A detachable metamaterial muffler

Abstract

The invention provides a detachable meta-material silencer, comprising a shell arranged in a cylindrical shape, a perforated pipe, a meta-material plate and a perforated plate, wherein the perforated pipe is arranged at the central axis position of the shell and the two ends thereof pass through the two bottom surfaces of the shell; the shell is composed of a plurality of sub-shells arranged side by side with the perforated pipe as the axis, the meta-material plate and the perforated plate are arranged parallel to the bottom surface of the shell and are sleeved on the perforated pipe between two adjacent sub-shells, and the meta-material plate and the perforated plate are detachably connected to the two adjacent sub-shells; a plurality of main resonance systems separated by vertical partitions are arranged between the upper and lower bottom surfaces of the shell, and a plurality of perforations are arranged on the perforated pipe between each main resonance system, the silencer is convenient to disassemble, and the meta-material plate is easy to replace, and the single-frequency silencing capability of the Helmholtz silencer is added to the back cavity of the silencer in the form of the meta-material plate, and the silencing effect of multiple silencing peaks is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of sound elimination treatment, and in particular to a detachable meta-material muffler. Background Art

[0002] With the development of industry and the progress of society, people have higher and higher requirements for the surrounding living environment. Noise is one of the three major pollutions in the world today. Effective control and noise reduction of pipeline noise is imminent. Traditional low-frequency silencers include Helmholtz silencers, micro-perforated tube silencers, quarter-wavelength tubes, etc. However, due to the occupied space and processing technology, noise spectrum characteristics, and the noise reduction effect caused by dust and other pollution after long-term use, the silencer must be disassembled and cleaned to meet normal noise reduction needs.

[0003] Secondly, for traditional Helmholtz silencers, the silencing frequency band is single, and when dealing with composite spectrum noise, multiple Helmholtz silencers need to be connected in series on one side of the pipe, which greatly increases the space occupied; for micro-perforated tube silencers, the silencing frequency band is wide, but it is relatively weak when dealing with lower or higher single-frequency noise; for traditional composite silencers, the sound attenuation volume is large and the sound attenuation range is wide, but it is easily contaminated after long-term exposure, and with the passage of time, the noise frequency generated by the machine will also change, so the silencer needs to be frequency-modulated, and the sound-absorbing cotton will also age and lose its silencing ability after long-term use.

[0004] The invention patent with application number CN112303033A discloses a sleeve-type Helmholtz resonance muffler with a small aspect ratio, in which a gap is provided between the outer shell of the muffler and the perforated tube to form an annular closed cavity. From the air inlet of the muffler to the outlet of the muffler, the closed cavity is divided into four annular resonance chambers in the axial direction by a partition, which are the first resonance chamber, the second resonance chamber, the third resonance chamber, and the fourth resonance chamber from left to right; the partition is welded to the perforated tube and the outer shell of the muffler, and silencer through holes are opened on the tube walls corresponding to the perforated tube and each annular resonance chamber, which can effectively suppress the broadband noise generated by the high-speed impeller. However, the muffler adopts an integrated fixed shell, which is not easy to disassemble and clean. Summary of the invention

[0005] The purpose of the present invention is to provide a detachable meta-material silencer with low-frequency broadband silencer effect, convenient disassembly and replacement of meta-material plates, easy cleaning, wide silencer range, large silencer volume, and capable of handling more complex composite spectrum noise.

[0006] The present invention provides the following technical solutions:

[0007] A detachable meta-material muffler comprises a cylindrical shell, a hollow perforated tube, a meta-material plate and a perforated plate, wherein the perforated tube is arranged at the central axis of the shell and the two ends thereof pass through the two bottom surfaces of the shell;

[0008] The shell is composed of a plurality of sub-shells arranged side by side with the perforated tube as the axis, the meta-material plate and the perforated plate are arranged parallel to the bottom surface of the shell, and are respectively sleeved on the perforated tube between two adjacent sub-shells, and the meta-material plate and the perforated plate are detachably connected to the two adjacent sub-shells;

[0009] A plurality of main resonance systems separated by vertical partitions are arranged between the upper and lower bottom surfaces of the shell, and a plurality of perforations are arranged on the perforated tubes between each main resonance system; the main resonance system includes a plurality of first main resonance systems and a second main resonance system arranged in sequence along the perforated tubes, the first main resonance system includes a plurality of secondary resonance cavities divided by two meta-material plates, and the second main resonance system is divided into chambers by the perforated plates.

[0010] Preferably, the meta-material plate is provided with neck tubes in an axial circumferential array, the neck tubes on the two meta-material plates in each of the first main resonance systems are arranged back to back, annular partitions are provided on the bottom inner wall of the shell and the two side walls of the vertical partition, and the annular partitions are arranged between each circumferential array of the neck tubes, dividing each of the secondary resonance systems into a plurality of Helmholtz muffler resonance units, and the chamber of the Helmholtz muffler resonance unit is an annular chamber.

[0011] Preferably, the annular chamber where the neck tube is located gradually increases from the inside to the outside along the direction of the perforated tube and the outer shell.

[0012] Preferably, annular melamine cotton is filled between the inner wall of the shell and the meta-structure material plate, between the shell and the perforated plate, and between adjacent annular partitions.

[0013] Preferably, both ends of the perforated pipe are connected to the noise pipeline through flanges or clamps.

[0014] Preferably, the shell and the perforated tube are connected symmetrically to the central axis by welding, and the distance between the end face of the shell and the corresponding end face of the perforated tube is 10 mm.

[0015] Preferably, the melamine cotton is glued to the inner wall of the shell.

[0016] Preferably, mounting plates are sleeved on both ends of the outer wall of the sub-shell, and the annular edge positions of the meta-material plate and the perforated plate are clamped between the mounting plates of two adjacent sub-shells and fixedly connected to the mounting plates by matching bolts and nuts.

[0017] Preferably, the number of the sub-shells is six, the number of the meta-material plates is four, and the number of the first main resonant systems is two.

[0018] Preferably, the number of each circular array of the neck tubes is 10, comprising 4 circular arrays in total.

[0019] The beneficial effects of the present invention are:

[0020] (1) The silencer adopts a method in which the sub-shell and the meta-material plate are arranged at intervals and are detachably connected, so that the silencer is easy to disassemble, the meta-material plate is easy to replace, and the cavity is easy to clean, thereby ensuring the durability and practicality of the silencer;

[0021] (2) The detachable meta-material plate can be designed according to the noise frequency characteristics, and the meta-material plate that meets the noise frequency requirements can be replaced to meet the noise reduction requirements;

[0022] (3) The single-frequency silencing capability of the Helmholtz silencer is added to the back cavity of the silencer in the form of a metamaterial plate, which has a silencing effect with multiple silencing peaks and a low-frequency broadband silencing effect. The silencing volume reaches 40dB in the frequency range of 250Hz-1715Hz, and can handle more complex composite spectrum noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 It is a schematic diagram of the structure of the present invention;

[0025] Figure 2 is a cross-sectional view of the main resonant system of the present invention;

[0026] Figure 3 is a schematic diagram of a meta-material plate of the present invention;

[0027] Figure 4 It is a schematic diagram of the structure of melamine cotton of the present invention;

[0028] Figure 5 is a transmission loss curve diagram of the first main resonance system in the third embodiment of the present invention;

[0029] Figure 6 is a transmission loss curve diagram of the second first main resonance system in the third embodiment of the present invention;

[0030] Figure 7 is a transmission loss curve diagram of the second main resonance system in the third embodiment of the present invention;

[0031] Figure 8 is a transmission loss curve diagram of the muffler of the present invention;

[0032] Marked in the figure are: 1. Shell; 2. Perforated tube; 3. Meta-structure material plate; 4. Perforated plate; 5. First main resonance system; 6. Second main resonance system; 7. Neck tube; 8. Mounting plate; 9. Vertical partition; 10. Annular partition; 11. Melamine cotton. DETAILED DESCRIPTION

[0033] Embodiment 1

[0034] like Figure 1-Figure 3 As shown, a detachable meta-material muffler includes a shell 1 arranged in a cylindrical shape, a perforated tube 2 arranged in a hollow shape, a meta-material plate 3 and a perforated plate 4, wherein the perforated tube 2 is arranged at the central axis position of the shell 1 and both ends pass through the two bottom surfaces of the shell 1, wherein the shell 1 and the perforated tube 2 are symmetrically connected to the central axis by welding, and the distance between the end face of the shell 1 and the corresponding end face of the perforated tube 2 is 10 mm.

[0035] The shell 1 is composed of a plurality of sub-shells arranged side by side with the perforated tube 2 as the axis. The meta-material plate 3 and the perforated plate 4 are arranged parallel to the bottom surface of the shell 1 and are respectively sleeved on the perforated tube 2 between two adjacent sub-shells. The meta-material plate 3 and the perforated plate 4 are detachably connected to the two adjacent sub-shells.

[0036] Specifically, mounting plates 8 are sleeved on both ends of the outer wall of the sub-shell, and the annular edge positions of the meta-material plate 3 and the perforated plate 4 are clamped between the mounting plates 8 of two adjacent sub-shells, and are fixedly connected to the mounting plates 8 by matching bolts and nuts. The silencer adopts a method in which the sub-shell and the meta-material plate 3 are spaced apart and detachably connected, so that the bolts and nuts are connected, which is convenient for disassembly, and it is easy to replace the meta-material plate 3 and clean the cavity, thereby ensuring the durability and practicality of the silencer. At the same time, the detachable meta-material plate 3 can be designed as needed according to the noise frequency characteristics, and can be replaced with the meta-material plate 3 that meets the noise frequency requirements to meet the sound insulation requirements.

[0037] A plurality of main resonance systems separated by vertical partitions 9 are arranged between the upper and lower bottom surfaces of the shell 1 , and a plurality of perforations are arranged on the perforated tube 2 between each main resonance system, and sound waves enter the main resonance system through the perforations on the perforated tube 2 .

[0038] The main resonance system includes a plurality of first main resonance systems 5 and a second main resonance system 6 which are sequentially arranged along the perforated tube 2 .

[0039] Among them, the first main resonance system 5 includes a plurality of secondary resonance cavities divided by two meta-material plates 3, and the meta-material plates 3 are provided with neck tubes 7 in an axial circumferential array. The neck tubes 7 on the two meta-material plates 3 in each first main resonance system 5 are arranged back to back. An annular partition 10 is provided on the inner wall of the bottom surface of the shell 1 and the two side walls of the vertical partition 9. The annular partition 10 is arranged between each circumferential array of the neck tube 7, and each secondary resonance system is divided into a plurality of Helmholtz silencer resonance units, and the silencing peak of the main chamber is further divided to form a multi-degree-of-freedom silencing effect; wherein, the chamber of the Helmholtz silencer resonance unit is an annular chamber, and the annular chamber where the neck tube 7 is located gradually increases from the inside to the outside along the direction of the perforated tube 2 and the shell 1. The deeper the neck tube 7 is, the lower the silencing frequency of the Helmholtz silencer resonance unit is, and the low-frequency silencing range is widened.

[0040] The second main resonance system 6 divides the chamber through the perforated plate 4 to form a double local resonance effect. This resonance system provides two sound-absorbing peaks that are missing from the first main resonance system 5, ultimately forming a low-frequency, broadband and efficient sound-absorbing effect.

[0041] Embodiment 2

[0042] like Figure 1-Figure 4 As shown, compared with the first embodiment, in this embodiment, annular melamine cotton 11 is filled between the inner wall of the shell 1 and the meta-structure material plate 3, between the shell 1 and the perforated plate 4, and between adjacent annular partitions 10. The melamine cotton 11 is a porous material, wherein the melamine cotton 11 is glued to the inner wall of the shell 1, which not only improves the sound-absorbing performance of the silencer, but also prevents the gas propagating in the pipeline from being polluted.

[0043] The other components and principles of this embodiment are the same as those of the first embodiment.

[0044] Embodiment 3

[0045] like Figure 1-Figure 4 As shown, compared with the second embodiment, the number of sub-shells in this embodiment is six, and the number of meta-material plates 3 is four. From left to right, the meta-material plate, sub-shell, meta-material plate, sub-shell, meta-material plate, sub-shell, meta-material plate, sub-shell, meta-material plate, sub-shell, perforated plate 4 and sub-shell are connected symmetrically in sequence along the central axis by bolt-nut connection.

[0046] The muffler in this embodiment has three main resonance systems in total, wherein the number of the first main resonance systems 5 is two.

[0047] The number of each circumferential array of the neck tubes 7 is 10, which includes 4 circumferential arrays in total.

[0048] Among them, the first main resonance system 5 has a total of 10 anechoic peaks, the second main resonance system 6 has a total of 2 anechoic peaks, the first main system includes two secondary resonance systems divided by the metastructure material plates 3, and each secondary resonance system includes four Helmholtz silencer resonance units;

[0049] The chamber of a single Helmholtz resonance unit is an annular chamber, which is separated from the inner chamber by a meta-material plate 3. The neck tube 7 of the meta-material plate 3 penetrates deep into the annular chamber. The deeper the neck tube 7 is, the lower the muffler frequency of the Helmholtz muffler resonance unit is, thereby widening the low-frequency muffler range.

[0050] A single meta-material plate 3 has four different neck tubes 7, the depths of the neck tubes 7 are inconsistent, the neck tubes 7 are arranged in an axial circumferential array, the number of the arrays is 10, the cavity where the neck tubes 7 are located gradually increases from the inside to the outside, and the corresponding sound-absorbing frequency gradually decreases.

[0051] The perforation rate of the second main resonance system 6 is greater than that of the first main resonance system 5. The back cavity is divided into chambers by a perforated plate 4 to form a double local resonance effect. This resonance system provides two sound-absorbing peaks that are missing from the first and second main resonance systems, ultimately forming a low-frequency, broadband and efficient sound-absorbing effect.

[0052] In a specific implementation, the distance between the plane of the shell 1 and the left side of the perforated tube 2 is 10 mm, and they are connected symmetrically to the central axis by welding.

[0053] An annular melamine cotton 11 with a thickness of 5 mm is placed in the outer shell 1 and 3 pieces of super-structure material plates, filled in the resonance cavity, and bonded to one side of the outer shell 1. There are a total of 17 and 5 types of annular porous materials. The melamine cotton 11 is also embedded between the outer shell 1 and the perforated plate 4, and placed close to the outer shell 1, forming a super-structure material muffler.

[0054] Among them, the acoustic impedance ξ on both sides of the perforated tube 2 is:

[0055]

[0056] Where k0 is the wave number, t ω is the perforation depth, d h is the perforation diameter, φ is the perforation rate, and j is the imaginary part.

[0057] The acoustic impedance of the Helmholtz muffler resonance unit is:

[0058]

[0059] Where A is the surface area of ​​the annular chamber, and its calculation formula is: A = π (r A -r B ) 2 , r A 、r Bare the outer diameter and inner diameter of the annular chamber respectively; S a is the area of ​​the circular hole, and its calculation formula is: da is the diameter of the circular hole; ρ cc 、c cc and k cc They represent the density, speed of sound and wave number of the air in the Helmholtz cavity respectively; k ca ,Ψ va and ha denote the wave number, viscosity term and thermal term of the neck tube 7 under narrow acoustics, δ i is the sound quality terminal correction coefficient, and its calculation formula is δ i =[1+(1-1.25ε)]·(4 / 3π)d a , where da is the aperture of the circular hole, ε is the perforation rate of the annulus; γ represents the specific heat capacity of air, ω represents the angular frequency, η represents the viscosity coefficient of air, ρ0 represents the density of air under natural conditions, and c0 represents the propagation speed of sound in the external air.

[0060] The overall acoustic impedance Z of the metamaterial plate 3 satisfies:

[0061]

[0062] Among them, Z HHn represents the acoustic impedance of the Helmholtz muffler resonance unit, and n is the number of the Helmholtz muffler resonance units.

[0063] The inlet and outlet of the perforated pipe 2 of the muffler are connected to the noise pipeline by flanges or clamps, which can effectively eliminate the noise propagating in the pipeline and reduce the loudness of the noise at the outlet.

[0064] pass Figure 5-8 It can be seen that the simulation calculation results of the silencer show that the silencer has a sound attenuation of 40dB in the frequency range of 250Hz-1715Hz, achieving a low-frequency broadband sound attenuation effect, large sound attenuation, easy cleaning, and frequency modulation capability; the porous material is placed between the outer shell 1 and the meta-material plate 3 to prevent contamination of the gas propagating in the pipeline.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A detachable metamaterial muffler, characterized in that: It comprises a shell in the form of a column, a perforated tube in the form of a hollow, a meta-structure material plate and a perforated plate, wherein the perforated tube is arranged at the central axis of the shell and the two ends thereof pass through the two bottom surfaces of the shell; The shell is composed of a plurality of sub-shells arranged side by side with the perforated tube as the axis, the meta-material plate and the perforated plate are arranged parallel to the bottom surface of the shell, and are respectively sleeved on the perforated tube between two adjacent sub-shells, and the meta-material plate and the perforated plate are detachably connected to the two adjacent sub-shells; A plurality of main resonance systems separated by vertical partitions are arranged between the upper and lower bottom surfaces of the shell, and a plurality of perforations are arranged on the perforated tubes between each main resonance system; the main resonance system comprises a plurality of first main resonance systems and a second main resonance system sequentially arranged along the perforated tubes, the first main resonance system comprises a plurality of secondary resonance cavities divided by two meta-material plates, and the second main resonance system is divided into chambers by the perforated plates; The meta-material plate is provided with neck tubes in an axial circumferential array, the neck tubes on the two meta-material plates in each of the first main resonance systems are arranged back to back, annular partitions are provided on the bottom inner wall of the shell and the two side walls of the vertical partition, and the annular partitions are arranged between each circumferential array of the neck tubes, so as to divide each of the secondary resonance cavities into a plurality of Helmholtz muffler resonance units, and the chamber of the Helmholtz muffler resonance unit is an annular chamber; Both ends of the perforated pipe are connected to the noise pipeline through flanges or clamps.

2. A detachable metamaterial muffler according to claim 1, characterized in that: The annular chamber where the neck tube is located gradually increases from the inside to the outside along the direction of the perforated tube and the shell.

3. The detachable metamaterial muffler according to claim 1, characterized in that: Annular melamine cotton is filled between the inner wall of the shell and the meta-structure material plate, between the shell and the perforated plate, and between adjacent annular partitions.

4. The detachable metamaterial muffler according to claim 1, characterized in that: The shell and the perforated tube are connected symmetrically along the central axis by welding, and the distance between the end face of the shell and the corresponding end face of the perforated tube is 10 mm.

5. The detachable metamaterial muffler according to claim 3, characterized in that: The melamine cotton glue is connected to the inner wall of the shell.

6. The detachable metamaterial muffler according to claim 1, characterized in that: Mounting plates are sleeved on both ends of the outer wall of the sub-shell, and the annular edge positions of the meta-material plate and the perforated plate are clamped between two adjacent mounting plates of the sub-shells and fixedly connected to the mounting plates by matching bolts and nuts.

7. A detachable metamaterial muffler according to any one of claims 1 to 6, characterized in that: The number of the sub-shells is six, the number of the meta-material plates is four, and the number of the first main resonant systems is two.

8. A detachable metamaterial muffler according to any one of claims 1-2, characterized in that: The number of each circumferential array of the neck tube is 10, which comprises 4 circumferential arrays in total.

Images