阅读说明：本技术 一种轴流通风机低噪机壳及设计方法 (Low-noise casing of axial flow fan and design method ) 是由 姚永利 陈琳琳 李宏安 陈余平 周根标 杜国栋 田玉宝 张红武 王水霞 翟晓宁 于 2020-07-08 设计创作，主要内容包括：本发明提供了一种轴流通风机低噪机壳及设计方法,包括同轴设置的机壳外筒和机壳内筒,机壳外筒为双层共振结构,包括外层筒板和内层筒板,外层筒板和内层筒板之间通过支撑筋架分割为多个共振腔,支撑筋架上开设有去重孔；与机壳内筒对应的每个共振腔的内层筒板上设置有多个穿孔,与安装在机壳内筒前端的叶轮相对应的共振腔的内层筒板上不设置穿孔；机壳外筒和机壳内筒之间安装有多个后导流叶片,后导流叶片采用单圆弧叶片；本发明的通风机机壳的机壳外筒采用双层机壳结构,无填充吸声材料,仅利用共振腔对特定频率的窄带噪声进行消除,从而达到机壳辐射噪声的大幅度降低；同时,对后端管道降噪提供极好的支持。(The invention provides a low-noise casing of an axial-flow fan and a design method thereof, wherein the casing comprises a casing outer cylinder and a casing inner cylinder which are coaxially arranged, the casing outer cylinder is of a double-layer resonance structure and comprises an outer-layer cylinder plate and an inner-layer cylinder plate, the space between the outer-layer cylinder plate and the inner-layer cylinder plate is divided into a plurality of resonant cavities through a support rib frame, and the support rib frame is provided with a weight removing hole; the inner layer cylinder plate of each resonant cavity corresponding to the inner cylinder of the shell is provided with a plurality of through holes, and the inner layer cylinder plate of the resonant cavity corresponding to the impeller arranged at the front end of the inner cylinder of the shell is not provided with through holes; a plurality of rear guide vanes are arranged between the outer cylinder and the inner cylinder of the shell, and the rear guide vanes adopt single arc vanes; the outer casing barrel of the ventilator casing adopts a double-layer casing structure, does not have filling sound absorption materials, and only utilizes the resonant cavity to eliminate narrow-band noise with specific frequency, thereby greatly reducing the radiation noise of the casing; meanwhile, the method provides excellent support for noise reduction of the rear pipeline.)

1. The utility model provides an axial-flow fan low noise casing, including casing urceolus (1) and casing inner tube (2) of coaxial setting, the axial length of casing urceolus (1) is greater than the axial length of casing inner tube (2), the rear end of casing urceolus (1) and the rear end of casing inner tube (2) are level and neat to be set up, casing inner tube (2) are used for installing motor (3), the front end of casing inner tube (2) is used for installing impeller (4) that drive through motor (3), its characterized in that in casing urceolus (1):

the casing outer cylinder (1) is of a double-layer resonance structure and comprises an outer cylinder plate (101) and an inner cylinder plate (102), the outer cylinder plate (101) and the inner cylinder plate (102) are divided into a plurality of resonant cavities (104) through a support rib frame (103), and the support rib frame (103) is provided with a weight-removing hole (105);

a plurality of through holes (5) are formed in the inner cylindrical plate (102) of each resonant cavity (104) corresponding to the inner cylinder (2) of the machine shell, and no through hole is formed in the inner cylindrical plate (102) of each resonant cavity (104) corresponding to the impeller (4) arranged at the front end of the inner cylinder (2) of the machine shell;

a plurality of rear guide vanes (6) are arranged between the casing outer cylinder (1) and the casing inner cylinder (2), and the rear guide vanes (6) adopt single arc vanes.

2. The low noise casing of axial flow fan according to claim 1, wherein: the support rib frame (103) comprises an axial rib plate (10301) and a circumferential rib plate (10302), and the axial rib plate (10301) and the circumferential rib plate (10302) are respectively provided with a weight removing hole (105).

3. The low noise casing of axial flow fan according to claim 1, wherein: the shell inner cylinder (2) is also provided with a through hole.

4. A method of designing a low noise casing for an axial-flow fan according to any one of claims 1 to 3, comprising the steps of:

the method comprises the following steps that firstly, an outer layer barrel plate and an inner layer barrel plate of an outer barrel of a machine shell are installed on a supporting rib frame in a thin plate welding mode, and a weight removing hole is formed in the supporting rib frame;

secondly, the rear guide vanes adopt single arc vanes, and the circumferential uniform distribution quantity is obtained through flow field analysis and calculation;

step three, adopting a double-layer thin plate cylinder structure to design a light low-noise casing:

obtaining an average sound insulation value by adopting a calculation formula as follows;

when m is less than or equal to 200kg/m²When R is 13.5logm + 14; when m is more than 200kg/m²When R is 16logm +8, formula:

r represents the calculated numerical value of the average sound insulation quantity, and the unit of the average sound insulation quantity is dB;

m represents a value of mass per unit area of the cylinder in kg/m²；

Setting initial structural parameters of the low-noise casing of the axial flow fan according to the average sound insulation value, wherein the structural parameters comprise the length of a resonant cavity, the outer diameter of an inner-layer cylindrical plate, the inner diameter of the inner-layer cylindrical plate, the perforation diameter, the thickness of the inner-layer cylindrical plate, the perforation rate and the perforation interval, giving a vibration eliminating frequency corresponding to the detected structural parameters, and obtaining the calculated sound eliminating volume through the noise reduction calculation of the resonant cavity; repeatedly adjusting the structural parameters and calculating the noise elimination volume corresponding to the structural parameters to obtain the optimal matching relation among the structural parameters, the noise elimination frequency and the noise elimination volume so as to obtain the structural parameters of the low-noise casing of the axial flow fan in a typical mode of primary screening;

and fifthly, manufacturing a prototype corresponding to the low-noise casing of the axial flow fan in the typical mode, and finding the result with the optimal matching through prototype testing and adjustment.

Technical Field

The invention belongs to the field of fans, relates to an axial flow fan casing, and particularly relates to a low-noise casing of an axial flow fan and a design method.

Background

All sounds with randomly varying sound intensity and frequency, as judged from the physical characteristics of the sound, can be defined as noise. The noise can cause hearing impairment, human diseases, influence daily life and the like. Also, in operation, noise can reduce labor productivity. Moreover, high levels of noise can damage buildings or facilities.

The fan is used as power equipment and belongs to a high noise source. Noise control of ventilators is made more difficult by the severe size and weight limitations of many mobile equipment (e.g., locomotives, ships, airplanes, etc.) on loaders. The fans can be divided into axial flow fans and centrifugal fans according to different structural forms. In the aspect of noise control of the axial flow fan, although the optimized blade profile is one of noise reduction ways, the performance of the fan is considered, and the noise reduction of the blade has limitation; and the measures such as noise isolation, noise absorption and the like are considered in the design of the stator parts such as the shell and the like, so that a relatively obvious noise reduction effect can be obtained, and the implementation is convenient. The invention of a light-weight low-noise axial-flow fan is a problem to be solved under the specific requirement because the size and the weight of parts are strictly controlled while reducing noise.

Axial fans are typically single-layer cylindrical casings. In order to meet the requirement of low noise, the casing is usually made of thick plates which are rolled and welded, or the casing is cast, so that the noise reduction effect is better. However, for light-weight requirements for carrying mobile equipment, sound insulation simply by means of the wall thickness of the enclosure is obviously not capable of achieving the aim.

The double-layer shell in the low-noise fan adopts a relatively common means, and the principle of the inquired prior art is mainly divided into two categories: firstly, a double-layer vacuum shell is adopted, and the effect of noise reduction is achieved by utilizing the principle of vacuum blocking; and secondly, the double-layer resonant cavity and the sound absorption material are adopted, and the purpose of reducing noise is achieved by utilizing limited resistance noise elimination and the main sound absorption function.

In order for an axial flow fan to meet specified low noise requirements, the thickness of the cylindrical housing is thick enough to achieve sound insulation. This sufficient thickness is not possible given the strict physical dimensions and weight constraints. Although the noise reduction effect of the cast enclosure is better, the cycle time and the mold opening cost are not advantageous. Meanwhile, the noise insulation design which only depends on the wall thickness cannot achieve the real noise reduction of the whole system, only the noise is temporarily isolated in the fan section, and the noise can still exist and continuously spread in the pipeline at the rear end, so that the noise reduction of the system is very unfavorable.

And for the double-layer vacuum shell, the application on the axial-flow fan with small batch and low cost is not feasible. For the double-layer resonant cavity and the sound absorption material, the important point of the mode is to utilize the effect of the sound absorption material to achieve the purpose of noise reduction. But for special applications, non-metallic sound absorbing materials are not available. Meanwhile, the double-layer structure resonant cavity matched with the sound absorption material has high aperture ratio which is usually more than 25 percent, and can be matched to achieve the sound absorption effect; therefore, the effect of the double-layer structure on noise resistance is very limited, and the single use of the double-layer structure has no practical significance.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a low-noise casing of an axial flow fan and a design method thereof, and solves the technical problem that the noise reduction effect of the casing of the axial flow fan designed in the prior art is insufficient on the premise of limiting the overall dimension and weight.

In order to solve the technical problems, the invention adopts the following technical scheme:

a low-noise casing of an axial-flow fan comprises a casing outer cylinder and a casing inner cylinder which are coaxially arranged, wherein the axial length of the casing outer cylinder is greater than that of the casing inner cylinder, the rear end of the casing outer cylinder and the rear end of the casing inner cylinder are arranged in a flush manner, the casing inner cylinder is used for mounting a motor, and the front end of the casing inner cylinder in the casing outer cylinder is used for mounting an impeller driven by the motor;

the outer cylinder of the shell is of a double-layer resonance structure and comprises an outer cylinder plate and an inner cylinder plate, the space between the outer cylinder plate and the inner cylinder plate is divided into a plurality of resonant cavities through a support rib frame, and the support rib frame is provided with a weight-removing hole;

the inner layer cylinder plate of each resonant cavity corresponding to the inner cylinder of the shell is provided with a plurality of through holes, and the inner layer cylinder plate of the resonant cavity corresponding to the impeller arranged at the front end of the inner cylinder of the shell is not provided with through holes;

a plurality of rear guide vanes are arranged between the outer casing cylinder and the inner casing cylinder, and the rear guide vanes are single arc vanes;

the invention also has the following technical characteristics:

the support rib frame comprises an axial rib plate and a circumferential rib plate, and weight removing holes are formed in the axial rib plate and the circumferential rib plate.

The inner cylinder of the shell is also provided with a through hole.

The invention also provides a design method of the low-noise casing of the axial-flow fan, which comprises the following steps:

the method comprises the following steps that firstly, an outer layer barrel plate and an inner layer barrel plate of an outer barrel of a machine shell are installed on a supporting rib frame in a thin plate welding mode, and a weight removing hole is formed in the supporting rib frame;

secondly, the rear guide vanes adopt single arc vanes, and the circumferential uniform distribution quantity is obtained through flow field analysis and calculation;

step three, adopting a double-layer thin plate cylinder structure to design a light low-noise casing:

obtaining an average sound insulation value by adopting a calculation formula as follows;

when m is less than or equal to 200kg/m²When R is 13.5logm + 14; when m is more than 200kg/m²When R is 16logm +8

In the formula:

r represents the calculated numerical value of the average sound insulation quantity, and the unit of the average sound insulation quantity is dB;

m represents a value of mass per unit area of the cylinder in kg/m²；

Setting initial structural parameters of the low-noise casing of the axial flow fan according to the average sound insulation value, wherein the structural parameters comprise the length of a resonant cavity, the outer diameter of an inner-layer cylindrical plate, the inner diameter of the inner-layer cylindrical plate, the perforation diameter, the thickness of the inner-layer cylindrical plate, the perforation rate and the perforation interval, giving a vibration eliminating frequency corresponding to the detected structural parameters, and obtaining the calculated sound eliminating volume through the noise reduction calculation of the resonant cavity; repeatedly adjusting the structural parameters and calculating the noise elimination volume corresponding to the structural parameters to obtain the optimal matching relation among the structural parameters, the noise elimination frequency and the noise elimination volume so as to obtain the structural parameters of the low-noise casing of the axial flow fan in a typical mode of primary screening;

and fifthly, manufacturing a prototype corresponding to the low-noise casing of the axial flow fan in the typical mode, and finding the result with the optimal matching through prototype testing and adjustment.

Compared with the prior art, the invention has the following technical effects:

the outer cylinder of the casing of the ventilator casing adopts a double-layer casing structure, does not have filling sound absorption materials, and only utilizes a resonant cavity to eliminate narrow-band noise with specific frequency, thereby greatly reducing the radiation noise of the casing; meanwhile, the method provides excellent support for noise reduction of the rear pipeline.

(II) the ventilator shell of the invention utilizes the resonance cavity principle, adopts the resistance resonance cavity to reduce noise on the noise reduction method, does not adopt any non-metallic material, does not increase the system resistance, greatly reduces the noise in the front and rear pipelines of the ventilator, thereby reducing the noise transmission. And the overall dimension and the weight of the fan are strictly controlled.

(III) the ventilator shell of the invention reduces the noise by the resonance cavity principle, and can achieve the aim of greatly reducing the noise in a limited space.

(IV) the ventilator casing of the invention ensures that the noise of the ventilator cannot exceed 76 decibels under the rated working condition under the limiting conditions that the overall dimension of the ventilator is ensured to be less than 765mm multiplied by 700mm multiplied by 630mm and the weight is less than 210 kilograms.

Drawings

Fig. 1 is a schematic view showing the overall structure of a low-noise casing of an axial-flow fan according to the present invention.

Fig. 2 is a schematic view of the internal structure of the low noise casing of the axial flow fan of the present invention.

FIG. 3 is a schematic structural diagram of a resonant cavity according to the present invention.

Fig. 4 is a schematic structural view of the support frame of the present invention.

Fig. 5 is a schematic distribution diagram of rear guide vanes.

Fig. 6 is a schematic view of a flow field analysis of the rear guide vane.

Fig. 7 is a diagram of the case radiation noise characteristic of the first embodiment.

Fig. 8 is a diagram of the chassis radiation noise characteristic of the first embodiment.

Fig. 9 is a radiation noise characteristic diagram of the casing pipeline inlet and the pipeline outlet in the first mode, in which the upper layer is the pipeline inlet and the lower layer is the pipeline outlet.

Fig. 10 is a radiation noise characteristic diagram of the casing pipeline inlet and the pipeline outlet in the second mode, in which the upper layer is the pipeline inlet and the lower layer is the pipeline outlet.

The meaning of the individual reference symbols in the figures is: 1-outer casing cylinder, 2-inner casing cylinder, 3-motor, 4-impeller, 5-perforation, 6-rear guide vane;

101-outer layer cylinder plate, 102-inner layer cylinder plate, 103-support rib frame, 104-resonant cavity, 105-duplication removing hole;

10301-axial rib and 10302-circumferential rib.

The present invention will be explained in further detail with reference to examples.

Detailed Description

The traditional ventilator shell can not realize the aim of the invention under the condition of limited external dimension and weight. It should be noted that the present invention is not limited to the only embodiment, and the object of the present invention can be achieved by adjusting the matching of the main parameters mentioned in the present invention. In the process of developing a specific engineering project, due to the consideration of comprehensive factors such as machining precision, production cost and the like, the area and the size of the through hole are properly selected and chosen as alternatives.

The technical requirements to be achieved by the invention are as follows: under the limiting conditions that the external dimensions of the ventilator are ensured to be less than 765mm multiplied by 700mm multiplied by 630mm and the weight is less than 210 kilograms, the noise of the ventilator cannot exceed 76 decibels under the rated working condition.

It is to be understood that all the components and materials of the present invention are not specifically described, and those known in the art are used.

The following embodiments of the present invention are provided, and it should be noted that the present invention is not limited to the following embodiments, and all equivalent changes based on the technical solutions of the present invention are within the protection scope of the present invention.