A multi-channel acoustic black hole sound absorption structure and a sound elimination device

Abstract

The present application relates to a kind of multi-channel acoustic black hole sound absorption structure and silencer, belong to noise control technical field, the defects of current acoustic black hole sound absorption structure are solved, including shell, the side of shell is open, the open side of shell is used to receive incident sound wave, partition is equipped in shell to separate the space in shell into multiple sound absorption channels, multiple rib plates are equipped in each sound absorption channel, the outer end of rib plate is fixed with the inner side of shell, rib plate is perpendicular to the incident direction of sound wave, multiple rib plates are spaced along the incident direction of sound wave, and along the incident direction of sound wave, the width of multiple rib plates gradually increases, the inner end of multiple rib plates is set power law function distribution, the inner end of multiple rib plates is bonded with the outer side of porous plate and is fixedly connected with porous plate, the sound absorption structure of the present application can better realize ultra-wideband sound absorption.

Description

Technical Field

[0001] This invention relates to the field of noise control technology, specifically to a multi-channel acoustic black hole sound-absorbing structure and a noise reduction device. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] With rapid societal development, noise pollution not only hinders people's pursuit of a higher quality of life but also limits the upgrading of machinery and equipment. Traditional porous sound-absorbing materials are ineffective at low frequencies under limited space conditions. While resonant sound-absorbing materials can effectively absorb sound waves of specific frequencies within small dimensions, they struggle to achieve broadband sound absorption. Both of these methods are insufficient to simultaneously meet the requirements for low-frequency broadband noise reduction within limited mass and volume constraints.

[0004] The concept of acoustic black holes offers a new approach to achieving low-frequency broadband and small-size vibration reduction and noise reduction. While traditional acoustic black hole structures can achieve broadband sound absorption, their sound absorption performance for low-frequency sound waves with frequencies below 500Hz is poor. To improve low-frequency sound absorption, researchers have conducted extensive studies. Patent application CN117437900A discloses a sound absorber based on an acoustic black hole and a multi-layered microporous plate. Its cylindrical shell contains multiple layers of microporous plates with circular perforated areas, extending from the outermost microporous plate to the innermost microporous plate. The sound absorber features a multi-layered micro-perforated plate design, where the diameter of the perforated areas decreases according to a power-law curve, and the outermost plate is fully perforated. This design improves the absorption of low-frequency sound waves. However, by designing a perforated plate at the entrance of the acoustic black hole, the sound waves will be reflected on the surface of the perforated plate as the frequency of the sound waves increases, preventing them from smoothly entering the internal region of the acoustic black hole. This results in poor high-frequency sound absorption performance. Furthermore, the use of a single sound absorption channel means that the channel parameters cannot be adjusted, limiting the frequency adaptability and making it difficult to achieve ultra-wideband sound absorption. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a multi-channel acoustic black hole sound absorption structure and silencing device, which overcomes the defects of the current sound absorption structure based on acoustic black holes and microporous plates.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] In a first aspect, embodiments of the present invention provide a multi-channel acoustic black hole sound-absorbing structure, including a shell, one side of which is open for receiving incident sound waves. A partition is provided inside the shell to divide the internal space into multiple sound-absorbing channels. Each sound-absorbing channel is provided with multiple ribs. The outer ends of the ribs are fixed to the inner side of the shell. The ribs are arranged perpendicular to the incident direction of the sound waves. The multiple ribs are spaced apart along the incident direction of the sound waves, and the width of the multiple ribs gradually increases along the incident direction of the sound waves. The inner ends of the multiple ribs are distributed in a predetermined power law function. The inner ends of the multiple ribs are attached to the outer side of a perforated plate and fixedly connected to the perforated plate.

[0008] Optionally, multiple ribs are distributed at equal intervals along the incident direction of the sound wave.

[0009] Optionally, the housing may have a cuboid structure.

[0010] Optionally, the housing is provided with a first partition and a second partition arranged in a cross shape, which divide the space inside the housing into four sound-absorbing channels.

[0011] Optionally, one end of the housing is open, and the other end is closed;

[0012] or,

[0013] One end of the shell is open, and the other end of the shell wall has an opening at the center. The edge of the opening is the boundary line between the perforated plate and the shell wall.

[0014] Optionally, the width of the ribs closest to the opening side of different sound-absorbing channels may vary, and the pore parameters of the perforated plates of different sound-absorbing channels may also vary.

[0015] Optionally, the power-law function is of order one, and correspondingly, the perforated plate is a flat plate.

[0016] Optionally, the perforated plate includes a plate body with multiple sets of through holes. The multiple sets of through holes are distributed along the length direction of the plate body, each set has multiple through holes, and the multiple through holes in the same set are distributed along the width direction of the plate body.

[0017] Optionally, multiple sets of through holes are distributed at equal intervals along the length of the plate, and multiple through holes in the same set are distributed at equal intervals along the width of the plate.

[0018] Secondly, embodiments of the present invention provide a noise reduction device, which is provided with the multi-channel acoustic black hole sound-absorbing structure described in the first aspect.

[0019] The beneficial effects of this invention are as follows:

[0020] 1. The sound-absorbing structure of the present invention comprises multiple ribs arranged at intervals along the incident direction of the sound wave, with the width of the multiple ribs gradually increasing along the incident direction of the sound wave. The inner ends of the multiple ribs are distributed along a set power law function, and the inner ends of the multiple ribs are attached and fixed to a perforated plate. The perforated plate is inclined relative to the incident direction of the sound wave rather than perpendicularly. A continuous conical cavity is formed between the perforated plate and the partition, making the impedance change more gradual. High-frequency sound waves are less likely to be reflected on the surface of the perforated plate and are more likely to enter the sound-absorbing channel. While improving the low-frequency sound absorption performance, it can maintain good high-frequency sound absorption performance. The sound-absorbing structure has multiple sound-absorbing channels, and the structural parameters of each sound-absorbing channel can be independently designed to adapt to the sound absorption requirements of different frequency sound waves. This avoids the overlap of the sound absorption valley frequency range of each sound-absorbing channel due to the design of a single parameter, which would lead to large fluctuations in the sound absorption performance of the structure over a wide frequency range. The entire sound-absorbing structure can better achieve ultra-wide frequency sound absorption.

[0021] 2. The sound-absorbing structure of the present invention has a rectangular shell, which is more regular in shape than a cylindrical structure. It can achieve large-area side-by-side installation with less space waste, making it suitable for large-scale noise control scenarios and improving the applicability of the entire sound-absorbing structure. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of the present invention;

[0024] Figure 2 This is a schematic diagram of the assembly of the shell, ribs, and partitions in Embodiment 1 of the present invention;

[0025] Figure 3 This is a schematic diagram of the rib distribution within the sound-absorbing channel in Embodiment 1 of the present invention;

[0026] Figure 4 This is a schematic diagram of the perforated plate in Embodiment 1 of the present invention;

[0027] Figure 5 This is a comparative structural diagram;

[0028] Figure 6 This is a graph showing the sound absorption coefficients of the sound-absorbing structure and the comparative structure in Embodiment 1 of the present invention.

[0029] Figure 7 This is a graph showing the sound absorption coefficient of the sound absorption structure and sound absorption channel S1 in Embodiment 1 of the present invention.

[0030] Figure 8This is a graph showing the sound absorption coefficient of the sound absorption structure and sound absorption channel S2 in Embodiment 1 of the present invention.

[0031] Figure 9 This is a graph showing the sound absorption coefficient of the sound absorption structure and sound absorption channel S3 in Embodiment 1 of the present invention.

[0032] Figure 10 This is a graph showing the sound absorption coefficient of the sound absorption structure and sound absorption channel S4 in Embodiment 1 of the present invention.

[0033] Among them, 1. shell, 2. first partition, 3. second partition, 4. rib, 5. perforated plate, 6. first cavity, 7. second cavity, 8. side cavity. Detailed Implementation

[0034] In this embodiment, the incident direction of the sound wave is defined as the first direction, and the direction perpendicular to the first direction is defined as the second direction.

[0035] Example 1

[0036] This embodiment provides a multi-channel acoustic black hole sound-absorbing structure, such as Figure 1 As shown, the device includes a housing 1, which has a partition inside. The partition divides the space inside the housing 1 into multiple sound-absorbing channels. One side of the housing 1 is open and the other end is closed. The open side of the housing 1 is used to receive incident sound waves, which can enter the multiple sound-absorbing channels.

[0037] The shell 1 adopts a cuboid structure and has two partitions inside, namely the first partition 2 and the second partition 3. The first partition 2 and the second partition 3 are arranged in a cross shape and are distributed diagonally along the opening of the shell 1. The first partition 2 and the second partition 3 divide the internal space of the shell 1 into four sound-absorbing channels. The cross section of the sound-absorbing channel perpendicular to the length direction of the shell 1 is triangular.

[0038] The length direction of the shell 1 is the incident direction of the sound wave. Four sound absorption channels are defined as sound absorption channel S1, sound absorption channel S2, sound absorption channel S3 and sound absorption channel S4. Sound absorption channels S1 and S3 are two sound absorption channels arranged opposite each other, and sound absorption channels S2 and S4 are the other two sound absorption channels arranged opposite each other.

[0039] In this embodiment, as Figure 2 As shown, each of the four sound-absorbing channels is provided with multiple ribs 4. The ribs 4 are arranged perpendicular to the first direction, that is, the ribs 4 are fixed perpendicularly to the inner side of the housing 1. In this embodiment, the outer end of the ribs 4 is fixedly connected perpendicularly to the inner side of the housing 1, and the two side ends of the ribs 4 are fixedly connected to the first partition 2 and the second partition 3. The ribs 4 are trapezoidal plates that match the cross-section of the sound-absorbing channel.

[0040] For the same sound absorption channel, the rib plate 4 is set perpendicular to the first direction, and multiple rib plates 4 are distributed at equal intervals along the first direction. Along the incident direction of the sound wave, the width of the multiple rib plates 4 gradually increases. The width of the rib plate 4 is the distance between the outer end and the inner end of the rib plate 4. The outer end of the rib plate 4 is fixedly connected to the inner side of the shell wall of the shell 1, and the inner ends of the multiple rib plates 4 are distributed along a set power law function.

[0041] In this embodiment, as Figure 3 As shown, the origin of the coordinate system containing the power-law function is the center point of the shell wall opposite the open side of shell 1, and the centerline of shell 1 is... Axis, perpendicular to The coordinate axis along the width direction of rib 4 is... axis.

[0042] Specifically, the power-law function is defined as follows:

[0043]

[0044] in, The distance from the origin of the coordinate system along the first direction is... x The point in the coordinate system y value, The distance from the center point of the open side to the inner end of the open side rib 4 is [distance missing]. n =1, 2, 3, 4, L This is the overall length of the sound-absorbing channel. It is the distance between the intersection of the distribution surface of the inner ends of the multiple ribs 4 and the closed side shell wall of the shell 1 and the centerline of the shell 1, i.e. x =0 y value.

[0045] e To control the order of the cross-section, in this embodiment, it is preferred that... e =1, the set power law function is a first power law function, at this time the distribution surface of the inner ends of multiple ribs 4 is a plane.

[0046] The inner end faces of multiple ribs 4 are attached to and fixedly connected to the outer side of the same perforated plate 5. The perforated plate 5 is a plate distributed along a set power law function. Since a first power law function is used, the perforated plate 5 is a flat plate. Compared with the curved conical perforated plate of a cylindrical acoustic black hole, the perforated plate 5 in this embodiment has a simpler structure and is easier to process and manufacture.

[0047] like Figure 4As shown, the perforated plate 5 is provided with multiple sets of through holes, which are distributed along the length direction of the perforated plate 5. Preferably, the multiple sets of through holes are evenly spaced along the length direction of the perforated plate 5, and each set has multiple through holes. The multiple through holes in the same set are distributed along a second direction, which is also evenly spaced along the second direction. The second direction is the width direction of the perforated plate 5.

[0048] The working principle of the multi-channel acoustic black hole sound-absorbing structure in this embodiment is as follows:

[0049] After noise waves enter the sound-absorbing channel through the open side of the shell 1, they pass through the ribs 4 whose width varies according to a set power law function. During propagation, the sound waves are gradually slowed down and focused at the end of the shell 1, thus significantly reducing sound energy reflection. When the energy is localized, the sound energy is dissipated through the cavity resonance between the ribs 4 inside the shell 1. On the one hand, by adding the porous plate 5, the energy dissipation capability of the acoustic black hole is increased, so that most of the energy is dissipated through the viscous effect of the microporous structure, thereby effectively improving the low-frequency sound absorption performance of the structure and widening the sound absorption bandwidth. On the other hand, by designing a certain initial width for the ribs 4 on the open side of a certain sound-absorbing channel, the depth of the side cavity 8 between the ribs 4 inside the shell 1 of the sound-absorbing channel can be increased as a whole. Since the sound absorption performance of the porous plate 5 structure increases with the increase of the depth of the side cavity 8, designing a certain initial width for the ribs 4 on the open side of a certain sound-absorbing channel can shift the overall sound absorption performance of the sound-absorbing channel to the low frequency, thus widening the low-frequency sound absorption range of the structure.

[0050] The perforated plate 5 with different parameters also affects the sound absorption frequency range. By designing the parameters of the perforated plate 5 embedded in the housing 1 in a reasonable way, the sound absorption performance can be balanced and large sound absorption valley values ​​can be avoided.

[0051] In this embodiment, the width of the initial rib 4 on the open side of different sound-absorbing channels is... m n , n =1, 2, 3, 4 are different. m 1. m 2. m 3. m 4 corresponds to the width of the ribs 4 on the open side of the sound absorption channels S1, S2, S3, and S4, respectively. m n Differentiated design is employed, with the perforated plate 5 for different sound absorption channels also having differentiated perforation parameters to avoid large sound absorption dips caused by using perforated plates 5 with the same parameters. Other dimensional parameters can be designed according to actual application conditions. The perforation parameters include the perforation diameter and the spacing between adjacent through-holes.

[0052] The sound-absorbing structure of this embodiment has four sound-absorbing channels. The internal parameters of each channel can be freely designed to achieve different sound absorption frequency ranges. The four channels do not affect each other. By combining the four channels in parallel, a low-frequency broadband sound absorption effect is achieved. Compared to the rectangular acoustic black hole structure with double ribs, this embodiment has ribs 4 in four directions, enabling more efficient sound absorption within the effective space. The perforated plates 5 within the four sound-absorbing channels are designed with different hole parameters to balance sound absorption performance and avoid large sound absorption dips caused by using perforated plates 5 with the same hole parameters. Other dimensional parameters can be designed according to actual application conditions.

[0053] In this embodiment, the inner ends of multiple ribs 4 are distributed along a set power law function, and the inner ends of multiple ribs 4 are attached and fixed to the perforated plate 5. The perforated plate 5 is inclined relative to the incident direction of the sound wave rather than vertically. A continuous conical cavity is formed between the perforated plate 5 and the partition, which makes the impedance transformation smoother. High-frequency sound waves are less likely to be reflected on the surface of the perforated plate 5 and are more likely to enter the sound absorption channel. While improving the low-frequency sound absorption performance, it can maintain good high-frequency sound absorption performance. The sound absorption structure has multiple sound absorption channels, and the structural parameters of each sound absorption channel can be independently designed to adapt to the sound absorption requirements of different frequency sound waves, avoiding fluctuations in sound absorption performance over a wide frequency range. The entire sound absorption structure can better achieve ultra-wide frequency sound absorption. Specifically, the sound absorption structure of this embodiment can maintain efficient sound absorption over a wide frequency range. There is no obvious sound absorption trough value after the first sound absorption peak appears. The average sound absorption coefficient can reach 0.971 in the frequency range of 300Hz-3000Hz.

[0054] In this embodiment, the housing 1 adopts a cuboid structure, which allows for the parallel installation of multiple sound-absorbing structures to achieve wide-area sound absorption in the face of large-area noise. This results in high space utilization and, compared to irregular structures, effectively utilizes the sound-absorbing space, avoiding space waste.

[0055] The sound absorption coefficient in this embodiment is calculated using the transfer matrix method. Since the four sound absorption channels have similar structures, sound absorption channel S1 is selected as an example for calculation. First, the sound absorption channel S1 is discretized according to the number of ribs 4 in the sound absorption channel S1. N A sound-absorbing unit, each sound-absorbing unit includes two ribs 4 and a side cavity 8 between the two ribs 4, for the first i ( i =1~ N The relationship between sound pressure and sound volume at the input and output ends of a sound-absorbing unit can be represented by a transfer matrix as follows:

[0056]

[0057] in, For the first iThe inner end of the inlet end rib 4 of each sound-absorbing unit forms a transmission matrix of the first cavity 6 between the center line of the housing 1. For the first i The transmission matrix of the second cavity 7 between the inner end of the space between two adjacent ribs 4 of each sound-absorbing unit and the center line of the shell 1. For the first i The transfer matrix of the perforated plate 5 corresponding to each sound-absorbing unit. Indicates the first i The transmission matrix of the side cavity 8 formed between two adjacent ribs 4 of each sound-absorbing unit. The characteristic impedance of air; Represents air density; This represents the speed of sound in air that has been damped. It is the complex wave number; ω is the angular frequency of the sound wave; f The frequency of the sound wave; S i Indicates the first i The cross-sectional area of ​​the inlet end of each rib plate is 4. S sur Indicates the first i Rib 4 and the first i +1 area of ​​the perforated plate 5 between the ribs 4; Y i Indicates the first i The admittance of the side cavity 8 of each sound-absorbing unit can be expressed by the following calculation relationship:

[0058]

[0059] V i Indicates the first i Rib 4 and the first i +1 volume of the side cavity 8 between the ribs 4 k 0 represents the air wavenumber. , The angular frequency of the sound wave is represented by c0, which represents the speed of sound in damped air, and j represents... .

[0060] d l The thickness of rib 4 is given. d k The width of the side cavity 8 between adjacent ribs 4. Z MPP This represents the impedance of the perforated plate 5.

[0061] For porous plate 5, the Beranek Ingard model is used to calculate the surface impedance. Z MPP Specifically:

[0062]

[0063]

[0064]

[0065] in R s Indicates surface acoustic resistance. To correct the length, R h This indicates the diameter of the through holes in the perforated plate 5. This indicates the perforation rate of the perforated plate 5. This indicates the thickness of the perforated plate 5. Represents air density, η This represents the aerodynamic viscosity, which is a constant. Represents the angular frequency of a sound wave. , f The frequency of the sound wave is j, where j represents... .

[0066] For a sound-absorbing channel, its transfer matrix T is the product of the transfer matrices of all adjacent sound-absorbing units:

[0067]

[0068] in, N The number of sound-absorbing units is specified. Each sound-absorbing unit consists of two adjacent ribs 4 and the side cavity 8 between them. i =1, 2, 3... N .

[0069]

[0070] No. n Acoustic impedance of each sound-absorbing channel for:

[0071]

[0072] T 11 T 12 T 21 and T 22 The four parameters in the transfer matrix T can be calculated, but they do not have a specific meaning.

[0073] The entire sound-absorbing structure is composed of four parallel sound-absorbing channels. Therefore, the acoustic impedance can be calculated using the acoustic-electric analogy method, and the total acoustic impedance is... Z all The calculation formula is:

[0074]

[0075] in, Indicates the first n The area ratio of the incident surface of the first sound-absorbing channel, i.e., the area of ​​the first sound-absorbing channel. n The ratio of the sound wave incident area of ​​each sound-absorbing channel to the sound wave incident area of ​​the entire shell 1 on the open side. Z n1 For the first n The acoustic impedance of each sound-absorbing channel.

[0076] Reflection coefficient of the entire sound absorption channel R for:

[0077]

[0078] z 0 represents the characteristic impedance of air.

[0079] sound absorption coefficient α for:

[0080] α =1-R

[0081] This embodiment is compared with a single-channel sound-absorbing structure without the porous plate 5 (comparison structure), such as... Figure 5 As shown, the comparative structure also includes a shell, the size of which is the same as that of shell 1 in this embodiment. Multiple annular ribs are evenly distributed along the length direction inside the shell. The outer surfaces of the multiple annular ribs are fixed to the inner surfaces of the shell. The inner surfaces of the annular ribs on the same side are distributed along a set power law function.

[0082] The shape of the sound-absorbing structure is determined as follows:

[0083] The length of the sound-absorbing channel. This refers to the distance between the shell walls of the two housings 1 corresponding to sound absorption channels S1 and S3. The distance between the shell walls of the two housings 1 corresponding to the sound absorption channels S2 and S4 is ignored in the calculation.

[0084] The specific structural parameters of the sound-absorbing structure in this embodiment are shown in Table 1:

[0085]

[0086] d l The thickness of rib 4 is given. d k The width of the side cavity 8 between adjacent ribs 4. m nThe width of the rib 4 closest to the open side. t The thickness of the perforated plate 5 is... R h The diameter of the through hole in the perforated plate 5 is... The perforation rate of the perforated plate 5 is... D n The distance is the distance from the center point of the open side of shell 1 to the inner end of the open side rib 4. n =1, 2, 3, 4.

[0087] The structural parameters of the shell in the comparison structure are the same as the dimensions of the shell in this embodiment, and the dimensions of the rib portion on each side of the annular rib are the same as the dimensions of the rib in the corresponding sound-absorbing channel in this embodiment.

[0088] Under these external conditions, the sound absorption coefficient was calculated using the transfer matrix method. Three comparison indicators were designed: 1) the sound absorption frequency at which the sound absorption coefficient of each sound absorption structure reached 0.6, and the frequency and magnitude of the sound absorption coefficient at which the first sound absorption peak appeared; 2) the average sound absorption coefficient in the frequency range of 300Hz-3000Hz; 3) the number and magnitude of the sound absorption valleys produced by various structures.

[0089] like Figure 6 As shown in the diagram, the sound absorption coefficient curves of the two sound-absorbing structures reveal that the sound absorption structure in this embodiment achieves a sound absorption coefficient of 0.6 at a frequency of 330Hz, with the first absorption peak occurring at 385Hz and a sound absorption coefficient of 0.959. In contrast, the comparative structure achieves a sound absorption coefficient of 0.6 at a frequency of 507Hz, with the first absorption peak occurring at 577Hz and a sound absorption coefficient of 0.74. Furthermore, it exhibits multiple wideband absorption valleys in the subsequent frequency range, demonstrating the superior low-frequency sound absorption performance of this embodiment. The average sound absorption coefficient of the sound absorption structure in this embodiment is 0.971 within the 300Hz-3000Hz range, while the average sound absorption coefficient of the comparative structure is 0.768. Therefore, the sound absorption structure in this embodiment exhibits better wideband sound absorption performance compared to the comparative structure.

[0090] like Figures 7-10As shown, for the sound-absorbing structure of this embodiment, the average sound absorption coefficients of sound-absorbing channels S1, S2, S3, and S4 in the frequency range of 300Hz-3000Hz are calculated to be 0.959, 0.953, 0.952, and 0.947, respectively. The average sound absorption coefficients of the four sound-absorbing channels are all lower than the average sound absorption coefficient of 0.971 of the sound-absorbing structure of this embodiment. The frequency at which sound-absorbing channel S1 produces the first sound absorption peak is 399Hz, and the sound absorption coefficient is 0. The absorption coefficient of sound absorption channel S2 is 0.998, and its maximum absorption valley value is 0.75. The first absorption peak frequency of sound absorption channel S2 is 439Hz, with an absorption coefficient of 0.998 and a maximum absorption valley value of 0.852. The first absorption peak frequency of sound absorption channel S3 is 377Hz, with an absorption coefficient of 0.974 and a maximum absorption valley value of 0.698. The first absorption peak frequency of sound absorption channel S4 is 507Hz, with an absorption coefficient of 0.987 and a maximum absorption valley value of 0.82. It can be seen that the absorption coefficients of the absorption valleys produced by the four sound absorption channels are all lower than the valley values ​​of the sound absorption structure in this embodiment. This embodiment's sound absorption structure, by combining the four sound absorption channels in parallel, makes the overall sound absorption coefficient change more stable and the sound absorption effect better.

[0091] Example 2

[0092] This embodiment provides a multi-channel acoustic black hole sound absorption structure. Compared with embodiment 1, the only difference is that one side of the shell 1 is open, and the center of the shell wall on the other side is provided with an opening. The edge of the opening is the boundary line between the perforated plate 5 and the shell wall. The rest of the structure is the same as that of embodiment 1, and will not be described again here.

[0093] Example 3

[0094] This embodiment provides a noise reduction device, which is equipped with the multi-channel acoustic black hole sound absorption structure described in Embodiment 1 or Embodiment 2. The remaining structure of the noise reduction device can adopt existing technology and will not be described in detail here.

[0095] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A multi-channel acoustic black hole sound-absorbing structure, characterized in that, The device includes a housing with an open side for receiving incident sound waves. Inside the housing, a partition divides the internal space into multiple sound-absorbing channels. Each sound-absorbing channel contains multiple ribs. The outer ends of the ribs are fixed to the inner side of the housing. The ribs are perpendicular to the incident direction of the sound waves. The multiple ribs are spaced apart along the incident direction of the sound waves, and the width of the multiple ribs gradually increases along the incident direction of the sound waves. The inner ends of the multiple ribs are distributed in a predetermined power law function. The inner ends of the multiple ribs are attached to the outer side of the perforated plate and fixedly connected to the perforated plate. The shell adopts a cuboid structure, and the shell has a first partition and a second partition arranged in a cross shape inside the shell. The first partition and the second partition divide the space inside the shell into four sound-absorbing channels. The perforated plate is inclined relative to the incident direction of the sound wave, and a continuous conical cavity is formed between the perforated plate and the partition. The power law function is defined as follows: in, The distance from the origin of the coordinate system along the first direction is... x The point in the coordinate system y value, This is the distance from the center point of the open side to the inner end of the open side rib. n =1, 2, 3, 4, L This is the overall length of the sound-absorbing channel. It is the distance between the intersection of the inner end distribution surfaces of multiple ribs and the closed side shell wall of the shell, and the centerline of the shell. e To control the order of the cross-section, e ≠1, the distribution surface is curved; The width of the ribs closest to the opening side varies in different sound-absorbing channels, and the pore parameters of the perforated plates in different sound-absorbing channels also vary.

2. The multi-channel acoustic black hole sound-absorbing structure as described in claim 1, characterized in that, Multiple ribs are evenly spaced along the incident direction of the sound wave.

3. The multi-channel acoustic black hole sound-absorbing structure as described in claim 1, characterized in that, The shell is open at one end and closed at the other end; or, One end of the shell is open, and the other end of the shell wall has an opening at the center. The edge of the opening is the boundary line between the perforated plate and the shell wall.

4. The multi-channel acoustic black hole sound-absorbing structure as described in claim 1, characterized in that, The perforated plate includes a plate body with multiple sets of through holes. The multiple sets of through holes are distributed along the length of the plate body, each set has multiple through holes, and the multiple through holes in the same set are distributed along the width of the plate body.

5. The multi-channel acoustic black hole sound-absorbing structure as described in claim 4, characterized in that, Multiple sets of through holes are evenly spaced along the length of the plate, and multiple through holes in the same set are evenly spaced along the width of the plate.

6. A silencer, characterized in that, The multi-channel acoustic black hole sound-absorbing structure as described in any one of claims 1-5 is provided.

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