Low-frequency broadband strong-sound-absorption underwater sound absorption wedge considering backing quality effect

Abstract

The utility model discloses a low-frequency broadband strong-sound-absorption underwater sound absorption wedge considering a backing quality effect, which relates to the technical field of underwater sound absorption, and is characterized in that a wedge main body has an impedance gradual change appearance, so that sound waves can gradually enter the underwater sound absorption wedge to be absorbed, and the efficient sound absorption of the underwater sound absorption wedge is ensured; when the dissipation unit absorbs sound wave energy, the dissipation unit is easy to vibrate, so that sound waves are easy to generate resonance action with the acoustic cavity, the side wall of the acoustic cavity generates shear deformation, the dissipation capability of the acoustic cavity is improved, and the low-frequency sound absorption performance of the acoustic wedge is improved under the condition that the length of the acoustic wedge is not prolonged; the size of the acoustic cavity is larger, incident longitudinal waves can be easily converted into transverse waves with shorter wavelength, and the low-frequency sound absorption capacity is improved; the fourth sound absorption cavity strengthens the shear deformation of the surface of the side, facing the third sound absorption cavity, of the fourth sound absorption cavity, and the impedance reinforcer increases the non-uniformity of stress strain in the underwater sound absorption wedge, so that the sound absorption frequency band range of the underwater sound absorption wedge is wider.

Description

Technical Field

[0001] This utility model relates to the field of underwater acoustic absorption equipment technology, and in particular to a low-frequency broadband strong sound-absorbing underwater acoustic wedge that takes into account the backing mass effect. Background Technology

[0002] Underwater acoustic low-frequency broadband strong sound-absorbing wedges, with excellent sound absorption properties, can minimize sound wave reflection from structural surfaces. They are key components for simulating free-field underwater acoustic propagation environments and are widely used in traveling wave field testing environments such as anechoic pools, anechoic tanks, anechoic troughs, and underwater acoustic impedance tubes. Furthermore, as important sound-absorbing elements, underwater acoustic low-frequency broadband strong sound-absorbing wedges are also often installed on the bulkhead of the sonar compartment in the bow of submarines to control the self-noise level inside the sonar compartment, thereby improving the signal-to-noise ratio of the sonar platform and enhancing its detection capabilities.

[0003] Currently, underwater acoustic low-frequency broadband strong sound-absorbing wedges, broadly speaking, can be classified into conical, wedge-shaped, and pyramidal configurations based on their structural shape. From the perspective of their internal acoustic structure, they can be divided into two main categories: solid underwater acoustic low-frequency broadband strong sound-absorbing wedges and cavity-type underwater acoustic low-frequency broadband strong sound-absorbing wedges. Solid underwater acoustic low-frequency broadband strong sound-absorbing wedges were the main form of early underwater acoustic low-frequency broadband strong sound-absorbing wedges. Their main mechanism is to reduce sound wave reflection caused by the impedance difference between the matrix material and the water medium by utilizing the impedance gradient effect of the transition section of the outer contour. Cavity-type underwater acoustic low-frequency broadband strong sound-absorbing wedges, on the other hand, introduce a macroscopic acoustic cavity inside the solid underwater acoustic low-frequency broadband strong sound-absorbing wedge. Their main design concept is to combine impedance gradient with cavity resonance, utilizing the cavity resonance effect to improve low-frequency sound absorption performance. Numerous theoretical and experimental studies have shown that the length of a solid low-frequency broadband strong sound-absorbing underwater acoustic wedge should not be less than 1 / 4 of the wavelength of the sound wave corresponding to the lowest effective sound absorption frequency. This means that a longer total length of the wedge is required when absorbing lower frequency sound waves. Improving low-frequency sound absorption performance and limited installation space have become a contradictory problem in the application of solid low-frequency broadband strong sound-absorbing underwater acoustic wedges in underwater equipment and anechoic pools and other testing environments.

[0004] In summary, how to make the sound absorption performance of the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge, while keeping its length relatively small, achieve lower frequency, wider bandwidth, and higher efficiency has become a technical problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0005] The purpose of this invention is to provide a low-frequency broadband strong sound-absorbing underwater acoustic wedge that takes into account the backing mass effect, so that the sound absorption performance of the low-frequency broadband strong sound-absorbing underwater acoustic wedge is lower, wider and more efficient with a smaller length.

[0006] To achieve the above objectives, this utility model provides the following solution:

[0007] This invention provides a low-frequency broadband strong sound-absorbing underwater acoustic wedge that considers the backing mass effect, the low-frequency broadband strong sound-absorbing underwater acoustic wedge comprising:

[0008] The device comprises a wedge-shaped body with an acoustic cavity inside. A dissipation unit is located within the acoustic cavity. The acoustic impedance of the dissipation unit is lower than that of the wedge-shaped body, and the dissipation unit is a flexible dissipation unit. The acoustic cavity includes a first sound-absorbing cavity, a second sound-absorbing cavity, a third sound-absorbing cavity, and a fourth sound-absorbing cavity, which are sequentially arranged and connected along a first direction. The first, third, and fourth sound-absorbing cavities are all fixed-diameter structures, and their radii increase sequentially along the first direction. The radius of the second sound-absorbing cavity gradually increases along the first direction, and the radii at both ends of the second sound-absorbing cavity are equal to the radii of the first and third sound-absorbing cavities, respectively. The fourth sound-absorbing cavity penetrates the wedge-shaped body at the end away from the first sound-absorbing cavity, and an impedance reinforcement member is located within the fourth sound-absorbing cavity.

[0009] A cover plate is disposed at the end of the wedge body away from the first sound-absorbing cavity and blocks the fourth sound-absorbing cavity;

[0010] The first direction extends from the first end of the wedge body toward the second end of the wedge body, and the first direction is perpendicular to the cross-section of the acoustic cavity.

[0011] Preferably, the wedge body includes a first sound-absorbing part and a second sound-absorbing part arranged sequentially and connected along the first direction. The cross-section of the first sound-absorbing part gradually increases along the first direction, and the cross-section of the second sound-absorbing part is the same in the first direction. The cross-section of the first sound-absorbing part near the second sound-absorbing part is equal to the cross-section of the second sound-absorbing part. The cross-sections of the first sound-absorbing part and the second sound-absorbing part are both perpendicular to the first direction.

[0012] The first sound-absorbing cavity and the second sound-absorbing cavity are located within the first sound-absorbing part, and the third sound-absorbing cavity and the fourth sound-absorbing cavity are located within the second sound-absorbing part.

[0013] Preferably, the acoustic absorbing wedge is applied to a steel structure water tank;

[0014] And / or, the dissipation unit includes air filling the acoustic cavity; or, the dissipation unit includes a flexible sound-absorbing element disposed within the acoustic cavity.

[0015] Preferably, the length of the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge in the first direction is H, the length of the first sound-absorbing part in the first direction is H1, the length of the second sound-absorbing part in the first direction is H2, and the length of the cover plate in the first direction is H3.

[0016] Where H = H1 + H2 + H3, H ≤ 470 mm, 40 mm ≤ H1 ≤ 450 mm, 40 mm ≤ H2 ≤ 250 mm; 2 mm ≤ H3 ≤ 6 mm.

[0017] Preferably, the first sound-absorbing part is frustum-shaped, and the second sound-absorbing part is cylindrical; the radius of the end of the first sound-absorbing part away from the second sound-absorbing part is R1, 1mm≤R1≤8mm, the radius of the end of the first sound-absorbing part near the second sound-absorbing part is R2, 10mm≤R2≤70mm, the radius of the end of the second sound-absorbing part near the first sound-absorbing part is R2, and the radius of the cover plate is R2.

[0018] Preferably, the radius of the first sound-absorbing cavity is r1, 1.5mm≤r1≤10mm, and the length of the first sound-absorbing cavity in the first direction is h1, 5mm≤h1≤300mm;

[0019] The length of the second sound-absorbing cavity in the first direction is h2, where 5mm ≤ h2 ≤ 250mm;

[0020] The radius of the third sound-absorbing cavity is r2, 2mm≤r2≤25mm, and the length of the third sound-absorbing cavity in the first direction is h3, 5mm≤h3≤200mm;

[0021] The radius of the fourth sound-absorbing cavity is r3, where r3 = r2 + d r ,1mm≤d r ≤20mm, the length of the fourth sound-absorbing cavity in the first direction is h4, 2mm≤h4≤40mm;

[0022] The impedance reinforcement is cylindrical, with a wall thickness of t, where 0.5 mm ≤ t ≤ 4 mm, a radius of r3, and a length of h4 in the first direction.

[0023] Preferably, the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge further includes a liner plate, which is disposed at the end of the cover plate away from the wedge body. The length of the liner plate in the first direction is H4, 10mm≤H4≤50mm, and the radius of the liner plate is R2.

[0024] Preferably, the first sound-absorbing cavity, the second sound-absorbing cavity, the third sound-absorbing cavity, the fourth sound-absorbing cavity, and the impedance reinforcement are coaxially arranged;

[0025] And / or, the first sound-absorbing part is wedge-shaped, and the second sound-absorbing part is cubic.

[0026] The present invention achieves the following technical advantages over the prior art:

[0027] This utility model relates to a low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge, comprising a wedge body, an acoustic cavity within the wedge body, and a dissipation unit within the acoustic cavity. When a sound wave enters the acoustic cavity, because the acoustic impedance of the dissipation unit is lower than that of the wedge body, and the dissipation unit is a flexible dissipation unit, it is prone to vibration after absorbing sound wave energy. This is equivalent to constructing an approximately free boundary for the acoustic cavity, which makes it easy for the sound wave to resonate with the acoustic cavity, i.e., resonate, and causes shear deformation of the sidewall of the acoustic cavity, thereby improving the dissipation capacity of the acoustic cavity. Thus, without extending the length of the low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge, the low-frequency sound absorption performance of the low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge is improved.

[0028] Furthermore, the acoustic cavity in this invention includes a first sound-absorbing cavity, a second sound-absorbing cavity, a third sound-absorbing cavity, and a fourth sound-absorbing cavity arranged sequentially and connected along a first direction; the first, third, and fourth sound-absorbing cavities are all fixed-diameter structures, and their radii increase sequentially along the first direction, while the radius of the second sound-absorbing cavity gradually increases along the first direction, and the radii at both ends of the second sound-absorbing cavity are equal to the radii of the first and third sound-absorbing cavities, respectively; the above-mentioned arrangement of the acoustic cavity makes the acoustic cavity larger in size, which can convert the incident longitudinal wave into a transverse wave with a shorter wavelength, thereby improving sound wave dissipation and improving low-frequency sound absorption capability;

[0029] Meanwhile, the radius of the third sound-absorbing cavity is smaller than that of the fourth sound-absorbing cavity. The end of the fourth sound-absorbing cavity away from the third sound-absorbing cavity passes through the end of the wedge body near the fourth sound-absorbing cavity. The cover plate is located at the end of the wedge body away from the first sound-absorbing cavity and seals the fourth sound-absorbing cavity. The fourth sound-absorbing cavity strengthens the shear deformation of the surface of the fourth sound-absorbing cavity facing the third sound-absorbing cavity, further improving the low-frequency sound absorption performance. The impedance reinforcement increases the non-uniformity of stress and strain inside the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge, strengthens the shear deformation of the surface of the fourth sound-absorbing cavity facing the third sound-absorbing cavity, improves the low-frequency sound absorption performance, and reduces the problem of obvious sound absorption valley in the mid-frequency band caused by cavity anti-resonance, making the sound absorption frequency range of the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge of this utility model wider.

[0030] Based on the above structure, this invention can achieve lower frequency, wider bandwidth, and higher efficiency sound absorption performance of the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge with a smaller length. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 A schematic diagram of a low-frequency broadband strong sound-absorbing underwater acoustic wedge with a frustum-shaped main body;

[0033] Figure 2 A longitudinal section of a low-frequency broadband strong sound-absorbing underwater acoustic wedge.

[0034] Figure 3 A schematic diagram of the structure of an acoustic cavity;

[0035] Figure 4 A schematic diagram of the structure of a low-frequency broadband strong sound-absorbing underwater acoustic wedge when the main body of the wedge is wedge-shaped;

[0036] Figure 5 A schematic diagram of the structure in which multiple low-frequency broadband strong sound-absorbing underwater sound-absorbing wedges are arranged in an alternating pattern when the main body of the wedge is wedge-shaped.

[0037] Figure 6 A schematic diagram showing the theoretical calculation results of the absorption coefficient of a low-frequency broadband strong sound-absorbing underwater acoustic wedge;

[0038] Figure 7 A schematic diagram comparing the sound absorption coefficients of other types of low-frequency broadband strong sound-absorbing underwater sound-absorbing wedges with those of this utility model.

[0039] Among them, 1. First sound-absorbing part; 2. Second sound-absorbing part; 3. Cover plate; 4. Acoustic cavity; 41. First sound-absorbing cavity; 42. Second sound-absorbing cavity; 43. Third sound-absorbing cavity; 44. Fourth sound-absorbing cavity; 45. Impedance reinforcement. Detailed Implementation

[0040] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0041] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] like Figures 1 to 7 As shown, this utility model discloses a low-frequency broadband strong sound-absorbing underwater acoustic wedge. The low-frequency broadband strong sound-absorbing underwater acoustic wedge includes: a wedge body, an acoustic cavity 4 inside the wedge body, and a dissipation unit inside the acoustic cavity 4. The acoustic impedance of the dissipation unit is lower than the acoustic impedance of the wedge body, and the dissipation unit is a flexible dissipation unit. The acoustic cavity 4 includes a first sound-absorbing cavity 41, a second sound-absorbing cavity 42, a third sound-absorbing cavity 43, and a fourth sound-absorbing cavity 44 arranged and connected sequentially along a first direction. The first sound-absorbing cavity 41, the third sound-absorbing cavity 43, and the fourth sound-absorbing cavity 44 are all fixed-diameter structures, and their radii are in the first direction. The radius of the second sound-absorbing cavity 42 gradually increases along the first direction, and the radii of the two ends of the second sound-absorbing cavity 42 are equal to the radii of the first sound-absorbing cavity 41 and the third sound-absorbing cavity 43, respectively. The fourth sound-absorbing cavity 44 penetrates the wedge body at the end away from the first sound-absorbing cavity 41, and an impedance strengthening member 45 is provided inside the fourth sound-absorbing cavity 44. The cover plate 3 is located at the end of the wedge body away from the first sound-absorbing cavity 41 and seals the fourth sound-absorbing cavity 44. The first direction is set from the first end of the wedge body toward the second end of the wedge body. The cross-section of the acoustic cavity 4 and the cross-section of the first sound-absorbing part are perpendicular to the first direction.

[0043] This utility model relates to a low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge, which includes a wedge body and an acoustic cavity 4 inside the wedge body. The acoustic cavity 4 contains a dissipation unit. When a sound wave enters the acoustic cavity 4, because the acoustic impedance of the dissipation unit is lower than that of the wedge body, and the dissipation unit is a flexible dissipation unit, it is easy to vibrate after absorbing the sound wave energy. This is equivalent to constructing an approximately free boundary for the acoustic cavity 4. This makes it easy for the sound wave to resonate with the acoustic cavity 4, and causes shear deformation of the sidewall of the acoustic cavity 4, thereby improving the dissipation capacity of the acoustic cavity 4. Thus, without extending the length of the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge, the low-frequency sound absorption performance of the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge is improved.

[0044] Furthermore, the acoustic cavity 4 in this invention includes a first sound-absorbing cavity 41, a second sound-absorbing cavity 42, a third sound-absorbing cavity 43, and a fourth sound-absorbing cavity 44 arranged and connected sequentially along a first direction; the first sound-absorbing cavity 41, the third sound-absorbing cavity 43, and the fourth sound-absorbing cavity 44 are all fixed-diameter structures, and their radii increase sequentially along the first direction. The radius of the second sound-absorbing cavity 42 gradually increases along the first direction, and the radii at both ends of the second sound-absorbing cavity 42 are equal to the radii of the first sound-absorbing cavity 41 and the third sound-absorbing cavity 43, respectively. The above-mentioned arrangement of the acoustic cavity 4 makes the acoustic cavity 4 larger in size, which can easily convert the incident longitudinal wave into a transverse wave with a shorter wavelength, thereby improving sound wave dissipation and improving low-frequency sound absorption capability.

[0045] Meanwhile, the radius of the third sound-absorbing cavity 43 is smaller than that of the fourth sound-absorbing cavity 44. The end of the fourth sound-absorbing cavity 44 away from the third sound-absorbing cavity 43 passes through the end of the wedge body away from the first sound-absorbing cavity 41. The cover plate 3 is located at the end of the wedge body close to the fourth sound-absorbing cavity 44 and seals the fourth sound-absorbing cavity 44. The fourth sound-absorbing cavity 44 strengthens the shear deformation of the surface of the fourth sound-absorbing cavity 44 facing the third sound-absorbing cavity 43, further improving the low-frequency sound absorption performance. The impedance reinforcement 45 increases the non-uniformity of stress and strain inside the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge, strengthens the shear deformation of the surface of the fourth sound-absorbing cavity 44 facing the third sound-absorbing cavity 43, improves the low-frequency sound absorption performance, and reduces the problem of obvious sound absorption valley in the mid-frequency band caused by cavity anti-resonance, making the sound absorption frequency range of the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge of this utility model wider.

[0046] Based on the above structure, this invention can achieve lower frequency, wider bandwidth, and higher efficiency sound absorption performance of the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge with a smaller length.

[0047] The first sound-absorbing cavity 41, the third sound-absorbing cavity 43, and the fourth sound-absorbing cavity 44 are all cylindrical; the second sound-absorbing cavity 41 is frustoconical. The wedge body and the cover plate 3 are made of rubber or viscoelastic polymers such as polyurethane; the acoustic properties of the materials used for the wedge body and the cover plate 3 can be the same or different. Specifically, both the wedge body and the cover plate 3 are made of butyl rubber, and the density ρ of the wedge body and the density ρ of the cover plate 3 are... m Both are 1160 kg / m 3 Young's modulus E of the wedge body and cover plate 3 m Both are 10MPa-200MPa, and the Poisson's ratio ν of the wedge body and cover plate 3 is... m Both are 0.497, and the loss factor η of the wedge body and cover plate 3 is 0.497. m All are 0.5-1.5;

[0048] The dissipation unit can specifically be air filling the acoustic cavity 4. By constructing an approximately free boundary for the wedge body through air, it facilitates shear deformation on the sidewalls of the acoustic cavity 4, thereby enhancing the dissipation capability of the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge. Alternatively, the dissipation unit can also be made of other flexible sound-absorbing materials that can construct an approximately free boundary for the wedge body, referred to as flexible sound-absorbing components. The fourth sound-absorbing cavity 44 enhances the shear deformation of its upper surface, further improving the low-frequency sound absorption performance of the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge. An impedance reinforcement member 45 is embedded within the fourth sound-absorbing cavity 44. Without the impedance reinforcement member 45, the acoustic cavity 4 is prone to anti-resonance, leading to a significant sound absorption valley in the mid-frequency range. The impedance reinforcement member 45 can be made of aluminum alloy, or it can be made of rigid plastic or porous aluminum foam; or it can be made of a material with the rigidity required by this invention and capable of improving impedance performance. The cover plate 3 seals the wedge body, keeping the acoustic cavity 4 closed; the cover plate 3 can be coaxially bonded to the wedge body.

[0049] The wedge body includes a first sound-absorbing part 1 and a second sound-absorbing part 2 arranged sequentially and connected along a first direction. The cross-section of the first sound-absorbing part 1 gradually increases along the first direction. An acoustic cavity 4 is opened in both the first sound-absorbing part 1 and the second sound-absorbing part 2. The cross-sections of each region of the second sound-absorbing part 2 along the first direction are equal in the first direction. The cross-section of the end of the first sound-absorbing part 1 near the second sound-absorbing part 2 is equal to the cross-section of the second sound-absorbing part 2. The cross-sections of both the first sound-absorbing part and the second sound-absorbing part are perpendicular to the first direction.

[0050] The wedge body includes a first sound-absorbing part 1 whose cross-section gradually increases along a first direction. The first direction extends from the first end of the wedge body to the second end of the wedge body, and the cross-section is perpendicular to the first direction. This gives the wedge body a gradually changing impedance shape, allowing sound waves to smoothly transition from the water into the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge, reducing sound wave reflection, and allowing sound waves to gradually enter the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge and be absorbed, thus ensuring the high-efficiency sound absorption of the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge.

[0051] like Figures 1-5 As shown, the first sound-absorbing cavity 41, the second sound-absorbing cavity 42, the third sound-absorbing cavity 43, the fourth sound-absorbing cavity 44, and the impedance reinforcement member 45 are coaxially arranged; this achieves a smooth transition of sound waves in the above structure, reduces sound wave reflection, and enhances the sound absorption effect. Figures 1-5 As shown, the first sound-absorbing cavity 41 and the second sound-absorbing cavity 42 are located inside the first sound-absorbing part 1, and the third sound-absorbing cavity 43 and the fourth sound-absorbing cavity 44 are located inside the second sound-absorbing part 2.

[0052] like Figures 1-3As shown, the length of the low-frequency broadband strong sound-absorbing underwater acoustic wedge in the first direction is H, the length of the first sound-absorbing part 1 in the first direction is H1, the length of the second sound-absorbing part 2 in the first direction is H2, and the length of the cover plate 3 in the first direction is H3, where H = H1 + H2 + H3. To ensure that the low-frequency broadband strong sound-absorbing underwater acoustic wedge has a small length, the value of H is in the range of H ≤ 470 mm, 40 mm ≤ H1 ≤ 450 mm, 40 mm ≤ H2 ≤ 250 mm, and 2 mm ≤ H3 ≤ 6 mm. Specifically, 50 mm ≤ H1 ≤ 400 mm and 50 mm ≤ H2 ≤ 200 mm. Considering that the cover plate 3 needs to have a certain pressure resistance, 3 mm ≤ H3 ≤ 5 mm.

[0053] like Figures 1-3 As shown, the first sound-absorbing part 1 is frustum-shaped, and the second sound-absorbing part 2 is cylindrical. The radius of the end of the first sound-absorbing part 1 away from the second sound-absorbing part 2 is R1, where 1mm ≤ R1 ≤ 8mm, specifically 2mm ≤ R1 ≤ 5mm; the radius of the end of the first sound-absorbing part 1 near the second sound-absorbing part 2 is R2, where 10mm ≤ R2 ≤ 70mm, specifically 18mm ≤ R2 ≤ 60mm; the radius of the end of the second sound-absorbing part 2 near the first sound-absorbing part 1 is R2, and the radius of the cover plate 3 is R2. Figure 3 , Figure 4 As shown, in addition to the above shapes, the first sound-absorbing part 1 can also be wedge-shaped, and the second sound-absorbing part 2 can also be cubic; the wedge-shaped first sound-absorbing part 1 is obtained by stretching the frustum-shaped first sound-absorbing part along the same direction to both sides, while keeping the geometric parameters such as the internal acoustic cavity and impedance reinforcement unchanged. Figure 4 As shown, multiple wedge-shaped low-frequency broadband strong sound-absorbing underwater acoustic sound-absorbing wedges are arranged in an alternating pattern. This can be obtained by assembling multiple wedge-shaped low-frequency broadband strong sound-absorbing underwater acoustic sound-absorbing wedges, or by integral molding. The first and second sound-absorbing parts of the wedge-shaped low-frequency broadband strong sound-absorbing underwater acoustic sound-absorbing wedges can be assembled by bonding or by pre-embedding mounting parts and mounting holes. In addition to the shape described above, while meeting the requirements of low-frequency broadband high-efficiency sound absorption of this utility model, the shape of the wedge body can also be plate-shaped, block-shaped (compared to plate-shaped, block-shaped wedge body is thicker), column-shaped, spherical, conical, pyramidal, etc.

[0054] like Figures 1-5As shown, the radius of the first sound-absorbing cavity 41 is r1, 1.5mm≤r1≤10mm, specifically 2mm≤r1≤8mm; the height is h1, 5mm≤h1≤300mm, specifically 10mm≤h1≤200mm; the height of the second sound-absorbing cavity 42 is h2, 5mm≤h2≤250mm, specifically 10mm≤h2≤150mm; the radius of the third sound-absorbing cavity 43 is r2, 2mm≤r2≤25mm, specifically 4mm≤r2≤15mm; the height is h3, 5mm≤h3≤200mm, specifically 10mm≤h2≤100mm; the radius of the fourth sound-absorbing cavity 44 is r3, r3=r2+d r ,1mm≤d r ≤20mm, specifically 2mm≤d r The thickness of the impedance reinforcement 45 is ≤10mm, and the height is h4, 2mm≤h4≤40mm, specifically 5mm≤r1≤30mm; the impedance reinforcement 45 is cylindrical, and the wall thickness of the impedance reinforcement 45 is t, 0.5mm≤t≤4mm, specifically 0.5mm≤t≤2mm; the radius of the impedance reinforcement 45 is r3, and the height is h4.

[0055] The low-frequency broadband strong sound-absorbing underwater acoustic wedge also includes a liner plate, which is located at the end of the cover plate 3 away from the wedge body. The length of the liner plate in the first direction is H4, 10mm≤H4≤50mm, specifically 10mm≤H4≤40mm, and the radius of the liner plate is R2. When the low-frequency broadband strong sound-absorbing underwater acoustic wedge of this invention is applied to an anechoic pool environment, and the anechoic pool is a water-filled container enclosed by a heavy liner plate of limited lateral length, the side of the liner plate away from the cover plate 3 is the air medium. The liner plate can be made of a rigid material such as steel. The underwater acoustic absorbing wedge of this invention can be understood as being applicable to water pool environments such as anechoic pools. When underwater acoustic absorbing wedges are used in anechoic pools, the pools are made of rigid materials such as metal or steel to ensure that the wedges have good low-frequency sound absorption performance; or, if the requirements for low-frequency sound absorption performance are lower, the pools can be made of other materials such as cement.

[0056] Due to the mass effect of the liner, the low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge, under low-frequency sound wave excitation, will exhibit an overall resonance mode with the liner as the equivalent mass and the low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge as the equivalent stiffness. This mode is beneficial to the improvement of low-frequency performance. In addition, after the method for preparing the low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge in this invention is reasonably designed, the external shape parameters of the low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge and the size parameters of the acoustic cavity 4 can achieve good impedance matching performance while exciting the sound wave dissipation capability of the low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge. This is an important foundation for the low-frequency broadband sound absorption of the low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge. On the other hand, the introduction of the fourth sound-absorbing cavity 44 and the impedance reinforcement 45 can increase the non-uniformity of stress and strain inside the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge while maintaining the impedance matching performance, strengthen the shear deformation of the surface of the fourth sound-absorbing cavity 44 facing the third sound-absorbing cavity 43, and thereby further improve the low-frequency sound absorption performance.

[0057] In other words, by utilizing the mass effect of the liner, the fourth sound-absorbing cavity 44, and the impedance reinforcement 45, this invention further improves the low-frequency sound absorption performance of the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge, enabling this invention to achieve a good sound absorption effect with low-frequency broadband and high efficiency. Under the constraint of a total length not exceeding 470mm, it achieves high-efficiency sound absorption (sound absorption coefficient greater than 0.95) in the low-frequency broadband (0.5kHz~80kHz frequency band).

[0058] Furthermore, this utility model also discloses a method for preparing the above-mentioned low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge, comprising the following steps: Step S1, using [H1, H2, H3, R1, R2, r1, r2, d r [h1, h2, h3, h4, t] are the optimization variables, and the constraints of the low-frequency broadband strong sound-absorbing underwater acoustic sound-absorbing wedge are determined; Step S2, according to the constraints of the low-frequency broadband strong sound-absorbing underwater acoustic sound-absorbing wedge, the minimum sound absorption coefficient of the low-frequency broadband strong sound-absorbing underwater acoustic sound-absorbing wedge in the required frequency band is used as the optimization objective function, an optimization model is established, optimization design is carried out, and the dimensional parameters of each structure in the low-frequency broadband strong sound-absorbing underwater acoustic sound-absorbing wedge are determined; Step S3, according to the dimensional parameters of each structure in the low-frequency broadband strong sound-absorbing underwater acoustic sound-absorbing wedge, the low-frequency broadband strong sound-absorbing underwater acoustic sound-absorbing wedge is manufactured; where H1 is the length of the first sound-absorbing part in the first direction, H2 is the length of the second sound-absorbing part in the first direction, H3 is the length of the cover plate in the first direction, R1 is the radius of the end of the first sound-absorbing part away from the second sound-absorbing part, R2 is the radius of the end of the second sound-absorbing part close to the first sound-absorbing part, r1 is the radius of the first sound-absorbing cavity, r2 is the radius of the third sound-absorbing cavity, d rh1 is the radius difference between the fourth and third sound-absorbing cavities, h2 is the height of the first sound-absorbing cavity, h3 is the height of the third sound-absorbing cavity, h4 is the height of the fourth sound-absorbing cavity, and t is the wall thickness of the impedance reinforcement. Low-frequency broadband strong sound-absorbing underwater acoustic wedges can be manufactured using CNC lathes and other machining equipment.

[0059] The wedge body and cover plate 3 can be made of butyl rubber, the impedance reinforcement 45 is made of aluminum alloy, and the steel liner is selected according to the typical application scenario. The length of the liner in the first direction is 38mm (or it can be adjusted to other parameters according to the working conditions).

[0060] Furthermore, before step S1, a genetic algorithm, such as the genetic algorithm toolbox in the commercial mathematical software MATLAB, and a finite element method, such as the commercial finite element software COMSOL Multiphysics, are combined to determine the materials of the wedge body, cover plate 3, impedance reinforcement 45, and liner plate according to the working conditions, and to determine the length H4 of the liner plate in the first direction. The liner plate is located at the end of the cover plate 3 away from the wedge body.

[0061] In step S2, the minimum and maximum sound absorption coefficients of the low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge within the 0.5kHz to 80kHz frequency band are used as the optimization objective function; the dimensional parameters of each structure of the low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge should meet the following constraints:

[0062] The constraint conditions for the low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge are:

[0063] Based on the above optimization model, the dimensional parameters of each structure of the low-frequency broadband strong sound-absorbing underwater acoustic wedge of this utility model are obtained as follows: H1 = 380mm, H2 = 85mm, H3 = 5mm, R1 = 13 / 2mm, R2 = 59mm, r1 = 3.8mm, r2 = 11mm, d r =15mm, h1=200mm, h2=54mm, h3=22mm, h4=20mm, t=1mm, H4=38mm.

[0064] like Figure 6 , Figure 7 As shown, Figure 6 The results are based on the theoretical calculation of the absorption coefficient of the low-to-medium frequency broadband strong sound-absorbing underwater sound-absorbing wedge of this invention. Figure 7 To compare the sound absorption coefficients under three different conditions—without the impedance reinforcement 45, the radius of the fourth sound-absorbing cavity 44 reduced to the same radius as the third sound-absorbing cavity 43, and the length of the first sound-absorbing cavity 41 shortened to 50mm in the first direction—with the sound absorption coefficients of the low-frequency broadband strong sound-absorbing underwater acoustic wedge of this utility model; by Figure 6 , Figure 7It can be seen that the sound absorption coefficient of the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge of this utility model is greater than 0.95 in the frequency range of 0.5kHz to 80kHz, and it has a low-frequency broadband and efficient sound absorption effect.

[0065] This utility model discloses multiple technical solutions, but does not provide any contrary technical teachings.

[0066] In this article, "and / or" refers to the text content preceding "and / or" and the text content following "and / or", which can exist simultaneously or separately; for example, "A and / or B" includes the case where only A or B exists, as well as the case where A and B exist simultaneously.

[0067] This utility model uses specific examples to illustrate its principles and implementation methods. The above description of the embodiments is only for the purpose of helping to understand the method and core idea of ​​this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the idea of ​​this utility model. In summary, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A low-frequency broadband strong sound-absorbing underwater acoustic wedge considering the backing mass effect, characterized in that, The low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge includes: The device comprises a wedge-shaped body with an acoustic cavity inside. A dissipation unit is located within the acoustic cavity. The acoustic impedance of the dissipation unit is lower than that of the wedge-shaped body, and the dissipation unit is a flexible dissipation unit. The acoustic cavity includes a first sound-absorbing cavity, a second sound-absorbing cavity, a third sound-absorbing cavity, and a fourth sound-absorbing cavity, which are sequentially arranged and connected along a first direction. The first, third, and fourth sound-absorbing cavities are all fixed-diameter structures, and their radii increase sequentially along the first direction. The radius of the second sound-absorbing cavity gradually increases along the first direction, and the radii at both ends of the second sound-absorbing cavity are equal to the radii of the first and third sound-absorbing cavities, respectively. The fourth sound-absorbing cavity penetrates the wedge-shaped body at the end away from the first sound-absorbing cavity, and an impedance reinforcement member is located within the fourth sound-absorbing cavity. A cover plate is disposed at the end of the wedge body away from the first sound-absorbing cavity and blocks the fourth sound-absorbing cavity; The first direction extends from the first end of the wedge body toward the second end of the wedge body, and the first direction is perpendicular to the cross-section of the acoustic cavity.

2. The low-frequency broadband strong sound-absorbing underwater acoustic wedge according to claim 1, characterized in that, The wedge body includes a first sound-absorbing part and a second sound-absorbing part arranged sequentially and connected along the first direction. The cross-section of the first sound-absorbing part gradually increases along the first direction, and the cross-section of the second sound-absorbing part is the same in the first direction. The cross-section of the first sound-absorbing part near the second sound-absorbing part is equal to the cross-section of the second sound-absorbing part. The cross-sections of the first sound-absorbing part and the second sound-absorbing part are both perpendicular to the first direction. The first sound-absorbing cavity and the second sound-absorbing cavity are located within the first sound-absorbing part, and the third sound-absorbing cavity and the fourth sound-absorbing cavity are located within the second sound-absorbing part.

3. The low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge according to claim 1, characterized in that, The underwater acoustic absorbing wedge is applied to a steel structure water tank; And / or, the dissipation unit includes air filling the acoustic cavity; or, the dissipation unit includes a flexible sound-absorbing element disposed within the acoustic cavity.

4. The low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge according to claim 2, characterized in that, The length of the low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge in the first direction is H, the length of the first sound-absorbing part in the first direction is H1, the length of the second sound-absorbing part in the first direction is H2, and the length of the cover plate in the first direction is H3. Where H = H1 + H2 + H3, H ≤ 470 mm, 40 mm ≤ H1 ≤ 450 mm, 40 mm ≤ H2 ≤ 250 mm; 2 mm ≤ H3 ≤ 6 mm.

5. The low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge according to claim 2, characterized in that, The first sound-absorbing part is frustum-shaped, and the second sound-absorbing part is cylindrical; the radius of the end of the first sound-absorbing part away from the second sound-absorbing part is R1, 1mm≤R1≤8mm, the radius of the end of the first sound-absorbing part closer to the second sound-absorbing part is R2, 10mm≤R2≤70mm, the radius of the end of the second sound-absorbing part closer to the first sound-absorbing part is R2, and the radius of the cover plate is R2.

6. The low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge according to claim 1, characterized in that, The radius of the first sound-absorbing cavity is r1, 1.5mm≤r1≤10mm, and the length of the first sound-absorbing cavity in the first direction is h1, 5mm≤h1≤300mm; The length of the second sound-absorbing cavity in the first direction is h2, where 5mm ≤ h2 ≤ 250mm; The radius of the third sound-absorbing cavity is r2, 2mm≤r2≤25mm, and the length of the third sound-absorbing cavity in the first direction is h3, 5mm≤h3≤200mm; The radius of the fourth sound-absorbing cavity is r3, where r3 = r2 + d r ,1mm≤d r ≤20mm, the length of the fourth sound-absorbing cavity in the first direction is h4, 2mm≤h4≤40mm; The impedance reinforcement is cylindrical, with a wall thickness of t, where 0.5 mm ≤ t ≤ 4 mm, a radius of r3, and a length of h4 in the first direction.

7. The low-frequency broadband strong sound-absorbing underwater acoustic wedge according to claim 1, characterized in that, The low-frequency broadband strong sound-absorbing underwater sound-absorbing wedge also includes a liner plate, which is located at the end of the cover plate away from the wedge body. The length of the liner plate in the first direction is H4, 10mm≤H4≤50mm, and the radius of the liner plate is R2.

8. The low-frequency broadband strong sound-absorbing underwater acoustic absorbing wedge according to claim 2, characterized in that, The first sound-absorbing cavity, the second sound-absorbing cavity, the third sound-absorbing cavity, the fourth sound-absorbing cavity, and the impedance reinforcement are coaxially arranged; And / or, the first sound-absorbing part is wedge-shaped, and the second sound-absorbing part is cubic.

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