Planar receiving array and underwater acoustic transducer with wide frequency range

Abstract

The application provides a planar receiving array with a wide frequency range, comprising a sound absorbing barrier, a receiving hydrophone element and a metal bottom plate; the sound absorbing barrier is installed on the metal bottom plate, and a plurality of receiving hydrophone elements arranged in an array are also installed on the metal bottom plate; the array spacing of the plurality of receiving hydrophone elements is half of the wavelength of the working frequency of the planar receiving array; the receiving hydrophone elements arranged along the width direction of the metal bottom plate are connected in series with each other; and the receiving hydrophone elements arranged along the length direction of the metal bottom plate are connected in parallel with each other. The receiving hydrophone element comprising a spherical transducer is used in cooperation with the orthogonally arranged sawtooth-shaped sharp wedge, so that the working frequency range of the planar receiving array is widened, and the universality of the planar receiving array is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of underwater acoustic transducer and array, in particular, to a planar receiving array and underwater acoustic transducer with wide frequency range, and more particularly, to a receiving transducer array capable of realizing large directivity opening angle. BACKGROUND

[0002] Underwater acoustic transducer is a basic component for converting electric energy into acoustic energy to realize underwater target detection and communication. With the continuous application of new technologies and new materials, underwater acoustic transducer technology is developing rapidly. Multi-beam sounding system is widely used in seabed mapping and other fields due to its high precision, high efficiency and full coverage.

[0003] Multi-beam detection is a high integration of underwater acoustic technology, computer technology, navigation and positioning technology, and digital sensor technology. Its main working principle is to perform wide-angle directional transmission and reception of acoustic waves through transmitting and receiving transducers, and to obtain strip-shaped water depth data in the direction perpendicular to the heading by calculating the spatial positions of various beam measurement points through various sensors, thereby greatly improving the mapping efficiency. In order to realize full-range scanning of the exploration area, the mainstream multi-beam sounding equipment currently uses a receiving transducer array with a certain directivity beam width. The wide directivity of the receiving transducer array can also reduce the sensitivity reduction caused by the main beam offset during reception.

[0004] In the underwater unit of the sonar system, the working principle of the sound absorbing barrier is to absorb and attenuate the sound waves propagating to the barrier. Combining the sound absorbing barrier with the receiving transducer can enhance the useful signal (such as improving the sensitivity of the array element), shield the harmful signal (such as isolating the ship's radiated noise), and improve the directivity of the array element on the array.

[0005] Most of the current planar receiving arrays need to redesign the parameters and structure of the receiving array for different working frequency bands, and do not have the universality within a wide working frequency range. Therefore, how to provide a planar receiving array capable of working in a wide working frequency range is a problem to be solved at present.

[0006] Patent document CNCN200920114824.6 discloses a planar receiving array capable of realizing large-angle beam scanning, mainly including a sound absorbing barrier, and a plurality of groups of hydrophone strips are mounted on the sound absorbing barrier, wherein the hydrophone strips are connected by a plurality of point element hydrophones, and the sound absorbing barrier is composed of upper and lower cover plates and an intermediate layer. However, this scheme has a narrow frequency range due to the use of air channels on the barrier, and does not have the universality within a wide working frequency range. SUMMARY

[0007] In view of the defects in the prior art, the purpose of the present application is to provide a planar receiving array and underwater acoustic transducer with wide frequency range.

[0008] According to the present application, a planar receiving array with wide frequency range is provided, which comprises a sound absorbing barrier, receiving hydrophone elements and a metal base plate.

[0009] The sound absorbing barrier is installed on the metal base plate, and a plurality of receiving hydrophone elements are arranged in an array on the metal base plate; the array pitch of the plurality of receiving hydrophone elements is half of the wavelength of the working frequency of the planar receiving array.

[0010] The receiving hydrophone elements arranged along the width direction of the metal base plate are connected in series.

[0011] The receiving hydrophone elements arranged along the length direction of the metal base plate are connected in parallel.

[0012] Preferably, a plurality of openings are arranged in an array on the sound absorbing barrier and the metal base plate, and the array pitch of the plurality of openings is half of the wavelength of the working frequency of the planar receiving array.

[0013] One end of the receiving hydrophone element penetrates through the opening in the sound absorbing barrier, extends to the opening on the metal base plate, and is connected to the metal base plate through the opening on the metal base plate, and the other end of the receiving hydrophone element extends to the outside of the sound absorbing barrier.

[0014] Preferably, the sound absorbing barrier comprises a plurality of sawtooth-shaped wedges arranged orthogonally, each sawtooth-shaped wedge comprises a plurality of wedge structures arranged in parallel, and the number of wedge structures in different sawtooth-shaped wedges is the same or different.

[0015] Preferably, the receiving hydrophone element comprises a spherical transducer and a connecting rod.

[0016] One end of the connecting rod is installed on the metal base plate, and the other end is connected to the spherical transducer through a decoupling material.

[0017] Preferably, the spherical transducer comprises a first ceramic hemisphere with a hole in the center and a second ceramic hemisphere of the same size; the first ceramic hemisphere and the second ceramic hemisphere are bonded together, and the centers of the two ceramic hemispheres coincide.

[0018] The decoupling material is connected to the spherical transducer through a small hole on the spherical transducer.

[0019] Preferably, the wide frequency range is 20k-30kHz.

[0020] Preferably, the cable is further provided, and the end of the wire in the cable is along the axial direction of the connecting rod, penetrates through the connecting rod and is connected to the spherical transducer.

[0021] Preferably, the length L of the wedge structure satisfies the following requirements:

[0022] c = λf;

[0023] L = λ / 4 = c / (4f)

[0024] Where c is the sound speed in the medium, f is the lower limit of the cutoff frequency, and λ is the wavelength.

[0025] Preferably, the first potting layer and the second potting layer are further included.

[0026] The first potting layer is located above the sound absorption barrier, and the thickness of the first potting layer is just not over the connecting rod and does not touch the spherical transducer.

[0027] The second potting layer is located above the first potting layer, and the spherical transducer is completely covered.

[0028] According to the underwater acoustic transducer provided by the application, the planar receiving array with a wide frequency range is adopted, the number of the planar receiving array with a wide frequency range is multiple, and the multiple planar receiving arrays with a wide frequency range are arranged in an array.

[0029] Compared with the prior art, the application has the following beneficial effects:

[0030] 1. The receiving hydrophone element including the spherical transducer is adopted in the application, and the sawtooth-shaped wedge arranged in quadrature is adopted, so that the working frequency range of the planar receiving array is widened, and the universality of the planar receiving array is improved.

[0031] 2. The wedge can be repeatedly used by being formed by mold glue injection, and cost is saved. DETAILED DESCRIPTION

[0032] Other features, objects and advantages of the application will become more apparent from the following detailed description of non-limiting embodiments with reference to the attached drawings:

[0033] Figure 1 The figure is a structural schematic diagram of the application;

[0034] Figure 2 The figure is a structural schematic diagram of the sound absorption barrier;

[0035] Figure 3 The figure is a structural schematic diagram of the first potting of the application;

[0036] Figure 4 The figure is a structural schematic diagram of the hydrophone element;

[0037] Figure 5 The figure is a structural schematic diagram of the second potting of the application;

[0038] Figure 6 The figure is related test data of the application.

[0039] The figure shows:

[0040] DETAILED DESCRIPTION

[0041] The application will be described in detail below with specific examples. The following examples will help those skilled in the art to further understand the application, but do not limit the application in any form. It should be pointed out that those skilled in the art can make several changes and improvements without departing from the concept of the application. These are all within the scope of protection of the application.

[0042] Example 1: Example 1 is the basic example of the application.

[0043] As shown in Figures 1-5 The application provides a planar receiving array with a wide frequency range, including a sound absorbing barrier 1, a receiving hydrophone element 2, and a metal bottom plate 3. The sound absorbing barrier 1 is installed on the metal bottom plate 3. In a preferred example, the metal bottom plate 3 is an aluminum plate, and the metal bottom plate 3 is adhesively connected to the sound absorbing barrier 1. A plurality of receiving hydrophone elements 2 are arranged in an array on the metal bottom plate 3; the array spacing of the plurality of receiving hydrophone elements 2 is half the wavelength of the operating frequency of the planar receiving array; the receiving hydrophone elements 2 arranged along the width direction of the metal bottom plate 3 are connected in series with each other; the receiving hydrophone elements 2 arranged along the length direction of the metal bottom plate 3 are connected in parallel with each other.

[0044] A plurality of arrayed openings 11 are provided on the sound absorbing barrier 1 and the metal bottom plate 3, and the array spacing of the plurality of openings is half the wavelength of the operating frequency of the planar receiving array; specifically, one end of the receiving hydrophone element 2 passes through the opening in the sound absorbing barrier 1 and extends to the opening on the metal bottom plate 3, and the other end of the receiving hydrophone element 2 extends to the outside of the sound absorbing barrier 1.

[0045] The sound absorbing barrier 1 is a sound absorbing wedge-shaped barrier; the sound absorbing barrier 1 includes a plurality of sawtooth-shaped wedges 12 arranged orthogonally in sequence, each sawtooth-shaped wedge 12 includes a plurality of wedge structures 13 arranged in parallel, and the number of wedge structures 13 in different sawtooth-shaped wedges 12 is the same or different. The wedge structure 13 is filled with porous sound absorbing material, and the wedge structure 13 gradually increases from the top to the bottom, which satisfies a larger sound absorbing contact area while realizing impedance matching. The sound absorbing barrier designed with sound absorbing wedges can effectively absorb sound.

[0046] The receiving hydrophone element 2 is a spherical hydrophone, specifically, the receiving hydrophone element 2 includes a spherical transducer 21 and a connecting rod 22; one end of the connecting rod 22 is installed on the metal bottom plate 3, and the other end is connected to the spherical transducer 21 through a decoupling material.

[0047] The spherical transducer 21 comprises a first ceramic half-sphere with a hole in the center and a second ceramic half-sphere of the same size; the first ceramic half-sphere and the second ceramic half-sphere are bonded together with the centers of the two ceramic half-spheres coinciding; the connecting rod 22 is connected to the spherical transducer 21 through a small hole on the spherical transducer 21; in order to ensure decoupling and insulation, the decoupling material is plastic. The length of the connecting rod 22 determines the distance from the spherical transducer 21 to the sound absorption baffle 1, and the influence of the sound absorption baffle on the directional beam width of the transducer is different at different distances, which can be optimized according to the actual situation.

[0048] In a preferred embodiment, as shown in Figure 1 The planar receiving array with a wide frequency range of operation further comprises a support column 4 and a cable 5, the support column 4 is installed at the bottom end of the metal bottom plate 3 and is threadedly connected with the metal bottom plate 3. The end of the wire in the cable penetrates through the connecting rod 22 along the axial direction of the connecting rod 22 and is connected with the spherical transducer 21. The other end of the wire is connected with an external transmitter.

[0049] In order to ensure the sound absorption effect, two conditions need to be met: the characteristic impedance matches the characteristic impedance of the propagation medium, so that the sound wave can propagate into the material without reflection; the material has a large sound attenuation performance, so that most of the incident sound waves are absorbed. Therefore, the sound absorption wedge (wedge structure 13) adopts a structure that gradually increases from top to bottom, increasing the contact area between the sound absorption wedge and the propagation medium. It is generally believed that when the sound absorption material appears at the position of the sound wave peak, that is, at 1 / 4 wavelength, the maximum absorption rate will occur, and the acoustic characteristics of the sound absorption wedge are usually represented by the sound pressure reflection coefficient. When the reflection coefficient is less than or equal to 0.01, the sound absorption coefficient is ≥0.99, and the lowest frequency corresponding to it is called the cutoff frequency. The sound absorption characteristics of the sound absorption wedge (i.e. the wedge structure 13) are mainly determined by the length and shape of the wedge. The length L of the wedge determines the cutoff frequency, and the length of the wedge structure 13 is usually not less than 1 / 4 of the wavelength corresponding to the cutoff frequency. The length L of the wedge structure 13 satisfies the following requirements: c = λf; L = λ / 4 = c / (4f), where c is the speed of sound in the medium, f is the lower limit of the cutoff frequency, and λ is the wavelength.

[0050] As shown in Figure 3 And Figure 5As shown, the planar receiving array with wide frequency band working range further comprises a first potting layer 6 and a second potting layer 7. The first potting layer 6 is located above the sound absorption barrier 1, and the thickness of the first potting layer 6 is just not over the connecting rod 22 and does not touch the spherical transducer 21. The second potting layer 7 is located above the first potting layer 6, and completely covers the spherical transducer 21. The purpose of setting the first potting layer 6 and the second potting layer 7 and the manufacturing process are as follows: in order to ensure the decoupling and insulation between the array elements and at the same time ensure the acoustic performance of the transducer, the transducer array needs to be potted for multiple times. First, the transducer array is loaded into a potting mold, and the first potting layer 6 is formed by potting with an optimal rubber material, so that the thickness of the first potting layer 6 is just not over the connecting rod 22 and does not touch the spherical transducer 21. After the first potting layer 6 is completely cured, the transducer is loaded into a new potting mold again, and the second potting layer 7 is formed by potting with epoxy rubber. Multiple potting can not only ensure the insulation performance of the transducer array and enhance the decoupling between the elements, but also can reduce the bubbles in the potting layer and improve the performance of the transducer. Finally, the transducer is potted as a whole with polyurethane rubber.

[0051] Embodiment 2: Embodiment 2 is a specific embodiment of the present application.

[0052] This embodiment is a module of a full-ocean-depth multi-beam sounding system receiving transducer array, and the working frequency band is 20 kHz-30 kHz. As shown in Figure 1 In this embodiment, the number of the sawtooth-shaped wedge 12 is 3, and each sawtooth-shaped wedge 12 comprises 5 parallel arranged wedge structures 13. The sound absorption barrier 1 is arranged with 16 receiving hydrophone elements 2 at equal intervals in the length direction, and is arranged with 6 receiving hydrophone elements 2 at equal intervals in the width direction. The array spacing of the receiving hydrophone elements 2 is arranged according to the half wavelength of the working frequency. The 6 receiving hydrophone elements 2 in the width direction of the sound absorption barrier 1 are connected in series with each other, and the receiving hydrophone elements 2 in the length direction are connected in parallel with the receiving hydrophone elements 2 in the width direction. The whole array is supported by the support column 4, which is distributed on the four corners of the array. The support column is connected with the metal bottom plate 3 through screw connection. The cable 5 is connected with the receiving hydrophone element 2 through the small hole in the bottom of the metal bottom plate 3. The support column 4 plays a supporting and positioning role in the transducer potting process, and the support column 4 has a threaded hole for testing and installation of the transducer after potting. In Figure 3 and Figure 5 there should also be a cable 5, but the highlight is omitted in the schematic diagram.

[0053] The sound absorption barrier 1 is selected with appropriate sound absorption material, and the metal bottom plate 3 also has corresponding installation and threading holes. In order to ensure the sound absorption performance of the sound absorption wedge, the reliability of the adhesion between the sound absorption barrier and the metal bottom plate needs to be ensured.

[0054] As shown in Figure 6The part of test data of the application is shown, during the test, the directivity of the transducer is measured at 20, 22, 24, 25, 26, 28, 30 kHz respectively in the frequency band of 20k-30kHz, wherein, dark green is 20k, blue is 22k, dark blue is 24k, red is 25k, green is 26k, purple is 28k, and black is 30k directivity; one circle of the coordinate axis is that the transducer is regarded as a point source, the normal line of the transducer radiation surface is 0 degree direction in the 360 degree direction around the transducer, the negative coordinate axis is the normalized logarithm of the sound pressure value received by the transducer, which reflects the size of the sound pressure receiving ability of the transducer in different directions, and the negative numbers on the coordinate axis are all decibels. It can be seen that the transducer array can achieve a horizontal directivity beam width greater than 140 degrees in the frequency band of 20k-30kHz, which is higher than 130 degrees in the prior art literature, that is, the application also has the characteristics of wide directivity flat angle, and simultaneously, Figure 6 It is also proved that the working frequency band of the application is 20k-30kHz, that is, the application has a wider working frequency band.

[0055] The application provides a receiving transducer array with a wider use frequency band designed by using a sound absorption barrier, so as to meet the use of receiving transducer arrays in different frequency bands; by using the application, the transducer directivity beam width can be wider by using the sound absorption barrier, so that the demand of flat array large-angle beam scanning can be better met.

[0056] The cutoff frequency of the sharp wedge sound absorption structure is determined by the length of the sharp wedge, and above the cutoff frequency, the sound absorption sharp wedge can well absorb sound, so that after the sharp wedge is designed, it can be used in a wide frequency band above the cutoff frequency, and the size parameters of the receiving hydrophone array in the application can be further designed according to the demand in combination with the length of the sharp wedge, so that the volume of the smaller array can be controlled by replacing the receiving hydrophone, and the sharp wedge can be repeatedly used by being formed by mold glue injection, thereby saving cost.

[0057] The application adopts a plurality of high-sensitivity spherical hydrophone point sources, and can also use external transmitters to realize circuit combination and phase control between point sources, improve the consistency between array elements, and make the transducer array directivity have a wider beam width in a wide frequency.

[0058] The application further provides a water acoustic transducer adopting the planar receiving array with a wide frequency band working range, the number of the planar receiving array with a wide frequency band working range is multiple, and multiple planar receiving arrays with a wide frequency band working range are arranged in an array.

[0059] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0060] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the specific embodiments described above, and various changes or modifications can be made by those skilled in the art within the scope of the claims, which does not affect the essential content of the present application. The embodiments of the present application and the features in the embodiments can be arbitrarily combined with each other without conflict.

Claims

1. A planar receiving array with a wide operating frequency range, characterized in that, Includes a sound-absorbing baffle (1), a receiving hydrophone unit (2), and a metal base plate (3). The sound-absorbing baffle (1) is installed on the metal base plate (3), and multiple receiver hydrophone elements (2) arranged in an array are also installed on the metal base plate (3); the array spacing of the multiple receiver hydrophone elements (2) is half the wavelength of the working frequency of the planar receiver array. The receiving hydrophone elements (2) arranged along the width direction of the metal base plate (3) are connected in series with each other; The receiving hydrophone elements (2) arranged along the length of the metal base plate (3) are connected in parallel with each other; The sound-absorbing baffle (1) includes a plurality of serrated wedges (12) arranged orthogonally in sequence. Each serrated wedge (12) includes a plurality of wedge structures (13) arranged in parallel. The number of wedge structures (13) in different serrated wedges (12) may be the same or different. The length L of the wedge structure (13) must meet the following requirements: ； Where c is the speed of sound in the medium. This is the lower limit of the cutoff frequency. λ is the wavelength.

2. The planar receiving array with a wide operating range according to claim 1, characterized in that, The sound-absorbing baffle (1) and the metal base plate (3) are provided with multiple arrayed openings (11), and the array spacing of the multiple openings is half the wavelength of the working frequency of the planar receiving array. One end of the receiving hydrophone unit (2) passes through the opening in the sound-absorbing baffle (1) and extends to the opening (11) on the metal base plate (3). It is connected to the metal base plate (3) through the opening (11) on the metal base plate (3). The other end of the receiving hydrophone unit (2) extends to the outside of the sound-absorbing baffle (1).

3. The planar receiving array with a wide operating range according to claim 1, characterized in that, The receiving hydrophone unit (2) includes a spherical transducer (21) and a connecting rod (22). One end of the connecting rod (22) is mounted on the metal base plate (3), and the other end is connected to the spherical transducer (21) through a decoupling material.

4. The planar receiving array with a wide operating range according to claim 3, characterized in that, The spherical transducer (21) includes a first ceramic hemisphere with a central hole and a second ceramic hemisphere of the same size; the first ceramic hemisphere and the second ceramic hemisphere are bonded together, and the centers of the two ceramic hemispheres coincide.

5. The planar receiving array with a wide operating range according to claim 1, characterized in that, The wideband is 20k-30kHz.

6. The planar receiving array with a wide operating range according to claim 4, characterized in that, It also includes a cable (5), in which the end of the conductor passes through the connecting rod (22) along the axial direction and is connected to the spherical transducer (21).

7. The planar receiving array with a wide operating range according to claim 1, characterized in that, It also includes a first potting layer (6) and a second potting layer (7); The first potting layer (6) is located above the sound-absorbing baffle (1), and the thickness of the first potting layer (6) just covers the connecting rod (22) and does not touch the spherical transducer (21). The second potting layer (7) is located above the first potting layer (6) and completely covers the spherical transducer (21).

8. A hydroacoustic transducer, characterized in that, The planar receiving array with a wide operating range according to any one of claims 1-7 is used, wherein there are multiple planar receiving arrays with a wide operating range, and the multiple planar receiving arrays with a wide operating range are arranged in an array.

Images