WO2022092646A1

WO2022092646A1 - Meta-muffler of fractal structure

Info

Publication number: WO2022092646A1
Application number: PCT/KR2021/014305
Authority: WO
Inventors: 이진우; 김명삼
Original assignee: 아주대학교산학협력단
Priority date: 2020-10-28
Filing date: 2021-10-15
Publication date: 2022-05-05
Also published as: KR20220056678A; KR102415416B1

Abstract

The present invention provides a meta-muffler of a fractal structure, which is capable of increasing a transmission loss of the noise flowing in a flow tube by maximizing a loss in sound energy of the noise that is incident in a resonance chamber, by using a resonance chamber having a fractal structure connected to the flow tube. To this end, the present invention is characterized in comprising: a flow tube in which a fluid flows; a first wavelength tube which extends from the flow tube in the direction intersecting with the flowing direction of the fluid; and a second wavelength tube which extends from between both end portions of the first wavelength tube in the direction intersecting with the direction in which the first wavelength tube extends.

Description

Fractal structure meta muffler

The present invention relates to a meta muffler, and more particularly, to a meta muffler capable of increasing the transmission loss of noise flowing in a flow tube by using a resonance chamber of a fractal structure connected to a flow tube.

In general, various noise reduction devices have already been developed and used. Among them, the sound-absorbing type using a sound-absorbing material has excellent performance in the high-frequency region, but the performance is significantly lower in the low-frequency region, and there is a problem of scattering of the sound-absorbing material and poor durability due to vulnerability to moisture or heat.

Recently, a reflection type using the principle of reflecting a sound wave using an impedance mismatch generated by a change in the shape of a flow tube is used together. Representative reflective types include models using an expansion pipe or a perforated pipe, which is a shape in which the cross-sectional area of the pipe is changed, but there is a problem in that the size or volume increases because the noise performance is directly related to the degree of change in the cross-sectional area of the pipe.

A silencer using a resonator reduces the noise by installing a resonator having the same frequency as the noise generated from the flow pipe in the pipe. However, in the case of the resonator, since the size of the resonator is limited within a certain range by various design conditions such as the positional relationship between the pipes and the relationship with the surrounding structures, there is a problem in that the noise reduction performance that does not belong to the target frequency is significantly lowered.

In general, a resonator having a relatively small size is required to remove noise in a high frequency region, and a resonator having a relatively large size is required to remove noise in a low frequency region. However, since the conventional flow tube is installed in a narrow space, there are many difficulties in installing a large resonator, so it was very difficult to remove the noise in the low frequency region, and it was far from the recent technological trend in pursuit of miniaturization of the device.

As prior art, reference may be made to Korean Patent Laid-Open No. 10-2017-0112867 (published on October 12, 2017).

An object of the present invention is to solve the problems of the prior art, and the present invention uses a resonance chamber of a fractal structure connected to a flow tube to maximize the loss of sound wave energy of noise incident into the resonance chamber, so that the noise flowing in the flow tube An object of the present invention is to provide a meta muffler having a fractal structure that can increase transmission loss.

In order to achieve the above object of the present invention, a meta muffler having a fractal structure according to an embodiment of the present invention includes a flow pipe through which a fluid flows; a first wave pipe extending in a direction crossing the flow direction of the fluid from the flow pipe; and a second wave length extending in a direction crossing the extension direction of the first wave length between both ends of the first wave length.

In the meta muffler having a fractal structure according to an embodiment of the present invention, a cross-sectional size may be formed to decrease from the first wavelength to the second wavelength.

In the meta muffler having a fractal structure according to an embodiment of the present invention, the length of the first wavelength and the length of the second wavelength are relatively long when the target frequency of the noise to be attenuated is relatively low. and may be formed to be relatively short when the target frequency is relatively high.

In the meta muffler having a fractal structure according to an embodiment of the present invention, the cross-sectional size of the first wave length or the cross-sectional size of the second wavelength is relatively low when the target frequency of the noise to be attenuated is relatively low. It may be formed large, and when the target frequency is relatively high, it may be formed relatively small.

In the meta muffler having a fractal structure according to an embodiment of the present invention, the distance from the flow pipe to the connection part between the first and second wave lengths is relatively low when the target frequency of the noise to be attenuated is relatively low. may be formed to be long, and when the target frequency is relatively high, it may be formed to be relatively short.

In the meta muffler having a fractal structure according to an embodiment of the present invention, a third wave path extending in a direction crossing the extending direction of the second wave path between both ends of the second wave path; may further include In this case, as the number of wave tubes increases, the target frequency of the noise to be attenuated may decrease.

A meta muffler having a fractal structure according to another embodiment of the present invention includes: a flow pipe through which a fluid flows; a first wave pipe extending in a direction crossing the flow direction of the fluid from the flow pipe; a second wave length extending in a direction crossing the extending direction of the first wave length between both ends of the first wave length; and a third wave length extending in a direction crossing the extension direction of the first wave length between both ends of the first wave length and extending in a direction opposite to the second wave length.

In the meta muffler having a fractal structure according to another embodiment of the present invention, the cross-sectional size may be formed to decrease from the first wavelength to the second wavelength, and from the first to the third wavelength. The cross-sectional size may be formed to become smaller as it goes on.

In the meta muffler having a fractal structure according to another embodiment of the present invention, the length of the first wave length, the length of the second wave length, and the length of the third wave length are relative to the target frequency of the noise to be attenuated. When it is low, it may be formed to be relatively long, and when the target frequency is relatively high, it may be formed to be relatively short.

In the meta muffler having a fractal structure according to another embodiment of the present invention, the cross-sectional size of at least one of the cross-sectional size of the first wave length, the cross-sectional size of the second wave length, and the cross-sectional size of the third wave length is , may be formed to be relatively large when the target frequency of the noise to be attenuated is relatively low, and may be formed to be relatively small when the target frequency is relatively high.

In the meta muffler having a fractal structure according to another embodiment of the present invention, a distance from the flow pipe to a connection part between the first wave length and the second wave length or the first wave length and the third wave length from the flow pipe The distance to the connection part of the may be formed to be relatively long when the target frequency of the noise to be attenuated is relatively low, and can be formed to be relatively short when the target frequency is relatively high.

In a meta muffler having a fractal structure according to another embodiment of the present invention, there is provided a meta muffler comprising: a fourth wave length extending in a direction crossing the extension direction of the second wave length between both ends of the second wave length; and a fifth wave length extending in a direction intersecting the extension direction of the third wave length between both ends of the third wave length, and in this case, noise to be attenuated as the number of wave tubes increases The target frequency of may be decreased.

According to the present invention, it is possible to increase the transmission loss of noise flowing in the flow tube through the resonance chamber of the fractal structure connected to the flow tube.

According to the present invention, the target frequency of the noise to be attenuated can be broadened by adjusting the resonance chamber of the fractal structure connected to the flow tube.

1 is a view showing a cross-section of a meta muffler according to an embodiment of the present invention.

FIG. 2 is a view showing a part of a cross-section of the meta muffler of FIG. 1 .

3 is a diagram illustrating a case in which the length of a wavelength tube is adjusted according to an embodiment of the present invention.

4 is a view showing a case in which the cross-sectional size of the wavelength tube is adjusted according to an embodiment of the present invention.

5 is a view showing a case in which the distance from the flow pipe to the connection part of the first wave pipe and the second wave pipe is adjusted according to an embodiment of the present invention.

6 is a view showing a modified example of the meta muffler according to an embodiment of the present invention.

7 is a view showing a cross-section of a meta muffler according to another embodiment of the present invention.

FIG. 8 is a view showing a part of a cross-section of the meta muffler of FIG. 7 .

9 is a diagram illustrating a case in which the length of a wavelength tube is adjusted according to another embodiment of the present invention.

10 is a view showing a case in which the cross-sectional size of the wavelength tube is adjusted according to another embodiment of the present invention.

11 is a view showing a case in which the distance from the flow pipe to the connection part of the first wave pipe and the second wave pipe is adjusted according to another embodiment of the present invention.

12 is a view showing a modified example of a meta muffler according to another embodiment of the present invention.

A meta muffler having a fractal structure according to an embodiment of the present invention is provided between a flow pipe through which a fluid flows, a first wave path extending from the flow pipe in a direction crossing the flow direction of the fluid, and both ends of the first wave pipe. By using a resonance chamber of a fractal structure connected to the flow tube, including a second wave length extending in a direction intersecting the extension direction of the first wave length, the loss of sound wave energy of noise incident into the resonance chamber is maximized. It is possible to increase the transmission loss of noise flowing in the flow pipe.

Hereinafter, preferred embodiments of the present invention in which the above-described problems to be solved can be specifically realized will be described with reference to the accompanying drawings. In describing the present embodiments, the same names and reference numerals may be used for the same components, and an additional description thereof may be omitted.

1 is a view showing a cross section of a meta muffler according to an embodiment of the present invention, and FIG. 2 is a view showing a part of a cross section of the meta muffler of FIG. 1 .

1 and 2, the meta muffler 100 according to an embodiment of the present invention is to maximize the loss of sound wave energy of the noise flowing in the flow pipe 110 to increase the transmission loss of the noise. (110), the first wave path 120 and the second wave path 130 may be included.

The flow pipe 110 has a fluid flowing therein, and may be provided in the flow direction A1.

The fluid flowing into the flow pipe 110 may be a liquid, a gas, or the like, and in this embodiment, the case of air, which is a gas, will be described as an example.

In this embodiment, the cross-sectional shape of the flow tube 110 is illustrated in a circular shape, but the cross-sectional shape of the flow tube 110 may be formed in a polygonal shape such as a square.

The first wave pipe 120 may extend from the flow pipe 110 in a direction crossing the flow direction A1 of the fluid. A portion of the fluid flowing in the flow pipe 110 may be introduced into the first wave pipe 120 .

The first wave length 120 may extend to have a first length L1 in a direction crossing the flow direction A1, and the first length L1 may be adjusted according to the target frequency of the noise to be attenuated. can

The first wave length 120 may have a first cross-sectional size A1, and the first cross-sectional size A1 may be adjusted according to a target frequency of noise to be attenuated.

The first cross-sectional size A1 may be formed to have the same size along the extending direction of the first wave tube 120, or may be formed to gradually increase or decrease in the extending direction.

The second wave pipe 130 may extend between both ends of the first wave pipe 120 in a direction crossing the extending direction of the first wave pipe 120 . A portion of the fluid introduced into the first waveguide 120 may flow into the second waveguide 130 .

The second wave length 130 may extend to have a second length L2 in a direction crossing the extension direction of the first wave length 120, and the second length L2 is the target of the noise to be attenuated. It can be adjusted according to the frequency.

The second wave length 130 may have a second cross-sectional size A2, and the second cross-sectional size A2 may be adjusted according to a target frequency of noise to be attenuated.

The second cross-sectional size A2 may be formed to have the same size along the extending direction of the second wave length 130, or may be formed to gradually increase or decrease along the extending direction.

As such, the noise flowing in the flow pipe 110 flows into the first wave path 120 and the second wave path 130 forming a fractal structure, and the sound wave energy of the noise can be effectively lost.

In addition, the cross-sectional size of the wavelength tube may be formed smaller as it goes from the first wavelength tube 120 to the second wavelength tube 130 . That is, the second cross-sectional size A2 may be smaller than the first cross-sectional size A1.

Meanwhile, referring to FIG. 1 , a plurality of first wave channels 120 and second wave channels 130 may be provided along the extension direction of the flow pipe 110 , that is, along the fluid flow direction A1 , and a plurality of The first wave path 120 and the second wave path 130 may be disposed to be spaced apart along the flow direction A1. That is, the unit cell 101 including the flow pipe 110, the first wave pipe 120, and the second wave pipe 130 is sequentially disposed along the flow direction A1 of the fluid, and the meta muffler 100 is removed. can provide

Accordingly, a plurality of sub resonance chambers may be provided along the flow direction A1 of the fluid. By designing and changing each sub resonance chamber differently, the target frequency of noise attenuated in each sub resonance chamber is formed differently can do.

That is, the first length (L1) and the first cross-sectional size (A1) of the first wave path 120 forming each sub resonance chamber, the second length (L2) and the second cross section of the second wave path 130 By individually adjusting and setting the size A2, the number of wavelength tubes, etc., the target frequency of the noise to be attenuated can be broadened.

Meanwhile, the meta muffler 100 according to the present embodiment may further include an outer cylinder 102 .

The outer cylinder 102 may be disposed to be spaced apart from the flow pipe 110 to the outside of the flow pipe 110 , and is formed to surround the flow pipe 110 , the first wave pipe 120 and the second wave pipe 130 . The outer shape of the muffler 100 may be formed. The outer cylinder 102 is preferably formed in a shape corresponding to the cross-sectional shape of the flow pipe 110 , and may be formed in a circular shape corresponding to the cross-sectional shape of the flow pipe 110 . Of course, the flow pipe 110 and the outer cylinder 102 may be formed to have different cross-sectional shapes.

As such, when the outer tube 102 is provided, the design of the first wave tube 120 and the second wave tube 130 may be changed within a limited space between the flow tube 110 and the outer tube 102 .

That is, the first wave length 120 and the second wave length 130 are the first length L1 and the first length of the first wave length 120 in the limited space between the flow tube 110 and the outer tube 102 The cross-sectional size A1, the second length L2 and the second cross-sectional size A2 of the second wavelength tube 130, and the number of wavelength tubes may be adjusted.

According to the present embodiment, it is possible to adjust and broaden the target frequency of noise to be attenuated by adjusting the length of the wavelength tube.

As shown in (a) of FIG. 3 , if the target frequency of the noise to be attenuated is relatively low, the entire length of the wavelength tube, that is, the first length L1 and the second wavelength length of the first wavelength tube 120 . If the second length L2 of 130 is formed to be relatively long, it can correspond to setting the volume of the resonance chamber of the Helmholtz resonator to be large, so that it is possible to effectively attenuate noise in a relatively low frequency band.

As shown in (b) of FIG. 3 , on the contrary, when the target frequency of the noise to be attenuated is relatively high, the total length of the wavelength tube, that is, the first length L1 and the second wavelength length of the first wavelength tube 120 . When the second length L2 of 130 is formed relatively short, it can correspond to setting the volume of the resonance chamber of the Helmholtz resonator to be small, so that it is possible to effectively attenuate noise in a relatively high frequency band.

According to this embodiment, it is possible to adjust and broaden the target frequency of noise to be attenuated even by adjusting the cross-sectional size of the wavelength tube.

As shown in (a) of FIG. 4 , if the target frequency of the noise to be attenuated is relatively low, the first cross-sectional size A1 of the first wave path 120 or the second wave length of the second wave path 130 is If the cross-sectional size A2 is made relatively large, it can correspond to setting the volume of the resonance chamber of the Helmholtz resonator to be large, so that noise in a relatively low frequency band can be effectively attenuated.

As shown in (b) of FIG. 4 , when the target frequency of the noise to be attenuated is relatively high, the first cross-sectional size A1 of the first wave path 120 or the second wave length of the second wave path 130 is relatively high. If the cross-sectional size A2 is made relatively small, it can correspond to setting the volume of the resonance chamber of the Helmholtz resonator to be small, so that noise in a relatively high frequency band can be effectively attenuated.

According to this embodiment, even by adjusting the distance d1 from the flow pipe 110 to the connection part of the first wave pipe 120 and the second wave pipe 130, the target frequency of the noise to be attenuated can be adjusted and broadband. can get angry

As shown in (a) of FIG. 5, if the target frequency of the noise to be attenuated is relatively low, the distance from the flow pipe 110 to the connection part of the first wave pipe 120 and the second wave pipe 130 ( By forming d1) to be relatively long, it is possible to effectively attenuate noise in a relatively low frequency band.

As shown in (b) of FIG. 5, when the target frequency of the noise to be attenuated is relatively high, the distance from the flow pipe 110 to the connection part of the first wave pipe 120 and the second wave pipe 130 ( By forming d1) relatively short, it is possible to effectively attenuate noise in a relatively high frequency band.

Referring to FIG. 6 , the meta muffler 100 according to the present embodiment may further include a third wave length 140 .

The third wave path 140 may extend between both ends of the second wave path 130 in a direction crossing the extending direction of the second wave path 130 . A portion of the fluid introduced into the second waveguide 130 may flow into the third waveguide 140 .

The third wave length 140 may extend to have a third length L3 in a direction crossing the extension direction of the second wave length 130, and the third length L3 is the target of the noise to be attenuated. It can be adjusted according to the frequency.

The third wave length 140 may have a third cross-sectional size A3, and the third cross-sectional size A3 may be adjusted according to a target frequency of noise to be attenuated.

The third cross-sectional size A3 may be formed to have the same size along the extension direction of the third wave tube 140 , or may be formed to gradually increase or decrease in the extension direction.

When the third wavelength tube 140 is provided, the cross-sectional size of the wavelength tube may be formed smaller toward the first wavelength tube 120 , the second wavelength tube 130 , and the third wavelength tube 140 . That is, the second cross-sectional size A2 may be formed smaller than the first cross-sectional size A1 and larger than the third cross-sectional size A3.

As such, the noise flowing in the flow pipe 110 flows into the first wave path 120, the second wave path 130, and the third wave path 140 forming a fractal structure, and the sound wave energy of the noise can be lost more effectively.

Furthermore, according to the present embodiment, it is possible to adjust and broaden the target frequency of noise to be attenuated even by adjusting the number of wavelength tubes constituting the fractal structure. That is, as the number of wave tubes increases, the target frequency of noise to be attenuated may decrease.

As shown in FIG. 6, if the target frequency of the noise to be attenuated is relatively low, forming a relatively large number (3) of wave tubes can correspond to setting the volume of the resonance chamber of the Helmholtz resonator to be large. It is possible to effectively attenuate noise in a relatively low frequency band.

As shown in FIG. 2, if the target frequency of the noise to be attenuated is relatively high, forming a relatively small number (two) of wavelength tubes may correspond to setting the volume of the resonance chamber of the Helmholtz resonator to be small. It is possible to effectively attenuate noise in a relatively high frequency band.

7 is a view showing a cross-section of a meta muffler according to another embodiment of the present invention, and FIG. 8 is a view showing a part of a cross-section of the meta muffler of FIG. 7 .

7 and 8 , the meta muffler 200 according to another embodiment of the present invention includes a flow pipe 210 , a first wave pipe 220 , a second wave pipe 230 , and a third wave pipe 240 . ) may be included.

Hereinafter, in describing the meta muffler 200 according to the present embodiment, the description of the same configuration as the meta muffler 100 according to the above-described embodiment will be minimized.

The flow pipe 210 may be provided in the flow direction A1, and the fluid flows therein.

The first wave pipe 220 may extend in a direction crossing the flow direction A1 of the fluid from the flow pipe 210 .

The first wave length 220 may extend to have a first length L1 in a direction crossing the flow direction A1, and the first length L1 may be adjusted according to the target frequency of the noise to be attenuated. can

The first wave length 220 may have a first cross-sectional size A1, and the first cross-sectional size A1 may be adjusted according to a target frequency of noise to be attenuated.

The second wave path 230 may extend between both ends of the first wave path 220 in a direction crossing the extending direction of the first wave path 220 .

The second wave length 230 may extend to have a second length L2 in a direction crossing the extension direction of the first wave length 220, and the second length L2 is a target of noise to be attenuated. It can be adjusted according to the frequency.

The second wave length 230 may have a second cross-sectional size A2, and the second cross-sectional size A2 may be adjusted according to a target frequency of noise to be attenuated.

The third wave length 240 extends in a direction intersecting the extending direction of the first wave length 220 between both ends of the first wave length 220, and extends in the opposite direction to the second wave length 230. can

The third wave length 240 may extend to have a third length L2 in a direction crossing the extension direction of the first wave length 220, and the third length L2 is the target of the noise to be attenuated. It can be adjusted according to the frequency.

The third wave length 240 may have a third cross-sectional size A2, and the third cross-sectional size A2 may be adjusted according to a target frequency of noise to be attenuated.

As such, the noise flowing in the flow pipe 210 flows into the first wave path 220, the second wave path 230, and the third wave path 240 forming the fractal structure, and the sound wave energy of the noise is more effectively can be lost

On the other hand, the cross-sectional size of the wavelength tube may be formed smaller as it goes from the first wavelength tube 220 to the second wavelength tube 230 . That is, the second cross-sectional size A2 may be smaller than the first cross-sectional size A1.

In addition, the cross-sectional size of the wavelength tube may be formed smaller as it goes from the first wavelength tube 220 to the third wavelength tube 240 . That is, the third cross-sectional size A2 may be smaller than the first cross-sectional size A1.

And, as shown, the second wave length 230 and the third wave length 240 may form a symmetrical structure around the first wave length 220, and unlike the illustration, the second wave length 230 ) and the third wave length 240 may form an asymmetric structure around the first wave length 220 .

As shown in (a) of Figure 9, if the target frequency of the noise to be attenuated is relatively low, the entire length of the wavelength tube, that is, the first length (L1) of the first wavelength tube 220, the second wavelength tube If the second length L2 of 230 and the third length L3 of the third wave length 240 are relatively long, it can correspond to setting the resonance chamber volume of the Helmholtz resonator to be large, so a relatively low frequency It can effectively attenuate the noise in the band.

As shown in (b) of FIG. 9 , when the target frequency of the noise to be attenuated is relatively high, the total length of the wavelength tube, that is, the first length L1 of the first wavelength tube 220, and the second wavelength tube If the second length L2 of 230 and the third length L3 of the third wave length 240 are relatively short, it can correspond to setting the volume of the resonance chamber of the Helmholtz resonator to be small. It can effectively attenuate the noise in the band.

Therefore, it is possible to adjust and broaden the target frequency of noise to be attenuated by adjusting the length of the wavelength tube.

As shown in (a) of FIG. 10 , if the target frequency of the noise to be attenuated is relatively low, the first cross-sectional size A1 of the first wave length 220 and the second wave length A1 of the second wave length 230 are relatively low. If the cross-sectional size of at least one of the cross-sectional size A2 and the third cross-sectional size A3 of the third wave length 240 is relatively large, it can correspond to setting the volume of the resonance chamber of the Helmholtz resonator to be large. can effectively attenuate noise in the low frequency band.

As shown in (b) of FIG. 10 , when the target frequency of the noise to be attenuated is relatively high, the first cross-sectional size A1 of the first wave length 220 and the second wave length A1 of the second wave length 230 are relatively high. If the cross-sectional size of at least one of the cross-sectional size A2 and the third cross-sectional size A3 of the third wave length 240 is relatively small, it can correspond to setting the volume of the resonance chamber of the Helmholtz resonator to be small. can effectively attenuate noise in the high-frequency band.

Accordingly, it is possible to adjust and broaden the target frequency of the noise to be attenuated even by adjusting the cross-sectional size of the wavelength tube.

11 (a), if the target frequency of the noise to be attenuated is relatively low, the distance from the flow pipe 210 to the connection part of the first wave pipe 220 and the second wave pipe 230 ( d1) or by forming a relatively long distance d1 from the flow pipe 210 to the connection part of the first wave pipe 220 and the third wave pipe 240, it is possible to effectively attenuate noise in a relatively low frequency band.

As shown in (b) of FIG. 11, when the target frequency of the noise to be attenuated is relatively high, the distance from the flow pipe 210 to the connection part of the first wave pipe 220 and the second wave pipe 230 ( d1) or by forming a relatively short distance d1 from the flow pipe 210 to the connection part of the first wave pipe 220 and the third wave pipe 240, it is possible to effectively attenuate noise in a relatively high frequency band.

Accordingly, the distance d1 from the flow pipe 210 to the connection between the first wave pipe 220 and the second wave pipe 230 or the first wave pipe 220 and the third wave pipe 240 from the flow pipe 210 ), the target frequency of the noise to be attenuated can be adjusted and broadened by adjusting the distance d1 to the connection part.

Referring to FIG. 12 , the meta muffler 200 according to the present embodiment may further include a fourth wave pipe 250 and a fifth wave pipe 260 .

The fourth wave pipe 250 may extend between both ends of the second wave pipe 230 in a direction crossing the extending direction of the second wave pipe 230 .

The fourth wave length 250 may extend to have a fourth length L4 in a direction crossing the extension direction of the second wave length 130, and the fourth length L4 is a target of noise to be attenuated. It can be adjusted according to the frequency.

The fourth wave length 250 may have a fourth cross-sectional size A4, and the fourth cross-sectional size A4 may be adjusted according to a target frequency of noise to be attenuated.

When the fourth wavelength tube 250 is provided, the cross-sectional size of the wavelength tube may be formed smaller toward the first wavelength tube 220 , the second wavelength tube 230 , and the fourth wavelength tube 250 . That is, the second cross-sectional size A2 may be formed smaller than the first cross-sectional size A1 and larger than the fourth cross-sectional size A4.

The fifth wave pipe 260 may extend between both ends of the third wave pipe 240 in a direction crossing the extending direction of the third wave pipe 240 .

The fifth wave length 260 may extend to have a fifth length L5 in a direction crossing the extension direction of the third wave length 240, and the fifth length L5 is a target of noise to be attenuated. It can be adjusted according to the frequency.

The fifth wave length 260 may have a fifth cross-sectional size A5, and the fifth cross-sectional size A5 may be adjusted according to a target frequency of noise to be attenuated.

When the fifth wavelength tube 260 is provided, the cross-sectional size of the wavelength tube may be formed smaller toward the first wavelength tube 220 , the third wavelength tube 240 , and the fifth wavelength tube 260 . That is, the third cross-sectional size A3 may be formed smaller than the first cross-sectional size A1 and larger than the fifth cross-sectional size A5.

And, as shown, the fourth wave length 250 and the fifth wave length 260 may form a symmetrical structure around the first wave length 220, and unlike the illustration, the fourth wave length ( 250 ) and the fifth wave length 260 may form an asymmetric structure around the first wave length 220 .

As described above, the noise flowing in the flow pipe 210 forms the fractal structure of the first wave length 220, the second wave length 230, the third wave length 140, the fourth wave length 250 and the second wave length The sound wave energy of the noise may be more effectively lost as it flows into the 5 wave tube 260 side.

On the other hand, as in FIG. 12 , if the target frequency of the noise to be attenuated is relatively low, if the number of wave tubes (5) is formed relatively large, it will correspond to setting the volume of the resonance chamber of the Helmholtz resonator to be large. Therefore, it is possible to effectively attenuate noise in a relatively low frequency band.

As shown in FIG. 9, when the target frequency of the noise to be attenuated is relatively high, forming a relatively small number (three) of wavelength tubes can correspond to setting the volume of the resonance chamber of the Helmholtz resonator to be small. It is possible to effectively attenuate noise in a relatively high frequency band.

In addition, a sixth wave length extending in a direction crossing the extension direction of the second wave length 230 between both ends of the second wave length 230 and extending in the opposite direction to the fourth wave length 250 is further added. A seventh wave extending in a direction intersecting the extension direction of the third wave channel 240 between both ends of the third wave channel 240 and extending in the opposite direction to the fifth wave channel 260 More ministers may be included.

In this way, it is possible to adjust and broaden the target frequency of noise to be attenuated by adjusting the number of wave tubes constituting the fractal structure.

Although the preferred embodiment of the present invention has been described with reference to the drawings as described above, those skilled in the art may make various changes to the present invention within the scope without departing from the spirit and scope of the present invention as set forth in the claims below. may be modified or changed.

Claims

a flow tube through which a fluid flows;

a first wave pipe extending in a direction crossing the flow direction of the fluid from the flow pipe; and

The meta muffler having a fractal structure, comprising: a second wave length extending in a direction crossing the extending direction of the first wave length between both ends of the first wave length.
According to claim 1,

The cross-sectional size is formed smaller from the first wavelength to the second wavelength.

A meta muffler of a fractal structure, characterized in that.
According to claim 1,

The length of the first wave length and the length of the second wave length are relatively long when the target frequency of the noise to be attenuated is relatively low, and relatively short when the target frequency is relatively high. A meta muffler of a fractal structure, characterized in that.
According to claim 1,

The cross-sectional size of the first wavelength tube or the cross-sectional size of the second wavelength tube is relatively large when the target frequency of the noise to be attenuated is relatively low, and is relatively small when the target frequency is relatively high. A meta muffler of a fractal structure, characterized in that it is formed.
According to claim 1,

The distance from the flow pipe to the connection part of the first and second wave lengths is relatively long when the target frequency of the noise to be attenuated is relatively low, and is relatively long when the target frequency is relatively high. A meta muffler of a fractal structure, characterized in that it is formed short.
According to claim 1,

It further comprises;

A meta muffler with a fractal structure, characterized in that the target frequency of the noise to be attenuated decreases as the number of wave tubes increases.
a flow tube through which a fluid flows;

a first wave pipe extending in a direction crossing the flow direction of the fluid from the flow pipe;

a second wave length extending in a direction crossing the extending direction of the first wave length between both ends of the first wave length; and

A fractal structure comprising a; of meta muffler.
8. The method of claim 7,

The meta muffler having a fractal structure, characterized in that the cross-sectional size decreases from the first wavelength to the second wavelength, and the cross-sectional size decreases from the first to the third wavelength.
8. The method of claim 7,

The length of the first wavelength, the length of the second wavelength, and the length of the third wavelength are relatively long when the target frequency of the noise to be attenuated is relatively low, and the target frequency is relatively When it is high, it is a meta muffler of a fractal structure, characterized in that it is formed relatively short.
8. The method of claim 7,

The cross-sectional size of at least one of the cross-sectional size of the first wave pipe, the cross-sectional size of the second wave pipe, and the cross-sectional size of the third wave path is relatively low when the target frequency of the noise to be attenuated is relatively low. A meta muffler having a fractal structure, characterized in that it is formed to be large and formed to be relatively small when the target frequency is relatively high.
8. The method of claim 7,

The distance from the flow pipe to the connection part of the first wave pipe and the second wave pipe or the distance from the flow pipe to the connection part between the first wave pipe and the third wave pipe is that the target frequency of the noise to be attenuated is relatively A meta muffler having a fractal structure, characterized in that when it is low, it is formed to be relatively long, and when the target frequency is relatively high, it is formed to be relatively short.
8. The method of claim 7,

a fourth wave length extending in a direction crossing the extending direction of the second wave length between both ends of the second wave length; and a fifth wave length extending in a direction crossing the extension direction of the third wave length between both ends of the third wave length,

A meta muffler with a fractal structure, characterized in that the target frequency of the noise to be attenuated decreases as the number of wave tubes increases.