Fan noise reduction structure, impeller, fan and mounting method

Abstract

A fan noise reduction structure, impeller, fan and installation method, comprising an asymmetric diffuser, two sealing rings, a fixed guide vane, an impeller and a movable guide vane; two sealing rings are arranged on the impeller cover and the impeller disc at the blade outlet of the fan impeller; the outer edges of the two sealing rings are fixedly provided with an asymmetric diffuser, one of the sealing rings is fixedly connected with a fixed guide vane, and the inner side of the fixed guide vane is provided with a movable guide vane in the direction close to the center of the impeller. The asymmetric diffuser can reduce the airflow speed at the outlet of the impeller and improve the uniformity of the circumferential speed distribution of the impeller, thereby reducing the aerodynamic noise caused by the jet wake phenomenon caused by the uneven speed distribution; the guide vane at the volute tongue can effectively suppress the large-scale vortex in the middle cavity between the front end surface of the volute and the wheel cover, thereby reducing the aerodynamic noise at the volute tongue. The method of coupling the diffuser with the guide vane can effectively suppress the impact of high-speed airflow inside the centrifugal fan on the volute tongue and the volute wall, thereby reducing the aerodynamic noise.

Description

Technical Field

[0001] This invention belongs to the technical field of fan noise reduction structure, and specifically relates to a fan noise reduction structure, impeller, fan and installation method. Background Technology

[0002] Centrifugal fans are energy-intensive devices widely used in factories, mines, tunnels, vehicles, ships, and buildings for ventilation and dust removal. Developing and designing high-efficiency, low-noise centrifugal fans can achieve energy conservation while protecting the environment and reducing noise pollution. The noise generated by centrifugal fans during operation is mainly divided into mechanical noise and aerodynamic noise, but aerodynamic noise is the primary factor contributing to the high noise levels of centrifugal fans. Aerodynamic noise is generated by the interaction between the high-speed rotating centrifugal impeller and the high-speed gas flowing through it and the fan impeller and volute; it is the main source of noise from centrifugal fans. Aerodynamic noise can be classified into monopole, dipole, and quadrupole source types based on its sound source radiation characteristics.

[0003] In centrifugal fans, the high-speed rotation of the impeller and the asymmetrical structure of the volute cause uneven circumferential distribution of the airflow velocity at the impeller outlet, resulting in a jet wake phenomenon. These unevenly distributed airflows periodically impact the volute tongue as the impeller rotates at high speed, generating significant aerodynamic noise, which is a major contributor to centrifugal fan noise. The airflow exiting the impeller outlet generates large high-speed vortices within the centrifugal volute; these vortices impact the volute wall, generating noise, another major noise source for centrifugal fans. Therefore, designing structures that reduce aerodynamic noise in centrifugal fans and improving the flow field of the impeller and volute is crucial for noise reduction.

[0004] Currently, there are various invention patents disclosed for devices and structures for reducing noise in centrifugal fans. The main implementation methods are to add sound-absorbing facilities to the outside of the centrifugal fan, such as soundproof covers and sound-absorbing cotton [1,2].

[0005] Jiang Haifeng, Duan Zhijun, Zhu Lanlan. A noise reduction device for centrifugal fans [P]. Chinese Patent: CN218991986U, 2023.05.09

[0006] Yang Gang, Kuang Haijun, Cen Yikang, Yang Zeyuan, Tian Liyuan, Xiong Xinhe, Yang Yibo, Zhao Jun. A vibration reduction and noise reduction device for centrifugal fans [P]. Chinese Patent: CN217873475U, 2022.11.22

[0007] Some patents also propose improving the uniformity of the inlet and outlet flow fields of centrifugal fans and the airflow inside the volute by adding shrouds, rectifiers, or guide vanes [3,4]. For example:

[0008] Xie Fujin, Xu Chaoqiang, Qin Jianbing, Jiang Zhiqiang, Ni Jianhua. A noise reduction structure for the outlet of a centrifugal fan [P]. Chinese Patent: CN219911301 U, 2023.10.27

[0009] Wang Wei, Zhang Xiang, Luo Xingqi, Lu Jinling, Huang Yujie. A centrifugal fan with a guide vane inside the volute [P]. Chinese Patent: CN212563813U, 2021.02.19

[0010] However, the aforementioned existing technologies have the following technical defects:

[0011] 1) Additional noise reduction equipment is required, increasing the manufacturing cost and operational complexity of the equipment.

[0012] 2) Increase the installation area

[0013] 3) Installing a rectifier screen will increase flow resistance, making it unsuitable for high-efficiency fans.

[0014] 4) The design structure is relatively complex, and the installation process is complicated. Summary of the Invention

[0015] The purpose of this invention is to provide a fan noise reduction structure, impeller, fan, and installation method to solve the above-mentioned problems.

[0016] To achieve the above objectives, the present invention adopts the following technical solution:

[0017] A noise reduction structure for a wind turbine includes an asymmetric diffuser, two sealing rings, a fixed guide vane, an impeller, and a movable guide vane. The two sealing rings are respectively disposed on the impeller cover and impeller disk at the blade outlet of the wind turbine impeller. An asymmetric diffuser is fixedly disposed on the outer edge of both sealing rings. A fixed guide vane is fixedly connected to one of the sealing rings, and a movable guide vane is disposed on the inner side of the fixed guide vane near the center of the impeller.

[0018] Furthermore, the asymmetric diffuser is annular, and its width gradually increases from the beginning to the end, forming a gap at the junction of the beginning and the end.

[0019] Furthermore, the asymmetric diffuser is divided into two parts, upper and lower. The end with fixed guide vanes is the front end, which corresponds to the impeller cover; the other end is the rear end, which corresponds to the impeller disk. The front end is connected to the front face of the volute by welding, and the rear end is connected to the rear face of the volute by fixing bolts.

[0020] Furthermore, both the fixed guide vanes and the movable guide vanes are arc-shaped.

[0021] Furthermore, the radius R of the fixed guide vane is the same as the radius of the sealing ring, while the radius of the movable guide vane is 0.8-0.9 times the impeller outlet radius.

[0022] Furthermore, the inlet ends of the fixed guide vane and the movable guide vane are located on the front side of the volute tongue inlet; the front end face of the volute is provided with a mounting slot, the movable guide vane is installed in the slot, and holes are drilled at the installation position for fixing using key connection or bolt connection; the movable guide vane is one or more segments.

[0023] Furthermore, the sealing ring is made of a rigid material.

[0024] Furthermore, an impeller includes a fan noise reduction structure, a disc, and a cover; the fan noise reduction structure is mounted on the disc and the cover.

[0025] Furthermore, an installation method for a fan noise reduction structure includes the following steps:

[0026] First, determine the size and relative installation position of the sealing ring and diffuser based on the installation position of the centrifugal fan volute and the outer diameter of the impeller. Then, install the two sealing rings on the impeller cover and impeller disk at the blade outlet of the fan impeller, respectively. Finally, connect the sealing rings to the asymmetric diffuser.

[0027] It is then connected to the front end face of the volute via a fixed guide vane;

[0028] The lower end of the diffuser is connected to the rear end face of the volute via fixing bolts;

[0029] After determining the radius of the movable guide vane, the movable guide vane is connected to the front end face of the volute.

[0030] Furthermore, a centrifugal fan, a fan noise reduction structure is installed on the fan impeller.

[0031] Compared with the prior art, the present invention has the following technical effects:

[0032] The asymmetric diffuser of this invention can reduce the airflow velocity at the impeller outlet and improve the uniformity of the velocity distribution along the circumference of the impeller, thereby reducing aerodynamic noise caused by jet wake phenomenon due to uneven velocity distribution. The guide vanes at the volute tongue can effectively suppress large-scale vortices in the cavity between the front face of the volute and the wheel cover. The method of coupling the diffuser with guide vanes can effectively suppress the impact of high-speed airflow inside the centrifugal fan on the volute tongue and the volute wall, thereby reducing aerodynamic noise.

[0033] The noise reduction structure in this invention has high versatility and can be used in commonly used centrifugal fans in general fields;

[0034] Compared to traditional noise reduction devices and structures, the noise reduction structure of this invention does not occupy additional installation space;

[0035] The diffuser in this invention is connected to the volute wall via fixed guide vanes and fixed bolts, and the whole unit is detachable, which is very convenient.

[0036] The fixed blades used in this invention can not only improve the airflow at the inlet of the volute tongue, but also serve to fix the diffuser.

[0037] The movable guide vanes in this invention have a wide range of variable sizes, which can effectively improve airflow and thus achieve noise reduction. Attached Figure Description

[0038] Figure 1 This is a schematic diagram showing the positions of the sealing ring, asymmetric diffuser, and fixed guide vane.

[0039] Figure 2 This is a schematic diagram of the meridional plane of a centrifugal impeller.

[0040] Figure 3 This is a schematic diagram showing the relative positions of the asymmetric diffuser and the impeller.

[0041] Figure 4 This is a top view of the centrifugal impeller during installation.

[0042] Figure 5 This is a schematic diagram showing the relative positions of the fixed guide vane and the movable guide vane within the volute.

[0043] Figure 6 This is a top view of the assembly.

[0044] Figure 7 This is a 3D view.

[0045] Figure 8 This is a schematic diagram of the installation of the movable guide vane and the slot.

[0046] in:

[0047] 1. Sealing ring; 2. Asymmetric diffuser; 3. Fixed guide vane; 4. Movable guide vane; 5. Wheel cover; 6. Wheel disc; 7. Blade; 8. Impeller. Detailed Implementation

[0048] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0050] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0051] This invention primarily aims to reduce the aerodynamic noise of centrifugal fans. Based on the classification of aerodynamic noise and its causes, a structure capable of reducing centrifugal fan aerodynamic noise is proposed. Compared to other noise reduction devices and structures, this invention has the unique advantages of strong universality and ease of operation and maintenance. The specific noise reduction structure of this invention consists of: a diffuser with different asymmetric structures that can be installed at the impeller outlet according to the centrifugal fan flow rate; and guide vanes coupled and installed near the volute tongue on the front end face of the volute outlet.

[0052] The specific device in this invention includes an asymmetric diffuser 2, a sealing ring 1, a fixed guide vane 3, and a movable guide vane 4.

[0053] A fan noise reduction structure includes an asymmetric diffuser 2, two sealing rings 1, a fixed guide vane 3, an impeller, and a movable guide vane 4. The two sealing rings 1 are respectively installed on the impeller cover and impeller disk at the blade outlet of the fan impeller. The asymmetric diffuser 2 is fixedly installed on the outer edge of both sealing rings 1. A fixed guide vane 3 is fixedly connected to one of the sealing rings 1. A movable guide vane 4 is installed on the inner side of the fixed guide vane 3 near the center of the impeller.

[0054] The specific structure of this invention is as follows:

[0055] Figure 1 This diagram shows the positions of the sealing ring 1, the asymmetric diffuser 2, and the fixed guide vane. The sealing ring 1 and the asymmetric diffuser 2 are directly welded together or formed using a mold. The installation position of the fixed guide vane 3 is determined based on the relative position of the centrifugal fan's volute tongue.

[0056] Figure 5 The angle θ shown is the volute tongue installation angle. This angle needs to be determined during the design of the wind turbine volute. This patent requires that the inlet ends of both the movable and fixed guide vanes be in front of the volute tongue inlet (i.e., Figure 5 The angle φ is smaller than θ, and the angle difference is generally taken as i = 5~10°.

[0057] The fixed guide vane 3 and the sealing ring 1 are directly connected by welding. The asymmetric diffuser 2 is divided into upper and lower parts. The end connected to the fixed guide vane 3 is the "front end," which corresponds to the impeller cover; the other end, the "rear end," corresponds to the impeller disk. The front end of the asymmetric diffuser is integrated with the fixed guide vane and connected to the front face of the volute casing by welding or other methods. The "rear end" of the diffuser is connected to the rear face of the volute casing by fixing bolts.

[0058] Figure 2 This is a schematic diagram of the meridional plane of a centrifugal impeller. The schematic diagram includes the main structure of the centrifugal impeller: impeller cover, impeller disk, blades, sealing ring 1, and asymmetric diffuser 2.

[0059] Figure 3 The diagram shows the relative positions of the asymmetric diffuser and impeller. The sealing ring, diffuser, and fixed guide vanes are integrated. The fixed guide vanes are welded to the front end face of the volute, and the rear end of the diffuser is connected to the rear end face of the volute via fixing bolts. The diffuser and fixed guide vanes are in a stationary state. Figure 3 As shown, the diffuser maintains a certain installation distance from the impeller outlet to avoid collision with the high-speed rotating impeller; the sealing ring is located at the impeller cover and the disc outlet to prevent gas leakage from the gap between the impeller outlet and the diffuser.

[0060] Figure 4 This is a top-view installation diagram of the centrifugal impeller, showing the asymmetry of the diffuser. Compared with traditional diffusers, the asymmetric diffuser in this invention is connected to the volute via fixed guide vanes and fixing bolts, and it does not directly contact the centrifugal impeller. This reduces the amount of impeller machining required to a certain extent, and the diffuser and fixed guide vanes can be disassembled at any time.

[0061] Figure 5 This diagram illustrates the relative positions of fixed and movable guide vanes within the volute. As shown, both types of guide vanes are single-circular arcs. The fixed guide vane serves two purposes: first, it connects the diffuser and the volute, providing support and fixation; second, it reduces the vortex size at the inlet of the volute's front face (the tongue). The movable guide vane is similarly used to control airflow and reduce vortex size. Figure 8 The radius R of the fixed guide vane is determined by the radius of the sealing ring, while the radius R of the movable guide vane is approximately 0.8-0.9 times the impeller outlet radius.

[0062] The installation and structural features of movable guide vanes are as follows: Figure 8 As shown: In this invention patent, the radius of curvature and extension angle α of the movable guide vane can be determined by the designer during the design process. The guide vane is fixed and moved by a slot welded to the front cover plate of the volute. For ease of installation, holes can be drilled at the installation positions corresponding to the slots of the movable guide vane, and "keys" or "bolts" can be used for fixing, moving, and disassembling. Furthermore, when designing and determining the extension angle α of the movable guide vane, a smaller value can be chosen, thereby enabling segmented installation of the guide vane.

[0063] Figure 6 and Figure 7 The images show a top view and a three-dimensional view of the assembly. The diffuser and two types of guide vanes in this invention are implemented as follows: Figure 7 As shown:

[0064] First, the dimensions and relative installation positions of the sealing ring and diffuser are determined based on the installation position of the centrifugal fan's volute tongue and the impeller's outer diameter. Then, the sealing ring is connected to the diffuser, and further connected to the front end face of the volute casing via fixed guide vanes. The fixed guide vanes are welded to the sealing ring, making the diffuser, sealing ring, and fixed guide vanes a single unit. The lower end of the diffuser is connected to the rear end face of the volute casing via fixing bolts.

[0065] The radius of the movable guide vane is determined based on the outer diameter of the centrifugal impeller. The movable guide vane is connected to the front end face of the volute.

[0066] The specific noise reduction principle of this invention is as follows: the asymmetric diffuser can reduce the airflow velocity at the impeller outlet and improve the uniformity of the velocity distribution along the circumference of the impeller, thereby reducing the aerodynamic noise caused by the jet wake phenomenon due to uneven velocity distribution; the guide vanes at the volute tongue can effectively suppress large-scale vortices in the cavity between the front face of the volute and the wheel cover. The method of coupling the diffuser with the guide vanes can effectively suppress the impact of the high-speed airflow inside the centrifugal fan on the volute tongue and the volute wall, thereby reducing aerodynamic noise.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fan noise reduction structure, characterized in that, It includes an asymmetric diffuser (2), two sealing rings (1), a fixed guide vane (3), an impeller, and a movable guide vane (4); the two sealing rings (1) are respectively set on the impeller cover and impeller disk at the blade outlet of the impeller; the asymmetric diffuser (2) is fixedly set on the outer edge of the two sealing rings (1), and a fixed guide vane (3) is fixedly connected to one of the sealing rings (1), and a movable guide vane (4) is set on the inner side of the fixed guide vane (3) near the center of the impeller; The asymmetric diffuser (2) is annular, and its width gradually increases from the beginning to the end, with a gap formed at the junction of the beginning and the end; The asymmetric diffuser (2) is divided into two parts, upper and lower. The end with the fixed guide vane (3) is the front end, which corresponds to the impeller cover; the other end is the rear end, which corresponds to the impeller disk. The front end is connected to the front face of the volute by welding, and the rear end is connected to the rear face of the volute by fixing bolts. The inlet ends of the fixed guide vane (3) and the movable guide vane are located on the front side of the volute tongue inlet; the front end face of the volute is provided with an installation slot, the movable guide vane is installed in the slot, and holes are drilled at the installation position for fixing using key connection or bolt connection; the movable guide vane is one or more sections.

2. The fan noise reduction structure according to claim 1, characterized in that, Both the fixed guide vane (3) and the movable guide vane (4) are arc-shaped.

3. The fan noise reduction structure according to claim 2, characterized in that, The radius R of the fixed guide vane is the same as the radius of the sealing ring (1), and the radius of the movable guide vane (4) is 0.8-0.9 times the impeller outlet radius.

4. The fan noise reduction structure according to claim 1, characterized in that, The sealing ring (1) is a rigid material sealing ring.

5. An impeller, characterized in that, The invention includes a fan noise reduction structure, a disc, and a wheel cover as described in any one of claims 1 to 4; the fan noise reduction structure is installed on the disc and the wheel cover.

6. An installation method for a fan noise reduction structure as described in any one of claims 1 to 4, characterized in that, Includes the following steps: First, determine the size and relative installation position of the sealing ring and diffuser based on the installation position of the centrifugal fan volute and the outer diameter of the impeller. Then, install the two sealing rings on the impeller cover and impeller disk at the blade outlet of the fan impeller, respectively. Finally, connect the sealing rings to the asymmetric diffuser. It is then connected to the front end face of the volute via a fixed guide vane; The lower end of the diffuser is connected to the rear end face of the volute via fixing bolts; After determining the radius of the movable guide vane, the movable guide vane is connected to the front end face of the volute.

7. A centrifugal fan, characterized in that, The fan noise reduction structure as described in any one of claims 1 to 4 is installed on the impeller of the fan.

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