KR20230076619A - Metaliner for reducing duct noise - Google Patents

Abstract

The present invention relates to a metaliner for reducing a noise of a duct. In order to reduce the noise of the duct having a hollow part, the metaliner for reducing the noise of the duct of the present invention comprises: a plurality of resonators having a neck wherein one end is open to the hollow part of the duct, and a cavity connected to the other end of the neck; and a dividing member dividing the hollow part of the duct into a plurality of unit hollow parts. According to the present invention, the dividing member includes the resonator, and the plurality of resonators are disposed along the inner peripheral surface of the unit hollow part. Therefore, noise reduction performance of the duct is excellent while flow resistance is minimized.

Description

Metaliner for reducing duct noise {METALINER FOR REDUCING DUCT NOISE}

The present invention relates to a metaliner, and more particularly, to a metaliner including a plurality of Helmholtz resonators to block noise generated inside a duct.

In many products and facilities, from vehicle exhausts, aircraft engines, home appliances, cooling towers and power plants, fluids are formed to flow in ducts during intake, exhaust, cooling, and compression processes. Accordingly, in the duct, as well as the fluid, there is a problem in that noise is propagated. Conventionally, a noise reduction facility is installed in the duct to reduce noise.

The noise reduction equipment can be largely divided into a reflective type and a sound absorption type. At this time, reflection-type noise reduction equipment such as a muffler is a technology that reflects noise toward a sound source using a change in acoustic impedance, and has a disadvantage in that the operating frequency range is narrow and the generated noise is reflected toward the sound source and does not reduce the size of the reflected wave. In addition, sound-absorbing noise reduction equipment such as sound-absorbing louver and acoustic liner is a technology that absorbs propagated noise and then dissipates it as thermal energy. In order to reduce low-frequency noise with a long wavelength, the use of thick materials is inevitable. And, when these conventional noise reduction facilities are installed in a duct, there is a problem in that flow resistance is increased.

To solve this problem, Korean Patent Laid-Open Publication No. 10-2005-0013325 (“Noise Reduction Apparatus Using Resonator Array”, published on February 4, 2005) reduces noise propagating through the pipe 1 as shown in FIG. A noise reduction device for removing, including a plurality of resonators (2) having different frequency ranges installed in the pipe (1), the resonators (2) in the longitudinal direction (serial) and circumferential direction of the pipe (1) A (parallel) arrangement technique is disclosed. This has the advantage of reducing noise in a wider frequency band while minimizing the installation space.

However, the duct is formed in various sizes depending on the place or product where it is installed, and when the cross-sectional area of the passage inside the duct is large, the noise reduction performance is deteriorated due to the reduction in sound absorption and transmission loss. Accordingly, there is a current demand for a sound-absorbing noise reduction facility having excellent noise reduction performance even when applied to a duct having a small volume and a large area due to its thin thickness.

KR 10-2005-0013325 A (2005.02.04. open)

The present invention is an invention made to solve the above-described problems of the prior art, and divides the hollow of the duct into a plurality of unit hollows using a dividing member, but a plurality of resonators along the inner circumferential surface and length of the plurality of unit hollows. It has the purpose of providing a meta writer that maximizes the noise reduction function while minimizing the flow resistance.

The tasks of the present invention are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, the present invention provides a meta liner for reducing noise of a duct having a hollow portion, comprising: a plurality of resonators having a neck having one end opened to the hollow portion of the duct and a cavity connected to the other end of the neck; and a dividing member dividing the hollow part of the duct into a plurality of unit hollow parts, wherein the dividing member includes a resonator and a plurality of resonators may be disposed along an inner circumferential surface of the unit hollow part.

In addition, in the meta liner according to the present invention, the dividing member divides the hollow part of the duct into both sides so that the dividing member includes a first unit hollow part and a second unit hollow part, but the dividing member is choked by the first unit hollow part. It may include a resonator that is opened and a resonator whose neck is opened to the second unit hollow.

In addition, in the metaliner according to the present invention, a plurality of different resonators are disposed along the longitudinal direction of the duct to form a plurality of rows, characterized in that the metaliner.

In addition, in the metaliner according to the present invention, the dividing member may be formed in a streamlined shape so that the neck radii, neck lengths, and cavity volumes of the resonators arranged in a plurality of rows are different from each other.

In addition, in the meta liner according to the present invention, the dividing member is formed in a streamlined shape in which the thickness decreases from a certain area at the front end to the rear end, and the neck radius, neck length and The volume of the cavity may be reduced.

In addition, the metaliner according to the present invention may have a frequency domain in which some of the plurality of adjacent resonators resonate in opposite phases.

)을 각각 가질 수 있다.In addition, in the metaliner according to the present invention, a resonant frequency region in which a pair of adjacent resonators among a plurality of resonators satisfies the following equation (

) can have each.

(From here,

: 하나의 공명기의 공명주파수 영역,

: Resonant frequency region of one resonator,

: 다른 하나의 공명기의 공명주파수 영역,

: Resonance frequency region of another resonator,

: 목표주파수)

: target frequency)

In addition, the meta liner according to the present invention, doedoe both ends of the split member are fixed to the inner circumferential surface of the duct, the auxiliary body is fixed to the split member to have a built-in resonator; may further include.

), 주파수 대역폭(

) 및 목표 투과손실(

)을 설정하는 단계; 한 쌍의 공명기의 캐비티 크기를 고정하고 한 쌍의 공명기 각각의 목 반경(

)을 조절하여 상기 목 반경(

)에 따른 투과손실 스펙트럼을 산출하는 단계; 및 아래의 식을 만족하는 설정주파수(

) 범위에서 목표 투과손실(

) 보다 큰 투과손실(

)을 가지는 목 반경(

)을 선정하는 단계;를 포함할 수 있다.In addition, the above-described metaliner design method, the target frequency (

), frequency bandwidth (

) and target transmission loss (

) setting; The cavity size of a pair of resonators is fixed, and the neck radius of each pair of resonators (

) by adjusting the neck radius (

Calculating a transmission loss spectrum according to ); And a set frequency that satisfies the following formula (

) target transmission loss in the range (

) greater than the transmission loss (

) with a neck radius (

); may include.

) 범위에서 투과 손실이 목표 투과손실(

) 보다 큰 목 반경(

)을 선정할 수 있다.In addition, in the design method of the metaliner according to the present invention, when a plurality of neck radii are selected, the transmission loss spectrum is calculated for each of a plurality of flow velocity conditions, and the set frequency (

), the transmission loss is the target transmission loss (

) with a neck radius greater than (

) can be selected.

The metaliner according to the present invention has the advantage of maximizing the noise reduction function while minimizing the flow resistance as the resonator is installed in each of the unit hollows partitioned through the dividing member.

In addition, in the metaliner according to the present invention, a pair of adjacent resonators resonate in opposite phases within the frequency bandwidth of the target frequency to minimize the energy sum of reflected and transmitted waves at the target frequency, while reducing noise in a wider band with a thinner thickness There is an advantage to providing a device having the ability.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 is a view showing a conventional noise reduction device.
Figure 2 is a perspective view of a partially cut meta liner according to the first embodiment of the present invention.
3 is a view showing the noise reduction efficiency of the meta liner according to the first embodiment of the present invention.
4 is a perspective view of a meta liner schematically illustrating a space according to a first embodiment of the present invention;
5 is a schematic perspective view of a space of a resonator according to a first embodiment of the present invention;
6 and 7 are views showing the transmission loss and sound absorption coefficient of the meta liner according to the first embodiment of the present invention.
8 is a perspective view of a meta liner having a large area according to a first embodiment of the present invention.
9 is a perspective view of a meta liner according to a second embodiment of the present invention.
10 is a view showing the transmission loss and the sound absorption coefficient of the meta liner according to the second embodiment of the present invention.
11 is a diagram comparing the sound pressure level in a large area situation between the first embodiment and the second embodiment of the present invention.
12 is a perspective view of a meta liner according to a third embodiment of the present invention.
13 is a perspective view of a meta liner according to a fourth embodiment of the present invention;
14 is a view comparing a streamlined split member and a flat split member of a meta liner according to a fourth embodiment of the present invention.
15 is a diagram showing a real part and an imaginary part of the effective impedance according to the neck radius of the resonator according to the fourth embodiment of the present invention.
16 is a diagram showing the real part and imaginary part of the transmission loss spectrum and effective impedance according to the design method of the metawriter of the present invention, respectively.
17 is a diagram showing the neck radius and average penetration loss for each background flow velocity according to the design method of the metawriter of the present invention.
18 is a flow chart according to the method of designing the metawriter of the present invention.

Hereinafter, a metaliner and a metaliner design method according to various embodiments of the present invention will be described in detail with reference to the accompanying drawings. The drawings introduced below are provided as examples to sufficiently convey the spirit of the present invention to those skilled in the art. Therefore, the present invention may be embodied in other forms without being limited to the drawings presented below. Also, like reference numbers indicate like elements throughout the specification.

Unless otherwise defined, the technical terms and scientific terms used at this time have meanings commonly understood by those of ordinary skill in the art to which this invention belongs, and the gist of the present invention is unnecessary in the following description and accompanying drawings. Descriptions of well-known functions and configurations that may be obscure are omitted.

[Metaliner]

<First Embodiment>

2 and 3 relate to a meta liner according to a first embodiment of the present invention, FIG. 2 shows a perspective view of a partially cut meta liner, and FIG. 3 shows a noise reduction efficiency of the meta liner, respectively.

Referring to FIG. 2, the meta liner 100 according to the present invention can be installed in a duct 10 having a hollow part 11 therein so that fluid can flow, and the neck penetrating the wall of the duct 10 111 and a plurality of resonators 110 having cavities 112 disposed on the outer circumferential surface of the duct 10. Here, a plurality of resonators 110 may be arranged along the circumferential direction of the duct 10, and may be arranged in multiple rows in the longitudinal direction of the duct 10 as well. At this time, the resonator 110 is designed to have different resonant frequencies by adjusting a pair of adjacent neck radii. In addition, it may be designed to have a cavity 112 with a minimized thickness, and there is no flow resistance to the fluid flowing in the hollow part 11 of the duct 10, but it absorbs the incident noise as if rubbing and transmits and reflects sound. At the same time, it may be provided to achieve a reducing opaque-non-reflection.

)와 소정 수치 가량 차이 나는 공명 주파수를 가져 서로 반대위상으로 공명하는 적어도 한 쌍의 아파장 크기의 공명기(110)를 포함함에 따라 입사파 파장의 대략 1/24배 수준의 두께로도 보다 넓은 주파수 대역에서 높은 투과손실(Transmission Los,

)의 달성이 가능한 장치를 제공할 수도 있다. Referring to FIG. 3 together, the metaliner 100 according to the present invention has a plurality of resonators 110 at each target frequency (

) and at least a pair of resonators 110 having a resonant size of a half-length, which have resonance frequencies different from each other by a predetermined value and resonate in opposite phases to each other, so that a wider frequency even with a thickness of about 1/24 times the wavelength of the incident wave High transmission loss in the band (Transmission Los,

) may be provided.

4 to 7 relate to the meta liner according to the first embodiment of the present invention, FIG. 4 is a perspective view of the meta liner schematized space, FIG. 5 is a perspective view schematized space of the resonator, FIG. 6 and FIG. 7 shows a diagram showing the transmission loss and sound absorption coefficient of the metaliner designed to target a single frequency or a dual frequency, respectively.

4 and 5, the hollow part 11 of the duct 10 may have a predetermined width W, width D, and length L, as shown, and a plurality of the resonators 110 may include four different resonators arranged along the length (L) and width (D) of the hollow part (11). Here, the four resonators are defined as a first resonator 110a, a second resonator 110b, a third resonator 110c, and a fourth resonator 110d.

)과 흡음 성능을 수치해석하기 위해 각각의 캐비티(112)의 크기와 목의 길이는 아래의 표 1과 같이 정의될 수 있다.The first resonator 110a, the second resonator 110b, the third resonator 110c, and the fourth resonator 110d may each have a neck 111 and a cavity 112, and the radius of the neck 111 or Transmission loss with diameter (

) And the size of each cavity 112 and the length of the neck can be defined as shown in Table 1 below in order to numerically analyze the sound absorption performance.

division Numerical value (unit: mm) Hollow width (W) 107.2 Width of hollow part (D) 42.9 Length of hollow part (L) 214.5 Cavity area (a×a) 19.5 × 19.5 Cavity height (b) 12.6 neck length (l) 5

)가 설정되는 경우에서 인접한 공명기가 서로 다른 위상으로 공명하기 위해, 제1공명기(110a), 제2공명기(110b), 제3공명기(110c) 및 제4공명기(110d) 각각의 목의 직경(d₁, d₂, d₃, d₄) 중제1공명기(110a)의 목의 직경(d₁)과, 제3공명기(110c)의 목의 직경(d₃)이 동일하고, 제2공명기(110b)의 목의 직경(d₂)과, 제4공명기(110d)의 목의 직경(d₄)이 동일하도록 설계되어, 상기 제1공명기(110a)와 제3공명기(110c)의 공명주파수가 서로 동일하고 제2공명기(110b)와 제4공명기(110d)의 공명주파수가 서로 동일하도록 설계될 수 있다. 그리고 상기 제1공명기(110a)의 목의 직경(d₁)과 상기 제2공명기(110b)의 목의 직경(d₂)은 서로 상이하게 설계되되, 각각의 공명주파수가 목표주파수(

)에서 소정 수치만큼 가감되도록 설계될 수 있다. 이는 도 6에서 도시된 바와 같이 목표주파수(

)가 1000 Hz인 상황에서 상기 제1공명기(110a)의 목의 직경(d₁)과 상기 제2공명기(110b)의 목의 직경(d₂)이 각각 4.06 mm 및 4.38 mm로 설계되어 93 dB/m의 높은 투과손실(

)을 달성함과 동시에 소음 에너지를 매우 높은 흡음률(α)로 흡수하도록 설계될 수 있다. 이때 장치의 두께는 입사파 파장 대비 1/20 수준으로 보다 소형화될 수 있으며, 93 dB/m 이상의 투과손실(

)을 달성하는 주파수 대역폭(

) 또한 112 Hz(중심주파수

= 1019 Hz 기준

= 0.11)로 보다 넓은 소음 저감 대역폭을 가질 수 있다. 이때 흡음률(α)은 반사 계수(

)와 투과계수(

)에 대해 아래의 수학식 1에 따라 산출될 수 있다.Here, a single target frequency (

) is set, the diameter of the neck of each of the first resonator 110a, the second resonator 110b, the third resonator 110c and the fourth resonator 110d in order to resonate with different phases of adjacent resonators ( d ₁ , d ₂ , d ₃ , d ₄ ), the neck diameter (d ₁ ) of the first resonator 110a and the neck diameter (d ₃ ) of the third resonator 110c are the same, and the second resonator ( 110b) and the neck diameter (d ₄ ) of the fourth resonator 110d are designed to be the same, _so that the resonant frequencies of the first resonator 110a and the third resonator 110c are The resonant frequencies of the second resonator 110b and the fourth resonator 110d may be identical to each other. And the neck diameter (d ₁ ) of the first resonator (110a) and the neck diameter (d ₂ ) of the second resonator (110b) are designed to be different from each other, and each resonance frequency is the target frequency (

) can be designed to increase or decrease by a predetermined value. As shown in FIG. 6, the target frequency (

) is 1000 Hz, the neck diameter (d ₁ ) of the first resonator (110a) and the neck diameter (d ₂ ) of the second resonator (110b) are designed to be 4.06 mm and 4.38 mm, respectively, resulting in 93 dB High transmission loss of /m (

) and at the same time can be designed to absorb noise energy with a very high sound absorption coefficient (α). At this time, the thickness of the device can be further miniaturized to the level of 1/20 of the wavelength of the incident wave, and the transmission loss of 93 dB / m or more (

) The frequency bandwidth that achieves (

) and 112 Hz (center frequency

= based on 1019 Hz

= 0.11), it is possible to have a wider noise reduction bandwidth. At this time, the absorption coefficient (α) is the reflection coefficient (

) and permeability coefficient (

) can be calculated according to Equation 1 below.

)와, 투과계수(

)를 얻도록 설계되어, 목표주파수(

)에서 1에 가까운 우수한 흡음성능을 달성할 수 있다. 여기서 보다 높은 성능으로 제공하기 위해 상기 제1공명기(110a)와 제3공명기(110c) 또는 상기 제2공명기(110b)와 제4공명기(110d)는 동일한 공명주파수에서 서로 반대 위상으로 공명하는 아파장 크기의 공명기로 형성될 수도 있다.That is, a lower reflection coefficient (

) and the transmission coefficient (

), the target frequency (

), excellent sound absorption performance close to 1 can be achieved. Here, in order to provide higher performance, the first resonator 110a and the third resonator 110c or the second resonator 110b and the fourth resonator 110d resonate in opposite phases at the same resonant frequency. It may be formed as a resonator of the size.

)가 설정되는 경우에서, 제1공명기(110a), 제2공명기(110b), 제3공명기(110c) 및 제4공명기(110d)는 서로 다른 목의 직경(d₁, d₂, d₃, d₄)을 가질 수 있다. 이때 상기 제1공명기(110a)와 제2공명기(110b)는 하나의 목표주파수(

)에서 서로 반대 위상으로 공명하고 상기 제3공명기(110c)와 제4공명기(110d)는 다른 하나의 목표주파수(

)에서 서로 반대 위상으로 공명하도록 설계될 수 있으며, 예시로 하나의 목표주파수(

)는 800 Hz으로 다른 하나의 목표주파수(

)는 1030 Hz로 설정될 수 있다. 그리고 상기 제1공명기(110a)의 목의 직경(d₁)은 3.26 mm로, 상기 제2공명기(110b)의 목의 직경(d₂)은 3.12 mm로, 상기 제3공명기(110c)의 목의 직경(d₃)은 4.14 mm로, 상기 제4공명기(110d)의 목의 직경(d₄)은 4.34 mm로 각각 설정될 수 있다. 이는 도 7에서 도시된 바와 같이 이중의 목표주파수(

)인 800 Hz와 1030 Hz에서 각각 68 dB/m와 99 dB/m의 높은 투과손실(

)을 달성함과 동시에 소음에너지를 0.95 이상의 흡음률로 흡수할 수 있다. 이때 800 Hz인 하나의 목표주파수(

) 기준, 장치의 두께는 입사파 파장 대비 1/24수준이다. 그리고 800 Hz인 하나의 목표주파수(

)에 대해 68 dB/m 이상의 투과손실(

)을 달성하는 주파수 대역폭(

)은 46 Hz(중심주파수

= 802 Hz 기준

= 0.06)이며, 1030 Hz인 다른 하나의 목표주파수(

)에 대해 99 dB/m 이상의 투과손실(

)을 달성하는 주파수 대역폭(

)은 65Hz(중심주파수

= 1030 Hz 기준

= 0.06)로 이중 주파수 대역의 소음도 효과적으로 차단될 수 있다. Then, the double target frequency (

) is set, the first resonator 110a, the second resonator 110b, the third resonator 110c, and the fourth resonator 110d have different neck diameters (d ₁ , d ₂ , d ₃ , d ₄ ). At this time, the first resonator 110a and the second resonator 110b have one target frequency (

), and the third resonator 110c and the fourth resonator 110d resonate in opposite phases to each other at the other target frequency (

) can be designed to resonate in opposite phases to each other, for example one target frequency (

) is 800 Hz, the other target frequency (

) can be set to 1030 Hz. The diameter d ₁ of the neck of the first resonator 110a is 3.26 mm, the diameter d ₂ of the neck of the second resonator 110b is 3.12 mm, and the neck diameter of the third resonator 110c is 3.12 mm. The diameter (d ₃ ) of may be set to 4.14 mm, and the diameter (d ₄ ) of the neck of the fourth resonator (110d) may be set to 4.34 mm, respectively. As shown in FIG. 7, this is a double target frequency (

), high transmission loss of 68 dB/m and 99 dB/m at 800 Hz and 1030 Hz, respectively (

) and at the same time can absorb noise energy with a sound absorption coefficient of 0.95 or more. At this time, one target frequency of 800 Hz (

) standard, the thickness of the device is 1/24 of the wavelength of the incident wave. And one target frequency of 800 Hz (

) with a transmission loss of more than 68 dB/m (

) The frequency bandwidth that achieves (

) is 46 Hz (center frequency

= 802 Hz standard

= 0.06), and another target frequency of 1030 Hz (

) with a transmission loss of more than 99 dB/m (

) The frequency bandwidth that achieves (

) is 65 Hz (center frequency

= based on 1030 Hz

= 0.06), the noise of the dual frequency band can be effectively blocked.

8 relates to a meta-liner according to a first embodiment of the present invention, and FIG. 8 shows a perspective view of a meta-liner having a large area.

Referring to FIG. 8, the meta liner 100 according to the present invention may include a separate body portion 100a including one or more unit hollows C and having a plurality of resonators 110 built into the wall, However, it may be inserted into a pre-installed structure and configured as a duct. Alternatively, as described above, the neck of the resonator 110 may be fastened to the tube of the duct in a penetrating manner. At this time, the metaliner 100 according to the present invention may include a plurality of unit hollow parts (C) so that the noise reduction performance is excellent even in a situation having a wider flow area, which will be described in more detail in the second embodiment to be described later. do.

<Second Embodiment>

9 and 10 relate to a meta liner according to a second embodiment of the present invention, FIG. 9 is a perspective view of the meta liner, and FIG. 10 shows a view showing transmission loss and sound absorption coefficient of the meta liner, respectively.

Referring to FIG. 9 , the meta liner 100 according to the present invention may further include at least one dividing member 100b to form a plurality of unit hollows by partitioning the flow path. In FIG. 9, it is exemplified as including four unit hollow parts (C ₁ , C ₂ , C ₃ , C ₄ ) by partitioning each in the width and width directions through a pair of dividing members (100b). At this time, the split member 100b may have a pair of resonators 110 having necks opened to adjacent places among the four unit hollows C ₁ , C ₂ , C ₃ , C ₄ . That is, when one dividing member 100b is divided into the first unit hollow part C ₁ and the second unit hollow part C ₂ in the left and right directions in the width direction, the dividing member 100b is divided in the left and right directions. A pair of open resonators 110 may be built in a form arranged in a vertical direction. In addition, when the other dividing member 100b is divided into the third unit hollow part C ₃ and the fourth unit hollow part C ₄ vertically in the height direction, the dividing member 100b has a vertical direction. A pair of resonators 110 opened in the left and right direction may be built in the form arranged. Accordingly, the resonator 110 inserted into the body part 100a of the meta liner 100 and the resonator 110 inserted into the dividing member 100b have four unit hollow parts (C ₁ , C ₂ , C ₃ , C ₄ ) may be arranged in a form arranged along the circumferential direction in each. Furthermore, the resonators 110 may be arranged in multiple rows in the longitudinal direction, that is, in the longitudinal direction.

In order to evaluate the performance of the meta liner 100 having such a structure, in the case of including the body portion 100a as described above, it may be configured with the numerical values shown in Table 2 below.

division Numerical value (unit: mm) Body width (W) 629 Body width (D) 629 Body length (L) 406 Cavity area (a×a) 24.3 × 24.3 Cavity height (b) 22 neck length (l) 7

)인 500 Hz에 대한 소음 저감 성능을 평가하도록, 제1공명기(110a)의 목의 직경(d₁)과 제3공명기(110c)의 목의 직경(d₃)은 3.6 mm로, 제2공명기(110b)의 목의 직경(d₂)과 제4공명기(110d)의 목의 직경(d₄)은 4 mm로 각각 설정될 수 있다. At this time, the four resonators 110a, 110b, 110c, and 110d arranged in the width or width and length directions have a single target frequency (

), to evaluate the noise reduction performance for 500 Hz, the diameter of the neck of the first resonator 110a (d ₁ ) and the diameter of the neck of the third resonator 110c (d ₃ ) are 3.6 mm, and the second resonator The diameter d ₂ of the neck of 110b and the diameter d ₄ of the fourth resonator 110d may be respectively set to 4 mm.

)인 500 Hz에서 46 dB/m의 높은 투과손실(

)을 달성함과 동시에 0.9 이상인 높은 흡음률(α)을 가지는 것으로 나타난다. 이때 장치의 두께는 입사자 파장 대비 1/24으로 보다 얇게 설계될 수 있어 분할부재(100b)의 두께를 줄여 유동 저항을 최소화하는 장점이 있다. 그리고 46 dB/m 이상의 투과손실(

)을 달성하는 주파수 대역폭(

)은 94 Hz(중심주파수

= 511 Hz 기준

= 0.18)로 설치 면적이 넓어지더라도 본 발명의 장치가 넓은 주파수 대역의 소음을 차단할 수 있음이 나타난다.As shown in FIG. 10, the meta liner 100 including the split member 100b has a target frequency (even for a structure having a wider width and height compared to Table 1)

), a high transmission loss of 46 dB/m at 500 Hz (

) and at the same time appear to have a high sound absorption coefficient (α) of 0.9 or more. At this time, the thickness of the device can be designed to be thinner than 1/24 of the incident wavelength, so there is an advantage in minimizing flow resistance by reducing the thickness of the dividing member 100b. And a transmission loss of 46 dB/m or more (

) The frequency bandwidth that achieves (

) is 94 Hz (center frequency

= 511 Hz standard

= 0.18), it is shown that the device of the present invention can block noise in a wide frequency band even if the installation area is widened.

In the plurality of resonators described in the first and second embodiments, a pair of adjacent resonators may be designed according to Equation 2 below for mixed resonance.

(From here,

: 하나의 공명기의 공명주파수 영역,

: Resonant frequency region of one resonator,

: 다른 하나의 공명기의 공명주파수 영역,

: Resonance frequency region of another resonator,

: 목표주파수)

: target frequency)

FIG. 11 shows a comparison of sound pressure levels between the first embodiment and the second embodiment of the present invention in a large area situation.

Referring to FIG. 11, when applied to a target having a large installation area, a meta liner 100 including a split member 100 b having a splitter function is a meta liner 100 without the split member 100 b. ) can be found to have better performance. In particular, after passing through a distance of 406 mm, the noise at the target frequency of 500 Hz shows a more marked difference between the two structures, and it is calculated that the maximum difference is about 12 dB. In addition, the sound absorption coefficient at 500 Hz is also 0.81 in the case of the meta liner 100 without the split member 100b, which is about 11% lower than 0.91 of the grid-type meta liner including the split member 100b. there is. As such, it can be seen that the split member 100b has a superior noise reduction performance when applied to a target having a large area.

<Third Embodiment>

12 relates to a metaliner according to a third embodiment of the present invention, and FIGS. 12-(a) to 12-(c) show perspective views of metaliners according to various shapes, respectively.

Referring to FIG. 12-(a), in the meta liner 100 according to the present invention, the dividing member 100b is arranged in a different number in the width or height direction, so that the arrangement of the plurality of unit hollows C is variable. can be configured to For example, two split members 100b are disposed on the left and right sides and one split member 100b is disposed on the upper and lower sides, so that six unit hollows C may pass through.

Referring to FIG. 12-(b), the meta liner 100 according to the present invention is such that the shape of the body portion 100a is applied to various types of structures such as polygonal, circular, and elliptical as well as rectangular cross sections having width and height. can be formed Both ends of the split member 100b may be fixed to the inner surface of the body 100a formed as a hollow part of the duct.

Referring to FIG. 12-(c), the meta liner according to the present invention includes a dividing member 100b fixed to the inner circumferential surface of the body portion 100a and an auxiliary body 100c fixed to the dividing member 100b. can include more. At this time, as an example of the auxiliary body 100c, the cross-sectional area of the body portion 100a may be designed in a reduced form, and in addition to this, it may be transformed into various shapes.

<The fourth embodiment>

13 to 15 relate to a meta liner according to a fourth embodiment of the present invention, FIG. 13 is a perspective view and an enlarged view of the main part of the meta liner, FIG. 14 is a view comparing a streamlined split member and a flat split member, 15 shows a diagram showing a real part and an imaginary part of the effective impedance according to the neck radius of the resonator, respectively.

Referring to FIG. 13, in the meta liner 100 having the split member 100b as described above, in order to solve the problem of flow resistance caused by the split member 100b, the split member 100b is It may be characterized in that it is formed in a streamlined shape. At this time, the streamlined shape means that the width/thickness of the width is partially varied from the front end to the rear end along the longitudinal direction, and as shown, it may include a shape that is convex at the front end and thin at the rear end. At this time, although not separately shown, the necks 111 of the plurality of resonators 110 may be arranged to be opened along the longitudinal direction of the streamlined dividing member 100b.

Referring to FIG. 14, the flow resistance of the streamlined dividing member 100b may be designed as follows to increase the sound absorption coefficient (α) while lowering the flow resistance. At this time, FIG. 14-(a) shows a flat split member and FIG. 14-(b) shows a streamlined split member, respectively. Here, the flat dividing member may be the inner wall of the body portion 100a, and shows the following differences under the same conditions as the streamlined dividing member.

)가 발생될 수 있으며, 1000 Hz에서 69 dB/m의 투과손실(

)과 0.97의 흡음률(α)이 달성되는 것으로 산출된다. 이때 임피던스는 메타라이너의 대표 음향 물성치로, 공명기의 목 반경, 목 길이, 캐비티 크기 등에 따라 유효 임피던스의 실수부(Z_r)와 허수부(Z_i)가 달라질 수 있다.In the flat split member, the effective impedance at the part where the metaliner is installed (

) can occur, and a transmission loss of 69 dB / m at 1000 Hz (

) and the absorption coefficient (α) of 0.97 is calculated to be achieved. At this time, the impedance is a representative acoustic property of the metaliner, and the real part (Z _r ) and imaginary part (Z _i ) of the effective impedance may vary depending on the neck radius, neck length, and cavity size of the resonator.

The streamlined dividing member may be divided into two regions based on the position where the sign of the inclination changes, and the front end may be divided into a first region and the rear end into a second region. At this time, since the impedance (Z ₂ ) of the second region at the rear end has a relatively small curvature and is relatively less affected by the incident angle, it may be designed to have the same impedance as the effective impedance (Z _MS ) above. In addition, the impedance (Z ₁ ) of the first region may be calculated through Equation 3 below in consideration of the influence of the angle of incidence according to the curvature of the tip.

)과 0.97의 흡음률(α)이 가능하여 기존 구조에 대비하여 유동 저항은 최소화하면서 보다 높은 수준의 투과손실(

)을 달성할 수 있는 장점이 있다.Here, cosθ may be an angle formed by an incident wave and a surface vector of the streamlined dividing member. And, when the dividing member designed by the streamlined curvature is installed as above, the transmission loss of 81 dB / m at 1000 Hz (

) and a sound absorption coefficient (α) of 0.97 are possible, resulting in a higher level of transmission loss (

) has the advantage of achieving

It can be designed to have better performance by appropriately setting the neck diameter (radius) of the resonator constituting the metaliner for the effective impedance condition in which the streamlined dividing member is considered. 15 shows the real and imaginary parts of the effective impedance according to the neck radii (r ₁ and r ₂ ) of the two resonators, which can be manufactured by matching the neck radii (r ₁ and r ₂ ) of the two resonators satisfying the condition. can

In addition, even if the metaliner is designed so that the second region of the streamlined dividing member has the same effective impedance (Z _MS ), it may be difficult to install a resonator of the same size because the thickness of the streamlined shape decreases toward the rear end. Considering this, the cavity size of the resonator can be designed to be smaller at the rear end, and the radius and length of the neck can be appropriately adjusted.

[Method of designing metaliner]

16 to 18 relate to a method of designing a metaliner according to the present invention, FIG. 16 shows a real part and an imaginary part of a transmission loss spectrum and effective impedance, respectively, and FIG. 17 shows the neck radius and average by background flow velocity Fig. 18 shows a flow chart of a method for designing a metaliner, respectively.

In the existing metaliner, the sound insulation performance of the metaliner decreases in the flow field, and especially in the section where the cross-sectional area of the duct is narrowed, the sound insulation performance of the metaliner is further reduced because the flow velocity further increases. Accordingly, in the following description, a metaliner design method for designing a metaliner with excellent sound insulation performance in a flow field will be described in detail.

)가 500 Hz인 메타라이너의 투과손실(

) 스펙트럼으로, 덕트 내 유속(

, 여기서 c₀는 음속)이 빨라질수록 투과손실(

) 스펙트럼의 피크 주파수는 고주파수로 이동하고, 투과손실(

) 성능은 떨어지는 것으로 도시되어 있다. 따라서 유동장 내에서 목표주파수(

)인 500 Hz의 소음을 저감하면서, 상기 투과손실(

) 값이 최대가 되기 위해서는, 유속이 0 m/s일 때, 투과손실(

) 스펙트럼의 피크 주파수를 목표주파수(

)보다 작도록 설계할 수 있다. 이는 도 16-(a)에서는 도시된 바와 같이 M=0.1인 경우에 500 Hz에서 투과손실 스펙트럼의 피크주파수가 형성되도록 설계됨에 따라, M=0인 경우에는 피크 주파수가 475 Hz인 것으로 도시되어 있다. 이때 도 16은 아래의 표 3의 수치를 통해 산출된 결과일 수 있다.16-(a) shows a target frequency (

) is 500 Hz, the transmission loss of the metaliner (

) spectrum, the flow velocity in the duct (

, where c ₀ is the speed of sound), the faster the transmission loss (

), the peak frequency of the spectrum shifts to higher frequencies, and the transmission loss (

) performance is shown to be poor. Therefore, the target frequency (

), while reducing the noise of 500 Hz, the transmission loss (

) value is maximized, when the flow velocity is 0 m/s, the permeation loss (

) the peak frequency of the spectrum to the target frequency (

) can be designed to be smaller than As shown in FIG. 16-(a), the peak frequency of the transmission loss spectrum is formed at 500 Hz when M = 0.1, and the peak frequency is 475 Hz when M = 0. . At this time, FIG. 16 may be a result calculated through the numerical values of Table 3 below.

division Numerical value (unit: mm) Body width (W) 51 Body width (D) 51 Body length (L) 406 Area of the cavity (a*a) 24.3*24.3 Cavity height (b) 22 neck length (l) 7

) 스펙트럼의 피크 주파수가 고주파수로 이동하는 것으로 도시되어 있다. 이는 유효 임피던스의 허수부(Z_i)가 0이 되는 주파수가 높아질수록, 투과손실(

) 스펙트럼의 피크 주파수가 높아지는 것과 연관될 수 있다. 따라서 정지 매질 내에서는 메타라이너의 유효 임피던스의 허수부(Z_i)가 크도록 설계하면, 유동장 내 목표 주파수에서 투과손실(

)이 최대가 되도록 만들 수 있다. 또한 공명기의 목 반경이 작을수록 유효 임피던스의 허수부(Z_i)가 커지기 때문에, 유동장 내 목표주파수(

)에서 투과손실(

)이 최대가 되도록 만들기 위해서는, 공명기의 목 반경을 정지 매질에서 차음 성능이 우수하도록 설계된 공명기의 목 반경보다 더 작게 설계할 수 있다. 아울러 덕트 단면적이 좁아지는 곳(유속이 빨라지는 곳)의 소음을 차단하기 위해서는 목 반경이 더 작은 공명기를 적용할 수도 있다.16-(b) and 16-(c) show the real part (Z _r ) and imaginary part (Z _i ) of the effective impedance of the metaliner according to the flow rate, respectively, and the same neck radius (r = 1.78mm) was calculated using four resonators with Here, as shown in FIG. 16-(c), as the flow rate increases, the imaginary part of the effective impedance (Z _i ) decreases, and accordingly, in FIG. 16-(a), the transmission loss (

) spectrum is shown shifting to higher frequencies. This is because the higher the frequency at which the imaginary part (Z _i ) of the effective impedance becomes 0, the transmission loss (

) can be associated with an increase in the peak frequency of the spectrum. Therefore, if the imaginary part (Z _i ) of the effective impedance of the metaliner is designed to be large in the stationary medium, the transmission loss (

) can be made to be the maximum. In addition, since the imaginary part (Z _i ) of the effective impedance increases as the neck radius of the resonator decreases, the target frequency in the flow field (

) in transmission loss (

) is maximized, the neck radius of the resonator can be designed to be smaller than that of a resonator designed to have excellent sound insulation performance in a stationary medium. In addition, a resonator with a smaller neck radius may be applied to block noise where the duct cross-section becomes narrower (where the flow velocity increases).

) 성능이 저하되는 것을 알 수 있다. 즉, 유속이 빠른 유동장 내에서는 메타라이너의 투과손실(

) 성능 저하 현상이 나타날 수 있으며, 이를 고려하여 정지 매질 내 유효 임피던스의 실수부(Z_r)을 작아지도록 설계하면, 유동장 내에서도 높은 투과손실(

) 성능을 달성할 수 있다. 아울러 정지 매질 내 메타라이너의 유효 임피던스의 실수부(Z_r)를 감소시킬 수 있는 방법으로 공명기의 목 길이 를 줄일 수 있으며, 공명기의 목 길이를 짧아질수록 유효 임피던스의 허수부(Z_i)도 함께 작아지는 것을 고려하여 목 반경, 목 길이가 설계될 수 있다.In addition, as shown in FIG. 16-(b), as the flow rate increases, the real part (Z _r ) of the effective impedance increases, and as the real part (Z _r ) of the effective impedance increases, the transmission loss at the peak frequency (

), it can be seen that the performance is degraded. That is, in a flow field with a high flow velocity, the permeation loss of the metaliner (

) performance degradation may occur, and considering this, if the real part (Z _r ) of the effective impedance in the static medium is designed to be small, the transmission loss is high even in the flow field (

) performance can be achieved. In addition, the neck length of the resonator can be reduced in a way that can reduce the real part (Z _r ) of the effective impedance of the metaliner in the stationary medium, and as the neck length of the resonator is shortened, the imaginary part (Z _i ) of the effective impedance is also reduced. The neck radius and neck length can be designed in consideration of being smaller together.

), 주파수 대역폭(

) 및 목표 투과손실(

)을 설정하는 단계, 한 쌍의 공명기의 캐비티 크기를 고정하고 한 쌍의 공명기 각각의 목 반경(

)을 조절하여 상기 목 반경(

)에 따른 투과손실 스펙트럼을 산출하는 단계 및, 아래의 수학식 4를 만족하는 설정주파수(

) 범위에서 목표 투과손실(

) 보다 큰 투과손실(

)을 가지는 목 반경(

)을 선정하는 단계를 포함할 수 있다.Accordingly, the metaliner design method according to the present invention, the target frequency (

), frequency bandwidth (

) and target transmission loss (

), fixing the cavity size of the pair of resonators and the neck radius of each pair of resonators (

) by adjusting the neck radius (

Calculating a transmission loss spectrum according to ), and a set frequency that satisfies Equation 4 below (

) target transmission loss in the range (

) greater than the transmission loss (

) with a neck radius (

) may be included.

)보다 큰 목 반경(

)를 선정하도록 형성될 수 있다. 여기서 다수의 유속 조건에 대해 찾은 목 반경(

)의 교집합 영역을 선정하면, 목표로 선정한 다수의 유속 조건에서 투과 손실이 목표 투과 손실보다 큰 메타라이너 설계 목 반경(

)을 찾을 수 있다. In addition, in the metaliner design method according to the present invention, the transmission loss in the frequency domain of Equation 4 is the target transmission loss (

) with a neck radius greater than (

) can be formed to select. Here, the neck radius found for a number of flow conditions (

), the metaliner design neck radius (

) can be found.

)를 500 Hz로, 주파수 대역폭(

)을 50 Hz로, 목표 투과손실(

)을 45 dB/m으로 목표치를 설정할 수 있다. 그리고 덕트의 중공부 또는 메타라이너의 몸체부의 외곽은 각각 51 × 51 × 406 mm으로 설정될 수 있으며, 한 쌍의 공명기의 캐비티 크기를 24.3 × 24.3 × 22 mm로, 목의 길이는 7 mm로 고정할 수 있다. 여기서 본 발명에 따른 메타라이너의 설계방법은 한 쌍의 공명기 각각에 대한 목 반경(

)을 조절하여 설정된 목표치를 달성하는 수치에 도달하는지 여부를 판단할 수 있으며, Hereinafter, with reference to FIG. 17, some numerical values in the design method of the meta liner will be described more clearly by exemplifying. The design method of the metaliner according to the present invention is the target frequency (

) to 500 Hz, the frequency bandwidth (

) to 50 Hz, the target transmission loss (

) can be set as a target value of 45 dB/m. In addition, the hollow part of the duct or the outline of the body part of the metaliner may be set to 51 × 51 × 406 mm, respectively, and the cavity size of the pair of resonators is fixed to 24.3 × 24.3 × 22 mm and the length of the neck is fixed to 7 mm. can do. Here, the design method of the metaliner according to the present invention is the neck radius for each of the pair of resonators (

) can be adjusted to determine whether or not a value that achieves the set target value is reached.

)에 따른 투과손실 스펙트럼을 산출하는 단계 및, 설정주파수(

) 범위에서 목표 투과손실(

) 보다 큰 투과손실(

)을 가지는 한 쌍의 공명기의 목 반경(

)을 선정하는 단계를 포함할 수 있다. 도 17-(a)에서 도 17-(c)는 여러 유속 상황 하에서 한 쌍의 공명기의 목 반경(

)에 따른 평균 투과손실(

) 등고선(contour) 테이블을 각각 나타낸다. 도 18을 참조하면, 한 쌍의 공명기의 목 반경(

)가 각각 (1.66, 1.78), (1.66, 1.82), (1.7, 1.74), (1.7, 1.78), (1.7, 1.82), (1.74, 1.74), (1.74, 1.78), (1.74, 1.82), (1.78, 1.78) mm인 경우에 모든 유속(M=0, 0.05, 0.1)에 대해 설계 조건을 만족하는 교집합인 것을 알 수 있으며, 위 수치 중에 하나를 선정하여 제품이 설계되도록 제작할 수 있다. 이는 위 형상으로 제작된 제품이 모든 유속에 대해 목표주파수(

)의 ㅁ5% 주파수 대역에서 45 dB/m 이상의 투과 손실을 달성할 수 있으므로, 소음 저감 성능이 보다 우수하도록 제공할 수 있다.The neck radius (

Calculating the transmission loss spectrum according to ), and the set frequency (

) target transmission loss in the range (

) greater than the transmission loss (

), the neck radius of a pair of resonators having (

) may be included. 17-(a) to 17-(c) show neck radii of a pair of resonators under various flow velocity conditions (

) Average transmission loss according to (

) represents a contour table, respectively. Referring to FIG. 18, the neck radius of a pair of resonators (

) are (1.66, 1.78), (1.66, 1.82), (1.7, 1.74), (1.7, 1.78), (1.7, 1.82), (1.74, 1.74), (1.74, 1.78), (1.74, 1.82) , (1.78, 1.78) mm, it can be seen that it is an intersection that satisfies the design condition for all flow velocities (M = 0, 0.05, 0.1), and the product can be designed by selecting one of the above values. This means that the product manufactured in the above shape is the target frequency (

), since it is possible to achieve a transmission loss of 45 dB/m or more in the ㅁ5% frequency band, it is possible to provide better noise reduction performance.

)을 선정하는 과정을 보다 상세히 설명한다. Referring to the flowchart of FIG. 18, in the method of designing a metaliner according to the present invention, the neck radius of a pair of resonators (

) will be described in more detail.

)을 선정하기 위해 변수를 입력하는 단계와, 입력된 변수를 기반으로 적어도 하나 이상의 연산과정을 통해 결과를 산출하는 단계와, 연산결과, 위 수학식 4의 목표주파수 대역에서의 메타라이너의 투과손실(

)이 목표 투과손실(

)보다 큰지 판단하는 단계를 포함할 수 있다. 이때 상기 변수를 입력하는 단계에서는 덕트 내 유속(

), 각 주파수(

), 메타라이너의 형상 수치(a, b, l, D, L) 등이 입력될 수 있다. 여기서 상기 메타라이너의 형상 수치에는 목 반경(

)이 입력될 수 있으며, 회귀분석 모델을 통해 상기 목 반경(

)의 수치를 변경하여 최종적으로 덕트 내 유속(

)의 유동장 내에서 목표 차음 성능을 달성하는 목 반경(

)이 선정될 수 있다.The design method of the metaliner according to the present invention, the neck radius of a pair of resonators satisfying the condition (

), calculating a result through at least one calculation process based on the input variable, and calculating the result of the calculation, the transmission loss of the metaliner in the target frequency band of Equation 4 above. (

) is the target transmission loss (

) may include a step of determining whether it is greater than. At this time, in the step of inputting the variable, the flow rate in the duct (

), each frequency (

), metaliner shape values (a, b, l, D, L), etc. can be input. Here, the shape of the meta liner has a neck radius (

) can be input, and the neck radius (

) by changing the value of the final flow rate in the duct (

) neck radius (

) can be selected.

)를 계산하는 제1단계를 포함할 수 있다. 이때 상기 제1단계에서는 아래의 수학식 5 내지 수학식 10을 통해 각 유효 임피던스의 보정길이를 산출할 수 있다.The calculation process of the metaliner design method is the effective wave number of the resonator neck and cavity, the effective impedance correction length (

) may include a first step of calculating At this time, in the first step, the correction length of each effective impedance can be calculated through Equations 5 to 10 below.

는 아래의 수학식 11에서 수학식 14를 통해 산출될 수 있다.In addition, the variables from Equation 5 to Equation 8 above

Can be calculated through Equation 14 in Equation 11 below.

(From here,

,

,

,

,

,

,

,

,

,

,

,

,

: density of air,

: speed of sound,

: density of air,

: speed of sound,

: dynamic viscosity of air,

: dynamic viscosity of air,

: prandtl number,

: specific heat ratio,

:prindtl number,

: specific heat ratio,

: Bessel function of the 1st kind, f : frequency)

: Bessel function of the 1st kind, f : frequency)

는 아래의 수학식 15 및 수학식 16을 통해 산출될 수 있다.In addition, the variables in Equations 9 and 10 above

Can be calculated through Equations 15 and 16 below.

(From here,

,

,

,

: Bessel function of the 1st kind

,

,

,

: Bessel function of the 1st kind

is the pth solution of the equation

)

is the pth solution of the equation

)

)를 계산하는 제2단계를 포함할 수 있다. 이때 상기 제2단계에서는 아래의 수학식 17 및 수학식 18을 통해 산출할 수 있다.The calculation process of the metaliner design method is the effective impedance of the ith resonator constituting the unit structure of the metaliner (

) may include a second step of calculating At this time, in the second step, it can be calculated through Equations 17 and 18 below.

(From here,

,

,

,

,

,

,

: 메타라이너 단위 구조의 I번째 공명기의 목 반경,

: Neck radius of the I-th resonator of the metaliner unit structure,

: density of air,

: speed of sound,

,

: density of air,

: speed of sound,

,

,

: dynamic viscosity of air)

,

: dynamic viscosity of air)

)를 계산하는 제3단계와, FE 해석에서 메타라이너의 투과손실(

)을 계산하는 제4단계를 포함하여 구성될 수 있으며, 상기 제3단계 및 제4단계는 아래의 수학식 19 및 수학식 20을 통해 각각 산출될 수 있다. The calculation process of the metaliner design method is the effective impedance of the metaliner (

), and the transmission loss of the metaliner in the FE analysis (

), and the third and fourth steps may be calculated through Equations 19 and 20 below, respectively.

(Where T is the power reflection coefficient)

As described above, the present invention has been described by specific details such as specific components and limited embodiment drawings, but this is only provided to help a more general understanding of the present invention, and the present invention is limited to each of the above-described embodiments. It is not, and those skilled in the art can make various modifications and variations from the above description, and several embodiments may be mixed or some components of each embodiment may be mixed.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and it can be said that not only the claims described later, but also all modifications equivalent or equivalent to these claims fall within the scope of the spirit of the present invention. will be.

C: unit hollow
C ₁ : first unit hollow part C ₂ : second unit hollow part
C ₃ : 3rd unit hollow part C ₄ : 4th unit hollow part
10: duct 11: hollow part
100: Metaliner
100a: body part 100b: dividing member
100c: auxiliary body
110: resonator
110a: first resonator 110b: second resonator
110c: 3rd resonator 110d: 4th resonator
111: neck 112: cavity

Claims (10)

In the metaliner for reducing noise of a duct having a hollow part,
a plurality of resonators having a neck having one end opened to the hollow part of the duct and a cavity connected to the other end of the neck; and
including,
A plurality of resonators are disposed along the inner circumferential surface of the hollow,
A metaliner, characterized in that a plurality of resonators are arranged along the longitudinal direction of the duct and formed in a plurality of rows.
According to claim 1,
a dividing member dividing the hollow part of the duct into a plurality of unit hollow parts;
Including more,
The meta liner, characterized in that the plurality of resonators are disposed along the inner circumferential surface of the unit hollow, including the resonator, the dividing member.
According to claim 2,
Divide the hollow part of the duct into both sides so that the dividing member includes a first unit hollow part and a second unit hollow part,
The split member comprises a resonator whose neck is opened to the first unit hollow part and a resonator whose neck is opened to the second unit hollow part.
According to claim 2,
The dividing member is made of a streamlined shape,
A metaliner characterized in that the cavities of the resonators arranged in a plurality of rows have different sizes or neck radii.
According to claim 4,
The dividing member is formed in a streamlined shape in which the thickness decreases from a certain area at the front end toward the rear end,
A metaliner, characterized in that the cavity size of the resonator decreases toward the rear end based on a certain area of the front end.
According to claim 1,
A metaliner characterized in that some of the plurality of adjacent resonators have the same resonant frequency region resonating in opposite phase.
According to claim 1,
A resonant frequency region in which a pair of adjacent resonators among a plurality of resonators satisfies the following equation (

) Metaliner, characterized in that each has.

(From here,

: Resonant frequency region of one resonator,

: Resonance frequency region of another resonator,

: target frequency)
According to claim 2,
The duct is formed in a rectangular, circular or elliptical shape, and both ends of the dividing member are fixed to the inner circumferential surface of the duct,
An auxiliary body fixed to the dividing member and having a built-in resonator;
Metaliner characterized in that it further comprises.
In the design method of the meta liner of claim 7,
Target frequency (

), frequency bandwidth (

) and target transmission loss (

) setting;
The cavity size of a pair of resonators is fixed, and the neck radius of each pair of resonators (

) by adjusting the neck radius (

Calculating a transmission loss spectrum according to ); and
The set frequency that satisfies the formula below (

) target transmission loss in the range (

) greater than the transmission loss (

) with a neck radius (

) Selecting;
A method of designing a metaliner including a.

According to claim 9,
If a plurality of neck radii are selected, the set frequency for each target flow rate condition (

) target transmission loss in the range (

) greater than the transmission loss (

) to achieve the neck radius (

) Method of designing a metaliner, characterized in that for selecting.

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