CN109637516B - Multi-cavity composite micro-perforated plate sound-absorbing structure for suppressing nonlinear effect at high sound intensity - Google Patents

Abstract

The invention relates to a multi-cavity composite micro-perforated plate sound-absorbing structure for suppressing nonlinear effects under high sound intensity, which includes a micro-perforated plate, side plates and a back plate; multiple side plates and multiple rigid back plates are vertically fixed Connect to form a plurality of rectangular cavities with one end open and one end closed; at one end of the cavity opening, two or more layers of micro-perforated plates are vertically fixedly connected to the side plates; the latter layer of micro-perforated plates and the back plate and side plates Together they form multiple closed spaces, that is, multiple resonant cavities; other layers of micro-perforated plates, rear micro-perforated plates and side plates also form a closed space, but the distance between each micro-perforated plate is extremely small, forming micro-slits, Rather than a resonant cavity, the width of the microslit is generally less than 0.2mm. The present invention introduces multiple resonant absorption peaks by using multiple cavities with different depths, and can obtain a linear broadband sound-absorbing structure with good nonlinear effect suppression effect under high sound intensity, and the thickness of the entire structure increases less, while the manufacturing cost and The structural weight is also lower.

Description

Multi-cavity composite micro-perforated plate sound-absorbing structure for suppressing nonlinear effect at high sound intensity

technical field

The invention relates to a sound-absorbing structure of a multi-cavity composite micro-perforated plate for suppressing nonlinear effects under high sound intensity, and belongs to the sound-absorbing and noise-reducing technology in the field of noise control.

Background technique

The Micro-perforated panel (MPP) sound-absorbing structure was proposed by Professor Ma Dayou, a famous acoustic expert in my country, in 1975. Since it was proposed, it has been widely used for its advantages of firmness, light weight, corrosion resistance and environmental friendliness. In many fields such as buildings, ships, and mufflers, it is known as the most attractive new-generation sound-absorbing material that can replace traditional porous sound-absorbing materials in the 21st century.

However, in the application environment with high-intensity sound fields, such as aero-engines, missile silos, etc., a significant disadvantage of traditional micro-perforated panels is that its acoustic impedance (including acoustic resistance and acoustic reactance) will depend on the incident sound pressure level, performance a strong nonlinear effect. The nonlinear effect not only reduces the sound absorption performance of micro-perforated panels, but also makes it difficult to establish an accurate theoretical model of acoustic impedance, which greatly limits the effective application of micro-perforated panels under high sound intensity. Although the ultra-microporous microperforated plate structure with a large aspect ratio has the potential to suppress nonlinear effects, the manufacturing cost and structural weight will increase significantly with the increase of the aspect ratio, which is obviously not conducive to engineering applications. On the other hand, a significant disadvantage of the traditional micro-perforated plate sound-absorbing structure is that the sound-absorbing bandwidth is narrow, generally 1 to 2 octaves, which is far from enough as a general-purpose sound-absorbing structure, which has also become a constraint The bottleneck of its practical engineering application. Although some improvement measures can improve the bandwidth of micro-perforated plates, such as double-layer or multi-layer micro-perforated plate structures, this method will lead to a significant increase in the thickness of the entire sound-absorbing structure, which is not conducive to practical engineering applications.

To sum up, in the field of noise control, it is urgent to find a linear broadband sound-absorbing structure that can effectively suppress nonlinear effects and have a wide absorption bandwidth, and the thickness of the structure is relatively thin.

Based on the above reasons, the present invention provides a linear multi-cavity composite micro-perforated plate sound-absorbing structure, which can not only effectively suppress the nonlinear effect under high sound intensity, improve the effective application of micro-perforated plates to high sound pressure levels, but also introduce multiple A resonant absorption peak, so that it has a wide sound absorption frequency bandwidth.

Contents of the invention

In view of the above problems, the purpose of the present invention is to provide a multi-cavity composite micro-perforated plate sound-absorbing structure that suppresses the nonlinear effect under high sound intensity. Compared with the traditional single-layer micro-perforated plate, it can not only effectively increase the The aspect ratio of the perforated plate increases the critical sound pressure level at which the nonlinear effect begins to act, thereby effectively suppressing the nonlinear effect. At the same time, multiple resonant absorption peaks can be introduced through multiple cavities with different depths, thereby broadening the absorption of the micro-perforated plate. Audio bandwidth. In addition, the thickness of the structure can be made thinner, and the manufacturing cost and the weight of the structure are also greatly reduced.

To achieve the above object, the present invention takes the following technical solutions:

A multi-cavity composite ultra-microporous micro-perforated plate structure that suppresses nonlinear effects under high sound intensity, including a micro-perforated plate, side plates and a back plate; multiple side plates and multiple rigid back plates are vertically fixedly connected to form a A plurality of rectangular cavities with one end open and one end closed; at one end of the cavity opening, several layers of micro-perforated plates are vertically fixedly connected to the side plates; several layers of micro-perforated plates include the innermost layer of micro-perforated plates and several intermediate layers of micro-perforated plates and the outermost micro-perforated plate; the innermost micro-perforated plate, the back plate and the side plate together form a plurality of closed spaces to form multiple resonance cavities; the innermost micro-perforated plate, the middle layer micro-perforated plate, the innermost The outer micro-perforated plate and the side plates enclose several closed spaces, forming micro-slits.

The width of the micro-slits is less than 0.2mm.

The above-mentioned rectangular cavities have different depths, and the cavities of different depths are arranged in parallel and separated by side plates.

The through holes of the micro-perforated plate are circular or square, and the diameter of the through holes is between 40 microns and 1 mm.

Due to the adoption of the above technical solutions, the present invention has the beneficial effect of providing a linear broadband sound-absorbing structure under high sound intensity, which is specifically manifested in: 1. Using multiple cavities with different depths can introduce multiple resonant absorption peaks, thereby broadening the The sound absorption bandwidth of the structure. And because different cavities are arranged in parallel, the thickness of the whole structure will not be significantly increased. 2. The micro-slits between the composite multi-layer micro-perforated plates can increase the damping path of the airflow, thereby increasing the aspect ratio of the micro-perforated plates, thereby enhancing its linear response under high sound intensity, and compared with the traditional single-layer large The length-to-diameter ratio micro-perforated plate structure greatly reduces its weight and manufacturing cost, which is beneficial to practical engineering applications.

Description of drawings

Figure 1 is a multi-cavity composite ultra-microporous micro-perforated plate structure that effectively suppresses the nonlinear effect under high sound intensity;

Figure 2 is a schematic diagram for actual noise control engineering.

In accompanying drawing 1, 1. Micro-perforated plate, 2. Side plate, 3. Rigid back plate, 13. Middle micro-perforated plate, 12. Innermost micro-perforated plate, 11 Outermost micro-perforated plate.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described The embodiments are only some of the embodiments of the present application, but not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

As shown in Figure 1, a multi-cavity composite ultra-microporous micro-perforated plate structure that suppresses the nonlinear effect under high sound intensity includes a micro-perforated plate 1, a side plate 2 and a back plate 3; its multiple side plates 2 and A plurality of rigid backboards 3 are vertically fixedly connected to form a plurality of rectangular cavities with one end open and one end closed; at one end of the cavity opening, several layers of micro-perforated plates 1 are vertically fixedly connected with side plates 2; several layers of micro-perforated plates 1 Including the innermost micro-perforated plate 12, a number of intermediate micro-perforated plates 13 and the outermost micro-perforated plate 11; the innermost micro-perforated plate 12, the back plate 3 and the side plate 2 together form a plurality of closed spaces, A plurality of resonant cavities are formed; the innermost micro-perforated plate 12, the middle layer micro-perforated plate 13, the outermost layer micro-perforated plate 11 and the side plate 2 enclose several closed spaces to form micro-slits.

The width of the micro-slits is less than 0.2mm.

The above-mentioned rectangular cavities have different depths, and the cavities of different depths are arranged in parallel and separated by side plates.

The through holes of the micro-perforated plate 1 are circular or square, and the diameter of the through holes is between 40 microns and 1 mm.

Example 1:

The invention includes a micro-perforated plate 1, a side plate 2 and a back plate 3; the three side plates 2 and two rigid back plates 3 are vertically fixedly connected to form two rectangular cavities with one end open and one end closed. At one end of the opening of the cavity, the three-layer stainless steel micro-perforated plate 1 is vertically fixedly connected to the side plate 2 . The structural parameters of the three-layer micro-perforated plate, such as aperture d , plate thickness t , and perforation rate ϕ , can be the same or different. In this embodiment, the structural parameters of each layer of micro-perforated plate are chosen to be the same, specifically, the aperture d= 0.06 mm, plate thickness t= 0.6 mm and perforation rate ϕ= 9.8%. The innermost micro-perforated plate 12, two back plates 3 and three side plates 2 together form two closed spaces to form two resonant cavities. The distance from the innermost micro-perforated plate 12 to one of the back plates 31 is, The cavity depth is 20 mm, and the cavity depth from the innermost micro-perforated plate 12 to another back plate 32 is 30 mm; the middle layer micro-perforated plate 13, the innermost layer micro-perforated plate 12 and the side plate 2 also form a closed space, but the distance between each micro-perforated plate 1 needs to be strictly controlled to form a micro-slit instead of a resonant cavity, and the width of the micro-slit is preferably 0.1 mm. In this example, since the three-layer micro-perforated plate adopts a composite structure based on micro-slits, compared with the aspect ratio ( t / d ) of the single-layer micro-perforated plate, the aspect ratio of the entire composite structure is >3 t / d , the improvement is significant, so the linear response of the composite structure under high sound intensity is greatly improved, and compared with the micro-perforated plate with a single-layer length-to-diameter ratio of 3 t / d , the manufacturing cost of the composite structure is greatly reduced, and the weight of the structure is also lighter. Small. At the same time, in this embodiment, since two resonant cavities with different depths are used, at least two resonant absorption peaks can be introduced, thereby widening the sound absorption frequency bandwidth of the composite structure. And since the multiple cavities adopt a parallel structure, the overall thickness of the structure will not be greatly increased. In summary, the present invention can realize a linear broadband sound-absorbing structure under high sound intensity with lower manufacturing cost, smaller structural weight and thickness.

When the present invention is in use, several broadband sound-absorbing structures shown in Figure 1 can be used in parallel, as shown in Figure 2, for actual noise control engineering.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (3)

1. A multi-cavity composite micro-perforated plate sound-absorbing structure that suppresses nonlinear effects under high sound intensity, characterized in that it includes a micro-perforated plate (1), a side plate (2) and a back plate (3); A side plate (2) and a plurality of rigid back plates (3) are vertically fixedly connected to form a plurality of rectangular cavities with one end open and one end closed; at one end of the cavity opening, several layers of micro-perforated plates (1) and side plates (2) Vertical fixed connection; several layers of micro-perforated plates (1) including the innermost layer of micro-perforated plates (12), several intermediate layers of micro-perforated plates (13) and the outermost layer of micro-perforated plates (11); the innermost The first layer of micro-perforated plates (12), the back plate (3) and the side plates (2) jointly enclose multiple closed spaces and form multiple resonance cavities; the innermost layer of micro-perforated plates (12), the middle layer of micro-perforated plates (13 ), the outermost micro-perforated plate (11) and the side plate (2) enclose several closed spaces to form micro-slits; the width of the micro-slits is less than 0.2 mm. 2. The multi-cavity composite micro-perforated plate sound-absorbing structure for suppressing nonlinear effects under high sound intensity according to claim 1, characterized in that: the depths of the rectangular cavities are different, and the cavities of different depths are connected in parallel lined up and separated by side panels. 3. The multi-cavity composite micro-perforated plate sound-absorbing structure for suppressing nonlinear effects under high sound intensity according to claim 1, characterized in that: the through holes of the micro-perforated plate (1) are circular or square, The diameter of the via hole is between 40 microns and 1 mm.

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