Pipeline orifice radiation impedance testing device and method
By using the acoustic decomposition method, transducers and hydrophones are used to collect acoustic signals inside the pipeline, and the radiation impedance of the pipe opening is indirectly calculated. This solves the problem of difficult measurement of particle velocity at the sea outlet of the pipeline and realizes accurate impedance measurement.
Patent Information
- Application Number
- CN202511048341.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-29
- Publication Date
- 2025-11-04
AI Technical Summary
Existing technologies make it difficult to directly measure the particle velocity at the outlet of a sea-crossing pipeline, which makes it difficult to calculate the radiation impedance of the outlet.
The acoustic decomposition method is adopted. The transducer sends sound source excitation into the pipeline under test, and multiple hydrophones are used to collect the internal time-domain acoustic signal in real time. The radiation impedance of the pipe outlet is calculated by acoustic decomposition through the host computer.
This method enables an indirect solution to the radiation impedance of the pipe opening, improving the accuracy and feasibility of the measurement.
Smart Images
Figure CN120890540A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of radiation impedance testing, and in particular to a device and method for testing the radiation impedance of a pipe outlet. Background Technology
[0002] In related technologies, the vibration velocity and sound pressure of the object being measured can be directly obtained. Therefore, it is feasible to directly extract the sound pressure and vibration velocity from the surface of the radiating body to calculate the radiation impedance of the pipe opening. However, for sea-through pipe openings, the particle velocity at the opening is difficult to measure. Therefore, it is difficult to directly obtain the radiation impedance of the opening by measuring the sound pressure and particle vibration at the opening. Summary of the Invention
[0003] The purpose of this application is to provide a device and method for testing the radiation impedance of a pipeline outlet, which can indirectly solve the radiation impedance of the pipeline outlet by means of acoustic decomposition.
[0004] To achieve the above objectives, this application provides the following solution:
[0005] In a first aspect, this application provides a device for testing the radiation impedance of a pipe outlet, comprising:
[0006] The host computer is used to generate control signals and acquire signals;
[0007] A transducer, connected to the pipeline under test and the host computer, is used to emit sound source excitation to the interior of the pipeline under test according to the control signal; the pipeline under test is placed vertically and filled with water.
[0008] Multiple hydrophones are distributed at different locations inside the pipeline under test and connected to the host computer to collect time-domain acoustic signals at different locations inside the pipeline under test in real time based on the acquired signals.
[0009] The host computer is also used to calculate the pipe outlet radiation impedance of the pipeline under test in real time based on the time-domain acoustic signals at different locations inside the pipeline under test using the acoustic wave decomposition method.
[0010] Secondly, this application provides a method for testing the radiation impedance of a pipe outlet, including:
[0011] The host computer generates control signals and acquires signals.
[0012] The transducer sends a sound source excitation to the inside of the pipeline under test according to the control signal; the pipeline under test is placed vertically and filled with water.
[0013] Multiple hydrophones are used to collect time-domain acoustic signals at different locations inside the pipeline under test in real time based on the collected signals.
[0014] The host computer calculates the pipe outlet radiation impedance in real time using the acoustic wave decomposition method based on the time-domain acoustic signals at different locations inside the pipe under test.
[0015] According to the specific embodiments provided in this application, this application has the following technical effects:
[0016] This application provides a device and method for testing the radiation impedance of a pipeline outlet. A host computer generates control and acquisition signals; a transducer emits sound source excitation into the pipeline under test according to the control signals; multiple hydrophones acquire time-domain acoustic signals at different locations inside the pipeline in real time based on the acquisition signals; and the host computer calculates the radiation impedance of the pipeline outlet in real time using the acoustic wave decomposition method based on the time-domain acoustic signals at different locations inside the pipeline. This application can indirectly solve for the radiation impedance of the pipeline outlet using the acoustic wave decomposition method. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a schematic diagram of the structure of a pipeline outlet radiation impedance testing device according to one embodiment of this application;
[0019] Figure 2 for Figure 1 A schematic diagram showing the installation position of a hydrophone in a pipeline outlet radiation impedance testing device.
[0020] Figure 3 A flowchart of a pipeline outlet radiation impedance testing method provided in another embodiment of this application;
[0021] Figure 4 This is a schematic diagram illustrating the principle of acoustic decomposition method in a pipeline outlet radiation impedance testing method provided in another embodiment of this application;
[0022] Figure 5 A schematic diagram of the finite element model of the pipeline under test in a pipeline outlet radiation impedance testing method provided in an embodiment of this application;
[0023] Figure 6A schematic diagram comparing the experimental first transfer function obtained by the method of testing the radiation impedance of a pipe outlet provided in an embodiment of this application with the first transfer function of the elastic wall and the first transfer function of the rigid wall obtained by simulating the elastic and rigid walls of the anechoic water tank using a finite element model.
[0024] Figure 7 A schematic diagram comparing the 1-1000Hz experimental pipe outlet radiation resistance obtained by the pipe outlet radiation impedance test method provided in an embodiment of this application with the 1-1000Hz simulated pipe outlet radiation resistance obtained by the finite element model.
[0025] Figure 8 This is a schematic diagram comparing the 1-1000Hz experimental pipe outlet radiation impedance obtained by conducting an experiment using a pipe outlet radiation impedance testing method provided in an embodiment of this application with the 1-1000Hz simulated pipe outlet radiation impedance obtained using a finite element model.
[0026] Figure label:
[0027] 1. Overhead crane, 2. Pipeline under test, 3. Transducer, 4. Hydrophone No. 3, 5. Hydrophone No. 1, 6. Host computer, 7. Acrylic glass plate, 8. Silencing water tank, 9. Sound-absorbing wedge, 10. Detailed Implementation
[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0029] To make the objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0030] In one exemplary embodiment, such as Figure 1 As shown, a pipeline outlet radiation impedance testing device is provided, including: a host computer 7, a transducer 3 and multiple hydrophones.
[0031] The host computer 7 is used to generate control signals and acquire signals.
[0032] The transducer 3 is connected to the pipeline under test 2 and the host computer 7. The transducer 3 is used to emit sound source excitation to the interior of the pipeline under test 2 according to the control signal. The pipeline under test 2 is placed vertically and filled with water. The transducer 3 is installed on the top of the pipeline under test 2. The transducer 3 is connected to the pipeline under test 2 via a flange.
[0033] The multiple hydrophones are distributed at different locations inside the pipe under test 2 and connected to the host computer 7. The multiple hydrophones are used to collect time-domain acoustic signals at different locations inside the pipe under test 2 in real time based on the acquired signals. The multiple hydrophones are connected to the host computer 7 via data transmission lines.
[0034] In this application, three hydrophones are installed inside the pipeline 2 under test, namely hydrophone 6 (number one), hydrophone 5 (number two), and hydrophone 4 (number three). Specifically, three hydrophone bases are installed downstream of the pipeline 2 near the pipe opening, as shown below. Figure 2 As shown, the hydrophone is flush-mounted into the pre-fabricated hydrophone base of the pipeline under test 2, and secured with bolts to prevent it from shaking. The distances between hydrophone 6 (number 1), hydrophone 5 (number 2), and hydrophone 4 (number 3) and the opening of the pipeline under test 2 are x1, x2, and x3, respectively.
[0035] The host computer 7 is also used to calculate the radiation impedance of the pipe opening of the pipe under test 2 in real time based on the time-domain acoustic signals at different locations inside the pipe under test 2 using the acoustic wave decomposition method. The pipe opening of the pipe under test in this application can be a sea-crossing pipeline opening.
[0036] In another exemplary embodiment of this application, the host computer 7 specifically includes: a control system, a data acquisition system, and a data analysis system. Wherein:
[0037] The control system is used to generate control signals.
[0038] The data acquisition system is used to generate acquisition signals and receive time-domain acoustic signals at different locations inside the pipeline under test.
[0039] The data analysis system is connected to the data acquisition system. The data analysis system is used to calculate the pipe outlet radiation impedance of the pipeline under test in real time based on the time-domain acoustic signals at different locations inside the pipeline under test using the acoustic wave decomposition method.
[0040] In another exemplary embodiment of this application, the pipe wall of the test pipe 2 is a thick-walled pipe. Because the acoustic decomposition method requires the internal acoustic waves of the test pipe 2 to be plane waves, when the pipe wall is thin and the frequency is high, the acoustic-vibration coupling effect is strong, leading to a large deviation in the measurement results based on the acoustic decomposition method. Therefore, a thick-walled pipe is used for measurement to reduce the interference of pipe wall vibration, thereby improving the flatness of the acoustic waves inside the pipe.
[0041] In another exemplary embodiment of this application, the pipeline outlet radiation impedance testing device further includes: a crane 1, an plexiglass plate 8, a sound-absorbing water tank 9, a sound-absorbing wedge 10, and a soft-haired long rod.
[0042] The overhead crane 1 is used to suspend the test pipeline 2 in a free-suspension manner. Specifically, the overhead crane 1 uses a steel wire rope to suspend the test pipeline 2, which reduces pipe wall vibration and the coupling effect with the foundation. The end of the test pipeline 2 is immersed in the anechoic water tank 9. After the test pipeline 2 is filled with water, a soft-bristled long rod is used to scrape off the air bubbles adhering to the pipe wall. The material sealing the pipe needs to match the impedance of the water; therefore, after the air bubbles are removed, an acrylic plate 8 is installed at the end of the pipe for sealing. The acrylic plate 8 can simulate the continuous radiation conditions at the pipe opening. The acrylic plate 8 is used to seal the test pipeline 2 and provide continuous boundary conditions for the test pipeline 2. The soft-bristled long rod is used to scrape off the air bubbles adhering to the inner wall of the test pipeline 2. The sound-absorbing wedge 10 is disposed on the inner wall of the anechoic water tank 9 to create a non-reflective wall surface.
[0043] Based on the same inventive concept, such as Figure 3 As shown in the figure, this application embodiment also provides a method for testing the radiation impedance of a pipeline outlet. Using the above-described pipeline outlet radiation impedance testing device, the method for testing the radiation impedance of a pipeline outlet includes steps 101 to 103.
[0044] Step 101: Generate control signals and acquisition signals through the host computer.
[0045] Step 102: The transducer sends a sound source excitation to the inside of the pipeline under test according to the control signal; the pipeline under test is placed vertically and filled with water.
[0046] Step 103: Using multiple hydrophones, time-domain acoustic signals at different locations inside the pipeline under test are collected in real time based on the acquired signals.
[0047] Specifically, the time-domain acoustic signal is measured by a hydrophone. When the sound pressure inside the pipe under test 2 fluctuates, the head of the hydrophone deforms, generating an electric charge. This charge is then converted into an electrical signal by a circuit for measurement. In the host computer 7, the electrical signal is converted back into a time-domain acoustic signal.
[0048] Step 104: The host computer calculates the pipe outlet radiation impedance in real time based on the time-domain acoustic signals at different locations inside the pipe under test using the acoustic wave decomposition method.
[0049] In one exemplary embodiment, the presence of air bubbles inside the pipe can significantly affect the measurement results of the testing device. Therefore, before the experimental measurement, it is necessary to scrape off the air bubbles adhering to the pipe wall and keep the pipe stationary. After scraping off the air bubbles, the pipe needs to be sealed to prevent water from flowing out during pipe movement. As another optional implementation, before step 101, the method further includes: after the pipe outlet radiation impedance testing device is installed, using the host computer 7 to measure the background noise at this time; using the transducer 3 to measure the sound pressure level inside the pipe when the transducer 3 is working, and adjusting the output power of the transducer 3 so that the sound signal inside the pipe 2 under test is more than 10 dB higher than the background noise.
[0050] As an optional implementation, step 104 specifically includes steps 201 to 203.
[0051] Step 201: The host computer 7 converts the time-domain acoustic signals at different locations inside the pipe under test 2 into frequency-domain acoustic signals. Fourier transform is used to convert the time-domain acoustic signals into frequency-domain acoustic signals. The Fourier transform formula is: Where ω is the angular frequency, j is the imaginary unit, t is the time, and f(t) is the sound signal at time t.
[0052] Step 202: Based on the frequency domain acoustic signal, obtain the transfer function and coherence curve between the frequency domain acoustic signals at any two different locations in the same direction.
[0053] Specifically, based on the frequency domain acoustic signal P1 from hydrophone 6 and the frequency domain acoustic signal P2 from hydrophone 5, the first transfer function and the first coherence curve are obtained. The first transfer function is H. 12 =P1 / P2.
[0054] Based on the frequency domain acoustic signal P1 at hydrophone 6 and the frequency domain acoustic signal P3 at hydrophone 4, the second transfer function and the second coherence curve are obtained. The second transfer function is H. 13 =P1 / P3.
[0055] Based on the frequency domain acoustic signal P2 from hydrophone 5 (number 2) and the frequency domain acoustic signal P3 from hydrophone 4 (number 3), the third transfer function and the third coherence curve are obtained. The third transfer function is H... 23 =P2 / P3.
[0056] The coherence curve measures the consistency of phase information between two signals in the frequency domain. The coherence function γ of the frequency domain acoustic signal P1 at hydrophone 6 and the frequency domain acoustic signal P2 at hydrophone 5 is shown. 12 (f) is defined as:
[0057]
[0058] Among them, S12 (f) represents the cross-power spectral density of P1 and P2, S 11 (f) represents the self-power spectral density of P1, S 22 (f) represents the self-power spectral density of P2.
[0059] Step 203: Based on the transfer function and the coherence curve, the radiation impedance of the pipe outlet of the pipeline under test 2 is calculated in real time using the acoustic decomposition method, specifically including steps 301 and 302.
[0060] Step 301: Determine the wave velocity inside the pipeline 2 under test based on the transfer function and the coherence curve.
[0061] Wave velocity measurement uses a three-sensor method, which is based on plane wave theory. During measurement, sound pressure signals at corresponding locations of three sensors are recorded simultaneously, and the true wave velocity value is obtained by analyzing the relationship between these three sound pressure signals.
[0062] Step 302: Based on the wave velocity and the transfer function, the radiation impedance of the pipe opening of the pipeline under test 2 is calculated in real time using the acoustic decomposition method.
[0063] The principle of the acoustic wave decomposition method is as follows: Figure 4 As shown, the sound source emits a swept-frequency sound wave, which forms a standing wave field inside the sound tube. Assuming the amplitude of the incident sound wave is I and the amplitude of the reflected sound wave is R, the expressions for the frequency domain sound signal P1 at hydrophone 6 and the frequency domain sound signal P2 at hydrophone 5 are as follows:
[0064]
[0065] Where j is the imaginary unit, k0 is the wave number.
[0066] The first transfer function is:
[0067]
[0068] Where r = R / I is the ratio of the amplitude of the reflected sound wave to that of the incident sound wave.
[0069] Simplifying the first transfer function yields:
[0070]
[0071] in, s is the distance between hydrophone 6 (number 1) and hydrophone 5 (number 2).
[0072] The radiation impedance of the pipe opening of the pipeline under test 2 can be expressed as: Among them, Z sLet ρ be the radiation impedance of the pipe outlet of the pipe under test 2, c0 be the wave velocity inside the pipe under test 2, and ρ0 be the density of water.
[0073] As an optional implementation, after step 104, the method further includes:
[0074] A numerical calculation model was built based on the geometry of the anechoic water tank and the pipeline under test. The wall of the anechoic water tank does not reflect sound waves when the sound frequency is greater than 100Hz.
[0075] The numerical calculation model was used to verify the radiation impedance of the pipe outlet of the pipeline under test.
[0076] In this embodiment, the numerical calculation model is a finite element model. For example... Figure 5 As shown, a finite element model of the pipeline under test 2 is established. The finite element model includes the pipeline under test 2 and the anechoic water tank 9 at a proportional scale.
[0077] The finite element model is used to calculate the inlet radiation impedance of the pipe under test 2, thus obtaining the simulated inlet radiation impedance. A plane wave radiation condition is applied at the inlet boundary of the pipe under test 2, and the wall of the anechoic pool 9 is set as a fully sound-absorbing boundary. A monitoring surface is set at the end of the pipe under test 2, and the sound pressure and particle velocity at the inlet of the pipe under test 2 are calculated, directly yielding the simulated inlet radiation impedance.
[0078] Specifically, a finite element model of the sea-crossing pipeline inlet is established. Monitoring surfaces are set at distances x1, x2, and x3 from the inlet. The acoustic-structure interaction model of the sea-crossing pipeline is calculated in the frequency domain. Wave velocity is calculated iteratively using the transfer function and correlation curve. The simulated inlet radiation impedance is then obtained through numerical calculations. The steps for obtaining the simulated inlet radiation impedance and the experimental inlet radiation impedance described above are feasible. Alternatively, the particle velocity at the inlet can be directly extracted from the finite element model. Based on the sound pressure and particle velocity at the inlet, the simulated inlet radiation impedance can be obtained. The simulated inlet radiation impedance is equal to the integral of the sound pressure p at the inlet divided by the average particle velocity at the inlet, i.e., Z = intop. 管口 (p) / aveop 管口 (u), where Z is the simulated orifice radiation impedance, intop 管口 (p) is the integral of the sound pressure p at the pipe opening, aveop 管口 (u) represents the average velocity of the particle at the pipe opening; this method is simpler and more convenient.
[0079] The simulated pipe outlet radiation impedance is compared and verified with the test pipe outlet radiation impedance; the test pipe outlet radiation impedance is the pipe outlet radiation impedance of the pipeline under test 2 obtained by real-time measurement.
[0080] As an optional implementation method, such as Figure 6As shown, the first transfer function of the experiment was obtained by using the pipeline inlet radiation impedance test method. The first transfer function of the elastic wall of the anechoic tank was obtained by simulating the elastic wall using a finite element model; the first transfer function of the rigid wall of the anechoic tank was obtained by simulating the rigid wall using a finite element model. From... Figure 6 It can be seen that the first transfer function of the elastic wall and the experimental first transfer function have a peak around 1000Hz, while the first transfer function of the rigid wall has a peak around 1140Hz. The peak occurs because the frequency domain acoustic signal P2 at hydrophone 5 is located at a node, causing a maximum value in the first transfer function. Similarly, as the frequency increases, an anti-resonance peak appears because the frequency domain acoustic signal P1 at hydrophone 6 is located at a node, causing a minimum value in the first transfer function.
[0081] As an optional implementation method, such as Figure 7 As shown, an experiment was conducted using the pipe outlet radiation impedance testing method. The obtained 1Hz-1000Hz experimental pipe outlet radiation impedance was compared with the simulated 1Hz-1000Hz pipe outlet radiation impedance obtained using a finite element model. Figure 8 As shown, an experiment was conducted using the pipeline outlet radiation impedance test method. The obtained 1Hz-1000Hz experimental outlet radiation impedance was compared with the 1Hz-1000Hz simulated outlet radiation impedance obtained using a finite element model. Here, radiation resistance is the real part of radiation impedance, and radiation reactance is the imaginary part of radiation impedance.
[0082] Figure 7 and Figure 8 The errors are relatively large at certain frequency points for the following reasons: First, compared to the characteristic impedance of the medium, the radiation impedance at the pipe opening is a small quantity. This increases the difficulty of measuring the radiation impedance at the pipe opening, placing high demands on factors such as the consistency of the measurement sensors, the phase hysteresis between measurement system channels, and the consistency of wavefronts between measurement points. Second, as the frequency increases, the absolute value of the radiation impedance gradually increases, and the measurement results become less sensitive to measurement errors. Therefore, the accuracy of the numerical calculation model can be further verified by measuring the radiation impedance in the high-frequency band.
[0083] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.
[0084] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.
[0085] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0086] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.
Claims
1. A device for testing the radiation impedance of a pipe outlet, characterized in that, The pipeline inlet radiation impedance testing device includes: The host computer is used to generate control signals and acquire signals; A transducer, connected to the pipeline under test and the host computer, is used to emit sound source excitation to the interior of the pipeline under test according to the control signal; the pipeline under test is placed vertically and filled with water. Multiple hydrophones are distributed at different locations inside the pipeline under test and connected to the host computer to collect time-domain acoustic signals at different locations inside the pipeline under test in real time based on the acquired signals. The host computer is also used to calculate the pipe outlet radiation impedance of the pipeline under test in real time based on the time-domain acoustic signals at different locations inside the pipeline under test using the acoustic wave decomposition method.
2. The pipeline outlet radiation impedance testing device according to claim 1, characterized in that, The pipeline outlet radiation impedance testing device further includes: an plexiglass plate, used to seal the pipeline under test and provide continuous boundary conditions for the pipeline under test.
3. The pipeline outlet radiation impedance testing device according to claim 1, characterized in that, The pipeline outlet radiation impedance testing device also includes: a crane, used to suspend the pipeline under test in a free-suspension manner.
4. The pipeline outlet radiation impedance testing device according to claim 1, characterized in that, The pipeline inlet radiation impedance testing device also includes: a noise-absorbing water tank; The end of the pipeline under test is immersed in the silencing water tank.
5. The pipeline outlet radiation impedance testing device according to claim 4, characterized in that, The pipeline inlet radiation impedance testing device also includes: a sound-absorbing wedge, which is installed on the inner wall of the anechoic water tank to create a wall surface without sound wave reflection.
6. The pipeline outlet radiation impedance testing device according to claim 1, characterized in that, The host computer includes: A control system for generating the control signal; A data acquisition system is used to generate the acquisition signal and receive time-domain acoustic signals at different locations inside the pipeline under test. The data analysis system, connected to the data acquisition system, is used to calculate the pipe outlet radiation impedance of the pipeline under test in real time based on the time-domain acoustic signals at different locations inside the pipeline under test, using the acoustic wave decomposition method.
7. A method for testing the radiation impedance of a pipe outlet, applied to the pipe outlet radiation impedance testing apparatus according to any one of claims 1-6, characterized in that, The method for testing the radiation impedance of the pipeline inlet includes: The host computer generates control signals and acquires signals. The transducer sends a sound source excitation to the inside of the pipeline under test according to the control signal; the pipeline under test is placed vertically and filled with water. Multiple hydrophones are used to collect time-domain acoustic signals at different locations inside the pipeline under test in real time based on the collected signals. The host computer calculates the pipe outlet radiation impedance in real time using the acoustic wave decomposition method based on the time-domain acoustic signals at different locations inside the pipe under test.
8. The method for testing the radiation impedance of a pipe outlet according to claim 7, characterized in that, The host computer calculates the pipe outlet radiation impedance in real time using the acoustic wave decomposition method based on the time-domain acoustic signals at different locations inside the pipe under test. Specifically, this includes: The host computer converts the time-domain acoustic signals at different locations inside the pipeline under test into frequency-domain acoustic signals. Based on the frequency domain acoustic signal, the transfer function and coherence curve between the frequency domain acoustic signals at any two different locations in the same direction are obtained; Based on the transfer function and the coherence curve, the radiation impedance of the pipe outlet of the pipeline under test is calculated in real time using the acoustic decomposition method.
9. The method for testing the radiation impedance of a pipe outlet according to claim 8, characterized in that, Based on the transfer function and the coherence curve, the acoustic decomposition method is used to calculate the inlet radiation impedance of the pipeline under test in real time, specifically including: Based on the transfer function and the coherence curve, the wave velocity inside the pipeline under test is determined; Based on the wave velocity and the transfer function, the radiation impedance of the pipe outlet of the pipeline under test is calculated in real time using the acoustic decomposition method.
10. The method for testing the radiation impedance of a pipe outlet according to claim 7, characterized in that, After calculating the pipe outlet radiation impedance in real time using the time-domain acoustic signals at different locations inside the pipe under test via the host computer and employing the acoustic wave decomposition method, the pipe outlet radiation impedance testing method further includes: A numerical calculation model was built based on the geometric structure of the anechoic water tank and the pipeline under test; the wall of the anechoic water tank has no sound wave reflection when the sound wave frequency is greater than 100Hz; The numerical calculation model was used to verify the radiation impedance of the pipe outlet of the pipeline under test.