An underwater far-field acoustic field measurement system based on spherical transducer surface vibration measurement

Abstract

The present invention relates to an underwater far-field sound field measurement system based on the surface vibration measurement of a spherical transducer. A plurality of sensor units are arranged on the surface of the spherical transducer. The system also includes a signal generating unit and a data acquisition unit. The signal generating unit sends a signal to excite the spherical transducer to generate a sound field underwater. The sensor unit and the spherical transducer vibrate together and output a voltage signal. The data acquisition unit performs data acquisition to complete the sound field measurement. The present invention can directly infer the radiated sound field of the spherical transducer under far-field conditions. The accuracy of the sound field measurement using the present invention is higher, and the influence of uneven sound field distribution is relatively low. When the spatial sound field needs to be analyzed, multiple sensor units can be placed on the surface of the transducer, and the arrangement method is simpler. The present invention can be applied to the measurement of the acoustic parameters of a spherical transmitting transducer in a free-field water area, and can also be applied to the measurement of the underwater acoustic parameters of a hydrophone when a spherical transducer is used as an auxiliary sound source.

Description

Technical Field

[0001] The invention relates to the technical field of measuring vibration using a detector in a fluid, and in particular to an underwater far-field acoustic field measurement system based on surface vibration measurement of a spherical transducer. Background Art

[0002] With the continuous development of underwater acoustic technology, the measurement of underwater transducer radiated sound field has always been one of the key research directions in the field of underwater acoustics. Usually, the radiated sound field of the transmitting transducer and the calibration of the hydrophone are usually carried out in a pool, tank or open water.

[0003] In the process of underwater acoustic measurement, the acoustic field of the transmitting transducer is a very important underwater electroacoustic parameter. The current measurement methods include single hydrophone measurement and measurement using methods such as spherical wave correction method and near-field acoustic holography.

[0004] For single hydrophone measurement, a standard hydrophone is placed in the sound field radiated by the transducer. The sensitivity of the standard hydrophone is known. The standard hydrophone is used to measure the transducer sound field. The advantage is that the principle itself is relatively simple and the measurement can be completed using only one standard hydrophone. However, this method has two problems:

[0005] 1) The measurement uncertainty of the standard hydrophone sensitivity is relatively large, which leads to a relatively large uncertainty in the sound field measurement when the standard hydrophone is used for measurement;

[0006] 2) Since standard hydrophones can only measure the sound field at one point, if it is necessary to measure the spatial sound field radiated by the transducer, multiple hydrophones need to be deployed, and a special bracket needs to be designed in conjunction with the hydrophones. The measurement operation is relatively cumbersome, and its positioning accuracy cannot be guaranteed.

[0007] However, if the measurement is performed using methods such as the spherical wave correction method and the near-field acoustic holography method, a large-scale array system needs to be established, which is very complicated to operate and is not conducive to the need to quickly and accurately obtain the measurement results of the transducer radiation sound field in the existing technology. Summary of the invention

[0008] The present invention solves the problems existing in the prior art and provides an optimized underwater far-field sound field measurement system based on spherical transducer surface vibration measurement. By measuring parameters including but not limited to the acceleration, velocity and displacement of the spherical transducer surface, the far-field sound field distribution of the spherical transducer is inferred, which can be applied to the measurement of the transducer radiated sound field and the calibration of the hydrophone sensitivity.

[0009] The technical solution adopted by the present invention is an underwater far-field sound field measurement system based on spherical transducer surface vibration measurement, comprising a spherical transducer body, wherein a plurality of sensor units are arranged on the surface of the spherical transducer;

[0010] The system also includes a signal generating unit and a data acquisition unit;

[0011] The signal generating unit sends out a signal to excite the spherical transducer to generate a sound field underwater. The sensor unit and the spherical transducer vibrate together and output a voltage signal. The data acquisition unit collects data to complete the sound field measurement.

[0012] Preferably, a mathematical model is established according to the acoustic field distribution law of the spherical transducer. In the free field acoustic field radiated by a point source, the sound pressure, particle velocity and particle vibration acceleration satisfy equation (1):

[0013]

[0014] In the formula, and They represent the distance from the sound source as r, the direction as θ and The sound pressure, particle vibration velocity and particle vibration acceleration at the location; About function of direction; in the three-dimensional coordinate xoy plane established based on the spherical transducer, θ is the direction of the angle between any particle and the x-axis, is the angle between any particle and the z-axis; ρ is the medium density, c is the sound speed in the medium, ω is the angular frequency, t is the time, k is the wave number, j is the imaginary factor,

[0015] Preferably, on the surface of the spherical transducer, the vibration velocity of the medium particle is equal to the vibration velocity of the spherical transducer surface, that is,

[0016]

[0017] In the formula, The surface of the spherical transducer The normal velocity at θ is related to the distribution of θ and related, is the particle velocity at r0 in the acoustic field on the surface of the spherical transducer; Combining equations (1) and (2), we get

[0018]

[0019] Expressed as acceleration:

[0020]

[0021] In the formula, The transducer surface Normal acceleration at ;

[0022] Combining equation (4) and equation (1), we get the expressions of sound pressure, velocity and acceleration in the sound field:

[0023]

[0024] Preferably, the number of the sensor units is one or more.

[0025] Preferably, the sensor units include an acceleration sensor, a velocity sensor and a displacement sensor, and the sensing direction of any of the sensor units is consistent with the normal direction of the spherical surface of the spherical transducer.

[0026] Preferably, in any direction of the spherical transducer n sensor units are arranged at the locations, and the spatial sound field radiated by the spherical transducer is obtained as follows:

[0027]

[0028] Among them, S i is the sensitivity of the i-th sensor unit, U ai is the output voltage of the i-th sensor unit, the radius of the spherical transducer is r0, R is the distance between the sound field and the center of the spherical transducer, and i is a positive integer between 1 and n.

[0029] Preferably, if the spherical transducer is symmetrical, its spatial sound field is,

[0030]

[0031] Among them, S0 is the sensitivity of the sensor unit, U a0 is the output voltage of the sensor unit, the radius of the spherical transducer is r0, and R is the distance between the sound field and the center of the spherical transducer.

[0032] Preferably, the signal generating unit comprises:

[0033] A function generator, used to generate the signal waveform required for measurement;

[0034] A linear power amplifier is arranged in conjunction with the output end of the function generator to apply the signal output by the function generator to the spherical transducer to stimulate the spherical transducer to generate the sound wave to be measured.

[0035] Preferably, the data acquisition unit comprises:

[0036] A preamplifier is provided in a one-to-one correspondence with each sensor unit and is used to preamplify the voltage signal output by any sensor unit vibrating;

[0037] A filter is provided in a one-to-one correspondence with the preamplifier and is used to filter any preamplified voltage signal;

[0038] The data acquisition device, in conjunction with one or more filter settings, is used to collect data on the measurement results and complete the corresponding analysis.

[0039] Preferably, the spherical transducer is fixed on a six-axis adjustable calibration bracket, with the positive direction of the three-dimensional coordinate as the three-dimensional 0° direction and the origin of the coordinate as the center of the spherical transducer; the horizontal direction θ is determined by rotating the fixture in the horizontal xoy direction, and the spherical transducer is determined by lifting and lowering the spherical transducer and using the trigonometric function relationship Direction; after determining the position, install the sensor unit at the corresponding position of the spherical transducer.

[0040] The present invention relates to an optimized underwater far-field sound field measurement system based on spherical transducer surface vibration measurement, comprising a spherical transducer body, a plurality of sensor monomers arranged on the surface of the spherical transducer; and a signal generating unit and a data acquisition unit. The signal generating unit sends a signal to stimulate the spherical transducer to generate a sound field underwater, the sensor monomers and the spherical transducer vibrate together and output a voltage signal, and the data acquisition unit performs data acquisition to complete the sound field measurement.

[0041] According to the specific relationship between the surface vibration and the radiated sound field of the spherical transducer when the spherical transducer generates sound waves underwater, the present invention can directly infer the radiated sound field of the spherical transducer under far-field conditions; since sensors, such as acceleration sensors, have lower measurement uncertainty, compared with hydrophone measurement, the accuracy of measuring the sound field using the present invention is higher, and the influence of uneven sound field distribution is relatively low. When it is necessary to analyze the spatial sound field, multiple sensor units can be placed on the surface of the transducer without arranging multiple hydrophones in the sound field, and the arrangement method is simpler.

[0042] The system and the corresponding measurement method can be applied to the measurement of acoustic parameters of a spherical transmitting transducer in free-field waters, and can also be applied to the measurement of water acoustic parameters of a hydrophone when a spherical transducer is used as an auxiliary sound source. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the system structure of the present invention;

[0044] Figure 2 It is a schematic diagram of the working principle of the system of the present invention. DETAILED DESCRIPTION

[0045] The present invention is further described in detail below in conjunction with embodiments, but the protection scope of the present invention is not limited thereto.

[0046] like Figure 1 , 2As shown, the present invention relates to an underwater far-field sound field measurement system based on spherical transducer surface vibration measurement, comprising a spherical transducer 1 body, wherein a plurality of sensor 2 monomers are arranged on the surface of the spherical transducer 1;

[0047] The system also includes a signal generating unit and a data acquisition unit;

[0048] The signal generating unit sends a signal to stimulate the spherical transducer 1 to generate a sound field underwater. The sensor 2 and the spherical transducer 1 vibrate together and output a voltage signal. The data acquisition unit collects data to complete the sound field measurement.

[0049] In the present invention, the spherical transducer 1 refers to a transducer 1 that is spherical in shape and vibrates in the radial direction of the sphere when generating sound waves.

[0050] In the present invention, the system includes a signal generating unit, a spherical transmitting transducer 1, one or more sensor 2 monomers, and a data acquisition unit; wherein the spherical transducer 1 is linear within the measurement frequency band, and the spherical transducer 1 is a piezoelectric type, and its vibration mode is pulsating vibration; the sensor 2 monomer can be selected according to the sound field to be measured, and the mass of any monomer is much smaller than the spherical transducer 1.

[0051] In the present invention, the sensor 2 monomers include but are not limited to the acceleration sensor 2 , the velocity sensor 2 and the displacement sensor 2 , and their mass is much smaller than the spherical transducer 1 , and they can be fixed on the surface of the spherical transducer 1 .

[0052] A mathematical model is established according to the acoustic field distribution law of the spherical transducer 1. In the free field acoustic field radiated by a point source, the sound pressure, particle vibration velocity and particle vibration acceleration satisfy equation (1):

[0053]

[0054] In the formula, and They represent the distance from the sound source as r, the direction as θ and The sound pressure, particle vibration velocity and particle vibration acceleration at the location; For about In the three-dimensional coordinate xoy plane established based on the spherical transducer 1, θ is the direction of the angle between any particle and the x-axis, is the angle between any particle and the z-axis; ρ is the medium density, c is the sound speed in the medium, ω is the angular frequency, t is the time, k is the wave number, j is the imaginary factor,

[0055] Furthermore, on the surface of the spherical transducer 1, the vibration velocity of the medium particle is equal to the vibration velocity of the surface of the spherical transducer 1, that is,

[0056]

[0057] In the formula, The surface of the spherical transducer 1 The normal velocity at θ is related to the distribution of θ and related, is the particle velocity at r0 in the acoustic field on the surface of the spherical transducer 1; Combining equations (1) and (2), we get

[0058]

[0059] Expressed as acceleration:

[0060]

[0061] (4); where The surface of transducer 1 Normal acceleration at ;

[0062] Combining equation (4) and equation (1), we get the expressions of sound pressure, velocity and acceleration in the sound field:

[0063]

[0064] Similarly, the expressions for sound pressure, velocity and acceleration in the sound field can be written as An expression for the normal velocity or displacement at .

[0065] In the application process of the present invention, the sensor 2 may be one or more units.

[0066] The sensor 2 monomers include an acceleration sensor 2 , a velocity sensor 2 and a displacement sensor 2 , and the sensing direction of any sensor 2 monomer is consistent with the normal direction of the spherical surface of the spherical transducer 1 .

[0067] In the practical application of the present invention, the surface of the spherical transducer 1 can be set as follows:

[0068] (1) A single acceleration sensor 2, a velocity sensor 2 or a displacement sensor 2;

[0069] (2) multiple acceleration sensors 2, multiple velocity sensors 2 or multiple displacement sensors 2;

[0070] (3) A combination of several acceleration sensors 2, velocity sensors 2 or displacement sensors 2.

[0071] In any direction of the spherical transducer 1 n sensors 2 are arranged at each location, and the spatial sound field radiated by the spherical transducer 1 is obtained as follows:

[0072]

[0073] Among them, S i is the sensitivity of the ith sensor 2, U ai is the output voltage of the i-th sensor 2, the radius of the spherical transducer 1 is r0, R is the distance between the sound field and the center of the spherical transducer 1, and i is a positive integer between 1 and n.

[0074] In the present invention, when the spherical transducer 1 is in any direction When placing the sensor 2 monomer, taking the acceleration sensor 2 as an example, its direction is along the normal direction of the spherical surface of the spherical transducer 1, ensuring that the acceleration sensor 2 and the spherical transducer 1 vibrate together, and the direction obtained is The sound field parameter value (far-field sound pressure) at the position is

[0075] In the present invention, n acceleration sensors 2 can be placed on the spherical transducer 1 as needed, and the corresponding directions are The spatial sound field is obtained as Each parameter with a subscript i refers to a corresponding parameter of the i-th acceleration sensor 2 .

[0076] In the present invention, when the sensor 2 is configured as an acceleration sensor 2, a velocity sensor 2 or a displacement sensor 2, the formula will be slightly different, but this is common knowledge to those skilled in the art and can be derived.

[0077] In the application process of the present invention, there is also a situation that the spherical transducer 1 is completely symmetrical, and its vibration is independent of direction and angle, and only related to distance; under this premise, the spatial sound field can be further simplified as Among them, S0 is the sensitivity of sensor 2, U a0 is the output voltage of the sensor 2, the radius of the spherical transducer 1 is r0, and R is the distance between the sound field and the center of the spherical transducer 1.

[0078] The signal generating unit comprises:

[0079] A function generator 3, used to generate a signal waveform required for measurement;

[0080] A linear power amplifier 4 is arranged in conjunction with the output end of the function generator 3 to apply the signal output by the function generator 3 to the spherical transducer 1 to stimulate the spherical transducer 1 to generate the sound wave to be measured.

[0081] In the present invention, the function generator 3 can generate a signal waveform required for measurement, which is usually a pulsed sine wave or a continuous sine wave, and can output a trigger signal while generating the signal.

[0082] In the present invention, the power of the linear power amplifier 4 should be large enough, and have a bandwidth that meets the requirements, and be sufficiently linear within the bandwidth to excite the spherical transducer 1 to generate the sound waves that need to be measured.

[0083] The data acquisition unit comprises:

[0084] Preamplifier 5, arranged in one-to-one correspondence with each sensor 2, for preamplifying the voltage signal output by the vibration of any sensor 2;

[0085] The filter 6 is arranged in a one-to-one correspondence with the preamplifier 5 and is used to filter any preamplified voltage signal;

[0086] The data acquisition device 7 is configured in conjunction with one or more filters 6 to collect data on the measurement results and perform corresponding analysis.

[0087] In the present invention, the filtering range of the filter 6 is controllable, and the filtering frequency covers the measurement frequency range.

[0088] In the present invention, the data acquisition device 7 can collect data and perform corresponding analysis on the measurement results, the acquisition range covers the measurement range, and has an external trigger function.

[0089] The spherical transducer 1 is fixed on a six-axis adjustable calibration bracket, with the positive direction of the three-dimensional coordinate as the three-dimensional 0° direction and the origin of the coordinate as the center of the spherical transducer 1; the horizontal direction θ is determined by rotating the fixture in the horizontal xoy direction, and the spherical transducer 1 is determined by lifting and lowering it and using the trigonometric function relationship After determining the position, the sensor 2 is installed in the corresponding position of the spherical transducer 1.

[0090] In the present invention, the spherical transducer 1 needs to be fixed on a six-axis adjustable calibration bracket as needed. The six-axis adjustable means that it can rotate around the X-axis and the Y-axis, can be raised and lowered along the Z-axis, and can display the rotation angle and the lifting height. This is content that is easy for technical personnel in the field to understand, and technical personnel in the field can set it themselves according to needs.

[0091] In the present invention, Wherein, h is the height of the spherical transducer 1 when it is lifted or lowered.

[0092] In the present invention, after determining the position, the sensor 2 monomer is installed at the corresponding position of the spherical transducer 1, and then the sensor 2 monomer and the spherical transducer 1 are put into water together; the function generator 3 generates the signal required for measurement, and the signal excites the spherical transducer 1 to generate a sound field underwater after passing through the linear power amplifier 4. At this time, the sensor 2 monomer fixed on the surface of the spherical transducer 1 vibrates together with the spherical transducer 1 and outputs a voltage signal. After the signal is amplified by the preamplifier 5, it is filtered by the filter 6, and the data acquisition device 7 completes the data acquisition, and the far-field sound pressure (one sensor 2 monomer) is calculated or the sound field of the spherical transducer 1 (multiple sensor 2 monomers) is calculated.

[0093] In the present invention, the system can also be used to measure the underwater sound pressure level, sensitivity level and other hydrophone parameters:

[0094] according to Calculate the sound pressure level generated by the spherical transducer 1 as Wherein, p0 is the reference value of sound pressure, p0=1μPa.

[0095] Furthermore, in the present invention, it is also possible to and To measure the sensitivity of the hydrophone:

[0096] Assuming that the distance between the spherical transmitting transducer 1 and the center of the hydrophone is R0, and the open circuit voltage of the hydrophone is U0, the sensitivity of the hydrophone is

Claims

1. An underwater far-field acoustic field measurement system based on spherical transducer surface vibration measurement, characterized in that: It comprises a spherical transducer body, the surface of which is provided with a plurality of sensor units, wherein the sensor units include an acceleration sensor, a velocity sensor and a displacement sensor, and the sensing direction of any of the sensor units is consistent with the normal direction of the spherical surface of the spherical transducer; The system also includes a signal generating unit and a data acquisition unit; The signal generating unit sends out a signal to excite the spherical transducer to generate a sound field underwater. The sensor unit and the spherical transducer vibrate together and output a voltage signal. The data acquisition unit collects data to complete the sound field measurement. In any direction of the spherical transducer n sensor units are arranged at the locations, and the spatial sound field radiated by the spherical transducer is obtained as follows: Where ρ is the density of the medium, c is the speed of sound in the medium, S i is the sensitivity of the i-th sensor unit, U ai is the output voltage of the i-th sensor unit, the radius of the spherical transducer is r0, R is the distance between the sound field and the center of the spherical transducer, k is the wave number, and i is a positive integer between 1 and n.

2. The underwater far-field acoustic field measurement system based on spherical transducer surface vibration measurement according to claim 1, characterized in that: A mathematical model is established according to the acoustic field distribution law of the spherical transducer. In the free field acoustic field radiated by a point source, the sound pressure, particle vibration velocity and particle vibration acceleration satisfy equation (1): In the formula, and They represent the distance from the sound source as r, the direction as θ and The sound pressure, particle vibration velocity and particle vibration acceleration at the location; About function of direction; in the three-dimensional coordinate xoy plane established based on the spherical transducer, θ is the direction of the angle between any particle and the x-axis, is the angle between any particle and the z-axis; ρ is the medium density, c is the sound speed in the medium, ω is the angular frequency, t is the time, k is the wave number, j is the imaginary factor, 3. The underwater far-field sound field measurement system based on spherical transducer surface vibration measurement according to claim 2, characterized in that: On the surface of the spherical transducer, the vibration velocity of the medium particle is equal to the vibration velocity of the spherical transducer surface, that is, In the formula, The surface of the spherical transducer The normal velocity at θ is related to the distribution of θ and related, is the particle velocity at r0 in the acoustic field on the surface of the spherical transducer; Combining equations (1) and (2), we get Expressed as acceleration: In the formula, The transducer surface Normal acceleration at ; Combining equation (4) and equation (1), we get the expressions of sound pressure, velocity and acceleration in the sound field:

4. The underwater far-field sound field measurement system based on spherical transducer surface vibration measurement according to claim 3, characterized in that: The number of the sensor units is one or more.

5. The underwater far-field sound field measurement system based on spherical transducer surface vibration measurement according to claim 4, characterized in that: If the spherical transducer is symmetrical, its spatial sound field is, Among them, S0 is the sensitivity of the sensor unit, U a0 is the output voltage of the sensor unit, the radius of the spherical transducer is r0, and R is the distance between the sound field and the center of the spherical transducer.

6. The underwater far-field acoustic field measurement system based on spherical transducer surface vibration measurement according to claim 1, characterized in that: The signal generating unit comprises: A function generator, used to generate the signal waveform required for measurement; A linear power amplifier is arranged in conjunction with the output end of the function generator to apply the signal output by the function generator to the spherical transducer to stimulate the spherical transducer to generate the sound wave to be measured.

7. The underwater far-field acoustic field measurement system based on spherical transducer surface vibration measurement according to claim 1, characterized in that: The data acquisition unit comprises: A preamplifier is provided in a one-to-one correspondence with each sensor unit and is used to preamplify the voltage signal output by any sensor unit vibrating; A filter is provided in a one-to-one correspondence with the preamplifier and is used to filter any preamplified voltage signal; The data acquisition device, in conjunction with the output end setting of one or more filters, is used to collect data on the measurement results and complete the corresponding analysis.

8. The underwater far-field sound field measurement system based on spherical transducer surface vibration measurement according to claim 1, characterized in that: The spherical transducer is fixed on a six-axis adjustable calibration bracket, with the positive direction of the three-dimensional coordinate as the three-dimensional 0° direction and the origin of the coordinate as the center of the spherical transducer; the horizontal direction θ is determined by rotating the fixture in the horizontal xoy direction, and the spherical transducer is determined by lifting and lowering the spherical transducer and using the trigonometric function relationship Direction; after determining the position, install the sensor unit at the corresponding position of the spherical transducer.

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