Dual cavity resonant underwater sound absorbing superstructure

Abstract

The application discloses an underwater sound absorption superstructure with double-cavity resonance, which comprises a cavity, two embedded necks and a sandwich layer. The cavity is a rectangular cavity, the sandwich layer is vertically arranged in the cavity and divides the cavity into a first chamber and a second chamber which are arranged in left and right sides, and a through hole is formed in the upper surface of the first chamber and the second chamber; the two embedded necks are hollow straight pipes, respectively penetrating the through holes in the upper surfaces of the first chamber and the second chamber to enter the cavity, so that the first chamber and the second chamber are communicated with the outside. The application utilizes Helmholtz resonance sound absorption, the first chamber and the second chamber of the cavity are connected in parallel through the two embedded necks and connected in series through the holes or gaps of the sandwich layer, so that the sound absorption of the application is different from the classical Helmholtz sound absorption, and the sound absorption is characterized by the coupling of the resonance frequencies of the two single chambers, the sound absorption with a wide frequency is formed, and the wide-frequency sound absorption is realized. The deformation loss of the sandwich layer is derived from the sound absorption mechanism of the pressure difference between the two chambers, so that the superstructure is still effective at high hydrostatic pressure, and the loss effect is increased.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of acoustic metamaterials, and particularly relates to an underwater sound absorption superstructure with double-cavity resonance. BACKGROUND

[0002] In recent years, the ocean occupies an increasingly important position in the national development and security strategy, and the development of underwater equipment such as submarines has attracted widespread attention. The sound stealth function is the key to improving the combat effectiveness of underwater equipment. With the development of underwater detection technology towards low frequency and deep sea, it is urgent to improve the performance of underwater sound absorption materials.

[0003] Traditional underwater sound absorption materials include micro-particle filled sound absorption materials, porous sound absorption materials, cavity resonance type sound absorption materials, etc., which mainly utilize molecular friction, wave conversion and cavity resonance caused by sound waves in the material to achieve sound wave loss. Traditional underwater sound absorption materials can achieve good sound absorption effect at high frequencies, but as the frequency decreases, the required size is often very large, limiting the practical application; on the other hand, under high hydrostatic pressure, the modulus of rubber and other high molecular polymers will increase, greatly reducing the conversion efficiency of acoustic energy to elastic energy; at the same time, with the increase of hydrostatic pressure, the cavities in the rubber material will produce large deformation under water pressure, causing the resonance peak to move to high frequency and losing low frequency sound absorption performance.

[0004] Therefore, the development of underwater sound absorption materials still faces challenges under high hydrostatic pressure. SUMMARY

[0005] (I) Technical problems to be solved

[0006] Therefore, the main purpose of the present application is to provide an underwater sound absorption superstructure with double-cavity resonance to achieve high-efficiency sound absorption in the frequency range of 100-1000 Hz.

[0007] (II) Technical solutions

[0008] To achieve the above purpose, the present application provides an underwater sound absorption superstructure with double-cavity resonance, which comprises a cavity 1, two embedded necks 2 and a sandwich layer 3, wherein:

[0009] The cavity 1 is a rectangular cavity, the sandwich layer 3 is vertically arranged inside the cavity 1 and divides the cavity 1 into a first chamber and a second chamber arranged adjacent to each other, and a through hole is opened on the upper surface of the first chamber and the second chamber;

[0010] The two embedded necks 2 are both hollow straight pipes, which respectively pass through the through holes on the upper surfaces of the first chamber and the second chamber and enter the cavity 1, so that the first chamber and the second chamber are both in communication with the outside.

[0011] In the above scheme, the through hole is located on the center line of the first chamber and the second chamber, so that the embedded neck 2 passing through the through hole is located at the center of the first chamber and the second chamber.

[0012] In the above scheme, the outer diameter of the embedded neck 2 is the same as the inner diameter of the through hole, so that the embedded neck 2 passes through the through hole without gaps.

[0013] In the above scheme, the material of the cavity 1 and the embedded neck 2 is steel.

[0014] In the above scheme, the interlayer 3 has a hole or a slit 4 at the center, so that the first chamber and the second chamber are communicated, and the hole or the slit 4 is used for damping loss.

[0015] In the above scheme, the interlayer 3 is a rubber layer, and the deformation loss of the interlayer 3 is caused by the pressure difference between the first chamber and the second chamber, so that the damping loss is mainly shear loss.

[0016] In the above scheme, the underwater sound absorption superstructure utilizes Helmholtz resonance sound absorption, the first chamber and the second chamber of the cavity 1 are connected in parallel through the two embedded necks 2, and are connected in series through the hole or the slit 4 of the interlayer 3, so that the sound absorption of the underwater sound absorption superstructure is different from the classical Helmholtz sound absorption, and is characterized by the coupling of two single-chamber resonance frequencies, forming a wide frequency sound absorption.

[0017] In the above scheme, in the underwater sound absorption superstructure, the sound absorption frequency band is adjusted by changing the length and diameter of the two embedded necks, the thickness of the interlayer, the diameter of the hole or the width of the slit, and is specifically realized based on the following structure design model:

[0018] find l1, d1, l2, d2, t, c

[0019] maximize

[0020] subject to f=f target，i (i=1, 2,..., n)

[0021] Wherein, l1 and l2 are the lengths of the two embedded necks, d1 and d2 are the diameters of the two embedded necks, t is the thickness of the interlayer, c is the diameter of the hole or the width of the slit, α is the sound absorption coefficient, which is calculated by finite element software, and f target is the sound absorption target frequency.

[0022] (Three) beneficial effects

[0023] From the above technical scheme, it can be seen that the underwater sound absorption superstructure with double-cavity resonance provided by the present application has the following beneficial effects:

[0024] 1. The underwater sound-absorbing superstructure with dual-cavity resonance provided by this invention utilizes the Helmholtz resonance principle to absorb low-frequency underwater sound waves. The first and second chambers of the cavity 1 are connected in parallel through two embedded necks 2, and simultaneously connected in series through the holes or slits 4 of the interlayer 3. This makes the sound absorption of the underwater sound-absorbing superstructure different from the classic Helmholtz sound absorption, exhibiting the coupling of the resonant frequencies of two single chambers, forming a wider frequency range sound absorption effect, achieving a wide frequency range sound absorption with good effect, and achieving efficient sound absorption in the frequency range of 100-1000Hz.

[0025] 2. The underwater sound-absorbing superstructure with dual-cavity resonance provided by this invention divides the cavity 1 into a first chamber and a second chamber arranged adjacent to each other by vertically setting the interlayer 3 inside the cavity 1. The first chamber and the second chamber are connected by a hole or slit 4 at the center of the interlayer 3. The interlayer 3, made of rubber material, not only separates the two chambers but also acts as a damping layer. The interlayer 3, made of rubber material, undergoes shear loss, which improves the loss efficiency. At the same time, the loss deformation originates from the sound absorption mechanism of the pressure difference between the two chambers, so that the superstructure remains effective under high hydrostatic pressure and avoids the failure of the sound absorption mechanism under high hydrostatic pressure.

[0026] 3. The underwater sound-absorbing superstructure with dual-cavity resonance provided by this invention can change the resonant frequency by adjusting geometric parameters such as the length and diameter of the two inner necks, the thickness of the interlayer, the diameter of the hole or the width of the slit, thereby adjusting the sound absorption frequency band and thus changing the sound absorption frequency band of the underwater sound-absorbing superstructure. Therefore, it can be adjusted according to different sound absorption requirements and has good adjustability. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a dual-cavity resonant underwater sound-absorbing superstructure with a hole at the center of the interlayer, according to an embodiment of the present invention.

[0028] Figure 2 This is a schematic diagram of a dual-cavity resonant underwater sound-absorbing superstructure with a slit at the center of the interlayer, according to an embodiment of the present invention.

[0029] Figure 3 According to Figure 1 The diagram shows the sound absorption effect of the underwater sound-absorbing superstructure with a hole in the center of the interlayer in the embodiment shown.

[0030] Figure 4 According to Figure 2 The diagram shows the sound absorption effect of the underwater sound-absorbing superstructure with a slit at the center of the interlayer in the embodiment shown.

[0031] In the diagram: 1-cavity, 2-inset neck, 3-layer, 4-hole or slit. Detailed Implementation

[0032] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to specific embodiments and drawings.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terminology used in the specification herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application; the present specification and claims can use terms such as "include" and "have" and their derivatives, which are intended to cover a non-exclusive inclusion.

[0034] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive or alternative embodiments. It is expressly understood that the embodiments described herein can be combined with each other in their various permutations and combinations.

[0035] The present application provides a double-cavity resonance underwater sound absorption superstructure, as shown in Figure 1 and Figure 2 , which comprises a cavity 1, two embedded necks 2 and a sandwich 3, wherein: the cavity 1 is a rectangular cavity, the sandwich 3 is vertically arranged inside the cavity 1 and divides the cavity 1 into a first chamber and a second chamber arranged side by side, and a through hole is opened on the upper surface of the first chamber and the second chamber; the two embedded necks 2 are both hollow straight tubes, which respectively pass through the through holes on the upper surfaces of the first chamber and the second chamber into the cavity 1, so that the first chamber and the second chamber are both in communication with the outside. The present application utilizes Helmholtz resonance sound absorption, the first chamber and the second chamber of the cavity are connected in parallel through the two embedded necks, and are connected in series through the holes or seams of the sandwich, so that the sound absorption of the double-cavity resonance underwater sound absorption superstructure of the present application is different from the classic Helmholtz sound absorption, which is characterized by the coupling of the resonance frequencies of the two single chambers, forming a wide frequency sound absorption, realizing wide frequency sound absorption, and being able to realize high-efficiency sound absorption in the frequency range of 100-1000 Hz. The deformation loss of the sandwich is derived from the sound absorption mechanism of the pressure difference between the two chambers, so that the superstructure is still effective under high hydrostatic pressure, and the loss effect is increased.

[0036] Please refer to Figure 1 and Figure 2 , the through holes opened on the upper surfaces of the first chamber and the second chamber are respectively located on the center lines of the first chamber and the second chamber, so that the embedded necks 2 passing through the through holes are located at the centers of the first chamber and the second chamber. Optionally, the outer diameter of the embedded neck 2 is the same as the inner diameter of the through hole, so that the embedded neck 2 passes through the through hole without gaps.

[0037] In order to make better use of Helmholtz resonance to absorb sound at a single frequency, the cavity 1 and the inset neck 2 are made of the same metal material, such as steel.

[0038] exist Figure 1 and Figure 2 In this structure, the interlayer 3 has a hole or slit 4 at its center, connecting the first and second chambers and serving as a damping layer. The interlayer 3 is a rubber layer, and its deformation loss originates from the pressure difference between the first and second chambers; therefore, the damping loss is primarily shear loss. This underwater sound-absorbing superstructure utilizes Helmholtz resonance for sound absorption. The first and second chambers of the cavity 1 are connected in parallel via the two embedded necks 2, and simultaneously connected in series via the hole or slit 4 in the interlayer 3. This distinguishes the sound absorption of this underwater sound-absorbing superstructure from classical Helmholtz sound absorption, exhibiting the coupling of the resonant frequencies of two single chambers to form a wider frequency range, achieving efficient sound absorption within the 100-1000Hz frequency range. The deformation loss of the interlayer 3 originates from the sound absorption mechanism of the pressure difference between the two chambers, ensuring the underwater sound-absorbing superstructure provided by this invention remains effective even under high hydrostatic pressure, thus increasing the loss-absorbing effect.

[0039] According to an embodiment of the present invention, in this dual-cavity resonant underwater sound-absorbing superstructure, the sound absorption frequency band is adjusted by changing the length and diameter of the two inner necks, the thickness of the interlayer, the diameter of the hole, or the width of the slit. Specifically, this is achieved based on the following structural design model:

[0040] find l1,d1,l2,d2,t,c

[0041] maximize

[0042] subject to f=f target，i (i = 1, 2, ..., n)

[0043] Where l1 and l2 are the lengths of the two embedded necks, d1 and d2 are the diameters of the two embedded necks, t is the thickness of the interlayer, c is the diameter of the hole or the width of the slit, α is the sound absorption coefficient, calculated by finite element software, and f target The target frequency for sound absorption.

[0044] based on Figure 1 The diagram shown is a schematic of a dual-cavity resonant underwater sound-absorbing superstructure with a hole at the center of the interlayer. Figure 3 It shows according to Figure 1 The diagram shows the sound absorption effect of the underwater sound-absorbing superstructure with a hole in the center of the interlayer, as illustrated in the embodiment.

[0045] like Figure 1As shown, the underwater sound-absorbing superstructure with dual-cavity resonance has a cavity height of 50mm, a length of 90mm, and a width of 45mm. The steel plate used for the cavity is 2mm thick. The two inner necks are 35mm and 10mm long, and 2mm and 4mm in diameter, respectively. The steel pipes used for the inner necks are all 1mm thick. The interlayer is 10mm thick; for simplicity, the interlayer is located at the center of the cavity, meaning the two chambers it divides are of equal size. A 6mm diameter hole is formed at the center of the interlayer. The cavity and inner necks are made of materials with a density of 7850kg / m³. 3 Structural steel with a Young's modulus of 200 GPa and a Poisson's ratio of 0.3. The interlayer uses steel with a density of 1100 kg / m³. 3 A rubber material with a Young's modulus of 300 MPa, a Poisson's ratio of 0.49, and an isotropic loss factor of 0.3.

[0046] Figure 3 This is a diagram showing the sound absorption effect of the sound-absorbing superstructure obtained from finite element simulation. The simulation results show that... Figure 1 The illustrated embodiment exhibits a sound absorption coefficient greater than 0.5 in the 475Hz-675Hz range, demonstrating a wide sound absorption bandwidth and achieving broad-band low-frequency sound absorption. Figure 1 As can be seen from the comparison of the sound absorption effect of the illustrated embodiment with that of a structure without interlayer and having the same geometric dimensions, the dual-cavity resonant structure of this embodiment changes the resonant frequency of the single cavity, causing the two frequencies to couple and forming a wider frequency range sound absorption effect.

[0047] based on Figure 2 The diagram shown is of a dual-cavity resonant underwater sound-absorbing superstructure with a slit at the center of the interlayer. Figure 4 It shows according to Figure 2 The diagram shows the sound absorption effect of the underwater sound-absorbing superstructure with a slit at the center of the interlayer in the embodiment shown.

[0048] like Figure 2 As shown, the underwater sound-absorbing superstructure with dual-cavity resonant structure has a cavity height of 50mm, a length of 90mm, and a width of 45mm. The steel plate used for the cavity is 2mm thick. The two inner necks are 38mm and 5mm long, and 2mm and 6mm in diameter, respectively. The steel pipes used for the inner necks are all 1mm thick. The interlayer is 10mm thick; for simplicity, the interlayer is located at the center of the cavity, meaning the two chambers it divides are of equal size. A slit with a width of 3mm is opened at the center of the interlayer. The cavity and inner necks are made of materials with a density of 7850kg / m³. 3 Structural steel with a Young's modulus of 200 GPa and a Poisson's ratio of 0.3. The interlayer uses steel with a density of 1100 kg / m³. 3 A rubber material with a Young's modulus of 300 MPa, a Poisson's ratio of 0.49, and an isotropic loss factor of 0.3.

[0049] Figure 4 The sound absorption effect diagram of the sound absorption superstructure obtained by the finite element simulation, from the simulation results, Figure 2 The embodiment shown has a sound absorption coefficient close to 1 at 850-1025Hz, realizing quasi-perfect sound absorption, and a sound absorption coefficient greater than 0.5 at 750Hz-1150Hz, realizing low-frequency wide-band sound absorption. The embodiment shown Figure 2 The sound absorption effect of the embodiment shown is compared with that of other seamless sandwich structures with the same geometric size, and it can be known that the series and parallel combination relationship formed by the slits on the sandwich makes the two single-cavity resonance frequencies coupled, improving the sound absorption effect.

[0050] The above embodiments are only used to illustrate the technical solutions of the present application, and do not limit the protection scope of the application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on these embodiments, all other embodiments obtained by those skilled in the art of underwater sound absorption without creative labor belong to the scope of protection of the present application. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art of underwater sound absorption can still combine, add or delete the features of the embodiments of the present application according to the circumstances without creative labor, so as to obtain different other technical solutions without departing from the concept of the present application. These technical solutions also belong to the scope of protection of the present application.

[0051] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only for specific embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A dual-cavity resonant underwater sound-absorbing superstructure, characterized in that, The underwater sound-absorbing superstructure includes a cavity (1), two embedded necks (2), and a sandwich layer (3), wherein: The cavity (1) is a rectangular cavity. The interlayer (3) is vertically arranged inside the cavity (1) and divides the cavity (1) into a first chamber and a second chamber arranged adjacent to each other on the left and right. A through hole is opened on the upper surface of the first chamber and the second chamber. The two inner necks (2) are both hollow straight tubes, which pass through the through holes on the upper surface of the first chamber and the second chamber respectively and enter the cavity (1), so that the first chamber and the second chamber are connected to the outside. The interlayer (3) has a hole or slit (4) at its center to connect the first chamber with the second chamber, which serves to dampen losses. The interlayer (3) is a rubber layer. The deformation loss of the interlayer (3) comes from the pressure difference between the first chamber and the second chamber. Therefore, the damping loss is mainly shear loss. The underwater sound-absorbing superstructure utilizes Helmholtz resonance for sound absorption. The first and second chambers of the cavity (1) are connected in parallel through the two inner necks (2) and connected in series through the holes or slits (4) of the interlayer (3). This makes the sound absorption of the underwater sound-absorbing superstructure different from the classic Helmholtz sound absorption, and it is characterized by the coupling of the resonant frequencies of the two single chambers to form a wider frequency range of sound absorption.

2. The underwater sound-absorbing superstructure with dual-cavity resonant structure according to claim 1, characterized in that, The through holes are located on the center lines of the first chamber and the second chamber respectively, so that the inlay neck (2) passing through the through hole is located at the center of the first chamber and the second chamber.

3. The underwater sound-absorbing superstructure with dual-cavity resonant structure according to claim 2, characterized in that, The outer diameter of the inset neck (2) is the same as the inner diameter of the through hole, so that the inset neck (2) passes through the through hole.

4. The underwater sound-absorbing superstructure with dual-cavity resonant structure according to claim 1, characterized in that, Both the cavity (1) and the inner neck (2) are made of steel.

5. The underwater sound-absorbing superstructure with dual-cavity resonant structure according to claim 1, characterized in that, In this underwater sound-absorbing superstructure, the sound absorption frequency band can be adjusted by changing the length and diameter of the two inner necks, the thickness of the interlayer, the diameter of the holes in the interlayer, or the width of the slits in the interlayer.

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