阅读说明：本技术 一种适用于高速风洞稳定段的消声器 (Silencer suitable for high-speed wind tunnel stable section ) 是由 马利川 石运军 黄炳修 晏硕 赵佳祥 王瑞祥 于 2020-12-29 设计创作，主要内容包括：本申请公开了一种适用于高速风洞稳定段的消声器,该消声器包括：并列排列的多个单片消声器；每个所述单片消声器包括依次连接的第一部件、第二部件以及第三部件,第二部件包括蒙皮、多个隔板、由所述蒙皮和隔板形成的多个谐振腔、消声结构、蒙皮表面的多个小孔以及共振器；多个隔板包括第一隔板和第二隔板,多个谐振腔包括由蒙皮折叠形成的第一矩形谐振腔、第二矩形谐振腔以及由第二隔板设置于第二矩形谐振腔对角线位置所形成的三角形谐振腔；消声结构设置于第二隔板上,用于吸收噪声；共振器是由多个小孔与三角形谐振腔形成,用于吸收噪声。本申请解决了现有技术中的消声器无法满足高速风洞高品质流场的要求的技术问题。(The application discloses silencer suitable for high-speed wind tunnel stable section includes: a plurality of monolithic mufflers arranged in parallel; each single-chip silencer comprises a first component, a second component and a third component which are connected in sequence, wherein the second component comprises a skin, a plurality of clapboards, a plurality of resonant cavities formed by the skin and the clapboards, a silencing structure, a plurality of small holes on the surface of the skin and a resonator; the plurality of partition plates comprise a first partition plate and a second partition plate, and the plurality of resonant cavities comprise a first rectangular resonant cavity formed by folding skins, a second rectangular resonant cavity and a triangular resonant cavity formed by arranging the second partition plate at the diagonal position of the second rectangular resonant cavity; the silencing structure is arranged on the second partition plate and used for absorbing noise; the resonator is formed by a plurality of small holes and a triangular resonant cavity and is used for absorbing noise. The silencer solves the technical problem that a silencer in the prior art cannot meet the requirement of a high-quality flow field of a high-speed wind tunnel.)

1. A silencer suitable for a high-speed wind tunnel stabilizing section is characterized by comprising: a plurality of monolithic mufflers arranged in parallel; each of the monolithic mufflers comprises a first component (1), a second component (2) and a third component (3) connected in sequence,

the second component (2) comprises a skin (21), a plurality of baffles (22), a plurality of resonant cavities (23) formed by the skin (21) and the baffles (22), a sound-attenuating structure (24), a plurality of small holes (25) arranged on the surface of the skin (21), and a resonator (26);

the plurality of partitions (22) comprise a first partition (221) and a second partition (222), and the plurality of resonant cavities (23) comprise a first rectangular resonant cavity (231) formed by folding the skin (21), a second rectangular resonant cavity (232) formed by arranging the first partition (221) inside the first rectangular resonant cavity (231), and a triangular resonant cavity (233) formed by arranging the second partition (222) at a diagonal position of the second rectangular resonant cavity (232);

the silencing structure (24) is arranged on the second partition plate (222) and is used for absorbing noise; the resonator (26) is formed by the plurality of small holes (25) and the triangular resonant cavity (233) for absorbing noise.

2. The muffler of claim 1, wherein the monolithic muffler has a row number in the range of (5, 10), a thickness of not more than 300mm, a height of not more than 2000mm, and a length in the range of (0.8D, D), wherein D represents a predetermined wind tunnel stabilizing section diameter.

3. The method according to claim 2, characterized in that the length of the second component (2) ranges from (0.75L, 0.85L) or (5H, 8H), wherein L represents the length of the monolithic muffler and H represents the preset adjacent monolithic muffler airflow channel spacing.

4. A muffler as claimed in claim 3, characterised in that the thickness of the skin (21) ranges from (2mm, 5 mm).

5. The muffler of claim 4, wherein the diameter of the orifice (25) is in the range of (2mm, 5mm) and the aperture ratio of the orifice (25) is in the range of (1%, 5%).

6. The muffler according to any one of claims 1 to 5, characterized in that the sound-absorbing material of the sound-attenuating structure (24) is foamed aluminum.

7. The muffler of claim 6, wherein the foamed aluminum has a pore size in the range of (1mm, 1.6mm) and a porosity in the range of (68%, 78%).

8. The muffler according to any of the claims 1-5, characterized in that the first part (1) is of a semi-circular configuration, the second part (2) is of a rectangular configuration, the third part (3) is of a tapered wedge configuration, and the first part (1), the second part (2) and the third part (3) are joined to form a guide vane configuration.

9. The muffler according to claim 8, characterized in that the tapering wedge-shaped structure of the third part (3) has a cone angle in the range of (30 °, 40 °).

Technical Field

The application relates to the technical field of silencers, in particular to a silencer suitable for a high-speed wind tunnel stabilizing section.

Background

Wind tunnels are a tunnel-like test device that artificially generates and controls a flow of air to simulate the flow of air around an aircraft or object, and that can measure the effect of the air flow on the object. Wind tunnels play a very important role in aerodynamic research and in the design of various aerospace aircraft. However, in a high-speed wind tunnel, a pressure regulating valve system, an ejector system or an axial flow driving fan system and other wind tunnel driving power systems at the upstream of the test section can generate serious airflow noise for the stable section of the wind tunnel, and the noise can be transmitted to the test section area along the airflow direction to generate adverse effects on the dynamic quality of the flow field of the test section. In order to reduce the adverse effect of noise on the dynamic quality of the flow field of the test section, a high-performance muffler is usually arranged at the upstream of the test section, generally the stable section, for rectifying and muffling, so as to reduce the intensity of the incoming flow noise.

At present, a silencer adopted in a high-speed wind tunnel stable section generally adopts a resistive silencer, the resistive silencer mainly utilizes sound absorption materials to absorb sound and reduce noise, the silencer is of a frame structure, and a layer of large-aperture skin steel plate is arranged on the periphery of a silencing plate. However, the prior art mufflers have the following drawbacks: on one hand, because the airflow speed of the high-speed wind tunnel changes greatly, the noise frequency band of the airflow in the flow channel is wider, the existing silencer only has certain silencing effect in a high-frequency range or a low-frequency range, and the pressure loss of the airflow flowing through the existing silencer is larger, even serious secondary noise is generated; on the other hand, the existing silencer has better sound absorption and noise reduction effects under the non-airflow static state, but if the silencer is placed in a flowing airflow environment, the noise reduction performance is reduced quickly along with the increase of the flow speed; and the sound absorption material filled in the resistive muffler can sink, accumulate, damp and corrode after long-term use, so that the noise reduction performance of the muffler is affected. Therefore, the silencer in the prior art cannot meet the requirement of a high-quality flow field of the high-speed wind tunnel.

Disclosure of Invention

The technical problem that this application was solved is: aiming at the problem that the silencer in the prior art cannot meet the requirement of a high-quality flow field of a high-speed wind tunnel. The application provides a silencer suitable for high-speed wind tunnel stable section, and in the scheme that this application embodiment provided, a plurality of apertures through the covering surface form the resonator with the triangle-shaped resonant cavity, absorb the air current noise in the high-speed wind tunnel runner through the resonator resonance, resistance noise elimination promptly to and absorb the noise through the noise cancelling structure who sets up on the second baffle, resistance noise elimination promptly. Therefore, in the scheme provided by the embodiment of the application, the resonator and the noise elimination structure are combined to eliminate noise, so that the defect of the noise reduction effect of a single noise elimination form is overcome, the noise reduction performance of the silencer is improved, the medium and low frequency bands are eliminated through the resonator, the high frequency end is eliminated through the noise elimination structure, the sound absorption and noise reduction frequency band range of the silencer is widened, the noise reduction effect in the wide frequency domain range of the incoming flow of the high-speed wind tunnel is improved, and the requirement of the high-quality flow field of the high-speed wind tunnel is met.

In a first aspect, an embodiment of the present application provides a silencer suitable for a high-speed wind tunnel stabilizing section, where the silencer includes: a plurality of monolithic mufflers arranged in parallel; each of the monolithic mufflers comprises a first component, a second component and a third component connected in series, wherein,

the second component comprises a skin, a plurality of clapboards, a plurality of resonant cavities formed by the skin and the clapboards, a sound attenuation structure, a plurality of small holes arranged on the surface of the skin and a resonator;

the plurality of partition plates comprise a first partition plate and a second partition plate, and the plurality of resonant cavities comprise a first rectangular resonant cavity formed by folding the skin, a second rectangular resonant cavity formed by arranging the first partition plate in the first rectangular resonant cavity, and a triangular resonant cavity formed by arranging the second partition plate in a diagonal position of the second rectangular resonant cavity;

the silencing structure is arranged on the second partition plate and used for absorbing noise; the resonator is formed by the small holes and the triangular resonant cavity and is used for absorbing noise.

In the scheme provided by the embodiment of the application, a resonator is formed by a plurality of small holes on the surface of the skin and a triangular resonant cavity, airflow noise in a high-speed wind tunnel flow passage is absorbed through the resonator, namely, resistance noise elimination, and noise is absorbed through a noise elimination structure arranged on the second partition plate, namely, resistance noise elimination. Therefore, in the scheme provided by the embodiment of the application, the resonator and the noise elimination structure are combined to eliminate noise, so that the defect of the noise reduction effect of a single noise elimination form is overcome, the noise reduction performance of the silencer is improved, the medium and low frequency bands are eliminated through the resonator, the high frequency end is eliminated through the noise elimination structure, the sound absorption and noise reduction frequency band range of the silencer is widened, the noise reduction effect in the wide frequency domain range of the incoming flow of the high-speed wind tunnel is improved, and the requirement of the high-quality flow field of the high-speed wind tunnel is met.

Optionally, the row number range of the single-chip silencer is (5, 10), the thickness is not more than 300mm, the height is not more than 2000mm, and the length range is (0.8D, D), where D represents a preset wind tunnel stable section diameter.

Optionally, the length of the second component ranges from (0.75L, 0.85L) or (5H, 8H), where L represents the length of the monolithic muffler and H represents a preset distance between airflow channels of adjacent monolithic mufflers.

Optionally, the thickness of the skin ranges from (2mm, 5 mm).

Optionally, the diameter of the small hole ranges from (2mm, 5mm), and the aperture ratio of the small hole ranges from (1%, 5%).

Optionally, the material of the sound attenuating structure is foamed aluminum.

In the scheme provided by the embodiment of the application, the silencer structure is made of foamed aluminum, and the foamed aluminum has the characteristics of difficult deformation, high specific stiffness, sound absorption performance, no combustion, good heat resistance and the like, so that the stability of the noise reduction performance of the silencer is improved.

Optionally, the pore diameter of the foamed aluminum is in a range of (1mm, 1.6mm) and the porosity is in a range of (68%, 78%).

Optionally, the first component is a semicircular structure, the second component is a rectangular structure, the third component is a tapered wedge-shaped structure, and the first component, the second component and the third component are connected to form a guide vane type silencer structure.

In the scheme that this application embodiment provided, the guide vane formula structure silencer appearance is smooth-going streamlined, the difficult emergence separation behind the air current flow guide vane formula structure silencer, can make air current resistance loss reduce, simultaneously because the wind-tunnel air current must pass through complicated pressure regulating valve system before reentrant stable section, and the air current behind the valve is very inhomogeneous, there are a lot of large scale vortexes, what the air current got into at first behind the valve was the wind-tunnel stable section silencer, and through the air current straightening effect between the silencer passageway, can provide better incoming flow stability condition for the wind-tunnel test section, cooperate stable section honeycomb ware, rectification measures such as damping net, the even stable air current quality of wind-tunnel test section has been guaranteed.

Optionally, the tapered wedge structure of the third part has a cone angle in the range of (30 °, 40 °).

Drawings

Fig. 1 is a schematic structural diagram of a silencer suitable for a high-speed wind tunnel stabilizing section according to an embodiment of the present application;

FIG. 2 is a partial sectional view of a left side view of a structure of a silencer suitable for a high-speed wind tunnel stabilizing section according to an embodiment of the present application;

FIG. 3 is a structural top view of a silencer suitable for a high-speed wind tunnel stabilizing section according to an embodiment of the present application;

fig. 4 is a flow chart of a silencer design suitable for a stable section of a high-speed wind tunnel according to an embodiment of the present application.

Labeling: 1: a first member; 2: a second component; 3: a third component; 21: covering a skin; 22: a plurality of partition plates; 23: a plurality of resonant cavities; 24: a sound-deadening structure; 25: a small hole; 26: a resonator; 221: a first separator; 222: a second separator; 231: a first rectangular resonant cavity; 232: a second rectangular resonant cavity; 233: a triangular resonator 233.

Detailed Description

In the solutions provided in the embodiments of the present application, the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In order to better understand the technical solutions, the technical solutions of the present application are described in detail below with reference to the drawings and specific embodiments, and it should be understood that the specific features in the embodiments and examples of the present application are detailed descriptions of the technical solutions of the present application, and are not limitations of the technical solutions of the present application, and the technical features in the embodiments and examples of the present application may be combined with each other without conflict.

Referring to fig. 1, 2 and 3, an embodiment of the present application provides a silencer suitable for a high-speed wind tunnel stabilizing section, where the silencer includes: a plurality of monolithic mufflers arranged in parallel; each of the monolithic mufflers comprises a first component 1, a second component 2 and a third component 3, which are connected in sequence, wherein,

the second component 2 comprises a skin 21, a plurality of baffles 22, a plurality of resonant cavities 23 formed by the skin 21 and the baffles 22, a sound attenuation structure 24, a plurality of small holes 25 arranged on the surface of the skin 21, and a resonator 26;

the plurality of partitions 22 include a first partition 221 and a second partition 222, and the plurality of resonant cavities 23 include a first rectangular resonant cavity 231 formed by folding the skin 21, a second rectangular resonant cavity 232 formed by disposing the first partition 221 inside the first rectangular resonant cavity 231, and a triangular resonant cavity 233 formed by disposing the second partition 222 diagonally to the second rectangular resonant cavity 232;

the silencing structure 24 is arranged on the second partition plate 222 and is used for absorbing noise; the resonator 26 is formed by the plurality of small holes 25 and the triangular resonant cavity 233 for absorbing noise.

Further, in a possible implementation manner, the row number range of the single-piece silencer is (5, 10), the thickness is not more than 300mm, the height is not more than 2000mm, and the length range is (0.8D, D), where D represents the preset diameter of the wind tunnel stabilizing section.

Further, in a possible implementation manner, the length of the second component (2) is in a range of (0.75L, 0.85L) or (5H, 8H), wherein L represents the length of the single-piece silencer, and H represents the preset distance between airflow channels of adjacent single-piece silencers.

Further, in a possible implementation manner, the thickness of the skin 21 ranges from (2mm, 5 mm).

Further, in a possible implementation manner, the diameter of the small hole 25 is (2mm, 5mm), and the aperture ratio of the small hole 25 is (1%, 5%).

Further, in a possible implementation, the material of the sound attenuation structure 24 is foamed aluminum.

In the scheme provided by the embodiment of the application, the silencer structure 24 is made of foamed aluminum, and the foamed aluminum has the characteristics of difficult deformation, high specific stiffness, sound absorption performance, no combustion, good heat resistance and the like, so that the stability of the noise reduction performance of the silencer is improved.

Further, in one possible implementation, the pore size of the aluminum foam is in the range of (1mm, 1.6mm) and the porosity is in the range of (68%, 78%).

Further, in order to reduce the flow resistance borne by the muffler, in a possible implementation manner, the first component 1 is of a hemispherical structure, the second component 2 is of a rectangular structure, the third component 3 is of a tapered and wedge-shaped structure, and the first component 1, the second component 2 and the third component 3 are connected to form a guide vane type structure.

Specifically, in the scheme provided by the embodiment of the application, the appearance of the guide vane type structure silencer is smooth and streamlined, airflow is not easy to separate after flowing through the guide vane type structure silencer, so that the airflow resistance loss is reduced, meanwhile, the airflow after the valve is very uneven because the wind tunnel airflow must pass through a complex pressure regulating valve system before entering the stable section, and the airflow after the valve is very uneven, a large number of large-scale vortices exist, the wind tunnel stable section silencer is firstly entered into the airflow after the valve, a better incoming flow stability condition can be provided for the wind tunnel test section through the airflow straightening function between silencer channels, rectification measures such as the stable section honeycomb device and the damping net are matched, and the uniform and stable airflow quality of the wind tunnel test section is ensured.

Further, in a possible realization, the taper angle of the tapered wedge-shaped structure of the third part 3 is in the range of (30 °, 40 °).

In order to facilitate understanding of the above-mentioned muffler, the design concept of the muffler will be briefly described below. Specifically, referring to fig. 4, the design concept process of the muffler is as follows:

(1) according to the noise reduction amount within the frequency band range required by the incoming flow of the stable section of the wind tunnel, the structure of the silencer at the stable section is selected to be a composite type, namely, a Helmholtz resonator is formed by utilizing the small holes in the skin and the triangular resonant cavity, then the sound is absorbed jointly by utilizing two modes of resonance sound absorption of the Helmholtz resonator and internal resistive sound absorption materials, and the resistive and resistive noise elimination coupling design method is adopted, so that the defect of the noise reduction effect of a single noise elimination mode is made up, and the airflow noise within the wide frequency range is reduced.

(2) And selecting the blocking degree of the section of the silencer in the stable section according to the requirements of the airflow velocity and the pressure loss among the silencers, and determining the basic shape parameters of the silencer. The section blocking degree of the silencer in the stable section is a basic parameter of silencer design, and the proper blocking degree can effectively limit the flow speed of an airflow channel between the silencers and reduce pressure loss. In order to obtain reasonable airflow channel speed and pressure loss, the local section blockage degree of the silencer is selected to be 40% -50%, and the flow speed of the channel between the silencers is limited to be about 30 m/s.

Specifically, the air density of the stable section is calculated from the pressure and the temperature of the stable section according to the following gas state equation:

the flow rate of the gas flow in the stable section is calculated by the following gas flow formula:

where ρ represents the plateau air density; p₀Representing the total pressure of the stable section; t is₀Represents the total temperature of the stable section; r represents the air constant, R is 287J/kg/K; m represents the steady-state segment gas flow density; a represents the area of the corresponding nozzle throat of the wind tunnel; c represents a constant, R when air gamma is 1.4₀287, C0.04042; q (λ) represents the flow coefficient, 1 at the nozzle throat.

The flow velocity of the channel between the silencers can be calculated according to the following formula:

wherein S represents the cross-sectional area of the stable section where the muffler is disposed; alpha represents the section blockage degree of the silencer in the stable section.

Substituting equations (1) and (2) into equation (3) yields:

(3) determining the length of a resonant cavity and the distance between partition plates in the silencer of the designed silencer. In order to obtain lower air flow pressure loss, the integral shape of the silencer adopts a smooth streamline guide vane type shape, the head part is semicircular, the tail part is in a tapered wedge shape, and in order to properly control the length of the integral silencing structure of the silencer, the contraction included angle of the tail part is selected to be within the range of 30-40 degrees. The amount of noise reduction of the muffler is proportional to the effective sound absorption length of the muffler. The effective sound absorption length of the silencer is increased by the interval of one adjacent partition plate, the noise reduction amount is increased by 2-3 dB, and the effective sound absorption length of the silencer is 5-8 times that of the silencer interval.

(4) And determining the structural parameters of the skin, such as the opening rate of the skin, the thickness of the skin, the diameter of small holes of the skin and the like of the silencer. The actual wind tunnel airflow noise is broadband, and low peak frequency noise and broadband noise need to be considered when determining the skin structure parameters. When the thickness of the skin is too large and the aperture is too large, the skin cannot play a role of a resonant cavity, and the skin is too thin and the aperture is too small, so that the noise-reduction main frequency peak value moves to high frequency, and the comprehensive consideration is needed in parameter design, wherein the thickness of the skin of the silencer is selected to be 2 mm-5 mm, and the diameter of the small hole of the skin is selected to be 2 mm-5 mm. According to theoretical calculation and analysis, the larger opening ratio can improve the noise reduction peak value, the lower opening ratio can widen the noise reduction frequency band, and the opening ratio of the silencer skin suitable for the high-speed wind tunnel stable section is selected to be 1-5%.

(5) The internal shape and the structural parameters of the resonant cavity of the silencer are selected, the internal depth of the resonant cavity of the silencer is increased, and the noise reduction main frequency of the silencer can be pushed towards the low-frequency direction; in order to effectively improve the noise reduction performance of the silencer, the shape of the inside of the silencer resonant cavity 3 is suitable for adopting a triangular resonant cavity. In the effective sound absorption length of the silencer, the cavity is divided into a plurality of longitudinal rectangular cavities, a partition board is arranged on the diagonal line of each rectangular cavity, and the rectangular resonant cavity is divided into a plurality of triangular resonant cavities. And sound absorption materials with larger sound absorption coefficients are arranged on two sides of the partition board in the diagonal direction of the separation cavity, so that the noise reduction effect of the whole silencer is improved. The parameters of the sound-absorbing materials arranged on the two sides of the partition board in the diagonal direction of the separation chamber are selected and arranged to be comprehensively determined with the internal space of the separation chamber and the sound-absorbing characteristics of the sound-absorbing materials. In order to avoid the phenomena that the sound absorption material in the silencer sinks, is accumulated, is damped and is drawn out after being used for a long time, the sound absorption material arranged on two sides of the partition board in the diagonal direction of the partition chamber is made of foamed aluminum, so that the long-term stable silencing performance of the silencer can be kept, and the service life of the silencer is long. The average pore diameter of the foamed aluminum is selected to be 1-1.6 mm, and the porosity is selected to be 68-78%.

(6) Predicting the noise reduction effect of the selected muffler design parameters according to the noise reduction performance calculation method of the muffler; and after the basic appearance parameters and the blockage degree of the silencer are determined, predicting the noise reduction effect of the selected parameters of the silencer, such as the length, the thickness, the distance between the partition plates, the thickness of the skin, the aperture ratio, the diameter of the small hole and the like according to the acoustical design principle of the silencer and the noise reduction performance calculation method.

The noise reduction characteristics of the resonance chamber muffler can be calculated by the following equations (5), (6), (7), (8) and (9). The sign in the formula is selected so that the sign with a smaller value of Re (v) is calculated.

Z＝R+jX (5)

R＝0.67ρu/p (6)

X＝[ωρ(t+δ)/ρ]-ρc·cot(kd) (7)

L_A＝8.69·l·Re(v) (8)

v＝jk{1-(2/kh)²[1+1/(1+4Z/jhkρC)±

[1+1/(1+4Z/jkhρC)²]^1/2]}^1/2 (9)

Wherein Z represents an acoustic impedance in Pa.s/m³(ii) a R represents acoustic resistance and has a unit of Pa.s/m³(ii) a X represents acoustic reactance in Pa.s/m³(ii) a C represents the sound velocity, and the size is 340 m/s; v represents an acoustic propagation constant, with a magnitude of 1/m; ω denotes angular frequency, ω ═ 2 π f, f denotes frequency in Hz; ρ represents the air density in kg/m³(ii) a u represents the air flow velocity between the mufflers in m/s; ρ c represents the air characteristic impedance in Pa.s/m³(ii) a l represents the effective sound absorption length of the silencer and has the unit of m; d represents the muffler thickness in m; h represents half of the muffler spacing in m; l is_ARepresenting the noise reduction in dB; k represents wave number, and k is ω/C; t represents the skin thickness in m; δ represents the corrected aperture, δ is 0.85a, and a represents the skin pore diameter in m; p represents the skin opening rate;

(7) and comparing the theoretically designed noise elimination amount with the target noise elimination amount, if the theoretically designed noise elimination amount does not meet the requirement of the target noise elimination amount, comprehensively considering and modifying various design parameters of the silencer, and then performing iterative calculation and comparison until an optimal silencer design parameter scheme meeting the requirement of the target noise elimination amount is obtained.

In the solution provided by the embodiment of the present application, a resonator 26 is formed by the plurality of small holes 25 on the surface of the skin 21 and the triangular resonant cavity 233, the airflow noise in the high-speed wind tunnel flow channel is reduced through the resonance of the resonator 26, that is, the reactive noise elimination, and the noise is absorbed through the noise elimination structure 24 and the sound absorption material arranged on the second partition 222, that is, the resistive noise elimination. Therefore, in the scheme provided by the embodiment of the application, the resonator 26 and the noise elimination structure 24 are combined to eliminate noise, so that not only is the defect of the noise reduction effect of a single noise elimination form overcome, and the noise reduction performance of the silencer improved, but also the middle-low frequency band is eliminated through the resonator 26 and the high-frequency end is eliminated through the noise elimination structure 24, so that the sound absorption and noise reduction frequency band range of the silencer is widened, the noise reduction effect in the wide frequency domain range of the incoming flow of the high-speed wind tunnel is improved, and further the requirement of the high-quality flow field of the high-speed wind tunnel is met.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.