An acoustic black hole sound-absorbing structure

Abstract

The present invention relates to an acoustic black hole sound absorption structure, which includes a cylindrical cavity, a support rod, and a circular plate array. The cylindrical cavity has an open structure at both ends. The circular plate array includes several circular plates with different diameters. The circular plates are parallel to each other and evenly fixed on the support rod. The diameter of the circular plates gradually increases from one end of the support rod to the other end. The diameter of the largest circular plate is equal to the inner diameter of the cylindrical cavity. The largest circular plate is fixed at one end of the cylindrical cavity and seals this end of the cylindrical cavity. The diameter of the circular plates gradually increases according to a power function, and the power function is #imgabs0# where the exponent n≥1, d represents the diameter of the circular plate, x represents the distance between any circular plate and the largest circular plate, L represents the length of the cylindrical cavity, D1 represents the minimum diameter of the circular plate, and the sum of D0 and D1 represents the inner diameter of the cylindrical cavity (1). The structure of the present invention is simple and does not require additional sound absorption materials or damping materials. Therefore, the cost of the present invention is low, it is easy to implement, and broadband sound absorption can be achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of noise control, and particularly relates to an acoustic black hole sound absorption structure. Background Art

[0002] The concept of acoustic black hole is extended from the concept of black hole in astrophysics. The traditional acoustic black hole structure refers to the phenomenon that when the thickness of a beam or plate structure gradually decays to zero according to a power function, the wave speed of the flexural wave inside the structure gradually slows down to zero, so that the flexural wave will not be reflected. Due to its simple structure and easy implementation, the acoustic black hole structure has currently become one of the important research directions for vibration control. For example, in the invention patent application with the application number 201810086724.0, it is proposed to achieve broadband vibration suppression of a vibrating structure through a one-dimensional acoustic black hole beam. In the invention patent applications with the application numbers 201711382962.8, 202110205344.6, and 202010894671.2, it is proposed to use the acoustic black hole structure in a dynamic vibration absorber to achieve the effect of broadband vibration control. In the invention patent application with the application number 202110538300.5, a vibration reduction and noise reduction enhancement structure hybridized with heterogeneous / heteromorphic acoustic black holes and phononic crystals is proposed, and broadband vibration reduction and noise reduction are achieved by combining a uniform circular two-dimensional acoustic black hole structure and a wedge-shaped two-dimensional acoustic black hole structure. In the invention patent application with the application number 202110986436.2, a hexagonal periodic acoustic black hole structure is proposed for structural vibration reduction and noise reduction.

[0003] It is noted that currently, the acoustic black hole structure mainly controls noise by reducing structural vibration, and it is necessary to paste a damping layer on the surface of the acoustic black hole structure, which is difficult to be applied to space sound absorption. The present invention applies the concept of acoustic black hole to the design of a muffler, and provides an acoustic black hole sound absorption structure with a simple structure, without the need for sound absorption materials or damping materials, for broadband control of noise. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention aims to provide an acoustic black hole sound absorption structure, which has a simple structure, does not require sound absorption materials or damping materials, has a low cost, is easy to implement, and can achieve broadband sound absorption.

[0005] The present invention is realized through the following technical solutions.

[0006] An acoustic black hole sound absorption structure includes a cylindrical cavity, a support rod, and a circular plate array. The cylindrical cavity has open ends at both ends. The circular plate array includes several circular plates with different diameters. The circular plates are parallel to each other and evenly fixed on the support rod. The diameter of the circular plates gradually increases from one end of the support rod to the other end. The diameter of the largest circular plate is equal to the inner diameter of the cylindrical cavity. The largest circular plate is fixed at one end of the cylindrical cavity to seal that end of the cylindrical cavity. The diameter of the circular plates increases gradually according to a power function, and the power function is where the exponent n≥1, d represents the diameter of the circular plate, x represents the distance between any circular plate and the largest circular plate, L represents the length of the cylindrical cavity, D1 represents the minimum diameter of the circular plate, and the sum of D0 and D1 represents the inner diameter of the cylindrical cavity (1).

[0007] Furthermore, the support rod is cylindrical, and the length of the support rod is equal to the length of the cylindrical cavity.

[0008] Furthermore, all the circular plates in the circular plate array have holes at the centers, and the hole diameter is greater than or equal to the diameter of the support rod.

[0009] Furthermore, the circular plates are perpendicular to the support rod, and the circular plates are fixed on the support rod by strong glue, welding or bolts.

[0010] Furthermore, the thickness of all the circular plates is not greater than 2 mm.

[0011] Furthermore, the diameter D1 of the smallest circular plate in the circular plate array is not greater than 5 mm.

[0012] Compared with the prior art, the advantages of the present invention are as follows: The structure of the present invention is simple, and there is no need to install additional sound absorption materials or damping materials. Therefore, the cost of the present invention is low, it is easy to implement, and broadband sound absorption can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic diagram of the present invention;

[0014] Figure 2 is an exploded three-dimensional schematic diagram of the present invention;

[0015] Figure 3 is a curve showing the variation of the sound absorption coefficient of the acoustic black hole sound absorption structure of the present invention with the incident noise frequency;

[0016] In the figure: 1. Cylindrical cavity, 2. Support rod, 3. Circular plate. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but it is not intended to limit the present invention.

[0018] As Figures 1 to 2As shown in the figure, an acoustic black hole sound absorption structure includes a cylindrical cavity 1, a support rod 2, and a circular plate array. The cylindrical cavity 1 has open ends at both ends. The circular plate array includes several circular plates 3 with different diameters. The circular plates 3 are parallel to each other and evenly fixed on the support rod 2. The diameter of the circular plates 3 gradually increases from one end of the support rod 2 to the other end. The diameter of the largest circular plate 3 is equal to the inner diameter of the cylindrical cavity 1. The largest circular plate 3 is fixed at one end of the cylindrical cavity 1 to seal that end of the cylindrical cavity 1. The diameter of the circular plates 3 increases gradually according to a power function, and the power function is where the exponent n ≥ 1, d represents the diameter of the circular plate 3, x represents the distance between any circular plate 3 and the largest circular plate 3, L represents the length of the cylindrical cavity 1, D1 represents the minimum diameter of the circular plate, and (D0 + D1) represents the inner diameter of the cylindrical cavity (1). The sum of D0 and D1 represents the inner diameter of the cylindrical cavity (1).

[0019] Further, the support rod 2 is cylindrical, and the length of the support rod 2 is equal to the length of the cylindrical cavity 1.

[0020] Further, all the circular plates 3 in the circular plate array have holes drilled at their centers, and the hole diameter is greater than or equal to the diameter of the support rod 2.

[0021] Further, the circular plates 3 are perpendicular to the support rod 2, and the circular plates 3 are fixed to the support rod 2 by strong glue, welding, or bolts.

[0022] Further, the thickness of all the circular plates 3 is not greater than 2 mm.

[0023] Further, the diameter D1 of the smallest circular plate in the circular plate array is not greater than 5 mm.

[0024] As a preferred embodiment of the present invention, the cylindrical cavity 1, the support rod 2, and the circular plate array can be made of aluminum alloy, plexiglass, or photosensitive resin. The diameter of the support rod 2 is between 2 - 5 mm, and the thickness of the circular plates 3 in the circular plate array is between 0.5 mm - 1 mm. The spacing between the circular plates 3 is less than 20 mm.

[0025] In this embodiment, the length L and the inner diameter (D0 + D1) of the cylindrical cavity 1 are selected to be 252 mm and 100 mm respectively, the length and diameter of the support rod 2 are 252 mm and 1 mm respectively, the thickness of all the circular plates 3 in the circular plate array is 1 mm, the number of the circular plate array is 18, the gap distance between adjacent circular plates 3 is 13 mm, and the diameters of the circular plates 3 are arranged in ascending order according to the power function The diameter D1 of the smallest circular plate in the circular plate array is 5 mm.

[0026] In this embodiment, the absorption coefficient curves of an acoustic black hole sound-absorbing structure according to the present invention are calculated respectively by using the transfer matrix method when the exponent n = 1 and n = 2, as Figure 3 shown. The solid line in the figure represents the absorption coefficient when the exponent n = 1, and the dashed line represents the absorption coefficient when the exponent n = 2. It can be found from the numerical calculation results that when the frequency is greater than 150 Hz, the absorption coefficient is greater than 0.5, and when the frequency is greater than 600 Hz, the absorption coefficient exceeds 0.9, which indicates that the acoustic black hole sound-absorbing structure according to the present invention has good broadband sound-absorbing characteristics.

[0027] The above are only the preferred embodiments of the present invention, and do not limit the implementation manners and protection scope of the present invention accordingly. For those skilled in the art, it should be realized that all the equivalent replacements and obvious changes made by using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. An acoustic black hole sound absorption structure, characterized in that, It includes a cylindrical cavity (1), a support rod (2), and a circular plate array. The cylindrical cavity (1) has an open structure at both ends. The circular plate array includes several circular plates (3) with different diameters. The circular plates (3) are parallel to each other and are evenly fixed on the support rod (2). The diameter of the circular plates (3) gradually increases from one end of the support rod (2) to the other end. The diameter of the largest circular plate (3) is equal to the inner diameter of the cylindrical cavity (1). The largest circular plate (3) is fixed at one end of the cylindrical cavity (1) and seals this end of the cylindrical cavity (1); the diameter of the circular plates (3) gradually increases according to a power function, and the power function is where the exponent n≥1, d represents the diameter of the circular plate (3), x represents the distance between any circular plate (3) and the largest circular plate (3), L represents the length of the cylindrical cavity (1), D1 represents the minimum diameter of the circular plate, and the sum of D0 and D1 represents the inner diameter of the cylindrical cavity (1).

2. The acoustic black hole silencing structure according to claim 1, characterized in that, The supported rod (2) is cylindrical, and the length of the supported rod (2) is equal to the length of the cylindrical cavity (1).

3. The acoustic black hole sound absorption structure according to claim 1, wherein All the circular plates (3) of the circular plate array are provided with holes at the centers, and the hole diameter is greater than or equal to the diameter of the support rod (2).

4. The acoustic black hole sound absorption structure according to claim 1, wherein The circular plate (3) is perpendicular to the support rod (2), and the circular plate (3) is fixed to the support rod (2) by strong glue, welding or bolts.

5. The acoustic black hole sound absorption structure according to claim 1, characterized in that The thickness of all the circular plates (3) is not greater than 2 mm.

6. The acoustic black hole sound absorption structure according to claim 1, characterized in that, The diameter D1 of the smallest circular plate (3) in the circular plate array is not greater than 5 mm.

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