CN103032381B - For reducing the casing of noise of axial flow fan - Google Patents

Abstract

The invention discloses a casing for reducing the noise of an axial flow fan, which belongs to the technical field of impeller noise reduction. The casing of the low-noise axial flow fan is composed of the inner layer of the casing, the sound-absorbing fabric of the inner layer, the metal foam aluminum plate, the sound-absorbing fabric of the outer layer, and the outer layer of the casing sequentially from the inner layer to the outer layer of the casing. The invention has the characteristics of light weight, reduced cavity noise, high temperature resistance, recyclable metal foam aluminum plate, high rigidity itself, and low manufacturing and installation costs. The noise reduction value of the fan is about 18 dB, and the sound absorption effect is better in the middle and low frequency range, and the noise reduction effect is very significant, thus improving the working environment of the operators.

Description

Chassis for noise reduction of axial fans

technical field

The invention belongs to the technical field of turbine noise reduction. It particularly relates to a casing for reducing the noise of an axial flow fan, in particular to a casing with a metal foam aluminum plate structure.

Background technique

During the operation of the axial flow fan, aerodynamic noise such as rotating noise and eddy current noise and mechanical noise will be generated. The noise is broadband noise, ranging from 35dB to 120dB. Noise pollution poses serious harm to people, animals, instruments and buildings. The state has promulgated and implemented the "Noise Hygienic Standards for Industrial and Mining Enterprises" and the "Regulations on the Prevention and Control of Urban Environmental Noise Pollution" to strictly stipulate the safety of workshops and workplaces of industrial enterprises. Noise limits in the workplace. Therefore, it is of great significance to design and develop a low-noise axial fan casing from the perspective of saving costs, reducing fan noise pollution, and improving the working environment of the staff.

At present, the existing fan noise reduction methods are mostly focused on the transformation of the fan structure (installing deflectors at the inlet and outlet of the fan, etc.) and the improvement of fan sound-absorbing materials (installing galvanized sheets on both sides of the fan inlet, etc.) . However, many noise reduction methods are relatively complicated to implement on site, and even involve the transformation of important structures of wind turbines (such as rotor blades, etc.), which are costly and have limited noise reduction effects, making it difficult to achieve effective noise reduction of wind turbines.

Contents of the invention

The object of the present invention is to provide a casing for reducing the noise of an axial flow fan, characterized in that the casing of the low-noise axial flow fan is formed from the inner layer of the casing to the outer layer by the inner layer 1 of the casing, the inner layer The sound-absorbing cloth 2, the metal foam aluminum plate 3, the outer sound-absorbing cloth 4, and the outer layer 5 of the casing are composed sequentially; among them, the metal foam aluminum plate has the function of absorbing or offsetting part of the sound wave, and the sound-absorbing cloth has sound insulation Function.

The inner layer of the casing and the outer layer of the casing are made of stainless steel plate or steel plate.

The metal foam aluminum plates are connected by straight tenons 6 and straight grooves 7, and connected with the inner and outer layers of the fan casing by rivets.

The beneficial effect of the present invention is to provide a low-noise casing with simple structure, convenient construction and good noise reduction effect, which has the characteristics of light weight, reduced cavity noise, high temperature resistance, and recyclable metal foam aluminum plate, and its own It has high rigidity and low manufacturing and installation costs. Compared with the existing technology, the casing has a fan noise reduction value of about 18 dB, and has a better sound absorption effect in the middle and low frequency range, and the noise reduction effect is very significant, thereby improving the working environment of the operating personnel.

Description of drawings

Figure 1 Schematic diagram of the casing structure of a low-noise axial flow fan.

Figure 2 Schematic diagram of the local structure of the low-noise axial flow fan casing.

Detailed ways

The invention provides a casing for reducing the noise of an axial flow fan. Describe below in conjunction with accompanying drawing.

In the schematic diagrams of the low-noise axial flow fan casing shown in Figure 1 and Figure 2, the low-noise axial flow fan casing is composed of the inner layer of the casing 1, the inner layer of sound-absorbing wiper material 2, the metal foam aluminum plate 3, and the outer layer The sound-absorbing wiper material 4 and the casing outer layer 5 are sequentially combined; wherein, the casing inner layer 1 is welded by stainless steel plates or steel plates, and a thick layer is laid between the casing inner layer 1 steel plate and the metal foam aluminum plate 3 The 10mm inner layer sound-absorbing wiper fabric 2 is used to reduce the mechanical vibration noise between the inner layer 1 steel plate of the fan casing and the metal foam aluminum plate 3, and has a good sound-absorbing effect on various noises from medium and low frequencies to high frequencies . The outer layer 5 of the fan casing is welded with a stainless steel plate or a steel plate, and the space between it and the metal foam aluminum plate 3 is also filled with a 10mm outer layer of sound-absorbing plastering fabric, and the bottom is fixed on the cement base on the ground. The casing is divided into four areas: the converging area (I), the moving blade area (II), the stationary blade area (III) and the diffuser area (IV). The edges of the low-noise casing in different areas are set to protrude outwards Bolts are used for connecting different parts and are easy to disassemble. The metal foam aluminum plates are connected by straight tenons 6 and straight grooves 7, and connected with the inner and outer layers of the fan casing by rivets. The above-mentioned metal foam aluminum plate is an aluminum plate with irregular through holes, which is handed over by wire mesh. The metal foam aluminum plate has the function of absorbing or offsetting part of the sound wave, and has a good noise reduction effect. The sound-absorbing wiper has a sound insulation function.

When the sound wave is incident on the metal foam, part of the sound wave penetrates into the porous structure of the metal foam aluminum plate, which will cause the air particles in the gap to vibrate, and the relative motion between the particles will form viscous resistance, thereby converting the sound energy into heat energy, so that the incident sound energy will be reduced. Secondly, the sound wave causes the air in the pore channel to compress and expand, and a temperature gradient will be generated between the adjacent compression zone and expansion zone, and the heat energy will be exported through the network metal skeleton, which will also reduce the sound energy; After being reflected on the rigid wall and returning to the surface through the sound-absorbing material, it is further attenuated. After such reciprocating attenuation, only part of the energy is transmitted to the air, and the other part is absorbed, so that the fan can achieve the noise reduction effect.

Example

Noise monitoring is carried out on the measuring point of an axial flow fan. The noise of the original fan model is about 98dB, and a low-noise casing is installed. The inner layer of the fan casing is made of 10mm thick stainless steel plate or steel plate, and the 10mm thick inner layer is made of sound-absorbing wipes. , 30mm thick metal foam aluminum plate, 10mm thick outer layer of sound-absorbing wipe fabric and 10mm thick stainless steel plate or steel plate for the outer layer of the casing. The fan noise monitoring shows that the fan noise is reduced to 80dB, and the reduction value is about 18 dB. The noise reduction effect is very good. Significantly, thereby improving the working environment of operators.

Claims (1)

1. for reducing a casing for noise of axial flow fan, the formation of low noise axial fan casing for from casing internal layer to skin by casing internal layer (1), internal layer absorb sound wipe one's face material (2), metal foamed aluminium board (3), outer absorb sound wipe one's face material (4) and casing skin (5) successively compound form; It is characterized in that, casing internal layer (1) is welded by corrosion resistant plate, the internal layer laying thick layer 10mm between casing internal layer (1) corrosion resistant plate and metal foamed aluminium board (3) absorbs sound to wipe one's face and expects (2), for reducing the mechanical vibration noise between fan casing internal layer (1) corrosion resistant plate and metal foamed aluminium board (3), all there is good acoustically effective to medium and low frequency to the various noises of high frequency simultaneously; Fan casing skin (5) adopts corrosion resistant plate welding, adopt 10mm skin same with between metal foamed aluminium board (3) absorbs sound to wipe one's face and expects to fill, and bottom is fixed on the cement pedestal on ground, wherein, metal foamed aluminium board has and absorbs or offset the effect of acoustic wave segment, and sound absorption material of wiping one's face has sound insulation function; Casing is divided into afflux district (I), movable vane district (II), stator blade district (III) and diffusion district (IV) totally four regions, the low noise casing edge of zones of different arranges outwardly directed bolt, for the connection of different parts.