A water-air interface acoustic penetration device and system based on helmholtz resonator

Abstract

The application discloses a water-gas interface sound antireflection device and system based on a Helmholtz resonator, which comprises a hollow cylinder, a supporting ring and a plurality of slits. The supporting ring is arranged in line with the central axis of the cylinder, and one end of the supporting ring extends into the cylinder to support a sound generating device, and the other end of the supporting ring extends to the outside and is provided with a rigid support. The slits are arranged at intervals along the axial wall of the cylinder and are located below the supporting ring, and the cross section of the slits is a regular or special-shaped structure. The device forms a Helmholtz resonator filled with gas through the cooperation of the cylinder and the slits, replaces the bubble structure which is easy to lose stability and the complex membrane-cavity metasurface, widens the sound wave transmission frequency band, improves the structural stability and environmental adaptability, reduces the sound energy loss relying on the impedance matching characteristics, significantly improves the water-gas interface sound energy transmission efficiency, and is simple in structure and convenient to operate, and is suitable for practical application in the marine field.

Description

Technical Field

[0001] This invention belongs to the field of water-air interface communication technology, specifically relating to a water-air interface acoustic enhancement device and system based on a Helmholtz resonant cavity. Background Technology

[0002] High-efficiency acoustic communication at the water-air interface is a key technology for marine network development, marine biological research, geological surveys, and remote sensing. In underwater environments, electromagnetic waves attenuate rapidly, making sound waves the only effective communication method. However, the acoustic impedance difference between air and water is significant, resulting in extremely low efficiency of sound wave energy transmission through the water-air interface and substantial sound energy loss. While acoustic metamaterials can flexibly control sound waves, they are mostly applicable to homogeneous media and it is difficult to construct stable resonant elements at the water-air interface.

[0003] Existing water-air interface acoustic transmission technologies each have their own shortcomings. Membrane-cavity metasurface structures have narrow operating bandwidths and complex structures; non-uniform plane wave transmission relies on idealized conditions and is limited to low frequencies; shallow source geometric compensation methods ignore actual losses and have extremely narrow applicable frequency bands; bubble-type antireflective structures are easily affected by factors such as buoyancy and are difficult to maintain morphological and positional stability, and structured bubbles also have problems such as poor gas-liquid interface stability and high environmental sensitivity. Summary of the Invention

[0004] The purpose of this invention is to provide a water-air interface acoustic transmission enhancement device and system based on a Helmholtz resonator, in order to solve the technical defects of existing water-air interface acoustic transmission technology, such as narrow bandwidth, reliance on idealized conditions, and limited applicable frequency band.

[0005] To achieve the above objectives, this application provides the following technical solution: A first aspect of this application provides a water-air interface acoustic enhancement device based on a Helmholtz resonator, comprising: Hollow cylindrical structure; A support ring is arranged collinearly with the central axis of the cylinder. One end of the support ring extends into the cylinder and is used to support the sound-generating device. The other end of the support ring extends to the outside of the cylinder and is equipped with a rigid support member. Several slits are spaced apart on the circumferential wall of the cylinder along its axial direction. Each slit is located below the support ring, and the cross-section of the slit is a regular or irregular structure.

[0006] In one alternative embodiment, the end of the support ring extending to the outside of the cylinder is enlarged to form an enlarged section, and the rigid support is sleeved and fixed to the outer peripheral wall of the enlarged section.

[0007] In one optional embodiment, the rigid support is an iron ring, which is fixedly connected to the expanded diameter end of the support ring body.

[0008] In one alternative embodiment, the sound-generating device is a loudspeaker, and one end of the support ring extending into the cylinder is adapted to the ring of the loudspeaker and supports the loudspeaker.

[0009] In one alternative embodiment, the slit has a regular cross-sectional structure that is rectangular or circular; The slit has a star-shaped cross-sectional structure.

[0010] In one alternative embodiment, the slits are spaced apart along the circumference of the cylinder.

[0011] In one alternative embodiment, the slits are arranged in multiple rows along the axial direction of the cylinder.

[0012] In one optional embodiment, the support ring and the cylinder are an integral structure or a detachable fixed connection structure.

[0013] In one optional embodiment, the cylinder is a cylindrical hollow cylinder, and the supporting ring is a ring-shaped structure adapted to the cylinder. The internal cavity of the cylinder is connected to the external space through a slit, and the cavity is used to fill gas to form a Helmholtz resonant cavity structure.

[0014] A second aspect of this application provides a water-air interface acoustic enhancement system, comprising: The sound transmission enhancement device based on a Helmholtz resonator cavity at a water-gas interface, as described above, and the sound-generating component and water-gas contact medium that cooperate with the sound transmission enhancement device. The sound-generating component is connected to the support ring of the sound-enhancing device. The cylindrical part of the sound-enhancing device is immersed in the water-air contact medium. The internal cavity of the cylindrical part is filled with gas. The sound waves emitted by the sound-generating component are modulated by the sound-enhancing device and propagate outward through the interface of the water-air contact medium.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The hollow cylinder, combined with slits, forms a closed cavity filled with gas to create a Helmholtz resonant cavity. This replaces easily unstable bubble-based antireflective structures and complex membrane-cavity metasurfaces, solving the problems of unstable morphology and position, high environmental sensitivity of bubble-based structures, and the complexity of membrane-cavity metasurface structures. The resonant cavity, combined with slits of various sizes, also overcomes the limitations of non-uniform plane waves, shallow-source geometric compensation methods relying on idealized conditions, and extremely narrow applicable frequency bands. A support ring precisely supports the sound-generating device, ensuring stable and directional sound wave emission. Rigid support components reinforce the outer end of the ring, improving the overall stability of the device. This device overcomes the limitation of acoustic metamaterials in constructing stable resonant elements at the water-air interface. The arrangement of multiple slits with regular / irregular cross-sections allows for flexible adjustment of the resonant frequency, solving the narrow bandwidth problem of membrane-cavity metasurfaces and avoiding the stringent requirements of precision manufacturing and accurate wavefront control. This significantly improves structural stability and environmental adaptability, broadens the acoustic transmission frequency band, and simplifies structure and operation. Furthermore, leveraging the impedance matching characteristics of the Helmholtz resonator, it improves the acoustic impedance difference between water and air, reduces acoustic energy loss, and significantly enhances the acoustic energy transmission efficiency at the water-air interface, making it suitable for practical applications in the marine field. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A schematic diagram of the overall acoustic enhancement device for the water-vapor interface based on a Helmholtz resonant cavity provided by the present invention. Figure 2 A schematic diagram of the slit construction in the water-vapor interface acoustic enhancement device based on a Helmholtz resonant cavity provided by the present invention. Figure 3 A bottom view of the acoustic enhancement device for the water-air interface based on a Helmholtz resonator provided by the present invention. Figure 4 A schematic diagram of the operation of the acoustic enhancement device for the water-air interface based on a Helmholtz resonant cavity provided by the present invention. Figure 5 A schematic diagram showing the simulation results of transmission frequencies with different numbers of slits in the acoustic enhancement device for the water-vapor interface based on a Helmholtz resonator provided by the present invention. Figure 6 A schematic diagram showing the underwater received signal change when the number of slits in the water-air interface acoustic enhancement device based on a Helmholtz resonator provided by the present invention is one. Figure 7A schematic diagram showing the underwater received signal variation when the number of slits in the water-air interface acoustic enhancement device based on a Helmholtz resonator provided by the present invention is six. Figure 8 A schematic diagram showing the underwater received signal variation when the number of slits in the water-air interface acoustic enhancement device based on a Helmholtz resonator provided by the present invention is twelve. Figure 9 A schematic diagram showing the underwater received signal change when the number of slits in the water-air interface acoustic enhancement device based on a Helmholtz resonator provided by the present invention is twenty-four. Figure 10 A schematic diagram of the acoustic enhancement effect when the number of slits in the water-vapor interface acoustic enhancement device based on a Helmholtz resonator provided by the present invention is one. Figure 11 A schematic diagram of the acoustic enhancement effect when the number of slits in the water-vapor interface acoustic enhancement device based on a Helmholtz resonator provided by the present invention is six. Figure 12 A schematic diagram of the acoustic enhancement effect when the number of slits in the water-vapor interface acoustic enhancement device based on a Helmholtz resonator provided by the present invention is twelve. Figure 13 A schematic diagram of the acoustic enhancement effect of the water-vapor interface acoustic enhancement device based on a Helmholtz resonator provided by the present invention when the number of slits is twenty-four. In the diagram: 1. Ring; 2. Slit; 3. Gas; 4. Loudspeaker. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0020] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0021] The present invention will now be described in further detail with reference to the accompanying drawings: like Figures 1-13 As shown, in a first aspect of the present invention, a water-air interface acoustic enhancement device based on a Helmholtz resonator is provided, comprising: a hollow cylindrical body; a support ring 1, arranged collinearly with the central axis of the cylindrical body, one end of the support ring 1 extending into the cylindrical body for supporting a sound-generating device, and the other end of the support ring 1 extending outside the cylindrical body, and the other end being provided with a rigid support member; and a plurality of slits 2, spaced apart along the axial direction of the cylindrical body on its peripheral wall, each slit 2 being located below the support ring 1, and the cross-section of the slit 2 having a regular or irregular structure.

[0022] During implementation, the entire structure can be integrally formed by 3D printing, without exposed gas-liquid interfaces, membrane structures or hydrophobic structures. It has excellent structural stability and environmental adaptability, and can be stably placed at the water-air interface for a long time to complete the sound transmission enhancement operation. Its specific structure includes a hollow cylinder, a support ring 1 and several slits 2.

[0023] In this embodiment, the cylinder is the basic load-bearing structure of the entire device. It is hollow, and the cavity formed inside it is the core component of the Helmholtz resonant cavity. It is used to fill gas 3, which is preferably air. It can form a stable resonant medium in the cavity, avoiding the instability of shape and position caused by buoyancy, Ostwald curing effect and other factors in existing bubble-type anti-reflection structures.

[0024] In a preferred embodiment, the cylinder is a cylindrical hollow cylinder. This structure is easy to process and is compatible with the mechanical characteristics of Helmholtz resonance, which can maximize the sound transmission effect of the resonant cavity. The specific dimensions of the cylindrical hollow cylinder can be flexibly designed according to the actual sound transmission requirements. In a specific implementation case, the inner diameter of the cylinder is set to 50.1 mm and the wall thickness is set to 4 mm. Under these dimensional parameters, the resonance effect and structural stability of the device are well balanced, which can be adapted to the support and sound transmission requirements of conventional loudspeaker 4.

[0025] In this embodiment, the peripheral wall of the cylinder serves as the carrier for opening the slit 2, while its closed sidewall structure can achieve reflection and constraint of sound waves, prevent sound waves from spreading to the side, reduce the energy loss of sound waves during transmission, and further improve the sound wave transmittance at the water-air interface.

[0026] During implementation, there are no special restrictions on the processing material of the cylinder. It can be selected according to the environmental requirements of the application scenario. In a preferred implementation case, polylactic acid (PLA) is used as the processing material of the cylinder. This material has the characteristics of being lightweight, having good formability, and low cost. It is compatible with FDM (Fused Deposition Modeling) 3D printing technology, which can realize the rapid one-piece molding of the device. Moreover, it has no corrosion or deformation problems in the normal environment of water-air interface, which can ensure the long-term stable use of the device.

[0027] Furthermore, the support ring 1 serves as a support and fixing structure for the sound-generating device. It is arranged collinearly with the central axis of the cylinder, with one end extending into the cylinder and the other end extending outwards. The overall structure is adapted to fit the cylinder. Specifically, the cylinder is a hollow cylindrical body, and the support ring 1 is a circular ring structure. The circular support ring 1 is collinear with the axis of the cylindrical body, which can ensure that the sound wave emission direction of the sound-emitting device is consistent with the axis of the cylinder, so that the sound wave is perpendicularly incident on the water-air interface and avoids transmission loss caused by the deviation of the sound wave incident angle.

[0028] There are two connection methods between the support ring 1 and the cylinder, which can be selected according to the processing technology and usage requirements. One is an integrated structure, in which the support ring 1 and the cylinder are integrally formed by 3D printing, with no connection gaps between them. The structure has strong integrity and excellent stability, and can withstand slight impacts and vibrations at the water-air interface. The other is a detachable fixed connection structure, in which the support ring 1 is fixed to the cylinder by conventional mechanical connection methods such as bolts and clips. This connection method facilitates the replacement and maintenance of the support ring 1. If the specifications of the sound-generating device change, only the appropriate support ring 1 can be replaced, without replacing the entire cylinder, thus reducing the use and maintenance costs of the device.

[0029] In a preferred embodiment, the sound-generating device is a loudspeaker 4. One end of the support ring 1 extending into the cylinder is adapted to the ring of the loudspeaker 4. The opening size of this end is slightly larger than the sound outlet size of the loudspeaker 4. This can achieve precise support for the ring of the loudspeaker 4 without blocking the sound outlet of the loudspeaker 4, ensuring that the sound waves can be incident into the Helmholtz resonant cavity inside the cylinder without obstruction.

[0030] In this embodiment, the loudspeaker 4 is a conventional civilian loudspeaker 4 on the market, which is inexpensive and does not need to meet the stringent requirements of water pressure resistance, waterproofing, antimicrobial properties, and corrosion resistance, thus greatly reducing the overall cost of the device.

[0031] The end of the support ring 1 extending to the outside of the cylinder is equipped with a rigid support member to reinforce the support ring 1, improve the structural strength of the support ring 1, prevent it from deforming due to supporting the sound-generating device or being affected by the water-air interface environment, thereby ensuring the support stability of the sound-generating device, and improving the structural stability of the entire device, overcoming the defect of existing acoustic metamaterials that are difficult to construct stable resonant elements at the water-air interface.

[0032] In one optional embodiment, the end of the support ring 1 extending to the outside of the cylinder is enlarged to form an enlarged section. A rigid support is sleeved and fixed to the outer peripheral wall of the enlarged section. The design of the enlarged section increases the contact area between the support ring 1 and the rigid support, so that the supporting force of the rigid support can be applied to the support ring 1 more evenly, resulting in a better reinforcement effect.

[0033] In a specific implementation case, the thickness of the expanded diameter section of the support ring 1 is set to 6mm. This thickness can ensure the structural strength of the expanded diameter section and prevent the expanded diameter section from deforming due to the installation and fixing of the rigid support.

[0034] Furthermore, the rigid support is an iron ring, which is fixedly connected to the expanded diameter section of the support ring body 1. The iron ring has the characteristics of high structural strength, low cost and corrosion resistance, and is suitable for the use environment of water-air interface. Its inner diameter is matched with the outer diameter of the expanded diameter section of the support ring body 1, and it can be tightly fitted onto the outer peripheral wall of the expanded diameter section. It is fixed by welding, bonding and other methods. The fixed iron ring can effectively limit the radial deformation of the support ring body 1, ensure that the axis of the support ring body 1 is collinear with the axis of the cylinder, and thus ensure the stability of the sound wave emission direction of the sound-generating device.

[0035] In this embodiment, several slits 2 are spaced apart on the circumferential wall of the cylinder along its axial direction. Each slit 2 is located below the supporting ring 1. The internal cavity of the cylinder is connected to the external space through the slits 2. The slits 2, as the narrow neck opening of the Helmholtz resonant cavity, are the key structure for realizing Helmholtz resonance. They cooperate with the cavity filled with gas 3 inside the cylinder to form a resonant system of spring and oscillator combination. The gas 3 inside the cavity is the spring, and the gas in the slit 2 is the oscillator. When the frequency of the sound wave matches the natural frequency of the resonant system, the gas inside the cavity resonates, significantly amplifying the sound wave of that frequency and realizing sound wave penetration enhancement at the water-air interface.

[0036] In practice, the cross-section of slit 2 can be a regular structure or an irregular structure. The design of the regular structure and the irregular structure can be flexibly selected according to the actual frequency requirements of sound transmission enhancement, so as to adapt to the sound wave transmission requirements of different scenarios.

[0037] In a preferred embodiment, the regular cross-sectional structure of the slit 2 is rectangular or circular, and the irregular cross-sectional structure of the slit 2 is star-shaped. The regular cross-sectional structures of rectangle and circle are easy to process and have good compatibility with 3D printing technology, enabling precise processing. The irregular cross-sectional structure of star can increase the contact area between the slit 2 and the gas, change the oscillator mass of the resonance system, and thus adjust the resonance frequency to achieve precise anti-reflection of sound waves at a specific frequency.

[0038] In implementation, since the arrangement of slits 2 directly affects the oscillator mass and resonant frequency of the resonant system, and thus affects the sound transmission enhancement effect of the device, the slits 2 are arranged in an intermittent manner to ensure that there is no obvious coupling of gas between each slit 2, making the frequency characteristics of the resonant system more stable. In the specific implementation process, the arrangement of slits 2 can be selected in the following two ways according to the requirements. In Method 1, all slits 2 have the same structural shape and are evenly spaced along the circumference of the cylinder. Under this arrangement, the acoustic characteristics of each slit 2 are consistent, which can make the oscillator mass of the resonant system evenly distributed, ensuring that the sound wave transmission effect of the device at the resonant frequency is uniform, and avoiding the sound wave transmission deviation caused by uneven slit arrangement. In a specific implementation case, the slit 2 is a cylindrical fan-shaped structure with a pore angle of 3° and a height of 20mm, and is evenly spaced along the circumference of the cylinder. Under this size and arrangement, the resonance effect of the device is stable, and the sound transmission can reach more than 20dB.

[0039] Method 2: Multiple rows of slits 2 are arranged along the axial direction of the cylinder. Each row of slits 2 is arranged at intervals along the circumference of the cylinder. The design of multiple rows of slits 2 can further adjust the oscillator mass of the resonance system, broaden the working frequency band of the device, and enable the device to achieve multi-frequency sound wave transmission enhancement, adapting to the water-air interface acoustic communication needs in complex scenarios.

[0040] In this embodiment, since the gas 3 inside the cavity is regarded as a spring and the gas in the slit 2 is regarded as an oscillator, the vibration frequency of this spring-oscillator system is:

[0041] Wherein, the elastic coefficient is:

[0042] Oscillator mass:

[0043] ρ 0 is the air density, and C0 is the speed of sound in air. S and l 0 represents the cross-sectional area and effective length of the slit, respectively. V 0 represents the cavity volume.

[0044] like Figures 5-13 As shown, by changing the number of slits 2, the mass of the oscillator in the resonant system can be directly changed, thereby altering its resonant frequency and achieving an anti-reflection effect on sound waves of a specific frequency. In a specific implementation example, such as... Figure 4 As shown, when the distance from the top of slit 2 to the water surface is set to 8cm, the number of slits 2 increases from 1 to 24. The optimal anti-penetration amount of the device is always higher than 20dB. At the same time, the optimal anti-penetration frequency gradually increases from 220Hz to 660Hz, which can achieve full coverage anti-penetration of sound waves from low frequency to mid-low frequency range.

[0045] In a second aspect, the present invention provides a water-air interface acoustic enhancement system. This system takes the aforementioned water-air interface acoustic enhancement device based on a Helmholtz resonator as its core, and together with the sound-generating component and the water-air contact medium, it forms a complete acoustic enhancement and transmission system. This system can achieve efficient and stable transmission of sound waves at the water-air interface, and solves the problems of complex structure, reliance on idealized conditions, and poor environmental adaptability of existing water-air interface acoustic transmission systems.

[0046] Furthermore, the water-air interface acoustic transmission enhancement device based on the Helmholtz resonant cavity serves as the core modulation component of the system. Its structure and characteristics are as described in the above embodiments. It can achieve resonant amplification and directional constraint of sound waves, reduce energy loss during sound wave transmission, and improve the sound wave transmittance of the water-air interface. The device is small in size and light in weight, and can be flexibly placed at the interface of the water-air contact medium to adapt to different application scenarios.

[0047] The sound-generating component is the source of sound waves and is connected to the support ring 1 of the sound enhancement device. The sound waves emitted by it are directly incident into the Helmholtz resonant cavity inside the sound enhancement device, and after resonance modulation, they propagate outward through the interface of the water-air contact medium.

[0048] In a preferred embodiment, the sound-generating component is a loudspeaker 4, which is adapted to the end of the inner side of the support ring 1. The support ring 1 provides stable support. The loudspeaker 4 is a common civilian product on the market, which is inexpensive and does not require special waterproofing or anti-corrosion treatment, thus significantly reducing the overall cost of the system.

[0049] The water-air contact medium is the sound wave transmission medium, including an aqueous phase medium and a gaseous phase medium. The gaseous phase medium is preferably air, and the aqueous phase medium can be seawater, fresh water, etc. The cylindrical part of the sound enhancement device is immersed in the water-air contact medium. The specific immersion method is as follows: like Figure 4 As shown, the device is placed near the water-air interface, with slit 2 above the water surface and the lower part of the cylinder submerged in the water, so that the cavity inside the cylinder corresponds precisely to the water-air interface, ensuring that the resonant sound waves can be incident perpendicularly to the water-air interface, thus achieving efficient transmission.

[0050] During operation, first select the processed sound transmission enhancement device according to the actual sound transmission enhancement frequency requirements, and ensure that the number and size of the slits 2 of the device match the target transmission enhancement frequency. The internal cavity of the cylinder is hollow and can be directly filled with air to form gas 3. To achieve acoustic enhancement at the water-air interface, the difference between the volume of the cavity above the water surface inside the cylinder and the total volume of slit 2 must be more than 100 times.

[0051] Wherein, cavity volume:

[0052] Total volume of the slit:

[0053] h The distance from the top of slit 2 to the water surface. r 1 is the inner diameter of the cylinder. r 2 is the outer diameter of the cylinder. n There are 2 slits. l The slit length is 2. α The angle of a single slit 2. The volume of the cavity inside the support ring 1 is ignored.

[0054] When slit 2 is circular, star-shaped, or other shapes, the volume of slit 2 is still calculated using the difference method. However, since the shape of slit 2 is too tortuous, an approximation method can be used, such as treating the shape of slit 2 as square.

[0055] Under the premise of ensuring the volume difference between the cavity and slit 2, the influence of the volume error of slit 2 can be ignored; the cross-sectional area of ​​slit 2 is calculated using the intermediate value method, therefore, the influence of the irregular slit 2 aperture on the resonant frequency can also be ignored.

[0056] The sound-generating component (loudspeaker 4) is placed at the end of the support ring 1 of the sound enhancement device that extends into the cylinder, so that the ring of the loudspeaker 4 is precisely fitted with the end of the support ring 1, ensuring that the sound outlet of the loudspeaker 4 faces the cavity inside the cylinder without obstruction; the distance between the loudspeaker 4 and the water surface is 8.6 cm. Place the sound-enhancing device with the assembled sound-generating components at the interface of the water-air contact medium, adjust the posture of the device so that the central axis of the cylinder is perpendicular to the water-air interface, the support ring 1 is above the water surface, the slits 2 are all above the water surface, and the lower part of the cylinder is appropriately submerged in water to ensure that the position of the cavity inside the cylinder corresponds to the water-air interface. Check the stability of the device to ensure that the rigid support (iron ring) of the support ring 1 is not shaking or shifting with the whole device, and that the connection between the sound-generating component and the support ring 1 is stable, thus completing the assembly of the entire system.

[0057] Then the sound-generating component (speaker 4) is powered on and emits sound waves of a specific frequency. The sound waves are perpendicularly incident into the hollow cavity inside the cylinder along the axis of the support ring 1. The gas 3 (air) filling the cavity is the transmission medium for the sound waves. When the frequency of the sound wave emitted by the sound-generating component matches the natural frequency of the Helmholtz resonance system formed by the cylinder and the slit 2, the gas 3 inside the cavity undergoes Helmholtz resonance. The gas in the slit 2 acts as an oscillator and vibrates with the sound wave. The gas inside the cavity acts as a spring and is compressed and relaxed, significantly amplifying the sound wave energy at that frequency and realizing the resonance modulation of the sound wave. The closed sidewalls of the cylinder form a reflection constraint on the resonant sound waves, preventing the sound waves from spreading to the side and concentrating the energy of the sound waves to propagate along the axial direction of the cylinder, reducing the lateral energy loss of the sound waves during transmission, and ensuring that the sound wave energy can be concentrated and incident on the water-air interface. After being amplified and directionally constrained by resonance, the sound wave is incident perpendicularly along the cylinder axis to the interface between the water and air contact medium. Due to the impedance matching characteristics of the Helmholtz resonance system, the acoustic impedance difference between air and water is effectively improved, allowing the sound wave energy to pass through the water-air interface efficiently and be transmitted from the gas phase medium (air) to the water phase medium (water), thus achieving efficient sound wave penetration and transmission at the water-air interface.

[0058] Throughout the operation, the natural frequency of the resonant system can be changed by adjusting the number and size of the slits 2, thereby achieving precise transmission enhancement for sound waves of different frequencies. When the number of slits 2 increases from 1 to 24, the optimal transmission enhancement frequency of the system can be adjusted from 220Hz to 660Hz, and the optimal transmission enhancement amount is always higher than 20dB, which can meet the needs of low-frequency to mid-low-frequency sound wave transmission in different scenarios.

[0059] The acoustic enhancement device at the water-vapor interface based on a Helmholtz resonant cavity of this invention is a solid structure with no complex assembly parts. It can be integrally formed by 3D printing, which is simple, convenient, and efficient. It does not require precision machining equipment and processes, making it suitable for mass production and personalized customization. The specific processing technology is FDM (Fused Deposition Modeling) 3D printing, and the processing steps are as follows: First, based on the actual sound transmission frequency requirements, determine the size of the device's cylinder, the structure of the support ring 1, and the number, size, and arrangement of the slits 2. Use 3D modeling software (such as Blender) to create an overall 3D model of the device. During the modeling process, ensure the dimensional accuracy and connection relationship of each component, especially the cross-sectional area, effective length, and arrangement spacing of the slits 2, as well as the collinearity of the axes of the support ring 1 and the cylinder. After the modeling is completed, generate a 3D printable model file.

[0060] Choose the appropriate 3D printing material based on the application scenario of the device. There are no special restrictions on the printing material. Conventional 3D printing materials such as polylactic acid (PLA), acrylonitrile-butadiene-styrene copolymer (ABS), and nylon can be selected. In outdoor scenarios such as marine environments and geological surveys, polylactic acid (PLA) is preferred because it is lightweight, has good formability, low cost, and has a certain degree of corrosion resistance. In scenarios with high requirements for structural strength, ABS material can be selected because it has high structural strength, good toughness, and can withstand slight impacts and vibrations.

[0061] Import the completed model file into the 3D printer (such as the Tuozhu H2D printer), and set the printing parameters, including the printing layer thickness, printing speed, and infill density. In a specific implementation case, the printing layer thickness was set to 0.2mm, the printing speed was set to 50mm / s, and the infill density was set to 80%. Under these parameters, the forming accuracy and structural strength of the device achieved a better balance.

[0062] The 3D printer is started and uses the FDM (Fused Deposition Modeling) process to heat the printing material to a molten state. The material is then deposited and shaped layer by layer according to the trajectory of the model file through the printing nozzle, directly printing an integrated sound enhancement device, including a cylinder, support ring 1 and slit 2. No subsequent assembly or splicing is required. The finished device has no connecting gaps, strong overall structure and excellent stability.

[0063] After the device is 3D printed, there may be slight burrs and layer textures on the surface. These can be treated with simple post-processing techniques such as sanding and polishing to ensure a smooth surface and prevent burrs and layer textures from affecting the transmission of sound waves and the structural stability of the device. If the support ring 1 needs to be equipped with a rigid support (iron ring), the iron ring can be fitted onto the expanded diameter section of the support ring 1 after printing and fixed by welding, bonding or other methods to complete the processing of the entire device.

[0064] The acoustic transmission enhancement device and system for the water-vapor interface based on a Helmholtz resonator of this invention has a simple structure, small size, light weight, convenient processing, and low cost. It also has excellent structural stability and environmental adaptability, and significant acoustic transmission enhancement effect (≥20dB). It can be flexibly adapted to various application scenarios of water-vapor interface acoustic communication. The core application scenarios include, but are not limited to, the following: In the construction of marine networks, efficient acoustic communication between the surface and underwater is required. This system can serve as a core component for enhancing acoustic transmission at the water-air interface. It can be placed at the connection point between the surface and underwater network nodes to efficiently transmit acoustic signals from the surface to the underwater, or vice versa. This solves the problems of low acoustic transmittance and high energy loss in existing marine network acoustic communication, improves the communication distance and quality of marine networks, and is small in size and can be flexibly deployed, making it suitable for the construction of nodes in large-scale marine networks.

[0065] In marine biological research, it is necessary to use sound waves to detect, track, and study marine organisms. This system can efficiently transmit the sound wave signals used for research through the water-air interface to the underwater environment, enabling precise detection of underwater marine organisms. At the same time, it can efficiently transmit the sound wave feedback signals of underwater marine organisms to the surface, facilitating collection and analysis by researchers. The device has no exposed gas-liquid interface, so it will not interfere with the living environment of marine organisms. Moreover, its structure is stable and can be placed on the sea surface for a long time to carry out continuous detection and research work.

[0066] In marine geology and lacustrine geology surveys, it is necessary to use sound waves to detect underwater geological structures. This system can efficiently transmit sound wave signals used for geological detection through the water-air interface to the underwater environment, enabling accurate detection of underwater geological structures, improving the intensity and resolution of the detection signal, reducing detection errors caused by sound wave energy loss, adapting to different water quality environments (seawater, freshwater), and being easy to manufacture. The enhanced transmission frequency can be flexibly adjusted according to detection needs to suit the detection requirements of different depths and geological structures.

[0067] In remote sensing of the water-air interface, acoustic communication between the remote sensing equipment and the underwater detection node is required. This system can serve as an acoustic communication enhancement component, efficiently transmitting the acoustic signals emitted by the remote sensing equipment to the underwater detection node, and simultaneously efficiently transmitting the feedback signals from the underwater detection node to the remote sensing equipment. This improves the distance and accuracy of remote sensing. The device is small in size and lightweight, and can be integrated with the remote sensing equipment to achieve integrated operation without the need for additional auxiliary equipment, thus improving the convenience and efficiency of remote sensing.

[0068] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A water-vapor interface acoustic enhancement device based on a Helmholtz resonator, characterized in that, include: Hollow cylindrical structure; A support ring is arranged collinearly with the central axis of the cylinder. One end of the support ring extends into the cylinder and is used to support the sound-generating device. The other end of the support ring extends to the outside of the cylinder and is equipped with a rigid support member. Several slits are spaced apart on the circumferential wall of the cylinder along its axial direction. Each slit is located below the support ring, and the cross-section of the slit is a regular or irregular structure.

2. The acoustic enhancement device for the water-air interface based on a Helmholtz resonator according to claim 1, characterized in that, The end of the support ring extending to the outside of the cylinder is enlarged to form an enlarged section, and the rigid support is sleeved and fixed to the outer peripheral wall of the enlarged section.

3. The acoustic enhancement device for the water-air interface based on a Helmholtz resonator according to claim 2, characterized in that, The rigid support is an iron ring, which is fixedly connected to the expanded diameter end of the support ring body.

4. The acoustic enhancement device for the water-air interface based on a Helmholtz resonator according to claim 1, characterized in that, The sound-generating device is a loudspeaker, and one end of the support ring extending into the cylinder is adapted to the ring of the loudspeaker and supports the loudspeaker.

5. The acoustic enhancement device for the water-air interface based on a Helmholtz resonator according to claim 1, characterized in that, The slit has a regular cross-sectional structure that is rectangular or circular; The slit has a star-shaped cross-sectional structure.

6. The acoustic enhancement device for the water-air interface based on a Helmholtz resonator according to claim 1, characterized in that, The slits are spaced apart along the circumference of the cylinder.

7. The acoustic enhancement device for the water-air interface based on a Helmholtz resonator according to claim 1, characterized in that, The slits are arranged in multiple rows along the axial direction of the cylinder.

8. The acoustic enhancement device for the water-air interface based on a Helmholtz resonator according to claim 1, characterized in that, The support ring and the cylinder are either an integral structure or a detachable fixed connection structure.

9. The acoustic enhancement device for the water-air interface based on a Helmholtz resonator according to claim 1, characterized in that, The cylinder is a hollow cylindrical body, and the supporting ring is a ring-shaped structure adapted to the cylinder. The internal cavity of the cylinder is connected to the external space through a slit, and the cavity is used to fill gas to form a Helmholtz resonant cavity structure.

10. A water-air interface acoustic enhancement system, characterized in that, include: The sound transmission enhancement device based on a Helmholtz resonator cavity at a water-air interface according to any one of claims 1-9, and the sound-generating component and water-air contact medium that cooperate with the sound transmission enhancement device; The sound-generating component is connected to the support ring of the sound-enhancing device. The cylindrical part of the sound-enhancing device is immersed in the water-air contact medium. The internal cavity of the cylindrical part is filled with gas. The sound waves emitted by the sound-generating component are modulated by the sound-enhancing device and propagate outward through the interface of the water-air contact medium.

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