A side suction pipeline silencer structure based on acoustic black hole effect and application

Abstract

The application discloses a kind of based on acoustic black hole effect's side suction pipeline silencer structure and application, including the columnar silencer pipeline of greater inner diameter being connected with the noise reduction main body pipeline, the two sides inner wall of columnar silencer pipeline is equipped with several metal baffles being distributed along the radial direction of noise reduction main body pipeline, the width of several metal baffles gradually expands in sequence along the minimum inner diameter of columnar silencer pipeline to the maximum inner diameter of columnar silencer pipeline, the connecting surface of the extension end of the two sides several metal baffles in noise reduction main body pipeline forms symmetrical arc surface and does not contact each other, and symmetrical arc surface is axisymmetric.Sound wave is propagated to acoustic black hole component by main pipeline, its energy will be concentrated into silencer due to acoustic black hole effect, and is dissipated by the damping of porous material or air itself.The structure does not change the inner diameter of main pipeline, does not reduce the flow rate of medium in main pipeline, does not produce new flow noise, and can achieve the purpose of good noise reduction.

Description

Technical Field

[0001] This invention relates to the field of pipeline noise reduction and sound propagation technology, and in particular to a side-suction pipeline silencer structure and its application based on the acoustic black hole effect. Background Technology

[0002] Vehicles with exhaust pipes, such as cars and motorcycles, agricultural tools like tractors, and machines with exhaust pipes are ubiquitous in daily life. When these vehicles emit exhaust gases, the exhaust pipes are usually accompanied by airflow noise. Excessive intensity of this broadband noise can easily damage the pipes and cause significant noise hazards to operators or people near the machines. In recent years, acoustic black hole structures, proposed in the field of acoustics, not only possess lightweight characteristics but also high damping, high-frequency dispersion, and high energy concentration properties, demonstrating great application potential in noise control, sound wave modulation, and efficient energy recovery.

[0003] The concept of an acoustic black hole can be compared to the concept of a black hole in astrophysics. In astrophysics, a black hole is a singularity with infinite density, infinite spacetime curvature, infinitely small volume, and infinite heat, capable of consuming all light and matter in its vicinity. The acoustic black hole effect can be analogous: by adjusting the diameter of a pipe using a power law and controlling the impedance of its inner walls, the phase velocity and group velocity of sound waves gradually decrease until they approach zero, thus creating a sound wave focusing effect at the end of the pipe, forming a high-energy-density region.

[0004] Current research on acoustic black holes mainly includes one-dimensional and two-dimensional structures. The diameter of an ideal acoustic black hole structure varies according to a power-law distribution. Ideally, the diameter of the acoustic black hole structure shrinks to zero along the axis from the center outwards.

[0005] However, for one-dimensional and two-dimensional acoustic black hole structures, it is necessary to reduce the diameter of the main pipe, for example, by adding baffles or filling other materials. This not only increases the complexity and cost of pipe processing, but also greatly reduces the flow rate of the fluid due to the reduced inner diameter of the pipe, which causes the fluid to generate new noise, seriously affecting the practicality of the pipe and hindering the application and promotion of acoustic black holes.

[0006] Therefore, in the process of noise reduction in fluid pipelines, it is very important to design a silencer based on the acoustic black hole effect that does not damage the original pipe diameter. Summary of the Invention

[0007] To address the aforementioned deficiencies in the existing technology, the present invention aims to provide a side-suction pipe silencer based on the acoustic black hole effect. By applying a side-suction pipe silencer component based on the acoustic black hole effect between two main pipe sections, a better noise reduction effect can be achieved without reducing the diameter of the main pipe.

[0008] The present invention is achieved through the following technical solution.

[0009] This invention provides a pipe-side absorption silencer structure based on the acoustic black hole effect, including a columnar silencer pipe coaxially connected to the noise reduction main pipe, wherein the inner diameter of the columnar silencer pipe is larger than that of the noise reduction main pipe; the inner walls on both sides of the columnar silencer pipe are provided with a plurality of metal baffles radially distributed along the noise reduction main pipe, the width of the plurality of metal baffles gradually increasing from the minimum inner diameter to the maximum inner diameter of the columnar silencer pipe, and the connecting surfaces of the extended ends of the plurality of metal baffles on both sides of the noise reduction main pipe form a symmetrical arc surface that does not contact each other, and the symmetrical arc surface is axially symmetrical.

[0010] Preferably, the inner diameter of the columnar silencer pipe is twice the inner diameter of the noise reduction main pipe.

[0011] Preferably, each metal baffle is a thin cylindrical shell structure with the same central axis as the columnar silencer pipe and the noise reduction main pipe.

[0012] Preferably, several metal baffles are rigidly connected to the inner wall of the columnar silencer pipe.

[0013] Preferably, adjacent metal baffles are equidistantly distributed on both sides of the inner wall of the columnar silencer pipe and do not contact each other.

[0014] Preferably, the spacing between the metal baffles with the longest symmetrical arc surfaces is the narrowest gap inside the columnar silencer duct with acoustic black hole effect, and the narrowest gap is no greater than 1 / 10 of the length of the columnar silencer duct.

[0015] Preferably, the material of the columnar silencer pipe is the same as that of the main noise reduction pipe, and the material of the metal baffle is the same as that of the main noise reduction pipe.

[0016] The present invention, by adopting the above technical solution, has the following beneficial effects:

[0017] 1. This invention relates to a side-suction duct silencer structure based on the acoustic black hole effect. The silencer is constructed by directly splicing the main duct to the main pipe, utilizing several metal baffles to form a black hole effect silencer. Taking advantage of the acoustic black hole effect, sound waves propagate through the main pipe to the acoustic black hole component. The plane wave energy within the main pipe is concentrated in the silencer due to the acoustic black hole effect and dissipated through the damping of the porous material or the air itself. This effectively dissipates the energy of noise within the duct.

[0018] 2. The width of several metal baffles in the columnar silencer pipe gradually increases with the inner diameter of the columnar silencer. The extended ends form symmetrical arc surfaces and do not contact each other. The plane wave energy in the main pipe is concentrated into the acoustic black hole structure composed of symmetrically distributed metal baffles. The sound wave has a high propagation loss after passing through the acoustic black hole silencer, thus achieving stable and broadband high sound absorption performance.

[0019] 3. This structure only requires replacing a portion of the main pipeline, is easy to disassemble, does not change the inner diameter of the main pipeline, does not reduce the flow velocity of the medium inside the main pipeline, and does not generate new flow noise, thus achieving a good noise reduction effect. This demonstrates the broad application prospects of the acoustic black hole structure in a range of pipeline structures where noise is generated by medium flow, such as industrial pipeline equipment, engine equipment, and gas emission equipment. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, do not constitute an undue limitation of the invention. In the drawings:

[0021] Figure 1 This is a three-dimensional structural diagram of the noise reduction structure of the present invention installed on the main pipeline;

[0022] Figure 2 A three-dimensional structural diagram showing the noise reduction structure of the present invention installed on the main pipeline, cut along the axial direction;

[0023] Figure 3 This is a schematic diagram of the acoustic black hole component in the noise reduction structure of the present invention;

[0024] Figure 4 This is a cross-sectional schematic diagram of the acoustic black hole component in the noise reduction structure of the present invention;

[0025] Figure 5 A comparison diagram showing the transmission loss of noise in the main pipeline after passing through the noise reduction structure of this invention and the cavity without the attached acoustic black hole component.

[0026] Figure 6 A comparison diagram showing the transmission loss of noise in the main pipeline after passing through the noise reduction structure of this invention and after the same length of main pipeline without any noise reduction measures;

[0027] The labels in the attached diagram are as follows: 1-Noise reduction main duct; 2-Columnar silencer duct; 3-Metal baffle. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0029] like Figure 1As shown, this embodiment of the invention provides a side-suction pipe muffler structure based on the acoustic black hole effect, including: a columnar muffler pipe 2 coaxially connected to the noise reduction main pipe 1, the inner diameter of the columnar muffler pipe 2 being larger than that of the noise reduction main pipe 1, and in this embodiment, the inner diameter of the columnar muffler pipe is twice that of the noise reduction main pipe.

[0030] like Figure 2 As shown, the inner walls of both sides of the columnar muffler pipe 2 are provided with several metal baffles 3 radially distributed along the main noise reduction pipe 1. The width of the several metal baffles 3 gradually increases from the minimum inner diameter to the maximum inner diameter of the columnar muffler pipe 2. The connecting surfaces of the extended ends of the several metal baffles on both sides of the main noise reduction pipe form symmetrical arc surfaces that do not contact each other. The symmetrical arc surfaces are axially symmetrical, constituting an acoustic black hole component with a noise reduction structure.

[0031] like Figure 2 As shown, adjacent metal baffles are equidistantly distributed on both sides of the inner wall of the columnar silencer duct 2 and do not contact each other. The thin metal baffles are rigidly connected to the inner wall of the columnar silencer duct 2.

[0032] like Figure 3 As shown, each metal baffle 3 is a thin cylindrical shell structure with the same central axis as the columnar silencer pipe 2 and the noise reduction main pipe 1. In this structure, the spacing between adjacent metal baffles 3 in each layer is the same, and the spacing is not less than the thickness of the metal baffle 3. In one embodiment, the thickness of each metal baffle 3 is not greater than 5mm, but when the number of metal baffles 3 is large, assuming the inner diameter of the noise reduction main pipe 1 is r0, the inner diameter of the columnar silencer pipe 2 is R0, and the number of metal baffles 3 is N, the thickness H of the metal baffle 3 is calculated according to the following formula:

[0033]

[0034] In one embodiment, if the inner diameter r0 of the noise reduction main pipe 1 is 100mm, the inner diameter R0 of the columnar silencer pipe 2 is 200mm, and the number N of metal baffles 3 is 25, then the thickness H of the metal baffles 3 should not exceed 2mm.

[0035] In this structure, the spacing between the longest symmetrical arc-shaped metal baffles 3 (the narrowest gap of the black hole effect) is no greater than 1 / 10 of the length of the muffler 2. In one embodiment, the length of the columnar muffler pipe 2 is 100mm, then the spacing between the longest symmetrical arc-shaped metal baffles 3 (the narrowest gap of the black hole effect) is less than 10mm.

[0036] like Figure 4 As shown, the width d of the metal baffle of the acoustic black hole component varies with the inner diameter of the columnar silencer pipe as follows:

[0037] d(r)=d c +ε(R0-r0)m

[0038] Where r0 is the inner diameter of the noise reduction main pipe, and R0 is the inner diameter of the columnar silencer pipe; d c The value of d is half the width of the columnar silencer duct minus the maximum width of the metal baffle. c ≥0; ε is the slope of the profile, ε>0; m is the order of the acoustic black hole, m≥2.

[0039] In this embodiment, the inner diameter r0 of the noise reduction main pipe 1 is selected as 0.1m, the inner diameter r of the columnar silencer pipe 2 is 0.2m, the length of the columnar silencer pipe is 0.1m, r0 is 0.05m, R is 0.1m, and d is... c Given that ε is 18 and m is 2, the width d of the thin metal baffle is 0.0324m (3.24mm).

[0040] The columnar silencer pipe 2 of this invention is made of the same material as the noise reduction main pipe 1, and the metal baffle 3 is made of the same material as the noise reduction main pipe 1.

[0041] The working principle of this invention is as follows: On the main pipeline, the silencer utilizes the acoustic black hole effect to concentrate the plane wave energy within the pipeline into the silencer, effectively dissipating the energy of noise within the pipeline. Furthermore, this structure only requires replacing a portion of the main pipeline, making disassembly convenient. It does not alter the inner diameter of the main pipeline, does not reduce the flow velocity of the medium within the main pipeline, and does not generate new flow noise, thus achieving a good noise reduction effect.

[0042] The following simulation model is established using Comsol Mutiphysics 6.1 finite element simulation software to optimize the parameters of the acoustic black hole component in the vibration reduction structure.

[0043] Solid mechanics simulations were performed using COMSOL Multiphysics 6.1 finite element simulation software to determine the optimal dimensions. The COMSOL Multiphysics 6.1 simulation model is shown below. Figure 1 As shown, in the simulation, the noise reduction main pipe 1 model has an inner diameter of 0.1m and a length of 1m, while the columnar silencer pipe 2 has an inner diameter of 0.2m and a length of 0.1m.

[0044] Furthermore, this invention provides a design method for the acoustic black hole component in a side-suction duct silencer structure based on acoustic black holes, comprising the following steps:

[0045] By comparing the transmission loss of the cavity under different inner diameters of the silencer pipe and the main pipe, the inner diameter of the columnar silencer pipe was finally selected to be twice the inner diameter of the noise reduction main pipe 1.

[0046] By comparing the sound wave transmission loss through the silencer when different numbers of thin metal baffles are used to construct the acoustic black hole component, the number of metal baffle units constituting the acoustic black hole component 3 is selected to be 100.

[0047] In this embodiment, the cylindrical silencer pipe 2 is made of the same material as the noise reduction main pipe 1, and the metal baffle 3 is made of the same material as the noise reduction main pipe 1.

[0048] 2. Analysis of Model Calculation Results

[0049] Depend on Figure 5 It can be seen that, in this embodiment of the invention, the propagation loss (i.e., sound absorption performance) of sound waves passing through the side-suction pipe silencer based on the acoustic black hole effect is much higher than that of the expansion pipe silencer without the acoustic black hole structure in the 500-1200Hz range, by a maximum of 35dB and an average of 8dB. The starting frequency of this acoustic black hole structure... Near the initial frequency, the silencer begins to exhibit stable, broadband high sound absorption performance. In the 1650Hz-3500Hz range, compared to an expansion tube silencer without an acoustic black hole structure, the propagation loss of sound waves after passing through the acoustic black hole silencer is stable at 10dB, with a maximum increase of 13dB and an average increase of 11dB.

[0050] Depend on Figure 6 As can be seen, in this embodiment of the invention, the propagation loss (i.e., sound absorption performance) of sound waves passing through the side-absorption pipe silencer based on the acoustic black hole effect is significantly higher than that of a pipe of the same length without a silencer in the 0-3500Hz range, with a maximum increase of 42dB and an average increase of 18dB. Near the initial frequency, the silencer begins to exhibit stable, broadband high sound absorption performance. In the 1500Hz-3500Hz range, compared to a pipe of the same length without a silencer, the propagation loss of sound waves after passing through the acoustic black hole silencer is consistently 13dB higher, with a maximum increase of 20dB and an average increase of 15dB.

[0051] This invention can be applied to the main pipelines of industrial pipeline equipment, engine equipment, and gas emission equipment. The silencer pipeline utilizes the acoustic black hole effect to concentrate the plane wave energy in the main pipeline into the silencer. The acoustic black hole effect can effectively dissipate the energy of noise in the pipeline without changing the inner diameter of the main pipeline, without reducing the flow velocity of the medium in the main pipeline, and without generating new flow noise, thus achieving a good noise reduction purpose.

[0052] This invention is not limited to the above embodiments. Based on the technical solutions disclosed in this invention, those skilled in the art can make some substitutions and modifications to some of the technical features without creative effort, and all such substitutions and modifications are within the protection scope of this invention.

Claims

1. A side-suction pipe silencer structure based on the acoustic black hole effect, characterized in that, The system includes a columnar muffler pipe coaxially connected to the main noise reduction pipe, wherein the inner diameter of the columnar muffler pipe is larger than that of the main noise reduction pipe; the inner walls on both sides of the columnar muffler pipe are provided with several metal baffles radially distributed along the main noise reduction pipe, the width of the several metal baffles gradually increases from the minimum inner diameter to the maximum inner diameter of the columnar muffler pipe, and the connecting surfaces of the extended ends of the several metal baffles on both sides of the main noise reduction pipe form a symmetrical arc surface that does not contact each other, and the symmetrical arc surface is axially symmetrical.

2. The side-suction pipe silencer structure based on the acoustic black hole effect according to claim 1, characterized in that, The inner diameter of the columnar silencer pipe is twice the inner diameter of the main noise reduction pipe.

3. The side-suction pipe silencer structure based on the acoustic black hole effect according to claim 1, characterized in that, Each metal baffle is a thin cylindrical shell structure with the same central axis as the columnar silencer pipe and the noise reduction main pipe.

4. The side-suction pipe silencer structure based on the acoustic black hole effect according to claim 1, characterized in that, Several metal baffles are rigidly connected to the inner wall of the columnar silencer pipe.

5. The side-suction pipe silencer structure based on the acoustic black hole effect according to claim 1, characterized in that, Interlayer adjacent metal baffles are evenly distributed on both sides of the inner wall of the columnar silencer pipe and do not contact each other.

6. The side-suction pipe silencer structure based on the acoustic black hole effect according to claim 1, characterized in that, The thickness H of the metal baffle is calculated according to the following formula: H= In the formula, The inner diameter of the noise reduction main pipe, The inner diameter of the columnar silencer pipe. N is the number of metal baffles.

7. The side-suction pipe silencer structure based on the acoustic black hole effect according to claim 1, characterized in that, Width of several metal baffles The inner diameter distribution of the cylindrical silencer duct satisfies the following formula: in, To reduce noise, the inner diameter of the main pipe, This refers to the inner diameter of the columnar silencer pipe. The value is half the width of the columnar silencer duct minus the maximum width of the metal baffle. ; The slope of the profile. ; For acoustic black hole order, .

8. The side-suction pipe silencer structure based on the acoustic black hole effect according to claim 1, characterized in that, The spacing between the longest symmetrical arc-shaped metal baffles is the narrowest gap inside the columnar silencer duct with acoustic black hole effect, and the narrowest gap is no greater than 1 / 10 of the length of the columnar silencer duct.

9. The side-suction pipe silencer structure based on the acoustic black hole effect according to claim 1, characterized in that, The material of the columnar silencer pipe is the same as that of the main noise reduction pipe, and the material of the metal baffle is the same as that of the main noise reduction pipe.

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