Calibration device and calibration method for acoustic measurement of surface pulsating pressure

Abstract

The invention discloses a calibration device and a calibration method for acoustic measurement of surface pulsating pressure. The calibration device comprises a signal generator used for generating noise and a plane wave generator arranged in a silencing box, and the plane wave generator can convert noise signals generated by the signal generator into plane waves; the plane wave generator is provided with a microphone interface used for being connected with a monitoring microphone, so that the monitoring microphone can monitor plane waves in the plane wave generator. The plane wave generator further comprises an output port for outputting plane waves, and the reference microphone and a measuring microphone of the surface pulsating pressure acoustic measuring device to be calibrated can monitor the plane waves in the plane wave generator through the output port. And the data acquisition module is used for acquiring data of the monitoring microphone, the reference microphone and the measurement microphone. The surface pulsating pressure acoustic measurement device can be calibrated, so that the measurement precision of the acoustic measurement device is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of aerodynamic test, and in particular relates to a calibration device and a calibration method for acoustic measurement of surface pulsation pressure. Background Art

[0002] Low-altitude economy is a comprehensive economic form. It drives the development of related industries with low-altitude flight activities as the core, covering many fields such as aircraft research and development, manufacturing, operation services, and comprehensive support. The low-altitude economic airspace is usually below 1,000 meters, with civil manned and unmanned aircraft as carriers. The application scenarios mainly include urban air traffic, logistics, fire rescue, emergency medical care, etc. In order to reduce pollutant emissions and reduce the requirements for runways, low-altitude economic aircraft are mainly electric vertical take-off and landing (EVTOL) multi-rotor drones. Due to the low flight altitude, the noise generated by aircraft such as multi-rotor drones will have a serious impact on the production and life of urban residents. According to aeroacoustic theory, the noise generated by the rotor will increase with the increase of load and flight speed. Therefore, it is necessary to focus on and solve the noise problem in the design and development of aircraft.

[0003] When an aircraft is in motion, when air flows over the surface of the aircraft body or rotor blades, complex flow phenomena such as flow separation and vortex shedding will occur, thereby inducing surface pulsating pressure. Surface pulsating pressure is the main source of aircraft structural vibration and aerodynamic noise. Due to the great difficulties in numerical calculation and prediction of turbulence, accurate measurement of surface pulsating pressure through wind tunnel tests is the main means to deeply understand the mechanism of aircraft aerodynamic noise generation and study and solve noise problems.

[0004] Conventional wind tunnel measurement methods for the pulsating pressure on the aircraft surface mainly include: pulsating pressure sensors, pressure-sensitive paint, pressure membrane tapes, etc. The above measurement methods have disadvantages such as "expensive, difficult to install, inconvenient to use and calibrate". The acoustic measurement method of the pulsating pressure on the aircraft surface mainly uses the sound pressure measured by the microphone to infer the surface pulsating pressure. At present, the microphone, as the core component of the measurement system, has been completely domestically produced in batches. Placing the microphone at the far end can improve the spatial resolution of the measurement point and is not restricted by the special surface of the object. Therefore, the use of acoustic methods to measure the surface pulsating pressure has the advantages of "low cost, high sensitivity, and easy installation".

[0005] Since there is viscous heat dissipation in the surface pulsation pressure acoustic measurement waveguide, which causes phase distortion and amplitude distortion of the signal, the measurement system needs to be calibrated in order to obtain accurate results. However, there is no equipment for calibrating the surface pulsation pressure acoustic measurement device in the prior art. Summary of the invention

[0006] The object of the present invention is to provide a calibration device and a calibration method for surface pulsation pressure acoustic measurement, which partially solve or alleviate the above-mentioned deficiencies in the prior art and can calibrate the surface pulsation pressure acoustic measurement device.

[0007] In order to solve the above-mentioned technical problems, the present invention specifically adopts the following technical solutions: A first aspect of the present invention is to provide a calibration device for surface pulsation pressure acoustic measurement, comprising a signal generator for generating noise and a plane wave generator arranged in a soundproof box, wherein the plane wave generator can convert the noise signal generated by the signal generator into a plane wave; the plane wave generator is provided with a microphone interface for connecting a monitoring microphone, so that the monitoring microphone can monitor the plane wave in the plane wave generator; the plane wave generator also includes an output port for outputting the plane wave, and a reference microphone and a measuring microphone of a surface pulsation pressure acoustic measurement device to be calibrated can monitor the plane wave in the plane wave generator through the output port; and also includes a data acquisition module for collecting data of the monitoring microphone, the reference microphone and the measuring microphone.

[0008] As an improvement, the silencer box is provided with a plurality of input interfaces and output interfaces; the plane wave generator is connected to the input interface for receiving a signal from a signal generator; the monitoring microphone, the reference microphone and the measuring microphone are connected to the output interface, and the data acquisition module is used to collect data from the monitoring microphone, the reference microphone and the measuring microphone.

[0009] As an improvement, it also includes a temperature, humidity and pressure sensor arranged in the silencer box, and the temperature, humidity and pressure sensor can output an analog voltage signal.

[0010] As an improvement, the sound-absorbing box is of a flip-top type, including a box body and a cover plate; sealing strips are provided at the edges where the box body and the cover plate are buckled together; the inside of the box body is filled with sound insulation material, and a vibration isolation pad is provided at the bottom of the box body.

[0011] As an improvement, a power amplifier is provided between the signal generator and the plane wave generator.

[0012] The present invention also provides a calibration method for surface pulsation pressure acoustic measurement, which uses the above-mentioned calibration device for surface pulsation pressure acoustic measurement to perform calibration, comprising: S1 selects a reference microphone and installs it on the object to be tested; The plane wave generator S2 generates a plane wave which is monitored by the monitoring microphone and the reference microphone to obtain a sound pressure signal; the transfer function between the monitoring microphone and the reference microphone is constructed by using the sound pressure signal output by the monitoring microphone and the sound pressure signal output by the reference microphone, i.e., transfer function I; S3 installing a measuring microphone of the surface pulsation pressure acoustic measuring device to be calibrated on the object to be measured; The plane wave generator S4 generates a plane wave which is monitored by the monitoring microphone and the measuring microphone to obtain a sound pressure signal; the sound pressure signal output by the monitoring microphone and the sound pressure signal output by the measuring microphone are used to construct a transfer function between the monitoring microphone and the measuring microphone, namely, transfer function II; S5: using the transfer function I and the transfer function II to obtain a transfer function between the measuring microphone and the reference microphone, that is, a transfer function III; S6 repeats steps S1 to S5 to obtain a plurality of transfer functions III, and constructs a verification transfer function using the plurality of transfer functions III.

[0013] As an improvement, the transfer function I is: ; Among them, TF 1 To pass parameter I, To monitor the frequency domain sound pressure signal of the microphone, is the frequency domain sound pressure signal of the reference microphone.

[0014] As an improvement, the transfer function II is: ； Among them, TF 2 To pass parameter II, To monitor the frequency domain sound pressure signal of the microphone, It is the frequency domain sound pressure signal of the measurement microphone.

[0015] As an improvement, the transfer function III is: ; Among them, TF is the transfer parameter III, TF 1 To pass parameters I, TF 2 To pass parameter II, To monitor the frequency domain sound pressure signal of the microphone, is the frequency domain sound pressure signal of the reference microphone, It is the frequency domain sound pressure signal of the measurement microphone.

[0016] As an improvement, the verification transfer function is: ; Among them, TF Cal To verify the transfer parameters, N is the number of transfer functions III, is the transfer function III with sequence i, where i is the sequence number of the transfer function.

[0017] Beneficial effect: The Helmholtz resonator of the plane wave generator in the present invention is designed according to the peak frequency of the sound wave resonance of the tube with equal cross-section, and its geometric parameters are determined by accurately calculating the sound volume and the sound mass of the cavity opening. It can accurately process sound waves of a specific frequency. When a sound wave of the specific frequency appears in the plane wave tube, the Helmholtz resonator resonates, consumes the sound wave energy, effectively eliminates the resonance peak, makes the sound wave propagation in the tube more stable, and avoids the interference of the resonance on the measurement calibration signal.

[0018] The special design of the continuous variable cross-section tube changes the propagation characteristics of sound waves in the tube. Its exponential smooth curve structure from the large end to the small end suppresses high-order sound wave modes, reduces the reflection and scattering of sound waves, and makes the sound waves propagate closer to the ideal state of plane waves. This propagation mode reduces the interaction with background noise and reduces the impact of background noise on the measurement signal, thereby improving the signal-to-noise ratio.

[0019] The calibration device of the present invention is provided with a muffler box for isolating external interference. During the acoustic measurement calibration process, external noise will interfere with the accuracy of the measurement results. The muffler box not only blocks the noise but also prevents the rapid exchange of air inside the box with the outside air, reduces the small air pressure changes and temperature fluctuations caused by air flow, maintains the stability of the acoustic environment inside the box, helps to improve the reliability of the measurement, and solves the problem of difficulty in isolating low-frequency background noise.

[0020] In addition, in the calibration method provided by the present invention, the sound pressure signals output by the monitoring microphone and the reference microphone are collected by the data acquisition module. However, the signals are time domain signals, so the time domain signals are usually converted into frequency domain signals by using methods such as Fourier transform to obtain the frequency domain sound pressure signal of the monitoring microphone and the frequency domain sound pressure signal of the reference microphone. The transfer function I between the monitoring microphone and the reference microphone is calculated based on the frequency domain sound pressure signal of the monitoring microphone and the frequency domain sound pressure signal of the reference microphone, and the transfer function reflects the conversion relationship between the sound pressure signals of the two at different frequencies.

[0021] Then the data acquisition module collects the sound pressure signals output by the monitoring microphone and the measuring microphone, and calculates the transfer function II between the monitoring microphone and the reference microphone according to the frequency domain sound pressure signal of the monitoring microphone and the frequency domain sound pressure signal of the measuring microphone.

[0022] Transfer function I describes the sound pressure signal transfer relationship between the monitoring microphone and the reference microphone, and transfer function II describes the sound pressure signal transfer relationship between the monitoring microphone and the measuring microphone. Since the monitoring microphone exists in both transfer relationships, the transfer function III between the measuring microphone and the reference microphone can be derived by mathematical operations using these two known transfer functions.

[0023] Transfer function III defines the transfer relationship between the measurement microphone and the reference microphone, whose performance is known and accurate. Through transfer function III, the measurement results of the measurement microphone can be compared with the reference microphone to determine the performance deviation of the measurement microphone. Based on this deviation, the measurement microphone can be calibrated to make its measurement results more accurate and reliable, thereby improving the accuracy of surface pressure pulsation acoustic measurements.

[0024] Finally, by taking multiple measurements and constructing a calibration transfer function, the impact of random errors on the measurement results can be effectively reduced. Random errors show a certain degree of randomness in multiple measurements. Some measurement results may be too large, while others may be too small. By averaging, these errors can be offset, thus obtaining a more accurate transfer function. Using this calibration transfer function to calibrate the measurement microphone can improve the accuracy of the calibration and make the measurement results of the measurement microphone closer to the true value.

[0025] In addition, the transfer function III obtained from a single measurement may have abnormal values. When constructing the verification transfer function, the influence of abnormal values ​​on the final result can be reduced by averaging multiple transfer functions III. The verification transfer function obtained in this way can better reflect the true relationship between the measurement microphone and the reference microphone, and enhance the reliability of the entire calibration process. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual scale. Obviously, the drawings described below are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without paying creative labor.

[0027] Figure 1 It is a structural schematic diagram of a calibration device in Embodiment 1 of the present invention; Figure 2 It is a schematic cross-sectional structural diagram of a plane wave generator according to a second embodiment of the present invention; Figure 3 It is a schematic diagram of the three-dimensional structure of a plane wave generator according to a second embodiment of the present invention; Figure 4 It is a schematic diagram of the structure of a Hertz resonator; Figure 5 is a schematic diagram of the structure of the mounting base; Figure 6 This is a flow chart of Embodiment 3 of the present invention.

[0028] Summary of reference numerals: 1 is a speaker; 2 is an outer tube; 3 is a continuously variable cross-section inner tube; 4 is a uniform cross-section inner tube; 5 is a uniform cross-section branch tube; 6 is a mounting seat; 7 is a microphone adapter; 8 is a Hertz resonator; 9 is an annular cover plate; 61 is a mounting cavity; 62 is a sound guide hole; 81 is an opening; 82 is a cavity.

[0029] 101 is a signal generator; 102 is a power amplifier; 103 is a plane wave generator; 104 is a monitoring microphone; 105 is a reference microphone; 106 is a temperature, humidity and pressure sensor; 107 is a silencer box; and 108 is an electrical interface. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] Herein, suffixes such as "module", "component" or "unit" used to represent elements are only used to facilitate the description of the present invention, and have no specific meanings by themselves. Therefore, "module", "component" or "unit" can be used mixedly.

[0032] In this document, the terms "upper", "lower", "inner", "outer", "front", "back", "one end", "the other end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0033] In this document, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] Herein "and / or" includes any and all combinations of one or more of the associated listed items.

[0035] Herein, "plurality" means two or more than two, ie, it includes two, three, four, five, etc.

[0036] Embodiment 1: Figure 1 As shown, the present invention provides a calibration device for surface pulsation pressure acoustic measurement, comprising a silencer 107, a signal generator 101 for generating a noise signal, and a plane wave generator 103 arranged in the silencer 107, wherein the plane wave generator 103 can convert the noise signal generated by the signal generator 101 into a plane wave; the plane wave generator 103 is provided with a microphone interface for connecting a monitoring microphone 104, so that the monitoring microphone 104 can monitor the plane wave in the plane wave generator 103; the plane wave generator 103 also includes an output port for outputting the plane wave, and a reference microphone 105 and a measuring microphone of the surface pulsation pressure acoustic measurement device to be calibrated (not shown in the figure) can monitor the plane wave in the plane wave generator 103 through the output port; and further includes a data acquisition module for acquiring data of the monitoring microphone 104, the reference microphone 105 and the measuring microphone.

[0037] The signal generator 101 generates a noise signal and transmits it to the plane wave generator 103. The plane wave generator 103 converts the noise signal into a plane wave. The reference microphone 105 and the measuring microphone are respectively installed on the object to be measured (not shown in the figure), and the plane wave is monitored through the output port of the plane wave generator 103. While the reference microphone 105 and the measuring microphone are monitoring the plane wave, the monitoring microphone 104 also participates in the monitoring, and the monitoring microphone 104 is used as an intermediate quantity to bridge the reference microphone 105 and the measuring microphone, so as to obtain the calibration transfer function of the measurement system and calibrate the system output.

[0038] Specifically, the signal generator 101 in this embodiment can generate white noise, pink noise and sine wave noise signals, and convert the audio signal through the speaker on the plane wave generator 103, and then convert it into a plane wave by the plane wave generator 103 to cope with different types of calibration scenarios.

[0039] The plane wave generator 103 in this embodiment is used to convert the noise signal generated by the signal generator 101 into a pure plane wave as a physical reference quantity for calibration, so as to calibrate the measurement system.

[0040] The plane wave generator 103 includes a speaker for sound generation and a sound tube for "purifying" the sound wave. The sound tube has an output port for outputting the plane wave, and the reference microphone 105 and the measurement microphone of the measurement system to be calibrated both monitor the plane wave through the output port. In addition, a microphone interface is also provided on the sound tube for connecting the monitoring microphone 104. The specific structure of the plane wave generator 103 is specifically introduced in the second embodiment and will not be repeated here.

[0041] The sound-absorbing box 107 is used to isolate external interference, and the entire calibration process is carried out in the sound-absorbing box. In order to accommodate the calibration equipment, its external dimensions can be above 500mm×500mm×500mm. In this embodiment, the sound-absorbing box 107 is a flip-top type, including a box body and a cover plate; the edges of the box body and the cover plate that are buckled together are provided with sealing strips; the box body is filled with sound insulation material, and in order to ensure the sound insulation effect, the thickness of the sound insulation material can be above 100mm. In addition, a vibration isolation pad is provided on the outer bottom of the box body.

[0042] The flip-top design makes it more convenient to install, debug and maintain the internal equipment of the muffler box 107. When installing, replacing or checking equipment such as a plane wave generator and a microphone, there is no need for a complicated disassembly process, and the cover can be opened to directly operate, thereby improving work efficiency.

[0043] The sealing strip can effectively fill the gap between the box body and the cover plate, preventing external noise from entering the anechoic box. During the acoustic measurement and calibration process, external noise will interfere with the accuracy of the measurement results. The presence of the sealing strip can greatly reduce the impact of external noise on the measurement and ensure a quiet environment inside the anechoic box. In addition to blocking noise, the sealing strip can also prevent the rapid exchange of air inside the box with the outside air, reduce the slight pressure changes and temperature fluctuations caused by air flow, maintain the stability of the acoustic environment inside the box, and help improve the reliability of the measurement.

[0044] When a plane wave propagates in the sound-absorbing box 107, it encounters the box wall and is reflected. The sound-insulating material can absorb these reflected sound waves, reducing the multiple reflections and reverberation of the sound waves in the box. This makes the sound waves received by the microphone purer and closer to the original characteristics of the plane wave, which is conducive to improving the measurement accuracy.

[0045] External vibrations (such as vibrations generated by the operation of laboratory equipment, vibrations from the ground, etc.) will be transmitted to the inside through the bottom of the silencer box, affecting the measurement accuracy of the microphone. Vibration isolation pads such as rubber vibration isolation pads can effectively isolate these vibrations, reduce the interference of vibrations on the measurement system, and ensure the stability of the measurement results.

[0046] To facilitate connection with other devices, the silencer box 107 is provided with several electrical interfaces 108, including an input interface and an output interface; the plane wave generator 103 is connected to the input interface for receiving a signal from a signal generator; the monitoring microphone 104, the reference microphone 105 and the measuring microphone are connected to the output interface, so that the data acquisition module can collect data from the monitoring microphone 104, the reference microphone 105 and the measuring microphone.

[0047] In some embodiments, the input interface and output interface on the silencer box 107 are pre-selected as BNC (Bayonet Neill–Concelman connector) interfaces to achieve stable signal transmission between devices, ensure the quality of the signal during the calibration process, and ensure the accuracy of the surface pulsation pressure acoustic measurement calibration.

[0048] More specifically, the input and output interfaces are set on the back of the silencer box and sealed, which is convenient for connecting other devices while avoiding noise pollution to the surrounding environment on the one hand, and preventing internal sound waves from leaking and affecting the stability of the acoustic environment inside the box on the other hand. In addition, the sealing treatment can also play a certain protective role, preventing dust, water vapor, etc. from entering the silencer box, avoiding damage to internal equipment, extending the service life of the equipment, and ensuring the long-term stable operation of the calibration device.

[0049] In addition, in some embodiments, a temperature, humidity and pressure sensor 106 is also included, which is arranged in the silencer box 107, and the temperature, humidity and pressure sensor 106 can output an analog voltage signal. The propagation characteristics of sound in the air will be affected by temperature, humidity and air pressure. Changes in temperature will change the thermal motion state of air molecules and affect the speed of sound; changes in humidity will affect the density and viscosity of the air, and then affect the propagation loss of sound waves; changes in air pressure will also affect the speed of sound and sound propagation characteristics. The temperature, humidity and pressure sensor monitors these environmental parameters in the silencer box in real time and outputs the measurement results as analog voltage signals. By obtaining these environmental data, the sound pressure signal collected by the microphone can be corrected to compensate for the measurement errors caused by environmental factors, thereby improving the accuracy of the surface pulsation pressure acoustic measurement calibration.

[0050] In some embodiments, a power amplifier 102 is provided between the signal generator 101 and the plane wave generator 103. The signal generated by the signal generator 101 is usually of low power, while the plane wave generator 103 requires sufficient power to drive its operation to generate a plane wave that meets the requirements. The power amplifier 102 can amplify the low-power signal output by the signal generator, increase the power and amplitude of the signal, so that it has sufficient energy to drive the plane wave generator, and ensure that the plane wave generator can generate a plane wave with a certain intensity and amplitude, so as to provide a stable and measurable sound source in the acoustic measurement calibration.

[0051] In addition, the calibration device in this embodiment also includes a data acquisition module for collecting and storing monitoring microphone 104, reference microphone 105, measurement microphone and temperature, humidity and pressure sensor data 106. This facilitates subsequent accurate comparison and analysis of different microphone data, thereby accurately measuring and evaluating acoustic parameters.

[0052] In this embodiment, the signal generator 101 adopts Puyuan DG1022Z, which has built-in sine waves, white noise and other signals, has continuous and scanning working modes, and the signal output interface is a BNC interface. The power amplifier 102 adopts Hivi HIFI260. Its output power is not less than 30W, the gain is adjustable, and the adjustment range is preferably 0dB-40dB. The signal generator and the power amplifier are connected by a 4m long 50-ohm coaxial cable, both ends of which are BNC interfaces. The impedance of the coaxial cable is 50Ω or 75Ω, preferably 50Ω. The output of the power amplifier is a Canon interface, which is connected to the input interface of the silencer 107 through an audio cable, and the silencer input interface is connected to the full-band speaker 1 in the plane wave generator 103.

[0053] The full-band speaker 1 used by the plane wave generator 103 has a frequency range of 10Hz-16000Hz, a diameter of 90mm, a cylindrical outer cylinder diameter of 100mm, and a height of 80mm. The microphone interface on the side of the plane wave generator 103 is made by 3D printing, preferably resin material. The inner diameter of the mounting seat cavity is 12.7mm, and after the cavity is installed with a 1 / 4-inch adapter, it supports a 1 / 4-inch microphone.

[0054] The shell of the silencer 107 is made of hardwood, with 8 BNC interfaces on the front as output interfaces and input interfaces, and the external dimensions are 500mm×500mm×500mm. The inside of the silencer is pasted with 100mm thick sound-absorbing cotton. The silencer includes an upper cover and a cavity, and a circle of rubber sealing rings are installed on the edge of the upper cover and the cavity. There are 4 rubber foot pads installed at the bottom of the silencer, with a height of 10mm.

[0055] The monitoring microphone 104, the reference microphone 105 and the measuring microphone all use MA411A prepolarized pressure field microphones (1 / 4 inch). The power supply and signal measurement of the microphones are provided by the data acquisition equipment, and the data acquisition equipment uses the XCQ108 expandable multi-channel data acquisition system. The temperature, humidity and pressure sensor 106 uses the MS8607 integrated sensor.

[0056] Embodiment 2: Figure 2As shown, this embodiment provides a plane wave generator 103 for surface pulsation pressure measurement and calibration, including a speaker 1 and a sound tube connected to the speaker 1; the sound tube includes a funnel-shaped continuously variable cross-section inner tube 3, the large end of the continuously variable cross-section inner tube 3 is connected to the sound-emitting end of the speaker 1, and the small end is connected to the uniform cross-section inner tube 4; the inner diameter of the uniform cross-section inner tube 4 is consistent with the inner diameter of the small end opening of the continuously variable cross-section inner tube 3, and the speaker 1, the continuously variable cross-section inner tube 3 and the uniform cross-section inner tube 4 are coaxially installed.

[0057] It also includes an outer tube 2 which is sleeved outside the continuous variable cross-section inner tube 3 and the uniform cross-section inner tube 4. The outer tube 2, the variable cross-section inner tube 3 and the uniform cross-section inner tube 4 form a cavity. The inner wall of the uniform cross-section inner tube 4 is provided with no less than two Hertz resonators 8 along its axial direction.

[0058] An equal-section branch pipe 5 is installed between the outer tube 2 and the equal-section inner tube 4, one end of the equal-section branch pipe 5 reaches the interior of the equal-section inner tube 4, and the other end extends to the outer tube 2; and a microphone interface for connecting to a microphone is installed at one end of the equal-section branch pipe 5 extending to the outer tube 2.

[0059] Speaker 1, as the sound source of the entire plane wave generator, can generate wide-band acoustic wave signals. In the process of surface pulsation pressure measurement calibration, it provides the system with initial acoustic energy, simulates various frequencies of acoustic waves that may be encountered in actual measurement scenarios, and is the basis for the entire measurement and calibration work.

[0060] The acoustic tube is the core functional module of the plane wave generator 103. Through structural optimization and resonance control, it provides a stable, broadband plane wave calibration signal for surface pulsation pressure measurement, solving the problems of signal distortion and noise interference in traditional acoustic measurement.

[0061] Among them, the continuously variable cross-section inner tube 3 is funnel-shaped, including a large end and a small end. The large end is connected to the sound-emitting end of the speaker 2, and the small end is connected to the equal-section inner tube 4. When the sound wave propagates from the large end to the small end, the tube diameter gradually decreases, which can suppress the generation of high-order sound wave modes. In traditional straight tubes, high-order modes may cause the propagation characteristics of sound waves to become complicated, affecting the accuracy of measurement. The design of the continuously variable cross-section inner tube makes the sound wave propagate in the form of a plane wave, reducing the interference of high-order modes on the measurement results.

[0062] More specifically, there is an exponential smooth curve between the large end opening and the small end opening of the continuously variable cross-section inner tube 3, that is, the cross-sectional area changes gradually according to an exponential function. The advantage of such a setting is that firstly, it can reduce the reflection and diffraction of sound waves in the tube, suppress the generation of high-order modes (such as radial modes), and make the sound waves propagate closer to the plane wave form, thereby improving the purity of the calibration signal. Secondly, the mathematical continuity of the exponential gradient curve reduces the phase distortion and amplitude attenuation of the sound wave during the propagation process, ensuring the accuracy of the calibration signal. Thirdly, the exponential gradient curve makes the connection between the continuously variable cross-section inner tube and the equal cross-section inner tube smoothly transition, reducing the risk of local turbulence and resonance. Finally, the exponential curve avoids sharp corners, reduces the generation of airflow separation and turbulent noise, and improves the signal-to-noise ratio.

[0063] In this embodiment, the area of ​​any cross section of the inner cavity of the continuously variable cross-section inner tube 3 is calculated using the formula: Calculate; where S(x) is the cross-sectional area at the large end x, and x is the distance from the large end; S 0 is the opening area of ​​the large end of the inner tube with continuous variable cross-section, δ is the winding index of the inner tube with continuous variable cross-section; Using the formula: Calculate the winding index of the continuously variable cross-section inner tube 3; where δ is the winding index of the continuously variable cross-section inner tube 3, L is the length of the continuously variable cross-section inner tube, d 0 is the inner diameter of the large end opening of the continuously variable cross-section inner tube, d 1 The inner diameter of the small end opening of the continuously variable cross-section inner tube; Using the formula: Calculate the length of the continuously variable cross-section inner tube 3; where L is the length of the continuously variable cross-section inner tube 3, d 0 is the inner diameter of the large end opening of the continuously variable cross-section inner tube 3, d 1 is the inner diameter of the small end opening of the continuously variable cross-section inner tube 3, f low is the lower limit frequency of the surface pulsating pressure measurement system, c 0 is the speed of sound in air.

[0064] In addition, it can be foreseen that the large end opening area of ​​the continuously variable cross-section inner tube 3 can be calculated using the formula: S 0 =π d 0 2 / 4 is used for calculation; where S 0 is the opening area of ​​the 3 large ends of the continuously variable cross-section inner tube, d 0 It is the inner diameter of the large end opening of the continuously variable cross-section inner tube 3.

[0065] In this embodiment, the inner diameter 4 of the uniform cross-section inner tube is consistent with the inner diameter of the small end opening of the continuously variable cross-section inner tube 3, and is coaxially installed with the speaker 1 and the continuously variable cross-section inner tube 3. Its function is to provide a stable propagation channel for the sound waves processed by the continuously variable cross-section inner tube 3, to ensure that the sound waves continue to propagate in a relatively stable state, to reduce the scattering and reflection of the sound waves, and to enable the sound waves to maintain good consistency and stability. The uniform cross-section inner tube also provides space for the installation of the Hertz resonator, which is convenient for processing sound waves of a specific frequency through the resonator. In addition, the outlet end of the uniform cross-section inner tube 4 also serves as the output port of the plane wave. When calibrating, the reference microphone and the measurement microphone of the measurement system to be calibrated both monitor the plane wave through the output port.

[0066] More specifically, the inner diameter of the uniform cross-section inner tube 4 is calculated using the formula: Calculate; where d 2 is the inner diameter of the inner tube with equal cross section, c 0 is the speed of sound in air, generally taken as c 0 =343m / s, f up The upper limit of the frequency range of the speaker. Since the inner diameter 4 of the inner tube with a constant cross section is consistent with the inner diameter of the small end opening of the inner tube with a continuously variable cross section 3, in this embodiment, the inner diameter of the inner tube with a constant cross section 4 can be determined first and then the inner diameter of the small end opening of the inner tube with a continuously variable cross section 3 can be determined.

[0067] The outer tube 2 is sleeved outside the continuous variable cross-section inner tube 3 and the equal cross-section inner tube 4, and forms a cavity with the continuous variable cross-section inner tube 3 and the equal cross-section inner tube 4. In some embodiments, the shape of the outer tube 2 is preferably cylindrical. The purpose of providing the outer tube 2 is to provide physical protection for the internal continuous variable cross-section inner tube 3 and the equal cross-section inner tube 4, to prevent external factors such as collision and extrusion from causing damage to the sound tube, and to ensure the integrity and stability of the sound tube structure. In addition, the cavity can play a certain role in sound insulation, reducing the interference of external environmental noise on the propagation of sound waves in the tube. At the same time, it can also buffer external vibrations to a certain extent and reduce the impact of vibration on the measurement results.

[0068] In addition, in this embodiment, the number of the Helmholtz resonators 8 is three and they are arranged at equal intervals along the axial direction of the inner tube 4 having a uniform cross-section.

[0069] The Hertz resonator 8 is an acoustic element that selectively absorbs the sound wave energy of a specific frequency by matching the sound volume and the sound mass, thereby eliminating the resonance phenomenon. In the present invention, it is integrated into the inner wall of the inner tube of the plane wave generator with a uniform cross section, and is used to calibrate the surface pulsation pressure measurement system. When there is a sound wave with the same resonant frequency as the resonator in the inner tube 4 of equal cross-section, the resonator will resonate with the sound wave and absorb the energy of the sound wave of this frequency, thereby eliminating or greatly reducing the resonance phenomenon of this frequency. Resonance may cause the sound wave to form a standing wave in the tube, affecting the accuracy of the measurement. The Hertz resonator can effectively avoid this situation. By eliminating the resonance of a specific frequency, the frequency characteristics of the sound wave in the tube are smoother, and the frequency response performance of the entire plane wave generator system is improved, thereby improving the accuracy of measurement calibration.

[0070] Specifically, the Helmholtz resonator 4 includes a cavity 82 embedded in the inner wall of the inner tube 4 with a uniform cross-section, an opening 81 of the cavity 82 faces the inner side of the inner wall of the inner tube 3 with a uniform cross-section, and a width of the opening 81 of the cavity 82 is smaller than a width of the cavity 82 .

[0071] In this embodiment, the cavity 82 of the Helmholtz resonator 8 is a cube; the acoustic capacity of the cavity 82 of the Helmholtz resonator 8 and the acoustic mass of the opening 81 are obtained according to the acoustic cavity resonance frequency of the inner tube 4 with a uniform cross section; and the depth of the cavity 82 of the Helmholtz resonator 8 is obtained according to the acoustic capacity of the cavity 82, and the length and diameter of the opening 81 are obtained according to the acoustic mass of the cavity opening 81. Specifically: The acoustic cavity resonance frequency of the inner tube 4 of the uniform cross section is calculated using the formula: Calculate; where f r is the resonance frequency of the acoustic cavity, c 0 is the speed of sound in air, d 2 The inner diameter of the inner tube 4 is equal to the cross section; The relationship between the acoustic capacity of the cavity 82 of the Helmholtz resonator 8 and the acoustic mass of the opening 81 of the cavity 82 and the acoustic cavity resonance frequency of the inner tube 4 of uniform cross section is: ; Among them, M b is the sound quality, C b is the acoustic capacity of the cavity, f r is the resonance frequency of the acoustic cavity; The cavity acoustic capacity uses the formula: Calculate; where C b is the cavity sound volume, H is the cavity depth of the Hertz resonator 8, ρ 0 is the density of air, c 0 is the speed of sound in air; The acoustic mass of the opening 81 of the Helmholtz resonator 8 is calculated using the formula: Calculate; where M b For sound quality,l is the length of the opening, d is the diameter of the opening, ρ 0 is the density of air.

[0072] In this embodiment, a branch pipe 5 of equal cross-section is further provided on the sound tube, which is used to guide the sound waves propagating in the inner pipe 4 of equal cross-section to the outside, so as to facilitate docking with the microphone and realize the collection of sound wave signals.

[0073] In addition, in this embodiment, the Hermetic resonator 8 farthest from the continuously variable cross-section inner tube 3 is directly opposite to the branch pipe 5 of equal cross-section. The directly opposite layout can reduce the interference of sound waves during propagation. If the Hermetic resonator and the branch pipe of equal cross-section are not positioned properly, it may cause additional reflection or interference of sound waves when propagating to the branch pipe.

[0074] In order to facilitate the installation of the microphone, a microphone interface for connecting with the microphone is installed at one end of the uniform cross-section branch pipe 5 extending to the outer tube 2. Specifically, the microphone interface includes a mounting seat 6 connected to the uniform cross-section branch pipe 5, and a sound guide hole 62 connected to the uniform cross-section branch pipe is opened on the mounting seat 6; a microphone adapter 7 is arranged in the mounting seat 6.

[0075] The sound guide hole 62 on the mounting base 6 provides a direct channel for the propagation of sound waves, and its aperture is 1mm-3mm, preferably 2mm, to ensure that the sound waves in the equal-section branch pipe 5 can smoothly and unimpededly enter the interior of the microphone interface. In actual measurement, the size and interface type of the microphone may vary, and the microphone adapter 7 can be specifically designed according to the specifications of the microphone. For example, in this embodiment, the microphone adapter 7 has two sizes of 1 / 2 inch and 1 / 4 inch, so that the plane wave generator can be compatible with a variety of microphones of different specifications, which improves the versatility and applicability of the plane wave generator and meets the connection requirements of different measurement scenarios and microphones.

[0076] More specifically, the mounting seat 6 is preferably made of resin material and is manufactured by 3D printing, with a rubber ring mounting groove reserved in the center.

[0077] In this embodiment, the speaker 1 uses the Hivi M3N full-band speaker, the rated power of the speaker is 15W, the frequency response curve is flat in the range of 100Hz-10000Hz, the panel diameter is 90mm, the opening size is 75mm, the depth is 53mm, and the total thickness of the speaker is 57.4mm.

[0078] The cylindrical outer tube 2 is made of 304 stainless steel, with an outer diameter of 100mm, an inner diameter of 90mm and a thickness of 5mm. There are four M3×6mm threaded holes on the top of the outer tube 2. The speaker 1 is connected to the outer tube 2 by screws, and the opening edge of the speaker 1 and the outer tube 2 are sealed with a rubber ring gasket. A 30mm (width) × 20mm (height) × 20mm (depth) groove is opened on the side of the outer tube 2 to accommodate the microphone interface, so that the microphone interface is flush with the outer surface of the outer tube 2, such as Figure 3 shown.

[0079] The continuously variable cross-section inner tube 3 is made of 304 stainless steel with a wall thickness of 2 mm, an inner diameter of the large end opening of 86 mm, and an inner diameter of the small end opening of 12 mm. The openings between the large end and the small end are exponentially smooth curves S(x) = S0*exp(-50*x), where x is the distance from the large end and the winding index δ=50. The small end of the continuously variable cross-section inner tube is provided with two M1.5×3mm positioning holes, and the large end is provided with a flange, which is circumferentially provided with four threaded holes in the same position as the threaded holes of the outer tube. The uniform cross-section inner tube 4 is made of 304 stainless steel, with a wall thickness of 2 mm and a length of 80 mm. Two M1.5×3 mm positioning holes are opened at the same position on the top of the uniform cross-section inner tube 4 and the bottom of the continuously variable cross-section inner tube 3. The two are connected by pins, and the contact surfaces are welded by argon arc welding.

[0080] In order to seal the bottom of the outer tube 2 and the inner tube 4 of equal cross section, an annular cover plate 9 may be provided at the bottom of both. Of course, the annular cover plate 9 may also be formed integrally with the outer tube.

[0081] like Figure 4 As shown, a 2mm single-side through hole is opened 30mm away from the bottom of the uniform cross-section inner tube 4, and a 2mm through hole is opened opposite to the through hole. A cavity 82 with an inner side length of 5mm and a thickness of 2mm is welded outside the through hole to form a Hertz resonator 8. There are three Hertz resonators 8 distributed along the height direction of the uniform cross-section inner tube, with a spacing of 10mm.

[0082] like Figure 5As shown, the microphone mounting seat 6 is made of resin material and is made by 3D printing. Its external dimensions are 30mm (width) × 20mm (height) × 30mm (depth). There is a microphone mounting cavity 61 with a diameter of 12.7mm inside. A rubber ring is provided in the center of the mounting cavity 61. The depth of the mounting cavity 61 is 20mm. A sound guide hole 62 is provided in the center of the bottom of the mounting cavity 61. Its diameter is 2mm and its depth is 10mm. The uniform cross-section inner tube 4 and the mounting seat 6 are connected by a stainless steel tube, i.e., a uniform cross-section branch pipe 5, which is 20mm in length, 2mm in outer diameter and 1.6mm in inner diameter. The microphone adapter 7 is made of resin material and is made by 3D printing. Its shape is a cylinder with an outer diameter of 12.7mm and an inner diameter of 6.35mm.

[0083] Embodiment 3: Figure 6 As shown, the present invention also provides a calibration method for surface pulsation pressure acoustic measurement, which uses the above-mentioned surface pulsation pressure acoustic measurement calibration device for calibration.

[0084] Before calibration begins, the signal generator 101, the power amplifier 102, the silencer 107, the plane wave generator 103 and the data acquisition module are connected in sequence through dedicated cables. A 4m long 50-ohm coaxial cable is used to connect the signal generator 101 and the power amplifier 102, and the power amplifier 102 and the silencer 107 are connected through an audio cable. The input interface of the silencer 107 is connected to the full-band speaker 1 in the plane wave generator 103. The monitoring microphone 4 is installed on the plane wave generator 103 from the microphone interface of the plane wave generator 103. The monitoring microphone 4 is connected to the output interface of the silencer 107, and the temperature, humidity and pressure sensor 106 is connected to the other three output interfaces of the silencer 107. There is another output interface on the silencer 107 that is connected to the reference microphone or the surface pulsation pressure sensor. Before calibrating the measurement system, the sensitivity of the monitoring microphone 104, the reference microphone 105 and the surface pulsation pressure measurement microphone needs to be calibrated using a piston calibrator.

[0085] The calibration steps for the surface pressure pulsation acoustic measurement device include: S1 selects a reference microphone and installs the reference microphone on the object to be measured.

[0086] The object to be measured is provided with a prefabricated mounting hole, which can be used to mount the reference microphone 105 or the measuring microphone of the surface pulsation pressure acoustic measuring device to be calibrated. The prefabricated mounting hole not only provides a standardized interface for the installation of the reference microphone and the measuring microphone, but also can conveniently mount the reference microphone or the measuring microphone on the object to be measured, and when the microphone needs to be replaced, the operation can be completed quickly and accurately, thereby improving work efficiency.

[0087] In this step, the reference microphone 105 is installed using the prefabricated installation hole, and the top of the reference microphone 105 should be flush with the surface of the object. When the top of the microphone is flush with the surface of the object, the microphone can directly sense the acoustic environment of the surface of the object, and the measured sound pressure signal can more truly reflect the pulsating pressure situation on the surface of the object, thereby providing a reliable basis for calibration.

[0088] In addition, the reference microphone should be a high-precision microphone, such as the MA411A prepolarized pressure field microphone. The reference microphone plays a benchmark role in the entire calibration process. It has known, relatively accurate and stable acoustic performance, and its measurement results serve as a reference standard for calibrating the measurement microphone. By comparing the measurement results of the measurement microphone with the reference microphone, the performance deviation of the measurement microphone can be determined, and then the measurement microphone can be calibrated to improve the accuracy and reliability of the entire measurement system.

[0089] The plane wave generator 103 generates a plane wave, which is monitored by the monitoring microphone 104 and the reference microphone 105 to obtain a sound pressure signal. The sound pressure signal output by the monitoring microphone 104 and the sound pressure signal output by the reference microphone 105 are used to construct a transfer function between the monitoring microphone 104 and the reference microphone 105, namely, a transfer function I. Specifically, the transfer function I is: ; Among them, TF 1 To pass parameter I, To monitor the frequency domain sound pressure signal of the microphone 104, is the frequency domain sound pressure signal of the reference microphone 105.

[0090] Turn on the data acquisition module, power amplifier 102 and signal generator 101 in sequence; set the sampling rate of the data acquisition module to 51.2kHz and the acquisition time to 10s; the signal generator 101 outputs a white noise signal; obtain the sound pressure signals measured by the monitoring microphone 104 and the reference microphone 105 through the host computer. It is worth noting that when collecting, the plane wave generator 103 needs to be placed directly above the reference microphone 105 so that the reference microphone 105 is within the range of the sound tube output port. At the same time, apply pressure to the full-band speaker to make the plane wave generator 103 tightly sealed to the surface of the object.

[0091] The plane wave generator 103 generates a plane wave after receiving the signal transmitted by the signal generator 101 through the power amplifier 102. The monitoring microphone 104 monitors the plane wave through the microphone interface on the plane wave generator 101, and the reference microphone 105 monitors the plane wave through the output port of the plane wave generator 104. The two microphones simultaneously obtain the sound pressure signal of the plane wave and convert it into an electrical signal for output.

[0092] The data acquisition module collects the sound pressure signals output by the monitoring microphone 104 and the reference microphone 105. However, the signals are time domain signals, so Fourier transform and other methods are usually used to convert the time domain signals into frequency domain signals to obtain the frequency domain sound pressure signals of the monitoring microphone and the frequency domain sound pressure signals of the reference microphone. The transfer function I between the monitoring microphone 104 and the reference microphone 105 is calculated based on the frequency domain sound pressure signals of the monitoring microphone and the frequency domain sound pressure signals of the reference microphone, and the transfer function reflects the conversion relationship between the sound pressure signals of the two at different frequencies.

[0093] S3: installing the measuring microphone of the surface pulsation pressure acoustic measuring device to be calibrated on the object to be measured.

[0094] After the transfer function I is constructed, the reference microphone 105 is replaced by the measurement microphone of the surface pulsation pressure acoustic measurement device to be calibrated, which is installed on the object to be measured in the same way as the reference microphone 105, and will not be repeated here.

[0095] S4 plane wave generator 103 generates a plane wave which is monitored by monitoring microphone 104 and measuring microphone to obtain a sound pressure signal; the transfer function between monitoring microphone 104 and measuring microphone is constructed by using the sound pressure signal output by monitoring microphone 104 and the sound pressure signal output by measuring microphone, i.e. transfer function II; the transfer function II is: ； Among them, TF 2 To pass parameter II, To monitor the frequency domain sound pressure signal of the microphone 104, It is the frequency domain sound pressure signal of the measurement microphone.

[0096] Similar to step S2, the data acquisition module acquires the sound pressure signals output by the monitoring microphone 104 and the measuring microphone, and converts the time domain signals into frequency domain signals by using methods such as Fourier transform, so as to obtain the frequency domain sound pressure signal of the monitoring microphone 104 and the frequency domain sound pressure signal of the measuring microphone. The transfer function II between the monitoring microphone 104 and the reference microphone is calculated based on the frequency domain sound pressure signal of the monitoring microphone 104 and the frequency domain sound pressure signal of the measuring microphone, and the transfer function reflects the conversion relationship between the sound pressure signals of the two at different frequencies.

[0097] S5 uses the transfer function I and the transfer function II to obtain the transfer function between the measurement microphone and the reference microphone 105, that is, the transfer function III; the transfer function III is: ; Among them, TF is the transfer parameter III, TF 1 To pass parameters I, TF 2To pass parameter II, To monitor the frequency domain sound pressure signal of the microphone 104, is the frequency domain sound pressure signal of the reference microphone 105, It is the frequency domain sound pressure signal of the measurement microphone.

[0098] Transfer function I describes the sound pressure signal transfer relationship between the monitoring microphone 104 and the reference microphone 105, and transfer function II describes the sound pressure signal transfer relationship between the monitoring microphone 104 and the measuring microphone. Since the monitoring microphone 104 exists in both transfer relationships, the transfer function III between the measuring microphone and the reference microphone 105 can be derived by mathematical operation using these two known transfer functions.

[0099] Transfer function III defines the transfer relationship between the measurement microphone and the reference microphone 105, and the performance of the reference microphone is known and accurate. Through transfer function III, the measurement results of the measurement microphone can be compared with the reference microphone 105 to determine the performance deviation of the measurement microphone. Based on this deviation, the measurement microphone can be calibrated to make its measurement results more accurate and reliable, thereby improving the accuracy of surface pulsation pressure acoustic measurement.

[0100] S6 repeats steps S1 to S5, obtains a number of transfer functions III, and uses the several transfer functions III to construct a verification transfer function. The verification transfer function is: ; Among them, TF Cal To verify the transfer parameters, N is the number of transfer functions III, is the transfer function III with sequence i, where i is the sequence number of the transfer function.

[0101] In the actual measurement and calibration process, due to the influence of various factors (such as fluctuations in environmental noise, slight differences in equipment, random errors in the measurement process, etc.), the transfer function III obtained by a single measurement may have certain errors and uncertainties. By repeating steps S1 to S5, multiple transfer functions III can be obtained, and these transfer functions III reflect the transfer relationship between the measurement microphone and the reference microphone 105 under different measurement conditions. Using these multiple transfer functions III to construct a verification transfer function is based on the principle of statistics. By averaging multiple measurement results, the influence of random errors is reduced to obtain a verification transfer function that can more accurately reflect the true transfer relationship between the measurement microphone and the reference microphone 105.

[0102] By taking multiple measurements and constructing a calibration transfer function, the impact of random errors on the measurement results can be effectively reduced. Random errors show a certain degree of randomness in multiple measurements. Some measurement results may be too large, while others may be too small. By averaging, these errors can be offset, thus obtaining a more accurate transfer function. Using this calibration transfer function to calibrate the measurement microphone can improve the accuracy of the calibration and make the measurement results of the measurement microphone closer to the true value.

[0103] In addition, the transfer function III obtained from a single measurement may have abnormal values. When constructing the verification transfer function, the influence of abnormal values ​​on the final result can be reduced by averaging multiple transfer functions III. The verification transfer function obtained in this way can better reflect the true relationship between the measurement microphone and the reference microphone, and enhance the reliability of the entire calibration process.

[0104] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0105] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A calibration device for acoustic measurement of surface pulsation pressure, characterized in that: The invention comprises a signal generator for generating a noise signal and a plane wave generator arranged in a soundproof box, wherein the plane wave generator can convert the noise signal generated by the signal generator into a plane wave; the plane wave generator is provided with a microphone interface for connecting a monitoring microphone, so that the monitoring microphone can monitor the plane wave in the plane wave generator; the plane wave generator also comprises an output port for outputting the plane wave, and a reference microphone and a measuring microphone of a surface pulsation pressure acoustic measuring device to be calibrated can monitor the plane wave in the plane wave generator through the output port; and the invention also comprises a data acquisition module for acquiring data of the monitoring microphone, the reference microphone and the measuring microphone.

2. The calibration device for surface pulsation pressure acoustic measurement according to claim 1, characterized in that: The silencer box is provided with a plurality of input interfaces and output interfaces; the plane wave generator is connected to the input interface for receiving a signal from a signal generator; the monitoring microphone, the reference microphone and the measuring microphone are connected to the output interface, so that the data acquisition module can collect data from the monitoring microphone, the reference microphone and the measuring microphone.

3. The calibration device for surface pulsation pressure acoustic measurement according to claim 1, characterized in that: It also includes a temperature, humidity and pressure sensor arranged in the silencing box, and the temperature, humidity and pressure sensor can output an analog voltage signal.

4. The calibration device for surface pulsation pressure acoustic measurement according to claim 1, characterized in that: The muffler box is of a flip-top type, comprising a box body and a cover plate; sealing strips are arranged at the edges where the box body and the cover plate are buckled with each other; the box body is filled with sound insulation material, and a vibration isolation pad is arranged at the bottom of the box body.

5. The calibration device for surface pulsation pressure acoustic measurement according to claim 1, characterized in that: A power amplifier is arranged between the signal generator and the plane wave generator.

6. A method for calibrating surface pressure pulsation acoustic measurement, using the calibration device for surface pressure pulsation acoustic measurement according to any one of claims 1 to 5 for calibration, characterized in that include: S1 selects a reference microphone and installs it on the object to be tested; The S2 plane wave generator generates a plane wave which is monitored by the monitoring microphone and the reference microphone to obtain a sound pressure signal; The transfer function between the monitoring microphone and the reference microphone, i.e., the transfer function I, is constructed by using the sound pressure signal output by the monitoring microphone and the sound pressure signal output by the reference microphone; S3 installing a measuring microphone of the surface pulsation pressure acoustic measuring device to be calibrated on the object to be measured; The plane wave generator S4 generates a plane wave which is monitored by the monitoring microphone and the measuring microphone to obtain a sound pressure signal; the sound pressure signal output by the monitoring microphone and the sound pressure signal output by the measuring microphone are used to construct a transfer function between the monitoring microphone and the measuring microphone, namely, transfer function II; S5: using the transfer function I and the transfer function II to obtain a transfer function between the measuring microphone and the reference microphone, that is, a transfer function III; S6 repeats steps S1 to S5 to obtain a plurality of transfer functions III, and constructs a verification transfer function using the plurality of transfer functions III.

7. A calibration method for surface pulsation pressure acoustic measurement according to claim 6, characterized in that The transfer function I is: ； Among them, TF1 is the transfer parameter I, To monitor the frequency domain sound pressure signal of the microphone, is the frequency domain sound pressure signal of the reference microphone.

8. A calibration method for surface pulsation pressure acoustic measurement according to claim 6, characterized in that The transfer function II is: ； Among them, TF2 is the transfer parameter II, To monitor the frequency domain sound pressure signal of the microphone, It is the frequency domain sound pressure signal of the measurement microphone.

9. A calibration method for surface pulsation pressure acoustic measurement according to claim 6, characterized in that The transfer function III is: ； Among them, TF is the transfer parameter III, TF1 is the transfer parameter I, and TF2 is the transfer parameter II. To monitor the frequency domain sound pressure signal of the microphone, is the frequency domain sound pressure signal of the reference microphone, It is the frequency domain sound pressure signal of the measurement microphone.

10. A calibration method for surface pulsation pressure acoustic measurement according to claim 6, characterized in that The verification transfer function is: ； Among them, TF Cal To verify the transfer parameters, N is the number of transfer functions III, is the transfer function III with sequence i, where i is the sequence number of the transfer function.

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