Axial flow fan silencer

Abstract

This utility model relates to an axial flow fan silencer, specifically for the grain storage industry. It includes a silencer body with a baffle device connected to its lower end. The silencer body comprises a fan connection part and a flow guide part. The fan connection part is bolted to the air outlet of the axial flow fan, and the flow guide part is welded to the baffle device. The flow guide part and the fan connection part are arranged at a 90° angle. The baffle device has an inverted right-angled trapezoidal structure and contains multiple sets of baffles, each set consisting of two baffles arranged with a narrower upper section and a wider lower section. Sound-absorbing cotton is attached to the inner walls of the silencer body and the baffle device, as well as to the baffles. This new technology effectively reduces the noise of the axial flow fan, with actual measurements showing a noise reduction of over 20 decibels, thus resolving the noise disturbance issue near residential areas.

Description

Technical Field

[0001] This utility model relates to the field of fan silencing equipment, specifically an axial flow fan silencer, and is relevant to the grain storage industry. Background Technology

[0002] Axial flow fans rely on the rotation of an impeller to drive gas to flow axially, thereby achieving gas delivery, ventilation, air exchange, or heat dissipation. With its large flow rate, simple structure, and convenient installation, axial flow fans play an important role in the ventilation of grain storage warehouses. Their working characteristics are highly compatible with the grain storage needs of grain storage warehouses, and through directional and efficient airflow delivery, they achieve safe storage and quality assurance of grain.

[0003] Grain storage depots are equipped with axial flow fans at the top of the grain silos to regulate the temperature and humidity of the grain piles through airflow, preventing the grain from overheating, mold, and pests. Currently, the outlets of these axial flow fans are directly exposed to the outside, resulting in significant noise during operation. This not only affects the surrounding environment (such as residential and office areas) but may also cause long-term hearing damage to nearby residents. Since the outlets of the current axial flow fans face directly out of the grain silo without any soundproofing equipment, there is an urgent need for a device to solve the problem of excessive noise during the operation of axial flow fans. Utility Model Content

[0004] The purpose of this invention is to provide an axial flow fan silencer that has a simple structure, effectively reduces noise, and minimizes the noise disturbance of the axial flow fan to surrounding residents.

[0005] The technical solution of this utility model:

[0006] An axial flow fan silencer includes a silencer body and a flow-dispersing device connected to the lower end of the silencer body. The silencer body consists of a fan connection part and a flow guide part. The fan connection part is connected to the air outlet of the axial flow fan by bolts. The flow guide part is welded to the flow-dispersing device. The flow guide part and the fan connection part are arranged at a 90° angle. The flow-dispersing device has an inverted right-angled trapezoidal structure and contains multiple sets of flow-dispersing plates. Each set of flow-dispersing plates has an inverted right-angled trapezoidal structure, with two flow-dispersing plates in each set. The distance between the two flow-dispersing plates is arranged in a shape that is narrower at the top and wider at the bottom. Sound-absorbing cotton is attached to the inner walls of the silencer body and the flow-dispersing device, as well as to the flow-dispersing plates.

[0007] The beneficial effects of this utility model are:

[0008] 1. The silencer of this application consists of a fan connection section, a flow guide section, and a flow-dispersing device. The duct routing and dimensions are varied, and the flow-dispersing device is designed as a right-angled trapezoidal truncated cone, containing V-shaped baffles. Utilizing this abrupt interface and resonant cavity on the duct, noise frequency sound waves propagating along the duct undergo reflection and interference at the abrupt interface, achieving noise reduction. Furthermore, sound-absorbing cotton is lined inside the silencer, which also contributes to noise reduction.

[0009] 2. The axial flow fan silencer of this application addresses the shortcomings of existing technology by using new technology to effectively reduce the noise of axial flow fans. Through actual measurement, the noise is reduced by more than 20 decibels, solving the problem of disturbing residents near residential areas. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of the overall structure of the axial flow fan silencer in this application.

[0012] Figure 2 This is a schematic diagram of the axial flow fan silencer from another angle.

[0013] Figure 3 This is a schematic diagram of the internal structure of the axial flow fan silencer in this application.

[0014] Figure 4 This is a front view of the turbulence device of the axial flow fan silencer in this application.

[0015] Figure 5 This is a schematic diagram of the baffle structure of the axial flow fan silencer in this application.

[0016] Figure label:

[0017] Silencer body 1; turbulence device 2; fan connection 11; air guide 12; air inlet 13; connecting edge 14; bolt hole 15; turbulence plate 21; sound-absorbing cotton 22. Detailed Implementation

[0018] In order to solve the problems in the background art, the axial flow fan silencer of this application has been invented to better solve the problem that the existing axial flow fans are noisy and unsuitable for use near residential areas.

[0019] It should be noted that in the description of this application, terms such as "inner", "outer", "upper", and "lower" that indicate direction or positional relationship are based on the direction or positional relationship shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application.

[0020] Axial flow fans, by providing high-flow-rate, low-resistance airflow, are installed above grain silos in grain storage facilities to extract hot air from the upper part of the silos, playing a crucial role in ventilation, cooling, and suppressing grain pile heating. They are essential equipment for ensuring safe grain storage. Their adaptability to the ventilation needs of grain depots makes them an indispensable part of mechanical ventilation systems, directly affecting the storage quality and duration of grain. However, in practice, axial flow fans are extremely noisy, already interfering with the normal lives of nearby residents. To address the shortcomings of existing technologies, this application presents an axial flow fan silencer:

[0021] Please see Figure 1-5 As shown, an axial flow fan silencer includes a silencer body 1 and a baffle device 2 connected to the lower end of the silencer body 1. The silencer body 1 is composed of a fan connection part 11 and a flow guide part 12. The fan connection part 11 is connected to the air outlet of the axial flow fan by bolts. The flow guide part 12 is welded to the baffle device 2. The flow guide part 12 and the fan connection part 11 are arranged at a 90° angle. The baffle device 2 has an inverted right-angled trapezoidal structure and contains multiple sets of baffle plates 21. The baffle plates 21 have an inverted right-angled trapezoidal structure. Each set of baffle plates 21 consists of two baffle plates. The distance between the two baffle plates 21 is arranged in a shape that is narrower at the top and wider at the bottom (the two baffle plates form an "eight" shape). Sound-absorbing cotton 22 is attached to the inner walls of the silencer body 1 and the baffle device 2, as well as to the baffle plates 21. The silencer in this application primarily targets low-to-mid-frequency noise. The ductwork routing and dimensions of the fan connection, guide section, and turbulence device all change. Utilizing these abrupt interface changes and resonant cavities on the ductwork, the noise frequencies and sound waves propagating along the duct undergo reflection and interference at these abrupt interfaces, achieving noise reduction. Sound-absorbing cotton is lined inside the fan connection, guide section, and interference device, further contributing to noise reduction. The air inlet of the fan connection is bolted to the axial flow fan outlet, with a square or rectangular cross-section for better matching with the axial flow fan outlet.

[0022] Please see Figure 2-3 As shown, the fan connection part 11 has a connecting edge 14 welded to the outer edge of the air inlet 13 facing the air outlet of the axial flow fan. Multiple bolt holes 15 are opened on the connecting edge 14. Bolts pass through the bolt holes 15 of the connecting edge 14 and connect them to the bolt holes on the edge of the air outlet of the axial flow fan. This connection structure is more compatible with the air outlet of the axial flow fan and is easier and faster to install and disassemble.

[0023] The sound-absorbing cotton is 22mm thick and 4-6cm. This thickness is more suitable for the sound absorption effect and the ventilation volume inside the silencer. If the thickness of the sound-absorbing cotton is increased, the amount of material used will increase, the cost will rise, but the improvement in noise absorption rate will not be significant. More importantly, it will limit the ventilation volume inside the silencer.

[0024] The silencer in this application adopts a bottom-outlet design to prevent rain and snow from flowing back in. The air inlet size of the fan connection is 1200×1200mm, and the air outlet size of the lower end of the turbulence device is 400×1200mm, which can effectively reduce noise while ensuring that the air volume is not restricted.

[0025] This application's silencer is installed at the outlet of the axial flow fan. The turbulence-reducing device adopts a right-angled trapezoidal design, and in particular, utilizes a "figure-eight" shaped turbulence-reducing plate to greatly avoid turbulence and disturbance of the flowing medium. Using this new technology, noise is effectively reduced; actual measurements show a reduction of over 20 decibels. This effectively reduces axial flow fan noise, resolving the disturbance to residents near residential areas. This application is not only applicable to grain storage but also to axial flow fans used in other fields.

[0026] like Figure 3 , 4 As shown, an embodiment of the axial flow fan silencer of this application is as follows:

[0027] Materials: The silencer body and the baffle are both made of stainless steel. Sound-absorbing cotton is lined inside the silencer body and the baffle, and the baffle plate also has sound-absorbing cotton, with a thickness of 5 cm. The fan connection part of the silencer body has a square cross-section, while the guide part has a rectangular cross-section.

[0028] Dimensions: The cross-section of the fan connection part is square, with a length and width of 1200mm; the cross-section of the guide part is rectangular, with a length of 1200mm and a width of 600mm; the turbulence device is 1200mm long, 600mm wide at the top, 400mm wide at the bottom, and 600mm high; the turbulence plate is 600mm wide at the top, 400mm wide at the bottom, and 600mm high.

[0029] Silencer installation location: upper part of the grain silo in the grain reserve.

[0030] Connection method: The air outlet of the silencer's fan connection is connected to the air outlet of the axial flow fan by bolts.

[0031] Noise reduction effect: Using a Delixi Electric decibel meter, model DSM D1, the noise level was 77.6 decibels before the silencer was installed, and 53.9 decibels after the silencer was installed, resulting in a noise reduction of 24 decibels.

[0032] The principle of the axial flow fan silencer in this application:

[0033] The silencer described in this application consists of a fan connection, a flow guide, and a flow disturbance device. The duct layout and dimensions vary, and by utilizing the abrupt interface and resonant cavity on this duct, noise frequencies and sound waves propagating along the duct undergo reflection and interference at the abrupt interface, achieving noise reduction. It primarily targets low-to-mid-frequency noise. Sound-absorbing cotton is also placed inside the fan connection, flow guide, and interference device, further reducing noise.

[0034] The turbulence device in this application is designed with an inverted right-angled trapezoidal structure, and a fixed turbulence plate in a figure-eight shape is installed inside the device. The figure-eight shaped turbulence plate divides the channel into a variable cross-section expansion cavity. When low-frequency noise (longer wavelength) from the axial flow fan flows through, the sound waves are reflected multiple times and phases are superimposed and canceled out due to the abrupt change in the channel width—when the sound wave peaks and troughs meet, the energy is attenuated. The figure-eight layout makes the sound wave propagation path tortuous, increasing the number of reflections and enhancing the energy dissipation of low-frequency noise. Sound-absorbing cotton is attached to the surface of the turbulence plate. The porous structure of the sound-absorbing cotton converts the energy of low-frequency sound waves into heat energy through air friction and viscosity, thereby reducing noise.

[0035] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art, inspired by this description, design similar structures and implementations to the above embodiments without departing from the technical essence of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. An axial flow fan silencer characterised in that: The device includes a silencer body and a baffle device connected to the lower end of the silencer body. The silencer body consists of a fan connection part and a flow guide part. The fan connection part is connected to the air outlet of an axial flow fan by bolts. The flow guide part is welded to the baffle device. The fan connection part and the flow guide part are arranged at a 90° angle. The baffle device has an inverted right-angled trapezoidal structure and contains multiple sets of baffles. The baffles have an inverted right-angled trapezoidal structure, with two baffles in each set. The distance between the two baffles is arranged in a shape that is narrower at the top and wider at the bottom. Sound-absorbing cotton is attached to the inner walls of the silencer body and the baffle device, as well as to the baffles.

2. An axial fan silencer according to claim 1, characterised in that: The fan connection part has a connecting edge welded to the outer edge of the air inlet facing the air outlet of the axial flow fan. Multiple bolt holes are opened on the connecting edge. Bolts pass through the bolt holes of the connecting edge and the bolt holes on the edge of the air outlet of the axial flow fan to connect the two.

3. An axial fan silencer according to claim 1, wherein: The cross-sections of the fan connection and the guide section are square or rectangular, and the inner cavity size of the fan connection is larger than that of the guide section.

4. An axial fan silencer according to claim 1, wherein: The sound-absorbing cotton is 4-6 cm thick.

5. An axial fan silencer according to claim 1, characterized in that: The air inlet of the fan connection has a size of 1200mm×1200mm, and the air outlet at the lower end of the turbulence device has a size of 400mm×1200mm.

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