Sound absorption scatterer based on Helmholtz resonance cavity

Abstract

The sound absorption scatterer comprises a back plate and a plurality of cavities, each cavity is composed of a resonance cavity and an embedded pipe, the two ends of each embedded pipe are open, the tail ends of the embedded pipes penetrate into the cavities, and the top ends of all the embedded pipes are located on the horizontal plane where the upper surfaces of the cavities are located. The tail ends of the embedded pipes are located on the same horizontal plane in the cavity, the embedded pipes comprise the large-hole embedded pipe and the small-hole embedded pipe, the radius of the large hole is larger than or equal to 4 mm and smaller than 7 mm, and the radius of the small hole is larger than or equal to 0.55 mm and smaller than 4 mm. The sound absorption scatterer achieves more than 50% of sound absorption within the frequency band of 1000-2000 Hz and has the sound scattering effect, and the scattering center frequency is 3430 Hz. The sound absorption and scattering performance requirements of the material can be met at the same time, customization can be carried out according to needs, space is saved, pollution is small, and the service life is long.

Description

Technical Field

[0001] The invention relates to a sound absorbing and scattering body, in particular to a sound absorbing and scattering body based on a Helmholtz resonance cavity. Background Art

[0002] At present, commonly used sound-absorbing materials include sponge, felt, micro-perforated plate, etc., which have good sound absorption performance at their respective working frequencies, but have almost no ability to scatter sound waves, and the sound absorption effect is seriously deteriorated at low frequencies. Commonly used sound scattering structures include Schroeder scatterers or quadratic residue scatterers, etc., which have good sound scattering performance in the working frequency band, but have almost no sound absorption ability. The regulation of indoor sound fields depends on the joint action of sound-absorbing materials and sound scattering structures. At present, the existing sound field control structures can often only achieve a single sound absorption or scattering function, which makes the materials or structures required for indoor sound field control more diverse, short life, high cost, difficult sound field control, and poor effect. Summary of the invention

[0003] Purpose of the invention: The present invention aims to provide a sound absorbing and scattering body based on a Helmholtz resonance cavity that satisfies both the sound absorption and sound scattering requirements.

[0004] Technical solution: The sound-absorbing scatterer based on the Helmholtz resonance cavity described in the present invention includes a back plate and a plurality of cavities, each cavity consisting of a resonance cavity and an embedded tube, both ends of the embedded tube are open and the ends thereof extend deep into the cavity, the top ends of all the embedded tubes are located at the horizontal plane where the upper surface of the cavity is located, and the ends are located at the same horizontal plane inside the cavity, the embedded tubes include large-hole embedded tubes and small-hole embedded tubes, the radius of the large hole is greater than or equal to 4 mm, and the radius of the small hole is greater than or equal to 0.55 mm and less than 4 mm.

[0005] Furthermore, the cavity containing the large-pore embedded tube constitutes a large-pore cavity, and the cavity containing the small-pore embedded tube constitutes a small-pore cavity, and the small-pore cavities are arranged around the large-pore cavity.

[0006] Furthermore, there is an interaction between the macroporous cavity and the microporous cavity, which can be described by the acoustic impedance formula shown below:

[0007]

[0008] Among them, Z1, Z2, ... Z n Represent the surface impedance of each cavity, Z total Represents the total impedance of the interaction between the cavities.

[0009] Furthermore, the scattering ability of the macroporous cavity comes from the phase modulation effect of the cavity on the incident sound wave. Under the premise that the impedance is determined and the incident sound wave is a plane wave, the modulation effect of the cavity on the incident sound wave is described by the following formula:

[0010]

[0011] Where Z0 is the surface impedance of the cavity, ρ0 and c0 are the air density and the speed of sound in the air respectively, S is the surface area of ​​the cavity, For phase.

[0012] Furthermore, all the cavities are oriented in the same direction and arranged in parallel, the lower surfaces of all the cavities are located in the same horizontal plane, and the upper and lower surfaces are parallel to each other.

[0013] Furthermore, the length of the embedded tube does not exceed 1 / 2 of the inner height of the cavity.

[0014] Furthermore, the number of macroporous cavities is at least 7 and at most 48, and the number of microporous cavities is at least 28 and at most 144.

[0015] Furthermore, the cavity and the back plate are processed separately by 3D printing, and each cavity and the back plate can be connected by epoxy resin adhesive.

[0016] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: the sound-absorbing scatterer based on the Helmholtz resonance cavity has both sound absorption and sound scattering properties; wherein, the sound absorption performance mainly comes from the contribution of the cavity with a smaller aperture in the panel surface, and its sound absorption frequency band is 600-2000Hz and can achieve more than 50% sound absorption. Compared with traditional acoustic materials, the low-frequency performance is better (below 1000Hz), and at the same thickness, the sound absorption performance is better and the threshold is lower; the sound scattering performance mainly comes from the cavity with a larger aperture in the panel surface, and each cavity realizes the phase regulation of the incident sound wave through the coupling effect with the sound-absorbing cavity around the cavity, and scatters the sound waves in a specific frequency band. The acoustic metastructure sound-absorbing scatterer described in the present invention integrates the functions of sound absorption and scattering, and can be customized for the required frequency band, saving more space while achieving the same function. It can be produced using environmentally friendly materials, has a long service life, and is energy-saving and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of the sound absorbing and scattering body of the present invention;

[0018] Figure 2 It is a three-view diagram of the structure of the sound absorbing and scattering body of the present invention;

[0019] Figure 3 is a schematic diagram of the cavity of the present invention;

[0020] Figure 4 is a schematic diagram of a backplane of the present invention;

[0021] Figure 5 It is the simulation result of the sound absorption coefficient of the sound absorbing scatterer of the present invention at 1000-2000Hz;

[0022] Figure 6 This is the simulation result of the scattering performance of 3430Hz materials. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0024] Example

[0025] like Figure 1-4 As shown, the length, width and height of the sound absorbing scattering structure provided in this embodiment are 255mm, 255mm and 35mm respectively. It is composed of 96 Helmholtz resonance cavities with different structural parameters, which are divided into two parts: cavity and back plate. Each cavity is composed of a resonance cavity and an embedded tube. The end of the embedded tube goes deep into the cavity, and the top is connected to the outside world. All cavities are oriented in the same direction and arranged in parallel. The tops of all embedded tubes are located at the horizontal plane where the upper surface of the cavity is located, the lower surface of the cavity is located at the same horizontal plane, and the upper and lower surfaces are parallel to each other. The cavity and the back plate are processed separately by 3D printing means and connected by epoxy resin adhesive. When determining the arrangement position of each cavity, the relative position of the large hole cavity in the sound absorbing scattering plate is determined first (usually located on the geometric symmetry axis of the cavity, with the plate surface as the center point, and the side length of each cavity as the unit, the edge of a 5*5 square), and then the small hole cavity used for sound absorption is arranged around the large hole cavity. The arrangement position of the small hole cavity is determined by the simulation iterative optimization of the sound absorption coefficient. Simulation iterative optimization operation process: establish a simulation model based on the structural parameters and calculate the sound absorption coefficient; adjust the structural parameters of individual cavities for the frequency bands that do not meet the sound absorption requirements based on the calculation results; make up for the insufficient sound absorption coefficient; and then use simulation for verification; repeat the above operations until the sound absorption coefficient meets the requirements.

[0026] In the sound absorption frequency band, when the sound wave is incident on the upper surface of the sound absorption scatterer, the air in each embedded Helmholtz cavity resonates, converting the energy carried by the sound into heat energy and dissipating it, thus playing a role in sound absorption. In the sound scattering frequency band, when the sound wave is incident on the upper surface of the sound absorption scatterer, the resonance cavity arranged based on the coupling effect and sound scattering principle plays a role in phase adjustment, and the sound scattering effect is achieved by adjusting the phase distribution.

[0027] like Figure 5 As shown, the average sound absorption coefficient of the sound-absorbing and scattering panel in the frequency band of 800-2000Hz is about 0.65, and it can achieve quasi-perfect sound absorption in some frequency bands, and can effectively absorb noise in different frequency bands.

[0028] like Figure 6As shown, at the center frequency of 3430 Hz, the sound absorbing and scattering plate modulates the phase of the incident sound wave perpendicular to the plate surface, thereby changing the distribution of the sound field perpendicular to the plate surface, making the sound pressure level distribution more uniform within the sound wave incident surface.

Claims

1. A sound absorbing scatterer based on a Helmholtz resonance cavity, characterized in that: It includes a back plate and a plurality of cavities, each cavity is composed of a resonance cavity and an embedded tube, both ends of the embedded tube are open and the ends thereof extend into the cavity, the top ends of all the embedded tubes are located at the horizontal plane where the upper surface of the cavity is located, and the ends are located at the same horizontal plane inside the cavity, the embedded tubes include large-hole embedded tubes and small-hole embedded tubes, the radius of the large hole is greater than or equal to 4 mm and less than 7 mm, and the radius of the small hole is greater than or equal to 0.55 mm and less than 4 mm.

2. The sound absorbing scatterer based on the Helmholtz resonance cavity according to claim 1, characterized in that: The cavity containing the large-pore embedded tube constitutes a large-pore cavity, and the cavity containing the small-pore embedded tube constitutes a small-pore cavity, and the small-pore cavities are arranged around the large-pore cavity.

3. The sound absorbing scatterer based on the Helmholtz resonance cavity according to claim 1, characterized in that: The acoustic impedance formula of the cavity is as follows: Among them, Z1, Z2, ... Z n Represent the surface impedance of each cavity, Z total Represents the total impedance of the interaction between the cavities.

4. The sound absorbing scatterer based on the Helmholtz resonance cavity according to claim 1, characterized in that: Under the premise that the impedance is determined and the incident sound wave is a plane wave, the modulation effect of the cavity on the incident sound wave is described by the following formula: Where Z0 is the surface impedance of the cavity, ρ0 and c0 are the air density and the speed of sound in the air respectively, S is the surface area of ​​the cavity, For phase.

5. The sound absorbing scatterer based on the Helmholtz resonance cavity according to claim 1, characterized in that: All cavities are oriented in the same direction and arranged side by side.

6. The sound absorbing scatterer based on the Helmholtz resonance cavity according to claim 1, characterized in that: The lower surfaces of all the cavities are located in the same horizontal plane, and the upper and lower surfaces are parallel to each other.

7. The sound absorbing scatterer based on the Helmholtz resonance cavity according to claim 1, characterized in that: The length of the embedded tube does not exceed 1 / 2 of the inner height of the cavity.

8. The sound absorbing scatterer based on the Helmholtz resonance cavity according to claim 1, characterized in that: The number of large-pore cavities is at least 7 and at most 48, and the number of small-pore cavities is at least 28 and at most 144.

9. The sound absorbing scatterer based on the Helmholtz resonance cavity according to claim 1, characterized in that: The cavity and the back plate are processed separately by 3D printing.

10. The sound absorbing and scattering body based on the Helmholtz resonance cavity according to claim 1, characterized in that: Epoxy resin adhesive is used to connect the cavities and the back panel.

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