Three-dimensional vector hydrophone sound intensity measurement method and system

Abstract

The invention relates to a method for measuring the sound intensity of a three-dimensional vector hydrophone, which comprises the following steps: step 1, the vector hydrophone has a three-dimensional direction, a vector hydrophone three-dimensional direction coordinate system and a sound wave space direction coordinate system are established, the vector hydrophone three-dimensional direction coordinate system is x, y and z, and the space sound wave three-dimensional direction coordinate system is X, Y and Z; the origin of space coordinates of the vector hydrophone coincides with the origin of space coordinates of the sound wave direction; the included angles between the three-dimensional direction of the vector hydrophone and the three-dimensional direction of the sound wave are phi, theta and xi respectively. According to the invention, the measurement of the three-dimensional sound intensity of the co-vibrating vector hydrophone can be realized in the standing wave tube and the free field, the vector sensitivity of the vector hydrophone in each direction can be directly obtained, and the metering test efficiency of the sensitivity of the vector hydrophone is further enhanced.

Description

Technical Field:

[0001] The present invention belongs to the technical field of underwater acoustic measurement, and particularly relates to a method and system for measuring the acoustic intensity of a three-dimensional vector hydrophone. Background Art:

[0002] In underwater acoustic measurement and detection, a vector hydrophone can not only measure the acoustic pressure information in the sound field, but also measure vector information such as particle velocity and particle acceleration simultaneously and at the same point, further increasing the types and quantities of underwater signals obtained and expanding the space for subsequent signal processing. At the same time, in the low-frequency measurement field, since the wavelength of the sound wave is relatively long at this time, if a directivity is to be formed, a huge array system usually needs to be constructed. Compared with traditional hydrophones, since the vector hydrophone itself has an "8"-shaped directivity, and this characteristic does not change with the change of frequency, this makes it have obvious advantages in the field of underwater acoustic low-frequency measurement.

[0003] For a long time, the vector parameters of the vector hydrophone have been measured in a single channel, that is, the measured channel of the vector hydrophone is aligned with the direction of the sound wave, and the other two channels are orthogonal to the direction of the sound wave. At this time, the channel aligned with the direction of the incoming sound wave can measure its sensitivity, and the outputs of the other two channels are approximately zero. This measurement method has low efficiency and cannot directly obtain the three-dimensional sensitivity of the vector parameters of the vector hydrophone. Therefore, a new measurement method is urgently needed. Summary of the Invention:

[0004] The technical problem to be solved by the present invention is to provide a method and system for measuring the acoustic intensity of a three-dimensional vector hydrophone. According to the three-dimensional spatial distribution characteristics of the vector hydrophone, the present invention constructs measurement models for the three-dimensional acceleration sensitivity, velocity sensitivity, underwater acoustic pressure gradient, and underwater acoustic pressure sensitivity of the vector hydrophone; and designs a rotation mechanism for the vector hydrophone, and adopts a cross-rotation method to cooperate with the reception theory of the vector hydrophone to realize the measurement of the three-dimensional vector parameters of the vector hydrophone, making up for the current deficiency in the measurement of the three-dimensional acoustic intensity parameters of the vector hydrophone.

[0005] The technical solution of the present invention is to provide a method for measuring the acoustic intensity of a three-dimensional vector hydrophone, including the following steps,

[0006] Step 1 is as follows,

[0007] The vector hydrophone has three dimensions. Establish a coordinate system for the three-dimensional direction of the vector hydrophone and the spatial direction of the sound wave. The three-dimensional direction coordinate system of the vector hydrophone is x, y, z, and the three-dimensional direction coordinate system of the spatial sound wave is X, Y, Z. The spatial coordinate origin of the vector hydrophone coincides with the spatial coordinate origin of the sound wave direction;

[0008] The included angles between the three-dimensional direction of the vector hydrophone and the three-dimensional direction of the sound wave are respectively θ, ξ;

[0009] In any direction, the three-dimensional space correction coefficient of the vector hydrophone velocity satisfies the following formula:

[0010]

[0011] where A and B are complex constants, and P n is the Legendre series of order n, and C n = e ikacosφ , a is the radius of the vector hydrophone, k is the wave number, and φ is the angle between the vector hydrophone and any sound wave direction;

[0012] In the three-dimensional vector space, the three-dimensional velocity correction coefficient function matrix can be expressed as Considering the spatial angle, the three-dimensional velocity matrix can be expressed as

[0013]

[0014] where A x , A y , A z , B x , B y , B z are complex constants, C yn = e ikacosθ , C zn = e ikacosξ , and I is the identity matrix.

[0015] The three-dimensional space matrix P of the vector hydrophone sound pressure is proposed:

[0016]

[0017] where p(θ) and p(ξ) are the three-dimensional direction sound pressures.

[0018] The three-dimensional voltage matrix of the vector hydrophone is obtained:

[0019]

[0020] where U vx , U vy , U vz are the output voltages of the three-dimensional vector channels of the vector hydrophone, and U p is the voltage output by the sound pressure channel of the vector hydrophone.

[0021] The three-dimensional sound intensity of the vector hydrophone is obtained, and the specific expression is as follows:

[0022]

[0023] In the formula, M p is the sensitivity of the sound pressure channel of the hydrophone, and M vx , M vy , M vz are the sensitivities of the three-dimensional vector channel velocity of the vector hydrophone.

[0024] Step 2: Fix the vector hydrophone in the underwater sound field through a three-dimensional space rotation mechanism. The three-dimensional space rotation mechanism is as Figure 1 shown. The three-dimensional space rotation mechanism consists of three rings. The outermost ring is the fixed ring 1, which is used to fix the whole vector hydrophone. This fixed ring is connected to other mechanisms; the inner side of the fixed ring 1 is the middle ring 2, and both sides of the middle ring 2 are rotationally connected to the fixed ring 1, and the rotation angle is ξ0; the innermost ring is the positioning ring 3, and the positioning ring 3 can rotate along the circumference of the middle ring 2; there is a hook on the positioning ring 3 to realize the positioning of the vector hydrophone 4, and the angle between the vector hydrophone and the middle ring is

[0025] Fix the vector hydrophone in the underwater sound field through a three-dimensional space mechanism, and adjust the angles of the two rings, which are θ0 and Measure the water surface vibration velocity u x in the standing wave tube by the optical method, and obtain the sound intensity sensitivity in the standing wave tube according to the sound field distribution law,

[0026] Measure the water surface vibration velocity u x in the standing wave tube by the optical method, and obtain the sound intensity sensitivity in the standing wave tube according to the sound field distribution law,

[0027]

[0028] In the formula, is the three-dimensional velocity correction coefficient function matrix, U V is the three-dimensional voltage matrix output by the vector channel of the vector hydrophone, U p is the three-dimensional voltage matrix output by the vector channel of the vector hydrophone, k is the wave number, and H is the water depth.

[0029] Step 3: Measure the underwater sound pressure p x in the sound field using a standard hydrophone in the free field, and obtain the sound intensity sensitivity according to the free field sound field distribution law, as shown in Equation (10),

[0030]

[0031] In the formula, ρ is the density, c is the sound speed in water, and r is the distance from the sound source.

[0032] The present invention can realize the measurement of the three-dimensional sound intensity of a co-vibrating vector hydrophone in a standing wave tube and a free field, and can directly obtain the vector sensitivity of the vector hydrophone in each direction, further enhancing the metrological test efficiency of the sensitivity of the vector hydrophone.

[0033] The present invention also provides a system for implementing the above three-dimensional vector hydrophone sound intensity measurement method. The system includes,

[0034] A function generator for generating a continuous sine signal;

[0035] A linear low-frequency power amplifier for exciting a low-frequency transducer to generate the sound wave to be measured;

[0036] A transmitting transducer for generating a low-frequency signal;

[0037] A preamplifier having phase consistency within the measurement frequency range;

[0038] A filter whose filtering frequency range covers the measurement frequency range;

[0039] A digital oscilloscope for realizing waveform display, data acquisition and data storage functions;

[0040] An electronic switch for switching between signal channels;

[0041] A computer for controlling the signal transmission and reception and data analysis of the entire system.

[0042] Preferably, the transmitting transducer is linear within the measurement frequency band.

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] The present invention combines the spatial directivity characteristics of the vector hydrophone and adopts a cross-deployment method to theoretically realize the measurement of the three-dimensional vector parameters of the vector hydrophone. At the same time, a vector hydrophone rotation mechanism is designed to cooperate with the reception theory of the vector hydrophone to realize the measurement of the three-dimensional vector parameters of the vector hydrophone. Compared with the traditional method, it is fast and accurate and realizes the measurement of sound intensity parameters. Description of the drawings:

[0045] Figure 1 It is a schematic diagram of the use of the three-dimensional space rotation mechanism of the present invention. Detailed implementation manners:

[0046] The following further describes the present invention in detail in conjunction with the drawings for the specific implementation manners:

[0047] The system of the present invention for implementing the above three-dimensional vector hydrophone sound intensity measurement method has the following composition and requirements:

[0048] 1) A function generator, which can generate a continuous sine signal;

[0049] 2) A linear low-frequency power amplifier, whose power is large enough to excite a low-frequency transducer to generate the sound wave to be measured;

[0050] 3) A transmitting transducer, which is linear within the measurement frequency band and can generate a low-frequency signal;

[0051] 4) A preamplifier, which has a high impedance, low noise, and phase consistency within the measurement frequency range;

[0052] 5) A filter, whose filtering frequency range covers the measurement frequency range;

[0053] 6) A digital oscilloscope, which needs to have waveform display, data acquisition, and data storage functions;

[0054] 7) An electronic switch, which is used for switching between signal channels;

[0055] 8) A computer, which is used to control the signal transmission and reception of the entire system and data analysis.

[0056] The method for measuring the sound intensity of the three-dimensional vector hydrophone is as follows:

[0057] Step 1: Establish a coordinate system for the three-dimensional direction of the vector hydrophone and the spatial direction of the sound wave. The three-dimensional direction coordinate system of the vector hydrophone is x, y, z, and the three-dimensional direction coordinate system of the spatial sound wave is X, Y, Z. The spatial coordinate origin of the vector hydrophone coincides with the spatial coordinate origin of the sound wave direction. The included angles between the three-dimensional direction of the vector hydrophone and the three-dimensional direction of the sound wave are θ, ξ;

[0058] Step 2: Fix the vector hydrophone in the underwater sound field through a three-dimensional space rotation mechanism. Among them, the three-dimensional space rotation mechanism consists of three rings. The outermost ring is a fixed ring, which is used to fix the whole vector hydrophone; the inner side of the fixed ring is an intermediate ring, and both sides of the intermediate ring are rotationally connected to the fixed ring, and the rotation angle is ξ0; the innermost ring is a positioning ring, and the positioning ring can rotate along the circumference of the intermediate ring; a hook is equipped on the positioning ring to realize the positioning of the vector hydrophone. The angle between the vector hydrophone and the intermediate ring is

[0059] Fix the vector hydrophone 4 in the underwater sound field through a three-dimensional space rotation mechanism, and adjust the angles of the intermediate ring 2 and the positioning ring 3, which are ξ0 and Measure the water surface vibration velocity u by the optical method in the standing wave tube x, the acoustic intensity sensitivity in the standing wave tube is obtained according to the sound field distribution law as follows:

[0060]

[0061] In the formula, is the three-dimensional velocity correction coefficient function matrix, and U V is the three-dimensional voltage matrix output by the vector channel of the vector hydrophone, and U p is the three-dimensional voltage matrix output by the vector channel of the vector hydrophone, k is the wave number, and H is the water depth of entry.

[0062] In the free field, the underwater sound pressure p in the sound field is measured using a standard hydrophone. x , and the acoustic intensity sensitivity is obtained according to the free field sound field distribution law as shown in the following formula:

[0063]

[0064] In the formula, ρ is the density, c is the sound speed in water, and r is the distance from the sound source.

[0065] According to the three-dimensional spatial distribution characteristics of the vector hydrophone, the present invention constructs measurement models for the three-dimensional acceleration sensitivity, velocity sensitivity, underwater sound pressure gradient, and underwater sound pressure sensitivity of the vector hydrophone. A rotation mechanism for the vector hydrophone is designed, and by adopting the cross-rotation method and cooperating with the reception theory of the vector hydrophone, the measurement of the three-dimensional vector parameters of the vector hydrophone is realized, making up for the deficiency that the three-dimensional acoustic intensity parameters of the vector hydrophone cannot be measured currently.

[0066] The above is only an illustration of the preferred embodiments of the present invention, and it should not be construed as a limitation to the claims. All equivalent process transformations made using the specification of the present invention are included within the scope of the patent protection of the present invention.

Claims

1. A method for measuring sound intensity of a three-dimensional vector hydrophone, characterized in that: Including the following steps, Step 1: Establish a three-dimensional direction coordinate system for the vector hydrophone and a three-dimensional direction coordinate system for the acoustic wave in space. The three-dimensional direction coordinate system of the vector hydrophone is x, y, z, and the three-dimensional direction coordinate system of the acoustic wave in space is X, Y, Z. The origin of the spatial coordinates of the vector hydrophone coincides with the origin of the spatial coordinates of the acoustic wave direction. The included angles between the three-dimensional directions of the vector hydrophone and the three-dimensional directions of the acoustic wave are respectively θ, ξ; Step 2: Fix the vector hydrophone in the underwater sound field through a three-dimensional space rotation mechanism. The three-dimensional space rotation mechanism consists of three rings. The outermost ring is the fixed ring, which is used to fix the whole vector hydrophone. Inside the fixed ring is the middle ring. The two sides of the middle ring are rotationally connected to the fixed ring, and the rotation angle is ξ0. The innermost ring is the positioning ring, which can rotate along the circumference of the middle ring. A hook is equipped on the positioning ring to realize the positioning of the vector hydrophone. The angle between the vector hydrophone and the middle ring is Measure the water surface vibration velocity u by the optical method in the standing wave tube x , and obtain the sound intensity sensitivity in the standing wave tube according to the sound field distribution law In the formula, is the three-dimensional velocity correction coefficient function matrix, and U V is the three-dimensional voltage matrix output by the vector channels of the vector hydrophone, and U p is the three-dimensional voltage matrix output by the vector channels of the vector hydrophone, k is the wave number, and H is the water entry depth; Step 3: Measure the underwater sound pressure p in the sound field using a standard hydrophone in a free field x , and obtain the sound intensity sensitivity of the vector hydrophone according to the distribution law of the free field sound field, as shown in the following formula: where ρ is the density, c is the speed of sound in water, and r is the distance from the sound source.

2. The method for measuring sound intensity of a three-dimensional vector hydrophone according to claim 1, wherein: In step 1, in any direction, the three-dimensional correction coefficient of the vector hydrophone velocity satisfies the following formula: where A and B are complex constants, P n is a Legendre series of order n, C n = e ikacosφ , a is the radius of the vector hydrophone, k is the wave number, and φ is the angle between the vector hydrophone and any acoustic wave direction; In a three-dimensional vector space, the three-dimensional velocity matrix is represented as In the formula, is a three-dimensional velocity correction coefficient function matrix, which can be expressed as where A x , A y , A z , B x , B y , B z are complex constants, C yn = e ikacosθ , C zn = e ikacosξ , and I is the identity matrix.

3. A system for implementing the method for measuring sound intensity of the three-dimensional vector hydrophone according to claim 1, characterized in that: This system includes, a function generator for generating a continuous sine signal; a linear low-frequency power amplifier for exciting a low-frequency transducer to generate the sound wave to be measured; a transmitting transducer for generating a low-frequency signal; a preamplifier that has phase consistency within the measurement frequency range; a filter whose filtering frequency range covers the measurement frequency range; a digital oscilloscope for realizing waveform display, data acquisition, and data storage functions; an electronic switch for switching between signal channels; a computer for controlling the signal transmission and reception of the entire system and data analysis.

4. The system according to claim 3, wherein: The transmitting transducer is linear within the measurement frequency band.

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