阅读说明：本技术 一种可调亚波长低频吸声结构 (A kind of adjustable sub-wavelength low-frequency sound-absorbing structure ) 是由 周玉坤 张学勇 王影 于 2019-08-13 设计创作，主要内容包括：本发明提出的一种可调亚波长低频吸声结构,其特征在于,包括多孔吸声材料基底和至少一个卷曲结构,卷曲结构嵌设在多孔吸声材料基底内,卷曲结构内部为中空结构,卷曲结构上设有用于使流体进入中空结构的开口,多孔吸声材料基底具有微孔,卷曲结构的开口与多孔吸声材料基底的微孔连通使卷曲结构与多孔吸声材料基底形成复合吸声结构,其中,复合吸声结构处于临界耦合状态时,实现完美吸声。本发明可有效提高低频吸声系数,尤其当复合吸声结构满足临界耦合条件时,可在低频区域实现完美吸声,甚至可实现多带的完美吸声,有效实现了基础共振模式和高次模式的综合利用。(A kind of adjustable sub-wavelength low-frequency sound-absorbing structure proposed by the present invention, it is characterized in that, including sound-absorbing porous material substrate and at least one coiled structure, coiled structure is embedded in sound-absorbing porous material substrate, it is hollow structure inside coiled structure, coiled structure is equipped with for making fluid enter the opening of hollow structure, sound-absorbing porous material substrate has micropore, the opening of coiled structure and the microporous connectivity of sound-absorbing porous material substrate make coiled structure and sound-absorbing porous material substrate form compound sound-absorption structural, wherein, when compound sound-absorption structural is in Critical Coupling state, realize perfect sound absorption.The present invention can effectively improve low frequency absorption coefficient, especially when compound sound-absorption structural meets critical coupling condition, can realize perfect sound absorption in low frequency region, or even can realize the perfect sound absorption of mostly band, effectively realize the comprehensive utilization of basic resonance mode and higher modes.)

1. a kind of adjustable sub-wavelength low-frequency sound-absorbing structure, which is characterized in that including sound-absorbing porous material substrate (1) and at least one Coiled structure (2)；

Coiled structure (2) is embedded in sound-absorbing porous material substrate (1), is hollow structure, coiled structure inside coiled structure (2) (2) it is equipped with for making fluid enter the opening of hollow structure, sound-absorbing porous material substrate (1) has micropore, coiled structure (2) Opening and the microporous connectivity of sound-absorbing porous material substrate (1) to form coiled structure (2) and sound-absorbing porous material substrate (1) multiple Close sound absorption structure；

Wherein, when compound sound-absorption structural is in Critical Coupling state, perfect sound absorption is realized.

2. adjustable sub-wavelength low-frequency sound-absorbing structure according to claim 1, which is characterized in that coiled structure (2) is winding At snail or the long tube of stereo spiral, long tube is closed at both ends, and long tube is equipped with for being connected to inside long tube and porous suction The opening of the micropore of sound material substrate (1).

3. adjustable sub-wavelength low-frequency sound-absorbing structure according to claim 1, which is characterized in that coiled structure (2) includes inhaling Sound monomer (21) and partition (22), sound absorption monomer (21) are embedded in sound-absorbing porous material substrate (2), and sound absorption monomer (21) has Inner cavity, partition (22) setting are divided into helical flow path in inner cavity and by inner cavity, and sound absorption monomer (21) is equipped with for being connected to spiral shell The opening in eddy flow road and the micropore of sound-absorbing porous material substrate (1).

4. adjustable sub-wavelength low-frequency sound-absorbing structure according to claim 1 to 3, which is characterized in that composite sound absorbing The Critical Coupling of structure makes the leakage energy of the compound sound-absorption structural and loss of energy reach balance via following equation, make its Reach theoretic perfect sound absorption under this condition:

Wherein,For quality factor are lost, in hot sticky stagnant and sound-absorbing porous material substrate (1) for describing coiled structure (2) Viscous loss；

To reveal quality factor, energy is revealed in the scattering for describing sound-absorbing porous material substrate (1).

5. adjustable sub-wavelength low-frequency sound-absorbing structure according to claim 4, which is characterized in that sound-absorbing porous material substrate (1) parameters such as flow resistance, porosity and aperture, length, width, thickness are selected according to actual conditions, the shape of coiled structure (2) The parameters such as shape, cross section, length, the opening direction parameter selection with sound-absorbing porous material substrate (1) according to the actual situation makes multiple It closes sound absorption structure and meets or be nearly in Critical Coupling state.

6. adjustable sub-wavelength low-frequency sound-absorbing structure according to claim 4, which is characterized in that when compound sound-absorption structural meets When critical coupling condition, the surface equivalent acoustic impedance of compound sound-absorption structural and the ratio of background fluid characteristic impedance are equal to 1.

7. adjustable sub-wavelength low-frequency sound-absorbing structure according to claim 4, which is characterized in that coiled structure (2) is beaten by 3D It prints.

8. adjustable sub-wavelength low-frequency sound-absorbing structure according to claim 4, which is characterized in that sound-absorbing porous material substrate (1) it is made of melamine material or flax.

9. adjustable sub-wavelength low-frequency sound-absorbing structure according to claim 4, which is characterized in that further include for by compound suction Acoustic form is fixed on the first connector of mounting surface, and compound sound-absorption structural connects by the way that the first connector and mounting surface are fixed It connects.

10. adjustable sub-wavelength low-frequency sound-absorbing structure according to claim 4, which is characterized in that further include for will be compound Sound absorption structure is fixed on mounting surface and makes the second connector between compound sound-absorption structural and mounting surface there are air chamber, multiple Sound absorption structure is closed to be fixedly connected by the second connector with mounting surface.

Technical field

The present invention relates to low frequency vibration damping noise reduction field fields, and in particular to a kind of adjustable sub-wavelength low-frequency sound-absorbing structure.

Background technique

Audible sound absorption is the important content of room acoustics, noise control in duct and environmental acoustics research.Due to all-bottom sound Weak loss in the material, low frequency high efficiency sound absorption face the challenge.Traditional porous material is widely used in sound absorption, but Since the thickness of 1/4 wavelength limits, the Low Frequency Sound Absorption material requested thickness limit use scope of porous material.Moreover, more Porous materials are suitable for high frequency sound absorption and effectively sound sucting band is wider, but its effect of low-frequency sound absorption is poor.In the prior art frequently with sky Chamber resonance improves low frequency absorption coefficient, but improves limitation.

Summary of the invention

Technical problems based on background technology, a kind of adjustable sub-wavelength low-frequency sound-absorbing structure proposed by the present invention.

A kind of adjustable sub-wavelength low-frequency sound-absorbing structure proposed by the present invention, which is characterized in that including sound-absorbing porous material base Bottom and at least one coiled structure；

Coiled structure is embedded in sound-absorbing porous material substrate, is hollow structure inside coiled structure, is set in coiled structure Have an opening for making fluid enter hollow structure, sound-absorbing porous material substrate has a micropore, the opening of coiled structure with it is porous The microporous connectivity of sound-absorbing material substrate makes coiled structure and sound-absorbing porous material substrate form compound sound-absorption structural；

Wherein, when compound sound-absorption structural is in Critical Coupling state, perfect sound absorption is realized.

Preferably, coiled structure is the long tube for being wound into snail or stereo spiral, and long tube is closed at both ends, on long tube Equipped with the opening for being connected to inside long tube with the micropore of sound-absorbing porous material substrate.

Preferably, coiled structure includes sound absorption monomer and partition, and sound absorption monomer is embedded in sound-absorbing porous material substrate, inhales Sound monomer has inner cavity, and partition setting is divided into helical flow path in inner cavity and by inner cavity, and sound absorption monomer is equipped with for being connected to The opening of helical flow path and the micropore of sound-absorbing porous material substrate.

Preferably, the Critical Coupling of compound sound-absorption structural via following equation make the compound sound-absorption structural leakage energy and Loss of energy reaches balance, it is made to reach theoretic perfect sound absorption with this condition:

Wherein,For quality factor are lost, in the hot sticky stagnant and sound-absorbing porous material substrate for describing coiled structure Viscous loss；

To reveal quality factor, energy is revealed in the scattering for describing sound-absorbing porous material substrate.

Preferably, the parameters such as the flow resistance of sound-absorbing porous material substrate, porosity and aperture, length, width, thickness are according to real Border situation selection, the parameters such as shape, cross section, length, opening direction of coiled structure according to the actual situation with porous sound absorption material The parameter selection for expecting substrate makes compound sound-absorption structural meet or be nearly in Critical Coupling state.

Preferably, when compound sound-absorption structural meets critical coupling condition, the surface equivalent acoustic impedance of compound sound-absorption structural It is equal to 1 with the ratio of background fluid characteristic impedance.

Preferably, coiled structure is formed by 3D printing.

Preferably, sound-absorbing porous material substrate is made of melamine material or flax.

It preferably, further include the first connector for compound sound-absorption structural to be fixed on to mounting surface, composite sound absorbing knot Structure is fixedly connected by the first connector with mounting surface.

It preferably, further include for compound sound-absorption structural to be fixed on mounting surface and makes compound sound-absorption structural and installation table There are the second connector of air chamber between face, compound sound-absorption structural is fixedly connected by the second connector with mounting surface.

A kind of adjustable sub-wavelength low-frequency sound-absorbing structure proposed by the present invention, has the advantages that

(1) by setting up composite sound absorbing made of being connected to of the hollow structure of coiled structure and sound-absorbing porous material substrate Structure can effectively improve low frequency absorption coefficient, can be in low frequency region especially when compound sound-absorption structural meets critical coupling condition Realize perfect sound absorption, i.e., the acoustic absorptivity of the compound sound-absorption structural reaches 100% in low frequency region.

(2) by the higher modes of coiled structure, adjusted and controlled medium-high frequency sound absorption effect, realization are wide in conjunction with constraint mode Frequently efficient sound absorption.

(3) made by the parameter of coiled structure in regulation compound sound-absorption structural and the parameter of sound-absorbing porous material substrate compound Sound absorption structure meets critical coupling condition, it might even be possible to the perfect sound absorption for realizing mostly band, effectively realize basic resonance mode and The comprehensive utilization of higher modes.

(4) by adjusting wideband of the number realization that coiled structure in sound-absorbing porous material substrate is arranged in different frequency range Band noise is eliminated.

Detailed description of the invention

Fig. 1 is a kind of structural schematic diagram of adjustable sub-wavelength low-frequency sound-absorbing structure proposed by the present invention.

Fig. 2 is the structural schematic diagram of helical baffle in the present invention.

Fig. 3 is the acoustic absorptivity test curve of embodiment 1 in the present invention.

Fig. 4 is the acoustic absorptivity test curve of embodiment 2 in the present invention.

Fig. 5 is the acoustic absorptivity test curve of embodiment 3 in the present invention.

Specific embodiment

Referring to Fig.1, a kind of adjustable sub-wavelength low-frequency sound-absorbing structure proposed by the present invention, including sound-absorbing porous material substrate 1 With at least one coiled structure 2；

Coiled structure 2 is embedded in sound-absorbing porous material substrate 1, is hollow structure, coiled structure 2 inside coiled structure 2 It is equipped with for making fluid enter the opening of hollow structure, sound-absorbing porous material substrate 1 has micropore, the opening of coiled structure 2 Coiled structure 2 and sound-absorbing porous material substrate 1 is set to form compound sound-absorption structural with the microporous connectivity of sound-absorbing porous material substrate 1；

Wherein, when compound sound-absorption structural is in Critical Coupling state, perfect sound absorption is realized.

In the present invention, when Acoustic Wave Propagation and after penetrating into the hollow structure of coiled structure 2 closed at one end, coiled structure 2 Opening be equivalent to extended helmholtz resonator neck, and remaining part is equivalent to its cavity portion.Therefore, the similar last of the twelve Earthly Branches The coiled structure 2 of Mu Huozi resonant cavity formation compound sound-absorption structural in parallel with sound-absorbing porous material substrate 1, can effectively improve low frequency Acoustic absorptivity reduces the size of compound sound-absorption structural.When compound sound-absorption structural meets critical coupling condition, thus in low frequency region Realize perfect sound absorption, i.e., the acoustic absorptivity of the compound sound-absorption structural reaches 100% in low-frequency resonance region.Meanwhile the present invention can To add air back chamber to realize that resonant structure is coupled with cavity or the higher modes and constraint of utilization coiled structure 2 using sound absorption structure The adjusted and controlled medium-high frequency sound absorption effect of Mode Coupling, realizes the sound absorption of high-efficient wide-frequency.Moreover, passing through regulation composite sound absorbing knot Structure, it might even be possible to which the perfect sound absorption for realizing mostly band effectively realizes the comprehensive utilization of basic resonance mode and higher modes.

In the present embodiment, coiled structure 2 is the long tube for being wound into snail or stereo spiral, two end seal of long tube It closes, long tube is equipped with the opening for being connected to inside long tube with the micropore of sound-absorbing porous material substrate 1.Long tube screw winding is to prolong The long length passed through by sound wave, the frequency range that makes to absorb sound have good assimilation effect for low-frequency sound wave to low frequency movement.

In the present embodiment, coiled structure 2 includes sound absorption monomer 21 and partition 22, and sound absorption monomer 21 is embedded in porous sound absorption In material substrate 2, sound absorption monomer 21 has inner cavity, and partition 22 is arranged in inner cavity and inner cavity is divided into helical flow path, absorbs sound Monomer 21 is equipped with the opening for being connected to the micropore of helical flow path and sound-absorbing porous material substrate 1.Pass through setting and porous suction The helical flow path of the microporous connectivity of sound material substrate 1 can effectively extend the length of sound wave process, can get depth sub-wavelength structure, Facilitate adjusting regulation compound sound-absorption structural to realize the mostly perfect sound absorption of band.

In the present embodiment, the Critical Coupling of compound sound-absorption structural makes the leakage of the compound sound-absorption structural via following equation Energy and loss of energy reach balance, it is made to reach theoretic perfect sound absorption with this condition:

Wherein,For quality factor are lost, for describing the hot sticky stagnant and sound-absorbing porous material substrate 1 of coiled structure 2 In viscous loss；

To reveal quality factor, energy is revealed in the scattering for describing sound-absorbing porous material substrate 1.

The present invention is based on Critical Coupling Theoretical Design compound sound-absorption structural, Critical Coupling theory calls compound sound-absorption structural When leakage energy and loss of energy reach balance, compound sound-absorption structural realizes perfect sound absorption.Critical Coupling theory ACOUSTIC WAVE EQUATION contains When part can be expressed as

Here, ω_resIt is the resonant angular frequency of coiled structure 2；

Wherein,It is loss quality factor, in the hot sticky stagnant and sound-absorbing porous material substrate for describing coiled structure Viscous loss；

To reveal quality factor, energy is revealed in the scattering for describing sound-absorbing porous material substrate.

Therefore, we can pass through regulator control systemIt is equal toRealize perfect sound absorption.Here, compound sound-absorption structural 'sFor the half width Δ f and resonant frequency f of the transmission peaks in lossy situation_rRatio,It is the half of reflection coefficient paddy Width Delta f resonant frequency f corresponding with paddy_rRatio.

In the present embodiment, the flow resistance of sound-absorbing porous material substrate 1, porosity and aperture, length, width, thickness etc. are joined Number is selected according to actual conditions, and the parameters such as shape, cross section, length, opening direction of coiled structure 2 are according to the actual situation and more The parameter selection of hole sound absorbing material substrate 1 makes compound sound-absorption structural meet or be nearly in Critical Coupling state, to realize perfection Sound absorption.Therefore, made by the relevant parameter of sound-absorbing porous material substrate 1 and coiled structure 2 compound sound-absorption structural meet or It is nearly in Critical Coupling state, to realize perfect sound absorption.

In the present embodiment, when compound sound-absorption structural meets critical coupling condition, the surface of compound sound-absorption structural is equivalent Acoustic impedance and the ratio of background fluid characteristic impedance are equal to 1, are conducive to sound importing.Specifically, background fluid is air, liquid Or other fluids.

In the present embodiment, coiled structure 2 is formed by 3D printing, convenient for conveniently and efficiently manufacturing coiled structure as needed 2。

In the present embodiment, sound-absorbing porous material substrate 1 using melamine material or or flax be made.

It in the present embodiment, further include the first connector for compound sound-absorption structural to be fixed on to mounting surface, it is compound Sound absorption structure is fixedly connected by the first connector with mounting surface, and compound sound-absorption structural is fixed on peace by the first connector Surface is filled, convenient for improving narrow frequency acoustic absorptivity.

In the present embodiment, further include for compound sound-absorption structural is fixed on mounting surface and make compound sound-absorption structural and There are the second connector of air chamber between mounting surface, compound sound-absorption structural connects by the way that the second connector and mounting surface are fixed It connects.It realizes that resonant structure couples adjusted and controlled medium-high frequency sound absorption effect with cavity using sound absorption structure plus air back chamber, realizes wide Frequently efficient sound absorption.

Below in conjunction with specific experiment data and program analogue data to the low frequency sub-wavelength sound absorption structure of the present embodiment Service performance is described.