Overflow underwater acoustic transducer with flexible acoustic mismatch backing

Abstract

The invention discloses an overflow underwater acoustic transducer with a flexible acoustic mismatch backing, which comprises an overflow transducer and a flexible acoustic mismatch, and is characterized in that the flexible acoustic mismatch is positioned on the inner side of a radiating surface of the overflow transducer; the flexible acoustic mismatch body is a cylindrical air bag and comprises a rubber layer and a fiber net layer from outside to inside, and compressed air is filled into the fiber net layer so that the maximum bearing pressure in the flexible acoustic mismatch body is not smaller than 5 MPa. The flexible acoustic mismatch is arranged on the inner side of the radiating surface of the overflow transducer, the rubber layer and the fiber net layer are arranged on the flexible acoustic mismatch of the cylindrical air bag from outside to inside, and the hydrostatic pressure of deep water is balanced by filling compressed air into the flexible acoustic mismatch; meanwhile, the fiber mesh layer has high sound transmission efficiency during shear vibration, most of sound waves penetrate through the fiber mesh layer and have phase jump, and the sound pressure phase of the sound waves is opposite to that of other sound waves emitted by the radiating surface on the inner side of the overflow transducer, so that the dipole vibration mode of the overflow transducer is greatly weakened, and then the energy conversion efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of underwater acoustic transducer, and particularly relates to an overflow underwater acoustic transducer with flexible acoustic mismatch body backing. BACKGROUND

[0002] The underwater acoustic transducer is a device for realizing underwater electric acoustic energy conversion. With the rapid development of modern sonar technology and the continuous expansion of the application range of underwater acoustics, the requirements for the working performance of underwater acoustic transducers are also increasing. At present, the transmitting transducer with the characteristics of deep water, low frequency, wide band, small size and large power is the main research direction of underwater acoustic transmitting transducers. However, the main design problem of the deep water low frequency transducer is that the low stiffness vibration structure of the low frequency transducer with air backing is difficult to maintain normal operation in the high pressure difference environment of deep water. In addition, although the overflow transducer does not need to bear the pressure difference generated by the hydrostatic pressure, the energy conversion efficiency of the dipole vibration mode is low. SUMMARY The present application provides an overflow underwater acoustic transducer with flexible acoustic mismatch body backing to solve the above technical problems.

[0003] In order to achieve the above purpose, the technical scheme of the present application is as follows: An overflow underwater acoustic transducer with flexible acoustic mismatch body backing, comprising an overflow transducer and a flexible acoustic mismatch body, the flexible acoustic mismatch body is located inside the radiation surface of the overflow transducer; the flexible acoustic mismatch body is a cylindrical air bag, and it comprises a rubber layer and a fiber mesh layer from outside to inside, and the fiber mesh layer is filled with compressed air so that the maximum pressure bearing in the flexible acoustic mismatch body is not less than 5MPa.

[0004] Preferably, the fiber mesh layer adopts aramid fiber mesh, nylon fiber mesh or carbon fiber mesh material.

[0005] Preferably, the two end faces of the flexible acoustic mismatch body comprise a rubber layer, and at least one end face is provided with an air nozzle which can charge air into the flexible acoustic mismatch body.

[0006] Preferably, the flexible acoustic mismatch body is a plurality of flexible acoustic mismatch bodies, the plurality of flexible acoustic mismatch bodies are arranged in parallel and at intervals, and the flexible acoustic mismatch bodies are parallel to the inside radiation surface of the overflow transducer.

[0007] Preferably, the structure form of the overflow transducer is a bending and stretching transducer, a bending disc transducer, a bending strip transducer or a slotted circular ring transducer.

[0008] Preferably, the structure form of the overflow transducer is an electrodynamic transducer or an electromagnetic transducer.

[0009] Preferably, the structure form of the overflow transducer is a bending and stretching transducer, the housing of the bending and stretching transducer is provided with mounting plates at both ends, the mounting plates are fixed on the housing through locking screw assemblies, and the flexible acoustic mismatch body is fixed on the mounting plates.

[0010] Preferably, a decoupling pad is further arranged between the mounting plate and the shell.

[0011] Advantages: The overflow water acoustic transducer with the flexible acoustic mismatch backing disclosed in the application balances the hydrostatic pressure brought by deep water by filling compressed air into the flexible acoustic mismatch body, and meanwhile, the fiber mesh layer has high acoustic transmission efficiency when shearing vibration, and most of the acoustic waves are transmitted through the fiber mesh layer and phase jump occurs, which makes the acoustic pressure phase of the acoustic waves emitted by the radiation surface inside the overflow transducer opposite to the phase of other acoustic waves, so that the dipole vibration mode of the overflow transducer is greatly weakened and the energy conversion efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0013] Figure 1 The structure diagram of the flexible acoustic mismatch body of the overflow water acoustic transducer with the flexible acoustic mismatch backing disclosed in the application; Figure 2 The structure diagram of the overflow water acoustic transducer with the flexible acoustic mismatch backing disclosed in the application; Figure 3 The pressure detection table of the burst test of the flexible acoustic mismatch body of the overflow water acoustic transducer with the flexible acoustic mismatch backing disclosed in the application; Figure 4 The structure diagram of the overflow water acoustic transducer with the flexible acoustic mismatch backing disclosed in the application adopts a bending and stretching transducer; Figure 5 The sending voltage response curve obtained by the prototype test.

[0014] In the figure: 1, flexible acoustic mismatch body; 11, rubber layer; 12, fiber mesh layer; 13, compressed air; 2, shell; 3, mounting plate; 4, locking screw assembly; 5, decoupling pad; 61, first transition block; 62, second transition block; 63, piezoelectric ceramic; 64, electrode sheet; 65, insulating sleeve; 7, prestressed screw. DETAILED DESCRIPTION

[0015] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0016] An overflow water acoustic transducer with a flexible acoustic mismatch backing, as shown in Figure 1 and Figure 2 includes an overflow transducer and a flexible acoustic mismatch body 1 located inside the radiation surface of the overflow transducer; the flexible acoustic mismatch body 1 is a cylindrical air bag, and it includes a rubber layer 11 and a fiber mesh layer 12 from outside to inside, and the fiber mesh layer 12 is filled with compressed air 13 so that the maximum pressure bearing in the flexible acoustic mismatch body 1 is not less than 5 MPa. By setting the flexible acoustic mismatch body 1 inside the radiation surface of the overflow transducer, the flexible acoustic mismatch body 1 of the cylindrical air bag is provided with a rubber layer 11 and a fiber mesh layer 12 from outside to inside; the fiber material undergoes high-speed stretching in the melt spinning process, and the molecular chains are highly oriented along the fiber axis direction, resulting in a lower transverse modulus than the axial modulus; the fiber mesh layer 12 made of fiber material with mechanical property anisotropy has high strength under radial stretching and high acoustic transmission efficiency when shearing vibration. The flexible acoustic mismatch body 1 is designed as a cylindrical air bag, and its annular structure can convert the radial gas pressure into uniform tangential stress applied on the fiber mesh layer 12 in the axial direction; the high axial modulus of the fiber mesh layer 12 enables the flexible acoustic mismatch body 1 to bear the high pressure of the high-pressure gas, and the static water pressure brought by deep water can be balanced after the compressed air is filled in the flexible acoustic mismatch body 1. Because the radial stiffness of the fiber mesh layer 12 is too different from that of the rubber layer 11, and the Poisson's ratio of the rubber layer 11 is very high, the vibration of the fiber mesh layer 12 has a complex shear component, so that the acoustic impedance generated by the shear vibration of the fiber mesh layer 12 is equivalent to that of water; the flexible acoustic mismatch body 1 is driven by the radial acoustic pressure of the inner radiation surface, the fiber mesh layer 12 has high acoustic transmission efficiency in shear vibration, so that most of the acoustic waves on the rubber-fiber interface pass through the fiber mesh layer 12, and full reflection occurs on the fiber-air interface to realize a 180° phase jump; these fully reflected acoustic waves have opposite phases to other acoustic waves emitted by the inner radiation surface at the same time, so that the acoustic power emitted by the inner radiation surface is limited in the form of standing wave inside the overflow transducer, which greatly weakens the dipole vibration mode of the overflow transducer and improves the electro-acoustic energy conversion efficiency.

[0017] Preferably, the flexible acoustic mismatch 1 is a slender cylindrical airbag, the rubber layer 11 is made of sound-permeable rubber material, and the fiber mesh layer 12 is made of aramid fiber mesh, nylon fiber mesh or carbon fiber mesh material. This application utilizes the high axial modulus and low transverse modulus of the fiber, the high Poisson's ratio of the rubber and the low characteristic impedance of the high-pressure air. The combination of the fiber mesh layer 12, the rubber layer 11 and the high-pressure air can not only improve the pressure resistance of the flexible acoustic mismatch 1, but also ensure that its working mechanism does not weaken as the frequency decreases. As a result, the conversion efficiency of the designed overflow underwater acoustic transducer is higher than that of ordinary overflow underwater acoustic transducers.

[0018] Preferably, the flexible acoustic mismatch body 1 has rubber layers 11 on both ends, and at least one end face is provided with an air nozzle for inflating the flexible acoustic mismatch body 1 to the required pressure. Figure 3 As shown, this is a burst test pressure measurement table for the flexible acoustic mismatch 1 in this embodiment. The horizontal axis represents time, and the vertical axis represents test pressure. It can be seen from the figure that the burst pressure of the test piece of the flexible acoustic mismatch 1 in this embodiment can reach 8.5 MPa, which meets the requirements for stable operation in deep-water environments.

[0019] Preferably, there are multiple flexible acoustic mismatches 1, which are arranged in parallel and at intervals. The flexible acoustic mismatches 1 are parallel to the radiation surface inside the overflow transducer. The cooperation of multiple flexible acoustic mismatches 1 can improve the hydrostatic pressure resistance of the entire overflow transducer.

[0020] Preferably, the overflow transducer is a bending transducer, a bending disk transducer, a bending slat transducer, or a slotted annular transducer. The flexible acoustic mismatch 1 in this application is applicable to most transducer structures and has broad application prospects, and can be used in underwater acoustic detection, countermeasures, communication, measurement, and marine resource exploration.

[0021] Preferably, the overflow transducer is an electric transducer or an electromagnetic transducer.

[0022] Preferably, such as Figure 4 As shown, the structure of the bending transducer is used as an example for explanation. The shell 2 of the bending transducer is a traditional type IV bending transducer shell. The shell 2 is made of titanium alloy material and the total length of the bending transducer is about 130mm.

[0023] The tension transducer includes an oscillator assembly, which comprises a first transition block 61, a second transition block 62, a piezoelectric ceramic 63, an electrode plate 64, and an insulating sleeve 65. The first transition block 61 and the second transition block 62 are made of titanium alloy. During the assembly of the tension transducer, pressure is applied to both ends of the short shaft of the housing 2 to increase the length of the long shaft. The oscillator assembly is then placed in the housing 2, and the pressure is released. At this time, prestress is applied using a prestressing screw 7 to fix the oscillator assembly in the housing 2, achieving a rigid connection between the oscillator assembly and the housing 2. Mounting plates 3 are provided at both ends of the housing 2 of the tension transducer. The mounting plates 3 are fixed to the housing 2 by locking screw assemblies 4, and the flexible acoustic mismatch body 1 is fixed on the mounting plates 3.

[0024] Specifically, the mounting plate 3 is provided with limiting holes, and the air nozzles at both ends of the flexible acoustic mismatch 1 extend into the limiting holes. The two mounting plates 3 clamp and fix the flexible acoustic mismatch 1.

[0025] Preferably, a decoupling pad 5 is provided between the mounting plate 3 and the housing 2.

[0026] like Figure 5 The figure shows the short-axis transmission voltage response curves of the prototype in this embodiment under different backing conditions. In the figure, the horizontal axis represents frequency, and the vertical axis represents transmission voltage response. It can be seen from the figure that the response of the flexible acoustic mismatch as a backing is higher than that of the full overflow, indicating that the flexible acoustic mismatch successfully reduces the dipole effect of the overflow bending transducer. It can also be seen from the figure that the response of the flexible acoustic mismatch at the resonance peak of the first bending mode is lower than that of the sound-absorbing rubber backing. This is because the nylon fiber mesh layer increases the damping of the transducer, but the maximum operating depth of the flexible acoustic mismatch is much greater than that of the sound-absorbing rubber backing. It can also be seen from the figure that the flexible acoustic mismatch backing has lower damping and performs better at resonance than the flexible acoustic mismatch backing. However, the modes of the flexible acoustic mismatch itself are not suppressed by the high damping of nylon, thus impairing the broadband performance of the transducer; furthermore, the flexible acoustic mismatch deforms drastically with depth changes, making it unsuitable for deep-water environments. In summary, flexible acoustic mismatches, due to their working mechanism being almost unaffected by frequency, exhibit broadband emission performance similar to that of sound-absorbing rubber backings when used as transducers. The high-pressure gas inside allows the transducer's performance to remain relatively stable under depth variations, and the overflow structure provides better heat dissipation compared to air-backed structures. As a result, schemes using flexible acoustic mismatches as backings have better overall performance and broad application prospects.

[0027] The response of the flexible acoustic mismatch backing is higher than that of the full overflow, indicating that the flexible acoustic mismatch successfully reduces the dipole effect of the overflow bending transducer. However, the response of the flexible acoustic mismatch backing at the resonance peak of the first bending mode is lower than that of the sound-absorbing rubber backing. This may be because the nylon reinforcement layer increases the damping of the transducer, but the maximum operating depth of the flexible acoustic mismatch is much greater than that of the sound-absorbing rubber. The flexible acoustic mismatch backing has lower damping and performs better at resonance than the flexible acoustic mismatch backing, but its own modes are not suppressed by the high damping of the nylon reinforcement layer, thus impairing the broadband performance of the transducer. Furthermore, the flexible acoustic mismatch deforms drastically with depth changes, making it unsuitable for deep-water environments. Because the working mechanism of the flexible acoustic mismatch is almost unaffected by frequency, the broadband emission performance of the transducer under its backing is similar to that of the sound-absorbing rubber backing. The high-pressure gas inside can keep the transducer performance relatively stable under depth changes, and the overflow structure is easier to dissipate heat than the air backing structure. Therefore, this design scheme can be considered to have a wide range of application prospects.

[0028] The working principle of the device in this application is as follows: When the overflow acoustic transducer is working, an alternating current load is applied to the piezoelectric ceramic 63 through the electrode plate 64. The piezoelectric ceramic 63 crystal has a piezoelectric effect, causing the entire piezoelectric crystal stack to produce longitudinal stretching vibration. Through mechanical coupling with the shell 2, the inner and outer sides of the shell 2 simultaneously radiate acoustic signals with opposite phases. Part of the acoustic signal radiated from the inner radiating surface of the shell 2 undergoes total reflection in the flexible acoustic mismatch body 1 and achieves a 180° phase jump. These total reflected sound waves are out of phase with the sound pressure of other sound waves emitted by the inner radiating surface at the same instant, thereby confining the acoustic power radiated from the inner radiating surface into the overflow acoustic transducer in the form of a standing wave. This allows the overflow transducer radiating surface to maintain a certain energy conversion efficiency without having to withstand high hydrostatic pressure on one side.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flexible acoustic mismatched backing backed overflow water acoustic transducer characterized by, The overflow transducer comprises a flexible acoustic mismatch body (1) located inside the radiation surface of the overflow transducer, the flexible acoustic mismatch body (1) is a cylindrical air bag, and it comprises a rubber layer (11) and a fiber mesh layer (12) from outside to inside, the fiber mesh layer (12) is filled with compressed air (13) so that the maximum pressure bearing in the flexible acoustic mismatch body (1) is not less than 5MPa.

2. A flexural mode acoustic mismatched backing backed flow- through underwater acoustic transducer according to claim 1, wherein, The fiber mesh layer (12) is made of aramid fiber mesh, nylon fiber mesh or carbon fiber mesh material.

3. The flush-mounted water sound transducer with a flexible acoustic mismatcher backing according to claim 1, characterized in that, The flexible acoustic mismatch body (1) comprises a rubber layer (11) on both end surfaces, and at least one end surface is provided with an air nozzle capable of inflating the flexible acoustic mismatch body (1).

4. The flush-mounted water sound transducer with a flexible acoustic mismatcher backing according to claim 1, characterized in that, The flexible acoustic mismatch body (1) is in multiple, and the multiple flexible acoustic mismatch bodies (1) are arranged in parallel and at intervals, and the flexible acoustic mismatch bodies (1) are parallel to the radiation surface inside the overflow transducer.

5. A flooded hydrophone according to any of claims 1-4, wherein, The overflow transducer is in the form of a bending transducer, a bending disc transducer, a bending strip transducer or a slotted ring transducer.

6. The flush-mounted water sound transducer with a flexible acoustic mismatcher backing according to claim 5, characterized in that The overflow transducer is in the form of an electric transducer or an electromagnetic transducer.

7. A flooded hydrophone according to any of claims 1-4, wherein, The overflow transducer is in the form of a bending transducer, the housing (2) of the bending transducer is provided with a mounting plate (3) at both ends, the mounting plate (3) is fixed on the housing (2) through a locking screw assembly (4), and the flexible acoustic mismatch body (1) is fixed on the mounting plate (3).

8. The flush-mounted water sound transducer with a flexible acoustic mismatcher backing according to claim 7, characterized in that A decoupling pad (5) is further arranged between the mounting plate (3) and the housing (2).

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