of sound;

[0141] The 2N port method is used to analyze and calculate the acoustic modal. The formula of the 2N port method is as follows:

[0142] a out (ω)=S(ω)a in (ω)+a s (ω)

[0143] In the formula, a in (ω), a out (ω) are the modal pressure amplitude matrices of the incident and reflected acoustic waves at the upstream and downstream of the element under test, and is the vector of acoustic modal coefficients, a s (ω) is the acoustic wave modal pressure amplitude matrix generated by the element itself under non-reflection conditions, S(ω)∈c [2N×2N] is the scattering matrix between the incident sound wave and the reflected sound wave, I and II represent the upstream and downstream sides of the 2N port;

[0144] Calculate the cross-spectral density G s , expressed as:

[0145] G s =E[a s (ω)(a s (ω) c ]

[0146] In the formula, E[] represents expectation and c represents the conjugate transpose of the matrix.

Claims

1. Pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis experimental device, characterized in that: The invention comprises a main pipe (1-1), one end of which is connected to an air source (2), the other end of which is connected to a first silencer (4-1), the other end of which is connected to a replaceable experimental pipe (1-2), and the other end of which is connected to a second silencer (4-2); the main pipe (1-1) and the replaceable experimental pipe (1-2) are on the same straight line; a flow regulating part (3) is arranged at a position of the main pipe (1-1) close to the air source (2); a modal analysis part (6) and a pressure detection part (5) are arranged in sequence along the airflow direction at a position of the replaceable experimental pipe (1-2) close to the second silencer (4-2); and the invention also comprises an experimental data acquisition part (7), which is respectively connected to the flow regulating part (3), the pressure detection part (5) and the modal analysis part (6).

2. The pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis experimental device according to claim 1 is characterized in that: A flexible pipe is provided between the main pipeline (1-1) and the gas source (2).

3. The pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis experimental device according to claim 1 is characterized in that: The flow regulating part (3) comprises a regulating ball valve (3-1) and a gas mass flow meter (3-2) which are sequentially arranged on the main pipeline (1-1) along the gas flow direction, and the regulating ball valve (3-1) and the gas mass flow meter (3-2) are respectively connected to the experimental data acquisition part (7).

4. The pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis experimental device according to claim 1 is characterized in that: The pressure detection part (5) comprises a pressure gauge (5-1) and a vibration acceleration sensor (5-2) which are sequentially arranged on a replaceable experimental pipeline (1-2) along the airflow direction, and the pressure gauge (5-1) and the vibration acceleration sensor (5-2) are respectively connected to the experimental data acquisition part (7).

5. The pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis experimental device according to claim 1 is characterized in that: The modal analysis part (6) includes a plurality of microphone arrays and a signal amplifier, each of the microphone arrays includes a plurality of microphones (6-1), and the plurality of microphones (6-1) are arranged at equal angles along the circumference of the replaceable experimental pipeline (1-2); the signal amplifier is connected to the plurality of microphones (6-1); and the signal amplifier is connected to the experimental data acquisition part (7).

6. The pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis experimental device according to claim 1 is characterized in that: The air source (2) is a centrifugal fan; the experimental data acquisition part (7) is a computer.

7. A method for detecting flow-induced and acoustic-induced vibrations in a pipeline and for acoustic modal analysis, using the experimental device for detecting flow-induced and acoustic-induced vibrations in a pipeline and for acoustic modal analysis as claimed in any one of claims 1 to 6, characterized in that: Including pipeline flow-induced and acoustic-induced vibration detection methods and acoustic modal analysis methods; The pipeline flow-induced and sound-induced vibration detection method specifically comprises the following steps: Step 1: along the airflow direction, select two microphone groups, and the microphones (6-1) at corresponding positions of the two microphone groups constitute a microphone pair; Step 2: Start the gas source (2) to fill the main pipeline (1-1) with gas, and start the flow regulating part (3) to regulate the flow of the gas; Step 3: Use different microphone spacings to measure the fluid excitation signal and the sound excitation signal, and use the cross-spectral density to characterize the flow-induced and sound-induced pressures; Take the signals obtained from several microphones to calculate the average of the cross-spectral density. The formula is: Where X(ω) and Y(ω) are the frequency domain signals obtained by Fourier transform of the time domain pressure pulsation signals collected by microphones at two corresponding positions, X*(ω) is the conjugate complex number of X(ω), and N represents the number of sampling points; f s represents the sampling frequency in Hz; ω=2πf is the angular frequency in rad / s, and f represents the frequency in Hz; Step 4: The vibration acceleration sensor collects the vibration signal on the pipeline surface; The acoustic modal analysis method specifically includes the following steps: Step 1: Place the component to be tested in the pipeline flow-induced, acoustic-induced vibration detection and acoustic modal analysis experimental device; Step 2: When there is no flow in the pipeline, first set up speakers at several microphone measurement points upstream of the element to be tested, turn on the speaker at any microphone and collect the sound pressure signals of other microphones; then repeat the operation downstream of the element to be tested to obtain the incident sound wave modal pressure amplitude matrix a upstream and downstream of the element to be tested in (ω) and the reflected acoustic wave modal pressure amplitude matrix a out (ω), calculate the scattering matrix S(ω) between the incident sound wave and the reflected sound wave; Step 3: Turn off the signal amplifier, start the centrifugal fan and adjust the flow control part (3) to a suitable opening. Select a section at the upstream and downstream of the replaceable experimental pipeline (1-2) to form a section pair. Take two sections with different positions to measure the cross-spectral density respectively. The two terminals of the pipeline flow-induced, acoustic-induced vibration detection and acoustic modal analysis experimental device generate acoustic reflections. Calculate the terminal matrix R and the acoustic wave modal pressure amplitude matrix a generated by the element itself under the non-reflection condition. s (ω); Step 4: Use the 2N-port method to analyze and calculate the acoustic modes.

8. The pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis method according to claim 7 is characterized in that: In the acoustic modal analysis method, in step 2, loudspeakers are respectively set at several microphone measuring points upstream of the element to be measured, the loudspeaker at any microphone is turned on and the sound pressure signals of other microphones are collected. The pressure signals of multiple microphones at the measuring points are expressed as: In the formula, s l represents the first group of microphones, z represents the axial coordinate, e is the electrical signal of the signal amplifier, is the transfer function between the lth microphone and the electrical signal; Repeat this operation downstream of the element to be tested to obtain the incident acoustic wave modal pressure amplitude matrix a upstream and downstream of the element to be tested in (ω) and the reflected acoustic wave modal pressure amplitude matrix a out (ω), there is no sound source in the tube, and the scattering matrix S(ω) between the incident sound wave and the reflected sound wave is: s(ω)=a out (ω)[a in (oh)] -1 In the formula, [] -1 represents the pseudo-inverse matrix.

9. The pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis method according to claim 8, characterized in that: In the acoustic modal analysis method, in step 3, the terminal matrix R is: R=a in (ω)[a out (oh)] -1 The acoustic wave modal pressure amplitude matrix a generated by the element itself under non-reflection conditions s (ω) is: a s (ω)=[I 2N -S(ω)R]a out (oh) In the formula, I 2N is the identity matrix of dimension 2N.

10. The pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis method according to claim 9, characterized in that: In the acoustic modal analysis method, in step 4, The element to be tested is placed in the experimental device for pipeline flow-induced and acoustic-induced vibration detection and acoustic modal analysis. The pressure field in the pipeline satisfies the Helmholtz equation, and at point s1 = (s1, z1): Where, the center of the cross section of the main pipe inlet is taken as the coordinate origin, s1 is the circumferential and radial position of the measuring point, and z1 is the axial distance between the microphone and the main pipe inlet; p ac is the sound pressure, ψ pq is the normalized pipeline mode, is the amplitude of the downstream propagating mode, The amplitude of the upstream propagation mode, i is an imaginary unit, ω is the angular frequency; is the axial wave number, expressed as: Where M is the Mach number, k is ⊥ is the circumferential wave number; k = ω / c is the wave number, c = 340 m / s is the speed of sound; The 2N port method is used to analyze and calculate the acoustic modal. The formula of the 2N port method is as follows: a out (ω)=S(ω)a in (ω)+a s (oh) In the formula, a in (ω), a out (ω) are the modal pressure amplitude matrices of the incident and reflected acoustic waves at the upstream and downstream of the element under test, and is the vector of acoustic modal coefficients, a s (ω) is the acoustic wave modal pressure amplitude matrix generated by the element itself under non-reflection conditions, S(ω)∈c [2N×2N] is the scattering matrix between the incident sound wave and the reflected sound wave, I and II represent the upstream and downstream sides of the 2N port; Calculate the cross-spectral density G s , expressed as: G s =E[a s (ω)(a) s (oh)) c ] In the formula, E[] represents expectation and c represents the conjugate transpose of the matrix.

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