Metastructure sound absorption device and sound absorption system

Abstract

The invention provides a super-structure sound absorption device and a sound absorption system, and the device comprises a housing which forms a cavity with an opening, and is provided with two inner walls which face each other in a first direction, and is provided with two inner walls which face each other in a second direction; the sound absorption assembly comprises a first sound absorption body which is arranged in the cavity, gaps are formed between the two ends, in the first direction, of the first sound absorption body and the opposite inner walls, and the two ends, in the second direction, of the first sound absorption body abut against the two opposite inner walls in the second direction respectively; the second sound absorption body is arranged in the cavity and is constructed to be of a gradually-shrinking structure in the third direction, the second sound absorption body is provided with two opposite side walls in the second direction, and the two side walls abut against the opposite inner walls respectively; a first acoustic cavity is defined by the first sound absorber, the second sound absorber and the shell, the acoustic cavity is used for absorbing signals of a second frequency band in external sound wave signals, and the frequency of the first frequency band is larger than that of the second frequency band.

Description

Technical Field

[0001] This invention relates to the field of sound absorption, and particularly to a metamorphic sound absorption device and system for use in the range of 50 Hz to 200 Hz. Background Technology

[0002] With the development and innovation of science and technology, acoustic wind tunnels have placed more stringent requirements on materials and structures with special acoustic functions, especially in terms of low-frequency sound absorption performance. These requirements demand both limited thickness and excellent sound absorption performance (for example, with a thickness of 400mm to 600mm, the acoustic performance requirement for a low-frequency noise reduction structure in the 50Hz to 200Hz frequency band (frequency resolution of 1Hz) is an absorption coefficient of over 0.9). Therefore, systematically developing low-frequency broadband metastructure sound-absorbing modules is of great significance and far-reaching strategic value.

[0003] Metamaterials are a class of artificial composite structures or composite materials with extraordinary physical properties not found in natural materials. As a new type of artificially designed and manufactured material, they break through the performance limitations of natural materials and inject strong impetus into scientific and technological progress and social development.

[0004] Existing low-frequency metamaterials (e.g., an epitaxial Helmholtz resonator structure composed of multiple epitaxial holes and cavities), multilayer micro-perforated plate sound-absorbing structures that incorporate sound-absorbing materials, and epitaxial Helmholtz resonator structures composed of multiple epitaxial holes and cavities, etc., all have limitations in sound absorption modules with limited thickness. They either have defects in the sound absorption coefficient in the 50Hz to 200Hz frequency band, failing to meet the aforementioned sound absorption performance (e.g., multilayer micro-perforated plate sound-absorbing structures that incorporate sound-absorbing materials); or they have complex structures, high manufacturing costs, and are prone to damage during use. Summary of the Invention

[0005] In view of this, the present invention provides a metamorphic sound-absorbing device and a sound-absorbing system, the metamorphic sound-absorbing device comprising:

[0006] A housing that forms a cavity with an opening, the housing having two inner walls facing each other along a first direction and two inner walls facing each other along a second direction;

[0007] Sound-absorbing components, including:

[0008] A first sound absorber is disposed in the cavity and located at one end near the opening of the shell. The two ends of the first sound absorber along the first direction respectively abut against two inner walls facing each other along the first direction. The two ends of the first sound absorber along the second direction each form a gap with the facing inner wall.

[0009] The second sound absorber is disposed within the cavity and is configured as a tapered structure along a third direction, which is perpendicular to the first direction and the second direction. The first end of the second sound absorber with a smaller cross-sectional area abuts against the first sound absorber, and the second end with a larger cross-sectional area abuts against the four inner walls of the housing. The second sound absorber has two opposing side walls along the first direction, and each of the two side walls abuts against the facing inner wall.

[0010] The first sound absorber, the second sound absorber, and the shell form a first acoustic cavity. The first and second sound absorbers are adapted to absorb signals of a first frequency band from external sound wave signals from the opening. The acoustic cavity is used to absorb signals of a second frequency band from the external sound wave signals. The frequency of the first frequency band is greater than the frequency of the second frequency band.

[0011] According to an embodiment of the present invention, the length of the gap along the second direction is less than the distance between the inner wall and the first end in the second direction.

[0012] According to an embodiment of the present invention, the projection of the first sound absorber onto the preset surface is rectangular, and the projection of the second sound absorber onto the preset surface is trapezoidal, wherein the preset surface is a plane determined according to the second direction and the third direction.

[0013] According to an embodiment of the present invention, the above-mentioned superstructure sound-absorbing device further includes a third sound absorber disposed in the cavity, located on the side with the larger cross-sectional area of ​​the second sound absorber. The third sound absorber abuts against the four inner walls of the housing, is spaced apart from the second sound absorber along the third direction, and forms a second acoustic cavity with the second sound absorber and the housing. The second acoustic cavity is used to further absorb the second frequency band signal in the sound wave signal absorbed by the first acoustic cavity.

[0014] According to an embodiment of the present invention, the projection of the third sound absorber onto a preset surface is rectangular, and the preset surface is a plane determined according to the second direction and the third direction.

[0015] According to an embodiment of the present invention, the height of the third sound absorber along the third direction ranges from 25mm to 100mm.

[0016] According to an embodiment of the present invention, the height of the second sound absorber in a third direction ranges from 325mm to 525mm.

[0017] According to an embodiment of the present invention, the height of the second acoustic cavity along the third direction is 25mm to 100mm.

[0018] According to an embodiment of the present invention, the height of the first sound absorber along the third direction ranges from 25mm to 100mm.

[0019] As a second aspect of the invention, a sound-absorbing system is also provided, comprising:

[0020] Multiple of the above-mentioned superstructure sound-absorbing devices are arranged in an array, wherein one end of the opening of the attraction device faces the same direction.

[0021] According to embodiments of the present invention, the first and second sound absorbers are primarily composed of porous sound-absorbing materials (e.g., melamine cotton, polyurethane foam). When sound waves are introduced, they penetrate the intricate micropores within the material, causing intense friction and viscous movement between air molecules in the pores and the fiber surface, thereby efficiently converting sound energy into heat energy for dissipation. However, low-frequency sound waves (e.g., the wavelength of a 50Hz sound wave is approximately 6.8m) have extremely long wavelengths and weak penetrating power, making it difficult to penetrate deep into the pores of porous materials. They can only undergo weak reflection on the material surface and cannot be effectively dissipated. Therefore, the first and second sound absorbers primarily absorb sound wave signals in the higher first frequency band (i.e., 100Hz~200Hz) of the 50Hz~200Hz sound wave range.

[0022] According to an embodiment of the present invention, the first acoustic cavity is similar to a Helmholtz resonator. This first acoustic cavity achieves absorption of sound wave signals in the lower frequency band (i.e., 50Hz~100Hz) of the 50Hz~200Hz sound wave range, particularly playing a decisive role in the absorption of sound wave signals in the 50-75Hz range. External sound wave signals enter the first acoustic cavity through a gap. The sealed air column inside the first acoustic cavity resonates with the signal in the second frequency band of the externally incident sound wave, efficiently converting the acoustic energy of the second frequency band of the 50Hz~200Hz sound wave into heat energy, thereby achieving selective and efficient absorption of the signal in the second frequency band of the sound wave. Specifically, when the lower frequency band of the sound wave entering the cavity matches the inherent resonant frequency of the first acoustic cavity (determined by parameters such as the volume of the first acoustic cavity and the size of the gap), the sealed air column inside the cavity will resonate strongly with the sound wave. During this process, the air column rubs against the cavity wall of the first acoustic cavity (especially the porous material surface of the sound absorber), and viscous forces are formed between air molecules, which can convert the mechanical energy of low-frequency sound waves into heat energy, thus dissipating sound energy.

[0023] According to an embodiment of the present invention, based on the principle of acoustic resonance, the first acoustic cavity has a high absorption coefficient in a very narrow frequency band near its resonant frequency. In this application, the bandwidth of the sound wave signal is relatively wide, ranging from 50Hz to 200Hz. Through the synergistic effect of the first sound absorber, the second sound absorber, and the first acoustic cavity, efficient absorption of sound waves from 50Hz to 200Hz can be achieved.

[0024] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0025] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings.

[0026] Figure 1 A cross-sectional view of a metamorphic sound-absorbing device provided according to an embodiment of the present invention is shown.

[0027] Figure 2 A schematic diagram of the space within the housing provided according to an embodiment of the present invention, not occupied by the first sound absorber, the second sound absorber, and the third sound absorber, is shown.

[0028] Figure 3 A schematic diagram of a housing provided according to an embodiment of the present invention is shown.

[0029] Figure 4 A perspective view of a simulation model of the metamorphic sound-absorbing device provided according to an embodiment of the present invention is shown.

[0030] Figure 5 The relationship between the sound absorption efficiency of the metamorphic sound-absorbing device provided according to an embodiment of the present invention and the length of the first sound-absorbing body is shown.

[0031] Figure 6 The relationship between the sound absorption efficiency of the metamorphic sound-absorbing device and the length variation of the first sound-absorbing body is shown in another embodiment of the present invention.

[0032] Figure 7 The relationship between the sound absorption efficiency of the metamorphic sound-absorbing device and the height variation of the second sound absorber provided according to an embodiment of the present invention is shown.

[0033] Figure 8 The relationship between the sound absorption efficiency of the metamorphic sound-absorbing device provided according to an embodiment of the present invention and the height variation of the second acoustic cavity is shown.

[0034] Figure 9 Simulation results of the sound absorption coefficient of the metamorphic sound-absorbing device provided according to a specific embodiment of the present invention are shown.

[0035] Figure 10 It shows Figure 9 The measured sound absorption coefficient of the superstructure sound absorption device in the middle.

[0036] Explanation of reference numerals in the attached figures

[0037] 10. Casing;

[0038] 21. First sound absorber;

[0039] 22. Second sound absorber;

[0040] 23 Third sound absorber

[0041] 30. First acoustic cavity;

[0042] 40. Second acoustic cavity;

[0043] 50 gaps

[0044] 70 incident end

[0045] 80 First Sound Absorbing Component

[0046] 90 Second Sound Absorbing Component

[0047] 100 Third Sound Absorbing Component

[0048] 110 casing

[0049] 120 gap

[0050] 130 First Cavity

[0051] 140 Second Cavity Detailed Implementation

[0052] Existing low-frequency metamaterials, such as multilayer micro-perforated sound-absorbing panels that combine sound-absorbing materials, couple the acoustic properties of porous sound-absorbing materials with those of multilayer micro-perforated panels to form a synergistic sound absorption system of "acoustic resistance-acoustic reactance-porous dissipation." The principle is that the multilayer micro-perforated panel structure provides an acoustic resistance-acoustic reactance resonance mechanism. By filling the interlayer spaces or behind the backplate with sound-absorbing materials, viscous and thermal conduction losses are increased, significantly increasing the acoustic resistance in the air layer. Furthermore, the elastic modulus of the sound-absorbing material, coupled with the air layer, can effectively adjust the system's "acoustic capacity" characteristics. Specifically, the principle can be summarized as follows: the multilayer micro-perforated panel structure combining sound-absorbing materials, through the synergy of the resonant sound absorption of the micro-perforated panels and the dissipative sound absorption of the porous materials, forms a composite mechanism of "frequency-selective resonance + full-band energy dissipation."

[0053] The extended Helmholtz resonator structure, composed of multiple extended holes and cavities, achieves sound wave absorption through the coupled resonance effect of the extended holes and cavities. Its principle can be summarized as an extension of the traditional Helmholtz resonator structure, optimizing the resonant frequency band and sound absorption efficiency through the combination of multiple extended holes and multi-stage cavities. The basic principle of the traditional Helmholtz resonator is as follows: The Helmholtz resonator consists of a neck (short tube) and a cavity. Its sound absorption essence is: when a sound wave is incident, the air column in the neck moves back and forth like a "mass block" (generating acoustic impedance), while the air in the cavity compresses and expands like a "spring" (generating acoustic resistance), forming a resonant system. When the frequency of the incident sound wave matches the system's natural frequency (determined by the neck length, neck diameter, and cavity volume), resonance causes friction between the air and the neck wall, converting sound energy into heat energy for dissipation. The epitaxial structure breaks through the limitations of the traditional single-cavity structure by extending the epitaxial aperture in multiple stages and combining the cavities in series / parallel. Through the acoustic impedance-acoustic reactance modulation of the epitaxial aperture and the resonant coupling of the multi-stage cavities, the traditional single-frequency absorption is extended into a broadband multi-peak absorption system.

[0054] In the process of realizing this invention, it was discovered that a low-frequency, wide-bandwidth, low-thickness, high-sound-absorbing metamorphic sound-absorbing device can be realized based on existing technology.

[0055] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0056] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0057] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0058] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0059] Figure 1 A cross-sectional view of a metamorphic sound-absorbing device provided according to an embodiment of the present invention is shown.

[0060] like Figure 1 As shown, the superstructure sound-absorbing device includes a housing 10 and a sound-absorbing assembly. The housing 10 forms a cavity with an opening, and has two inner walls facing each other along a first direction and two inner walls facing each other along a second direction. The sound-absorbing assembly includes a first sound-absorbing body 21 and a second sound-absorbing body 22. The first sound-absorbing body 21 is disposed in the cavity, and its two ends along the first direction each form a gap with the facing inner wall, while its two ends along the second direction respectively abut against the two inner walls facing each other along the second direction.

[0061] The second sound absorber 22 is disposed in the cavity and is constructed as a tapered structure along a third direction, which is perpendicular to the first and second directions. The first end of the second sound absorber 22 with a smaller cross-sectional area abuts against the first sound absorber 21, and the second end with a larger cross-sectional area abuts against the four inner walls of the housing 10. The second sound absorber 22 has two opposing side walls along the second direction, and each abuts against the facing inner wall.

[0062] The first sound absorber 21, the second sound absorber 22, and the housing 10 form a first acoustic cavity 30. The first sound absorber 21 and the second sound absorber 22 are used to absorb signals in the first frequency band of external sound wave signals transmitted through the opening. The acoustic cavity 30 is used to absorb signals in the second frequency band of external sound wave signals. The frequency of the first frequency band is greater than the frequency of the second frequency band. In this embodiment of the invention, the first frequency band is 100Hz~200Hz, and the second frequency band is 50Hz~100Hz.

[0063] According to an embodiment of the present invention, the first sound absorber 21 and the second sound absorber 22 are mainly composed of porous sound-absorbing materials (such as melamine cotton or polyurethane foam). When a sound wave signal is introduced, it penetrates the intricate micropores inside the material, causing the air molecules in the pores to undergo intense friction and viscous motion with the fiber surface, thereby efficiently converting sound energy into heat energy for dissipation. However, low-frequency sound waves (such as 50Hz sound waves with a wavelength of about 6.8m) have extremely long wavelengths and weak penetration capabilities, making it difficult to penetrate deep into the pores inside the porous material. They can only be weakly reflected on the surface of the material and cannot be effectively dissipated. Therefore, the first sound absorber 21 and the second sound absorber 22 mainly absorb sound wave signals in the first frequency band (100Hz~200Hz) of the 50Hz~200Hz sound wave signal range.

[0064] According to an embodiment of the present invention, the first acoustic cavity 30 is similar to a Helmholtz resonator. In this invention, the first acoustic cavity 30 achieves signal absorption for the lower frequency band of sound waves in the 50Hz-200Hz range. External sound waves enter the first acoustic cavity 30 through the slit 50. The enclosed air column inside the first acoustic cavity 30 resonates with the signal of the second frequency band in the incident sound waves, efficiently converting the acoustic energy of the second frequency band into heat energy, thereby achieving selective and efficient absorption of the signal of the second frequency band in the sound waves. Specifically, when the second frequency band sound wave signal entering the first acoustic cavity 30 matches the inherent resonant frequency of the first acoustic cavity (determined by parameters such as the volume of the first acoustic cavity 30 and the size of the slit 50), the enclosed air column inside the first acoustic cavity 30 will resonate strongly with the sound waves. During this process, the air column rubs against the cavity wall (especially the porous material surfaces of the two sound absorbers), and viscous forces are formed between air molecules, which can convert the mechanical energy of low-frequency sound waves into heat energy, thus dissipating the sound energy.

[0065] According to an embodiment of the present invention, based on the principle of acoustic resonance, the first acoustic cavity 30 has a high absorption coefficient within a very narrow frequency band near its resonant frequency. The configuration of the first acoustic cavity 30 plays a crucial role in the effective absorption of sound waves in the 50-70Hz range. In this application, the bandwidth of the sound waves is relatively wide, ranging from 50Hz to 200Hz. Through the synergistic effect of the first sound absorber 21, the second sound absorber 22, and the first acoustic cavity 30, efficient absorption of sound waves in the 50Hz-200Hz range can be achieved.

[0066] According to an embodiment of the present invention, the length of each slit 50 along the first direction is less than the distance between the inner wall and the first end of the second sound absorber 22 in the first direction. If the length of the slit 50 along the first direction is greater than or equal to the distance between the inner wall and the first end of the second sound absorber 22 in the first direction, the resonance mechanism will fail, thereby affecting the sound absorption effect of the metamaterial sound absorption device.

[0067] According to an embodiment of the present invention, the projection of the first sound absorber 21 onto the preset surface is rectangular, and the projection of the second sound absorber 22 onto the preset surface is trapezoidal. The preset surface is a plane determined according to the first direction and the third direction.

[0068] According to an embodiment of the present invention, the first sound absorber 21 with a rectangular projection provides a uniform frontal acoustic surface, ensuring that the sound wave signal can be efficiently and consistently initially incident and enter the interior of the metastructure sound absorption device; the trapezoidal second sound absorber, through its tapered geometry, guides the sound wave to undergo multiple reflections, diffractions and scatterings within the first acoustic cavity 30, effectively extending the sound wave propagation path, increasing the interaction time and contact area between the sound energy and the sound-absorbing material, thereby improving the absorption effect of the sound wave signal.

[0069] The regular and parameterized geometry of the first and second sound absorbers 21 and 22 makes it easy to model, parameterize and optimize their acoustic characteristics through simulation, which simplifies the sound absorption performance debugging process for different target frequencies (such as 50Hz-200Hz) and improves product development efficiency and performance consistency.

[0070] According to an embodiment of the present invention, the above-mentioned superstructure sound-absorbing device further includes a third sound-absorbing body 23, which is disposed in the cavity and located on the side with a larger cross-sectional area of ​​the second sound-absorbing body. The third sound-absorbing body 23 abuts against the four inner walls of the housing 10, is spaced apart from the second sound-absorbing body 22 along a third direction, and together with the second sound-absorbing body 22 and the housing 10, forms a second acoustic cavity 40. The second acoustic cavity 40 is used to further absorb the second frequency band signal in the sound wave signal after absorption by the first acoustic cavity 30.

[0071] The residual sound waves of the second frequency band that are not completely dissipated after being absorbed by the resonance of the first acoustic cavity will penetrate into the second acoustic cavity 40 through the pores of the second sound absorber 22. When the residual second frequency band sound waves enter the second acoustic cavity 40, the sealed air column inside the cavity will resonate with the sound waves. During the resonance process, the air column will generate friction with the inner wall of the cavity (the upper surface of the third sound absorber 23, the lower surface of the second sound absorber 22, and the inner wall of the shell), and at the same time, the air molecules will form a viscous force, which will further convert the sound energy of the residual sound waves into heat energy.

[0072] According to an embodiment of the present invention, the projection of the third sound absorber 23 onto the preset surface is rectangular. The regular rectangular projection facilitates the processing, cutting, and installation of the third sound absorber, reducing the complexity of the production process and manufacturing costs, and ensuring product consistency. In terms of acoustic performance, the rectangular structure provides a uniform acoustic impedance distribution, which is beneficial for the smooth transition of sound wave signals and their dissipation deep into the material, avoiding sound wave scattering or reflection caused by irregular shapes, thereby improving sound energy conversion efficiency and forming a more effective coupling with the second acoustic cavity 40, enhancing the broadband absorption effect on residual mid-to-low frequency sound waves. The space inside the housing not occupied by the first sound absorber 21, the second sound absorber 22, and the third sound absorber 23 is as follows: Figure 2 As shown.

[0073] According to an embodiment of the present invention, the housing 10 is used to fix the first sound absorber 21, the second sound absorber 22, and the third sound absorber 23. The housing 10 may be a hollow structure (e.g., Figure 3 (As shown) or a solid structure.

[0074] According to an embodiment of the present invention, in practical applications, one end of the superstructure sound-absorbing device near the third sound absorber 23 is disposed on the mounting surface. The third sound absorber 23, the mounting surface, and the housing 10 form a third acoustic cavity, which is generally a mounting cavity suitable for further absorbing the absorbed sound wave signal. The distance between the third sound absorber and the mounting surface can be, for example, 100 mm.

[0075] According to an embodiment of the present invention, the sum of the heights of the first sound absorber 21, the second sound absorber 22, the third sound absorber 23, and the second acoustic cavity 40 along a third direction ranges from 400 nm to 600 mm, preferably 575 mm. The height of the first sound absorber along a third direction ranges from 25 mm to 100 mm. The height of the second sound absorber along a third direction ranges from 275 mm to 525 mm. The height of the second acoustic cavity along a third direction ranges from 25 mm to 100 mm. The height of the third sound absorber 23 along a third direction ranges from 25 mm to 100 mm.

[0076] According to an embodiment of the present invention, the first sound absorber 21, the second sound absorber 22, and the third sound absorber 23 are precisely height-distributed and spatially arranged to achieve an optimal balance between acoustic performance and structural compactness. The first sound absorber 21, as the frontal surface, provides sufficient porous material thickness to ensure efficient dissipation of mid-to-high frequency sound waves. The second sound absorber 22, as the core, cleverly utilizes malleable porous material to create the first acoustic cavity 30, significantly enhancing low-frequency capture and dissipation capabilities while achieving sound absorption through porous material. The third sound absorber 23, as a secondary dissipation layer, works synergistically with the second acoustic cavity 40 to ensure deep absorption of residual low-frequency sound waves. The matching design of the sum of the three heights with the total height avoids wasted internal space, maximizing the sound energy processing capacity within a limited overall size. Ultimately, this enables the module to stably achieve a high sound absorption coefficient of over 0.9 in the target frequency band of 50Hz-200Hz, while ensuring the module's strength and engineering applicability.

[0077] According to an embodiment of the present invention, the provided meta-absorbing sound device can be seen to achieve a sound absorption coefficient of 0.9 or higher for sound waves in the 50Hz to 200Hz frequency band (frequency resolution 1Hz) when the sum of the heights of the first sound absorber 21, the second sound absorber 22, the third sound absorber 23 and the second acoustic cavity 40 along a third direction is in the range of 400nm to 600mm.

[0078] According to an embodiment of the present invention, a simulation model of a metamorphic sound-absorbing device is constructed below.

[0079] Figure 4 A perspective view of a simulation model of the metamorphic sound-absorbing device provided according to an embodiment of the present invention is shown.

[0080] The sound absorption performance of this metamorphic sound-absorbing device can be simulated and analyzed in simulation software. For example... Figure 4 As shown, when simulating the metamorphic sound-absorbing device, an incident end 70 needs to be set in the simulation model. The incident end 70 represents the incident situation of the sound wave signal. In this simulation model, the first sound-absorbing component 80 is used to simulate the first sound-absorbing body 21 of the metamorphic sound-absorbing device, the second sound-absorbing component 90 is used to simulate the second sound-absorbing body 22 of the metamorphic sound-absorbing device, and the third sound-absorbing component 100 is used to simulate the third sound-absorbing body 23 of the metamorphic sound-absorbing device. The gap 120 is used to simulate the slit 50, the first cavity 130 is used to simulate the first acoustic cavity 30, and the second cavity 140 is used to simulate the second acoustic cavity 40. The simulation model can be used to simulate the sound absorption effect of the metamorphic sound-absorbing device.

[0081] To analyze the impact of various parameters on sound absorption performance, multiple embodiments were subjected to sound absorption efficiency simulation tests for four dimensional variables of the metamorphic sound absorption device, including different lengths of the gap 50 along the first direction, different heights of the first sound absorber 21, different heights of the second sound absorber 22, and different heights of the third sound absorber 23. The test results show that the length of the gap 50 along the first direction and the heights of each sound absorber all affect the sound absorption performance of the metamorphic sound absorption device. The initial dimensions of each part of the metamorphic sound absorption device are shown in Table 1. In the following embodiments, the first direction is represented by the X direction, the second direction by the Y direction, and the third direction by the Z direction.

[0082] Table 1

[0083]

[0084] According to an embodiment of the present invention, the length of the two gaps 50 in the X direction (hereinafter referred to as the total gap cc (where the lengths of the two gaps 50 are the same)) is used as a variable. When cc increases, the length of the first sound absorber decreases. Furthermore, the change in cc is the same as the change in the length of the first sound absorber. Using a parametric scanning function, with other conditions remaining constant, a system simulation of the metamorphic sound-absorbing device is performed within the range of cc from 0.001m to 0.049m (step size 0.002m). The simulation results are as follows: Figure 5 As shown.

[0085] Figure 5 The relationship between the sound absorption efficiency of the metamorphic sound-absorbing device provided according to an embodiment of the present invention and the length of the first sound-absorbing body is shown.

[0086] like Figure 5 As shown, the horizontal axis represents frequency, denoted by freq, and the vertical axis represents the sound absorption coefficient, denoted by c. This parameter represents the sum of the gaps 50 on both sides of the first sound absorber in the X direction. In this embodiment of the invention, the sound absorption effect of the meta-absorbing device under different c values ​​is simulated. Except for c, the parameters of all other components are initial parameters. Based on the simulation results, this embodiment of the invention establishes a curve showing the relationship between the sound absorption efficiency of the meta-absorbing device and the length of the first sound absorber. Figure 5 Looking at the curves above, there is an intersection around 60Hz. Since the metamorphic sound-absorbing device of this embodiment is used to absorb sound wave signals from 50Hz to 200Hz, and aims to achieve a sound absorption coefficient of 0.9 or higher at each frequency point, the curves with sound absorption efficiencies below 0.9 in the 50Hz-200Hz range are excluded. Further analysis of the sound absorption coefficient of the metamorphic sound-absorbing device with a sound absorption efficiency greater than 0.9 is then performed, and the results are as follows... Figure 6 As shown.

[0087] Figure 6The relationship between the sound absorption efficiency of the metamorphic sound-absorbing device provided according to another embodiment of the present invention and the length of the first sound-absorbing body is shown.

[0088] like Figure 6 As shown, the horizontal axis represents frequency, denoted by freq, and the vertical axis represents the sound absorption coefficient, denoted by c. It can be seen that when c ranges from 0.001 to 0.025 m, the sound absorption coefficients of the curves corresponding to each c value are greater than 0.9 in the 50Hz-200Hz range.

[0089] by Figure 6 Taking the sound absorption efficiency at 50Hz as an example, the general trend is that the longer the gap 50 (the larger the cc value), the lower the sound absorption coefficient. Furthermore, several curves in the figure intersect at 55-65Hz, but overall, the curves tend to smooth out after 100Hz. In this embodiment of the invention, a curve with a relatively smooth surface and a high average sound absorption coefficient across the entire frequency band (cc=0.011m) is selected as the target curve. The length of a single gap 50 corresponding to this target curve (0.0055m) is the preferred gap length. According to an embodiment of the invention, by adjusting the size of the gap 50 in the first direction (i.e., the X direction), effective control of the low-frequency absorption performance of the metamaterial sound absorption device is achieved.

[0090] According to an embodiment of the present invention, taking the height of the second sound absorber 22 in a third direction (hereinafter referred to as the height of the second sound absorber) as a variable, the height of the second sound absorber 22 is gradually decreased. At different heights of the second sound absorber 22 (the dimensions of the other components are their respective initial dimensions in Table 1), the sound absorption efficiency of the metastructure sound absorption device is simulated, and the results are as follows: Figure 7 As shown. The height of the second sound absorber 22 is reduced by gradually cutting (cutting in the plane formed by the X and Y directions) the first end of the second sound absorber 22 based on the initial parameters set in Table 1. The cutting step size is 0.05m, and the cutting height hh ranges from 0m to 0.3m.

[0091] Figure 7 The relationship between the sound absorption efficiency of the metamorphic sound-absorbing device and the height variation of the second sound absorber provided according to an embodiment of the present invention is shown.

[0092] like Figure 7 As shown, the horizontal axis represents frequency, denoted by f, and the vertical axis represents the sound absorption coefficient, denoted by c. It can be seen that the general rule is: as hh increases (the height of the second sound absorber decreases), the sound absorption efficiency decreases. Furthermore, this rule is more pronounced in the 50Hz-100Hz band, while in the 100Hz-200Hz band, the change in sound absorption efficiency gradually flattens out with variations in hh.

[0093] Figure 8The relationship between the sound absorption efficiency of the metamorphic sound-absorbing device provided according to an embodiment of the present invention and the height variation of the second acoustic cavity is shown.

[0094] like Figure 8 As shown in the embodiment of the present invention, the sound absorption effect of the meta-acoustic sound-absorbing device is simulated under different heights of the second acoustic cavity 40 in a third direction (hereinafter referred to as the height of the second acoustic cavity) as a variable. The sound absorption efficiency of the meta-acoustic sound-absorbing device under different heights of the second acoustic cavity is obtained. The height of the second acoustic cavity 40 is gradually reduced based on the initial parameters set in Table 1, with each reduction step being 0.001m and the height reduction amount hhh ranging from 0m to 0.05m.

[0095] It can be seen that as the height of the second acoustic cavity 40 decreases, the absorption coefficient of the sound-absorbing module for 50Hz sound waves gradually decreases, but the overall decrease is within an acceptable range. At hhh=0.001m, the absorption coefficient of the sound-absorbing module for 50Hz sound waves reaches its maximum value of 0.90; at hhh=0.041m, the absorption coefficient reaches its minimum value of 0.8417.

[0096] The following specific embodiments illustrate the sound absorption coefficient of the metamorphic sound-absorbing device of the present invention.

[0097] Figure 9 Simulation results of the sound absorption coefficient of the metamorphic sound-absorbing device provided according to a specific embodiment of the present invention are shown.

[0098] like Figure 9 As shown, this embodiment presents the results of a simulation of the sound absorption effect of a meta-absorbing device with the following dimensions. Specifically, the sum of the heights of the first sound absorber 21, the second sound absorber 22, the second acoustic cavity 40, and the second sound absorber 23 along a third direction is 0.575m. The length of the first sound absorber 21 along the first direction is 0.189m, the width of the first sound absorber 21 along the second direction is 0.2m, and the height of the second sound absorber 22 along the third direction is 0.025m.

[0099] exist Figure 9 It can be seen that the sound absorption coefficient of the meta-absorbing device in this embodiment is greater than 0.9 at each frequency in the 50~200Hz frequency band.

[0100] Figure 10 It shows Figure 9 The measured sound absorption coefficient of the superstructure sound absorption device in the middle.

[0101] like Figure 10As shown, the superstructure sound-absorbing device was actually measured in this embodiment. The measured sound absorption coefficient was measured using the transfer function method in Part 2 of GB / T 18696.2-2002, Measurement of Sound Absorption Coefficient and Acoustic Impedance in Acoustic Impedance Tubes. The measurement results show that the sound absorption coefficient of the superstructure sound-absorbing device is greater than 0.9 in the 50~200Hz frequency band (frequency resolution 1Hz).

[0102] According to embodiments of the present invention, it can be seen that the choice of cc has the greatest impact on low-frequency sound absorption efficiency. Considering the technical requirement that the sound absorption coefficient needs to be maintained above 0.9 in the 50-200Hz frequency band, cc=0.011m was ultimately selected as the optimal parameter. The sound absorption curve corresponding to this value is smooth and stable across the entire frequency band, effectively achieving the design goal of shifting the frequency response bandwidth towards lower frequencies while ensuring that the overall sound absorption performance meets project requirements. This research result verifies the design concept that adjusting the gap size can effectively optimize the low-frequency characteristics of the sound absorber.

[0103] According to an embodiment of the present invention, a sound-absorbing system is also provided, the sound-absorbing system comprising: a plurality of metamorphic sound-absorbing devices arranged in an array, wherein one end of the opening of the attracting device faces the same direction.

[0104] According to an embodiment of the present invention, a composite sound absorption device is formed by a first sound absorber 21, a second sound absorber 22, a first acoustic cavity 30, a second acoustic cavity 40, and a third sound absorber 23, which integrate a four-stage mechanism of "filtering-porous medium sound absorption-cavity resonance-back-layer dissipation". This composite structure achieves full-frequency coverage and enhanced absorption from high to low frequencies through a four-stage sound absorption mechanism of "pre-treatment-porous medium sound absorption-cavity resonance-back-layer dissipation". The first sound absorber 21, including the slit, performs initial filtering and dissipation of sound energy; the second sound absorber 22 further extends mid-to-low frequency sound absorption through impedance gradient; the first acoustic cavity 30 and the second acoustic cavity 40 act as frequency "tuners" to selectively absorb specific frequency bands; and the third sound absorber 23 deeply dissipates residual sound energy and supplements low-frequency absorption. The core advantage of the aforementioned superstructure sound absorption device lies in the fact that through the coordinated design of parameters of each layer (the height of the first sound absorber 21, the height of the second sound absorber 22, the height of the third sound absorber 23, and the height of the second acoustic cavity 40), it can achieve multiple functions of "wideband sound absorption + structural protection" in complex noise environments. It is especially suitable for wind tunnel corner guide vane scenarios where high requirements for low-frequency sound absorption performance and harsh operating environments are required.

[0105] The heights of the first sound absorber 21, the second sound absorber 22, the third sound absorber 23, and the respective positional order of the second acoustic cavity 40 cannot be changed, and the gap 50 plays an important role in this embodiment of the invention. The gap 50, the first sound absorber 21, and the shell 10 constitute a resonant cavity. On the one hand, sound waves enter the cavity through the gap 50, increasing the contact area between the sound waves and the porous sound-absorbing material, thus increasing the sound absorption effect at mid-to-high frequencies. On the other hand, different gap sizes produce resonance at different frequencies. Through software simulation, the optimal gap 50 parameters were obtained, thereby obtaining the optimal sound absorption coefficient.

[0106] The embodiments of the present invention have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of the invention. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the invention, and all such substitutions and modifications should fall within the scope of the invention.

Claims

1. A metamorphic sound-absorbing device, comprising: A housing that forms a cavity with an opening, the housing having two inner walls facing each other along a first direction and two inner walls facing each other along a second direction; Sound-absorbing components, including: A first sound absorber is disposed in the cavity. The two ends of the first sound absorber along the first direction each form a gap with the inner wall facing it. The two ends of the first sound absorber along the second direction respectively abut against the two inner walls facing each other along the second direction. The second sound absorber is disposed in the cavity and is configured as a tapered structure along a third direction, which is perpendicular to the first direction and the second direction. The first end of the second sound absorber with a smaller cross-sectional area abuts against the first sound absorber, and the second end with a larger cross-sectional area abuts against the four inner walls of the shell. The second sound absorber has two opposing side walls along the second direction, and each of the two side walls abuts against the facing inner wall. The first sound absorber, the second sound absorber, and the shell form a first acoustic cavity. The first and second sound absorbers are adapted to absorb signals of a first frequency band from external sound wave signals from the opening. The acoustic cavity is used to absorb signals of a second frequency band from the external sound wave signals. The frequency of the first frequency band is greater than the frequency of the second frequency band.

2. The metamorphic sound-absorbing device according to claim 1, wherein, The length of the gap along the first direction is less than the distance between the inner wall and the first end in the first direction.

3. The metamorphic sound-absorbing device according to claim 1, wherein, The projection of the first sound absorber onto the preset surface is rectangular, and the projection of the second sound absorber onto the preset surface is trapezoidal. The preset surface is a plane determined according to the first direction and the third direction.

4. The metamorphic sound-absorbing device according to claim 1 further comprises: The third sound absorber is disposed in the cavity and located on the side with the larger cross-sectional area of ​​the second sound absorber. The third sound absorber abuts against the four inner walls of the shell and is spaced apart from the second sound absorber along the third direction. The third sound absorber, the second sound absorber, and the shell together form a second acoustic cavity. The second acoustic cavity is used to further absorb the second frequency band signal in the sound wave signal after it has been absorbed by the first acoustic cavity.

5. The metamorphic sound-absorbing device according to claim 1, wherein, The projection of the third sound absorber onto the preset surface is a rectangle, and the preset surface is a plane determined according to the first direction and the third direction.

6. The metamorphic sound-absorbing device according to claim 3, wherein, The height of the third sound absorber along the third direction ranges from 25mm to 100mm.

7. The metamorphic sound-absorbing device according to claim 1, wherein, The height of the second sound absorber along the third direction ranges from 275mm to 525mm.

8. The metamorphic sound-absorbing device according to claim 1, wherein, The height of the second acoustic cavity along the third direction is 25mm to 100mm.

9. The metamorphic sound-absorbing device according to claim 1, wherein, The height of the first sound absorber along the third direction ranges from 25mm to 100mm.

10. A sound-absorbing system, comprising: A plurality of superstructure sound-absorbing devices as described in any one of claims 1 to 9 are arranged in an array, wherein one end of the opening of the attraction device faces the same direction.

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