CN114321553A - Broadband pipeline silencer based on gradual change impedance boundary - Google Patents
Broadband pipeline silencer based on gradual change impedance boundary Download PDFInfo
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- CN114321553A CN114321553A CN202111633932.6A CN202111633932A CN114321553A CN 114321553 A CN114321553 A CN 114321553A CN 202111633932 A CN202111633932 A CN 202111633932A CN 114321553 A CN114321553 A CN 114321553A
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- 230000008859 change Effects 0.000 title claims abstract description 19
- 230000003584 silencer Effects 0.000 title claims abstract description 14
- 238000010521 absorption reaction Methods 0.000 claims abstract description 27
- 239000000463 material Substances 0.000 claims description 6
- 229920000742 Cotton Polymers 0.000 claims description 3
- 230000030279 gene silencing Effects 0.000 abstract description 11
- 238000000034 method Methods 0.000 abstract description 4
- 230000008569 process Effects 0.000 abstract description 2
- 230000000694 effects Effects 0.000 description 6
- 230000008030 elimination Effects 0.000 description 6
- 238000003379 elimination reaction Methods 0.000 description 6
- 230000009467 reduction Effects 0.000 description 6
- 238000004088 simulation Methods 0.000 description 3
- 238000010146 3D printing Methods 0.000 description 2
- 239000011358 absorbing material Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000004026 adhesive bonding Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 230000001743 silencing effect Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000010897 surface acoustic wave method Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
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Abstract
The invention discloses a broadband pipeline silencer based on a gradual change impedance boundary, which comprises a sound pipeline, gradual change impedance boundary blocks and a sound absorption circular ring block, wherein the section of the sound pipeline is circular, the gradual change impedance boundary blocks are arranged on the periphery of the wall of the sound pipeline, through holes with one closed end are arranged in the gradual change impedance boundary blocks, the open ends of the through holes are communicated with the inside of the sound pipeline, the through holes are integrally divided into two parts, the length of the through holes in the former part is gradually increased, and the lengths of all the through holes in the latter part are kept unchanged; the inner wall of one end of the sound pipeline is laid with the sound absorption circular ring block, and meanwhile, the sound pipeline is provided with a strip-shaped rectangular mounting slotted hole. The silencing process can be divided into two types, namely resistive silencing and reflective silencing; for a specific division frequency point, the device works in a resistive silencing state in a frequency range smaller than the frequency point, and works in a reflective silencing state in a frequency range larger than the frequency point.
Description
Technical Field
The invention belongs to the field of noise elimination and reduction, and particularly relates to a broadband pipeline silencer based on a gradient impedance boundary.
Background
The pipeline is a common acoustic environment, and the noise reduction of the pipeline has important significance for preventing and treating noise pollution. For example, in modern industries, the development of large fans, gas turbines, and jet devices has made strong noise pollution in these duct structures increasingly serious, and noise reduction has become important. The common pipe muffling devices at present are expanding pipe mufflers, resonant mufflers and the like.
The existing expansion pipe type muffler or resonance type muffler realizes the effect of sound attenuation by introducing a section of expanded pipe or a wall-side resonator structure into the pipe. Due to the sudden change of the acoustic impedance brought by the introduced expansion pipe and the wall-side resonator in the pipeline, the sound wave propagating in the pipeline is reflected and transmitted at the position of the sudden change of the impedance, part of energy is reflected, part of energy is absorbed, a small amount of energy is transmitted, and the effect of sound absorption in the transmission direction is achieved.
To the technical scheme of the prior pipeline noise elimination, the method has the following disadvantages: the frequency band of sound attenuation is narrow. For an expansion pipe type or resonance type silencer, the silencing principle of the silencer depends on a resonance mechanism, and effective silencing effect can be achieved only in a specific resonance frequency point or points and a narrow bandwidth range around the resonance frequency point or points. Outside these bands, the sound-deadening effect almost disappears.
Disclosure of Invention
The invention aims to provide a broadband pipeline silencer based on a gradual change impedance boundary, which realizes the silencing capability of a broadband in a pipeline and overcomes the problem of small sound absorption bandwidth in the background technology.
In order to achieve the purpose, the invention adopts the technical scheme that: the broadband pipeline silencer based on the gradual change impedance boundary is characterized by comprising a sound pipeline, gradual change impedance boundary blocks and a sound absorption circular ring block, wherein the section of the sound pipeline is circular, the gradual change impedance boundary blocks are arranged on the periphery of the wall of the sound pipeline, through holes with one closed ends are arranged in the gradual change impedance boundary blocks, the open ends of the through holes are communicated with the inside of the sound pipeline, and the sound absorption circular ring block is laid on the inner wall of one end of the sound pipeline.
Furthermore, the acoustic pipeline is provided with strip-shaped rectangular mounting slotted holes, each mounting slotted hole is arranged along the axial direction of the acoustic pipeline, the mounting slotted holes are uniformly distributed along the circumferential direction of the acoustic pipeline, and one end of the gradient impedance boundary block, which is provided with a through hole, is mounted on the mounting slotted hole.
Furthermore, the internal through hole of the gradual change impedance boundary block is divided into two parts, the length of the through hole of the former part is gradually increased, and the length of all the through holes of the latter part is kept unchanged and is kept consistent with the length of the last through hole of the former part.
Furthermore, the sound absorption ring block is laid on the inner wall of the sound pipeline at the position of a part of through holes behind the gradual impedance boundary block and is positioned at the boundary position close to the last through hole of the gradual impedance boundary block.
Furthermore, the sound absorption ring block is made of sound absorption materials, and comprises various porous sound absorption materials or sound absorption cotton.
Furthermore, the radial thickness of the sound absorption circular ring block is one fifth of the radius of the pipeline.
Further, the length of the gradually-increased through hole of the former part of the gradually-changed impedance boundary block is 0.6-0.8 times of the length of the whole boundary block.
Further, the graded impedance boundary blocks are arranged in a circle around the outer wall of the acoustic duct, and the number of the graded impedance boundary blocks is set to be 24.
Furthermore, the length of the gradient impedance boundary block is less than that of the sound pipeline, the length of the gradient impedance boundary block is 6-12 times of the diameter of the sound pipeline, and the length of the sound pipeline in the axial direction is 6-12 times of the diameter of the sound pipeline.
Furthermore, the final length of the through holes which are arranged in parallel inside the gradient impedance boundary block is 0.8-1.2 of the diameter of the sound pipeline; and the diameter of the through hole is 1/10 of the diameter of the sound pipeline, and the upper limit of the through hole does not exceed 1/5 of the wavelength corresponding to the lower limit of the low frequency of the noise.
The invention has the beneficial effects that: when the plane sound wave enters the pipeline as noise, the plane sound wave and the gradient impedance boundary act to gradually transit and change into surface sound wave which advances along the boundary and is reflected or absorbed, so that the effect of noise elimination is achieved. The silencing process of the device can be divided into two types, namely resistive silencing and reflective silencing. For a specific division frequency point, in a frequency range smaller than the frequency point, the device works in a resistive silencing state, and incident sound waves are converted into surface waves which can be transmitted and absorbed by a sound absorption block at the tail end of the pipeline. Within the frequency range larger than the frequency point, the device works in a reflection noise elimination state, incident sound waves are converted into surface waves and finally transition to a surface wave mode which cannot be continuously transmitted, and all sound energy is reflected back to realize noise elimination.
Drawings
FIG. 1 is a schematic view of the overall structure of the present invention;
FIG. 2 is a front view of the present invention;
FIG. 3 is a side view of the present invention;
FIG. 4 is a partial cross-sectional view of the present invention;
FIG. 5 is a schematic view of the acoustic duct structure of the present invention;
FIG. 6 is a schematic diagram of a graded impedance boundary block structure according to the present invention;
FIG. 7 is an assembly view of the present invention;
fig. 8 is a plane wave-surface wave conversion chart in which (a) is a state of resistive noise cancellation and (b) is a state of reflection noise cancellation;
fig. 9 is a graph of simulation and experimental results of the muffling bandwidth.
Labeled as: 1-a graded impedance boundary block; 2-an acoustic pipe; and 3-sound absorption circular ring blocks.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
As shown in fig. 1-4, a broadband duct muffler based on a gradual impedance boundary comprises three parts: the sound absorption device comprises a sound pipeline 2 with a circular section, a graded impedance boundary block 1 attached to the boundary of the sound pipeline, and a sound absorption circular ring block 3 laid on the inner wall of the sound pipeline. The graded impedance boundary blocks are arranged around the outer wall of the pipeline for 24 blocks, and the boundary blocks form the boundary acoustic boundary of the pipeline and influence the movement of sound waves in the pipeline. The number and size of the boundary blocks may vary with the pipe diameter, incident noise properties. The sound absorption circular ring block 3 is arranged at the rear end of the structure and used for sound absorption. The annular block may be any sound absorbing material (e.g., various types of porous sound absorbing materials, sound absorbing cotton, etc.). The ring block is laid against the inner wall of the pipeline, the radial thickness of the ring block is about one fifth of the radius of the sound pipeline, the radial thickness of the sound absorption ring block can be increased or decreased, the material of the sound absorption ring block is changed, or a proper shade is additionally arranged on the ring block according to the ventilation requirement of the pipeline, the fluid characteristic of the flowing pipeline, the noise reduction requirement and the like.
Fig. 5 shows the structure of the acoustic duct in which the boundary block is installed, and in order to facilitate installation or replacement of the boundary block, 24 rectangular slots are formed through the wall of the acoustic duct. Depending on the material (metal, plastic, etc.) of the sound duct and the boundary block, the boundary block may be assembled by welding, gluing, etc.
Fig. 6 shows the structure of the graded impedance boundary block, the interior of the boundary block is composed of a series of parallel arranged through holes with one end closed, and the open ends of the through holes are flush with the boundary of the acoustic pipeline and allow the sound wave to enter. The ends and walls of the pipes are acoustically hard boundaries, and the lengths of the pipes increase linearly and gradually along the propagation direction of sound waves, and from zero, the lengths do not increase after reaching the final length designed in advance. The length of the pipeline length increasing region is preferably 0.6-0.8 times of the length of the whole boundary block.
Figure 7 shows an overall assembly view of the structure. When the boundary block is installed on the sound pipeline, any reinforcing device such as a hoop can be additionally installed according to actual requirements, and the structural strength of the boundary block is maintained. Such reinforcement means are not marked on the figures.
In addition, the related dimension parameters of the silencer structure can be subjected to frequency spectrum according to actual conditions (the size of an actually used sound pipeline, the nature of incident noise and the like). Typical dimensional parameters are as follows:
(1) the length of the entire device in the axial direction of the acoustic pipe is about 6 to 12 times the diameter of the acoustic pipe, based on the diameter of the acoustic pipe. The longer the device, the better the effect, but the more space it takes up.
(2) The length of the boundary block corresponds to the length of the whole device, i.e. 6-12 times the diameter of the sound duct.
(3) The final length of the parallel-arranged through holes inside the boundary block is preferably about 0.8-1.2 times the diameter of the acoustic duct.
(4) The number of boundary blocks is preferably as large as possible to surround the acoustic duct in a full-face and high-density manner. Which is about 24 blocks in number.
(5) The length of the growing region of the through holes arranged in parallel inside the boundary block is 0.6 to 0.8 times the overall length of the boundary block.
(6) The sound absorbing ring is required to be arranged at the tail end of the device, and the arrangement position is preferably not beyond the range of the parallel pipelines in the boundary block.
(7) The radial thickness of the sound absorbing ring is preferably set to 1/10 to 1/5 of the radius of the sound duct.
(8) The diameter of the parallel through holes in the boundary block is about 1/10 of the diameter of the pipeline, and the upper limit of the parallel through holes does not exceed 1/5 of the wavelength corresponding to the lower limit of the low frequency of the noise.
Fig. 8 shows the conversion of a planar acoustic wave incident on the acoustic pipe to a surface acoustic wave. Fig. 8(a) shows a state of resistive noise reduction, and fig. 8(b) shows a state of reflective noise reduction.
FIG. 9 shows the results of testing an example embodiment (experimental model) of the present invention. To simplify the model, in this experimental model the acoustic duct is a resin two-dimensional structure fabricated using 3D printing, since for an axisymmetric device the two-dimensional structure can represent the properties of a three-dimensional structure. Experimental structure used for simulation: the diameter of the acoustic pipeline is 0.05m, and the length of the acoustic pipeline is 0.4 m. The boundaries on both sides of the acoustic duct are tapered impedance boundaries manufactured by 3D printing, where the length of the tapered portion is about 0.267m and the final length of the parallel through holes in the tapered impedance boundary is 0.04 m. The left side of the acoustic duct uses a loudspeaker to generate a plane sound wave as an incident sound source.
During the measurement, we use the frequency sweep signal of 0-10000Hz as input to measure the sound field at the end of the pipe to calculate the transmittance of the pipe.
The results in fig. 9 show that the experimental results and the simulation results are good, the noise elimination effect is achieved in the wider frequency range of 2000-7000Hz, only a small amount of sound energy is transmitted, and most of the sound energy is reflected or absorbed.
The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It should be understood by those skilled in the art that the above embodiments do not limit the scope of the present invention in any way, and all technical solutions obtained by using equivalent substitution methods fall within the scope of the present invention.
The parts not involved in the present invention are the same as or can be implemented using the prior art.
Claims (10)
1. The broadband pipeline silencer based on the gradual change impedance boundary is characterized by comprising a sound pipeline, gradual change impedance boundary blocks and a sound absorption circular ring block, wherein the section of the sound pipeline is circular, the gradual change impedance boundary blocks are arranged on the periphery of the wall of the sound pipeline, through holes with one closed ends are arranged in the gradual change impedance boundary blocks, the open ends of the through holes are communicated with the inside of the sound pipeline, and the sound absorption circular ring block is laid on the inner wall of one end of the sound pipeline.
2. The broadband pipeline silencer according to claim 1, wherein the acoustic pipeline is provided with strip-shaped rectangular mounting slots, each mounting slot is arranged along an axial direction of the acoustic pipeline, the mounting slots are evenly distributed along a circumferential direction of the acoustic pipeline, and one end of the graded impedance boundary block, provided with the through hole, is mounted on the mounting slot.
3. The broadband pipeline silencer according to claim 1, wherein the internal through holes of the impedance gradually changing boundary block are divided into two parts, the length of the through holes of the former part is gradually increased, and the length of all the through holes of the latter part is kept constant and is kept consistent with the length of the last through hole of the former part.
4. The broadband pipeline silencer according to claim 3, wherein the sound absorption ring block is laid on the inner wall of the sound pipeline at a position of a part of through holes behind the gradual impedance boundary block and is positioned at a boundary position close to the last through hole of the gradual impedance boundary block.
5. The broadband pipeline muffler based on the gradually changing impedance boundary as claimed in claim 4, wherein the sound absorption ring block is made of sound absorption materials, and comprises various porous sound absorption materials or sound absorption cotton.
6. The broadband duct muffler based on a graded impedance boundary as set forth in claim 4 or 5, wherein the radial thickness of the sound absorbing annular block is one fifth of the radius of the sound duct.
7. The broadband conduit muffler based on a graded impedance boundary according to claim 3, wherein the length of the gradually-increasing through hole of the previous part of the graded impedance boundary block is 0.6-0.8 times the length of the whole boundary block.
8. The broadband duct muffler based on a graded impedance boundary according to claim 3 or 7, wherein the graded impedance boundary blocks are arranged in a circle and 24 blocks in number around the outer wall of the acoustic duct.
9. The wideband pipe muffler based on graded impedance boundary as claimed in claim 1, wherein the length of the graded impedance boundary block is less than the length of the acoustic pipe, the length of the graded impedance boundary block is 6-12 times the diameter of the acoustic pipe, and the length of the acoustic pipe in the axial direction is 6-12 times the diameter of the acoustic pipe.
10. The broadband pipeline silencer according to claim 1, wherein the final length of the through holes arranged in parallel inside the gradual impedance boundary block is 0.8-1.2 of the diameter of the sound pipeline; and the diameter of the through hole is 1/10 of the diameter of the sound pipeline, and the upper limit of the through hole does not exceed 1/5 of the wavelength corresponding to the lower limit of the low frequency of the noise.
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| CN202111633932.6A CN114321553B (en) | 2021-12-29 | 2021-12-29 | Broadband pipeline silencer based on gradual change impedance boundary |
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| CN202111633932.6A CN114321553B (en) | 2021-12-29 | 2021-12-29 | Broadband pipeline silencer based on gradual change impedance boundary |
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| CN114321553B CN114321553B (en) | 2023-03-24 |
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2876172A1 (en) * | 2004-10-01 | 2006-04-07 | Peugeot Citroen Automobiles Sa | Acoustic attenuation duct device for ventilation of an automobile vehicle, includes an opening and an ensemble having foam/fibrous/porous layer, external sheet, in which the periphery edge is fixed continuously and tightly on the duct |
| CN104234890A (en) * | 2013-06-21 | 2014-12-24 | 重庆长安汽车股份有限公司 | High-frequency muffler used on automobile intercooler intake pipe |
| CN104505085A (en) * | 2014-12-03 | 2015-04-08 | 南京大学 | Ultra-wideband acoustic absorber |
| CN106402565A (en) * | 2016-11-08 | 2017-02-15 | 江苏英思达科技有限公司 | Sound absorption flow guide body |
| CN108138707A (en) * | 2015-10-19 | 2018-06-08 | 法国诺华公司 | For the acoustic attenuation device of admission line |
| CN211016506U (en) * | 2019-07-25 | 2020-07-14 | 中国科学院声学研究所 | Beam cavity resonance composite structure silencer |
| CN113035166A (en) * | 2021-03-29 | 2021-06-25 | 合肥工业大学 | Ventilating sound-absorbing metamaterial |
-
2021
- 2021-12-29 CN CN202111633932.6A patent/CN114321553B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2876172A1 (en) * | 2004-10-01 | 2006-04-07 | Peugeot Citroen Automobiles Sa | Acoustic attenuation duct device for ventilation of an automobile vehicle, includes an opening and an ensemble having foam/fibrous/porous layer, external sheet, in which the periphery edge is fixed continuously and tightly on the duct |
| CN104234890A (en) * | 2013-06-21 | 2014-12-24 | 重庆长安汽车股份有限公司 | High-frequency muffler used on automobile intercooler intake pipe |
| CN104505085A (en) * | 2014-12-03 | 2015-04-08 | 南京大学 | Ultra-wideband acoustic absorber |
| CN108138707A (en) * | 2015-10-19 | 2018-06-08 | 法国诺华公司 | For the acoustic attenuation device of admission line |
| CN106402565A (en) * | 2016-11-08 | 2017-02-15 | 江苏英思达科技有限公司 | Sound absorption flow guide body |
| CN211016506U (en) * | 2019-07-25 | 2020-07-14 | 中国科学院声学研究所 | Beam cavity resonance composite structure silencer |
| CN113035166A (en) * | 2021-03-29 | 2021-06-25 | 合肥工业大学 | Ventilating sound-absorbing metamaterial |
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