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A tunable sub-wavelength low-frequency sound-absorbing structure

A sub-wavelength, sound-absorbing technology, used in sound-generating equipment, instruments, etc., can solve the problems of effective sound-absorbing frequency bandwidth, poor low-frequency sound-absorbing effect, limited porous materials, etc., achieve broadband high-efficiency sound absorption, and improve low-frequency sound absorption coefficient. , to achieve the effect of sound absorption

Active Publication Date: 2021-10-12
ANHUI UNIVERSITY OF ARCHITECTURE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Traditional porous materials are widely used in sound absorption, but due to the thickness limitation of 1 / 4 wavelength, the material thickness required for low-frequency sound absorption limits the application range of porous materials
Moreover, porous materials are suitable for high-frequency sound absorption and have a wide effective sound absorption frequency band, but their low-frequency sound absorption effect is poor
In the prior art, cavity resonance is often used to improve the low-frequency sound absorption coefficient, but the degree of improvement is limited

Method used

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  • A tunable sub-wavelength low-frequency sound-absorbing structure
  • A tunable sub-wavelength low-frequency sound-absorbing structure
  • A tunable sub-wavelength low-frequency sound-absorbing structure

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0055] refer to figure 1 and figure 2 , the curled structure 2 includes a sound-absorbing unit 21 and a partition 22, the partition 22 is a spiral partition, and is in the shape of an Archimedes spiral, and the spiral partition is a rigid partition. Take the spiral center of the spiral partition as the coordinate system circle point, take the straight line from the origin to the starting point of the spiral partition as the x-axis, and take the horizontal straight line perpendicular to the x-axis as the y-axis to establish a plane Cartesian coordinate system, such as figure 2 shown. Among them, the inner edge of the spiral partition satisfies the following equation:

[0056]

[0057] Among them, m is the ordinal number of the Archimedes spiral coil,

[0058] is the space azimuth,

[0059] g is the interval between adjacent spirals of the Archimedes spiral, which is a constant,

[0060] r 0 for when polar diameter at time.

[0061] further,

[0062] Wherein, ...

Embodiment 2

[0067] We adjust the parameters of the spiral partition in Example 1 to r 0 =16mm, The spatial azimuth angle in the range of -π-3π / 2, m=2, g=5mm, the thickness of the spiral partition t=1mm, and the opening angle θ=0°. The length, width and thickness of the porous material remain unchanged, and the parameters of the Johnson-Champoux-Allard model of the porous material remain unchanged. The sound absorption coefficient simulation result of embodiment 2 of the present invention sees Figure 4 .

[0068] from Figure 4 It can be seen in f 1 = 310Hz, f 2 =1130Hz, there are two perfect sound absorption coefficients respectively, and the single structure realizes the perfect sound absorption of double belts. f 1 corresponds to the fundamental resonance mode of the coiled structure, f 2 Corresponds to the higher-order resonance modes of the coiled structure. The frequency equal to 1379Hz corresponds to the bound mode of the structure. Due to the joint action of the bound mo...

Embodiment 3

[0070] An air cavity with a thickness of 30 mm is left between the composite sound-absorbing structure and the installation surface in Example 1 to simulate the situation where there is an air cavity between the composite sound-absorbing structure and the installation surface. The sound absorption coefficient of embodiment 3 of the present invention sees Figure 5 .

[0071] from Figure 5 It can be seen that the sound absorption coefficient of the composite sound-absorbing structure can reach more than 80% at 300Hz-1000Hz, and the sound absorption coefficient measurement results show that the existence of the air cavity greatly improves the low-frequency sound absorption performance.

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Abstract

An adjustable sub-wavelength low-frequency sound-absorbing structure proposed by the present invention is characterized in that it includes a porous sound-absorbing material base and at least one curled structure, the curled structure is embedded in the porous sound-absorbing material base, and the inside of the curled structure is a hollow structure, The curled structure is provided with an opening for fluid to enter the hollow structure, the porous sound-absorbing material substrate has micropores, and the opening of the curled structure is connected with the micropores of the porous sound-absorbing material substrate to form a composite sound-absorbing structure between the curled structure and the porous sound-absorbing material substrate structure, wherein, when the composite sound-absorbing structure is in a critical coupling state, perfect sound absorption is achieved. The invention can effectively improve the low-frequency sound absorption coefficient, especially when the composite sound-absorbing structure satisfies the critical coupling condition, it can realize perfect sound absorption in the low-frequency region, and can even realize perfect sound absorption in multiple bands, effectively realizing the basic resonance mode and high-order Comprehensive use of models.

Description

technical field [0001] The invention relates to the field of low-frequency vibration reduction and noise reduction, in particular to an adjustable sub-wavelength low-frequency sound-absorbing structure. Background technique [0002] Audible sound absorption is an important content in the study of room acoustics, duct noise control and environmental acoustics. Due to the weak loss of low-frequency sound in materials, efficient sound absorption at low frequencies is challenging. Traditional porous materials are widely used in sound absorption, but due to the thickness limitation of 1 / 4 wavelength, the material thickness required for low-frequency sound absorption limits the application range of porous materials. Moreover, porous materials are suitable for high-frequency sound absorption and have a wide effective sound absorption frequency band, but their low-frequency sound absorption effect is poor. In the prior art, cavity resonance is often used to improve the low-frequen...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G10K11/172G10K11/162
CPCG10K11/162G10K11/172
Inventor 周玉坤张学勇王影
Owner ANHUI UNIVERSITY OF ARCHITECTURE
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