Multi-wing centrifugal fan outlet composite flow guide device and multi-wing centrifugal fan

Abstract

The invention discloses a composite flow guide device for an outlet of a multi-wing centrifugal fan and the multi-wing centrifugal fan. According to the outlet composite flow guide device, through structural innovation and flow field optimization design, the aerodynamic efficiency and the outlet flow can be effectively improved, and energy consumption and operation noise are reduced; the centrifugal fan comprises a volute and an impeller arranged in the volute. A fluid director is arranged at the outlet section of the volute; the fluid director is in transmission connection with the motor A, and the circumferential posture can be adjusted under the driving of the motor A; the fluid director is in an X shape and is composed of two flow deflectors which intersect with each other. The impeller comprises a mounting disc and a mounting ring which are oppositely distributed, and a group of rectiblocks which are arranged between the mounting disc and the mounting ring and are distributed along the circumferential direction of the impeller at intervals; micropores are formed in the surfaces of the rectiblocks; the two ends of the rectiblocks are fixedly connected with the mounting disc and the mounting ring respectively; a shaft sleeve connected with an output shaft of a motor B is arranged in the middle of the mounting disc; and the flow deflectors and the rectification sheets are arc-shaped curved surfaces.

Description

Technical Field

[0001] This invention belongs to the field of fluid machinery, specifically relating to a composite flow guiding device for the outlet of a multi-bladed centrifugal fan and a multi-bladed centrifugal fan equipped with the flow guiding device. Background Technology

[0002] Multi-blade centrifugal fans are centrifugal fans with forward-curved blades, numerous blades, and a compact impeller structure, and are currently widely used in air conditioning, ventilation, and cooling equipment. However, their internal flow field still has some significant defects: ① Gas backflow within the impeller: Under low flow conditions, insufficient static pressure gradient at the volute outlet causes airflow to backflow to the impeller inlet, forming local vortices, reducing impeller efficiency, and consequently reducing the fan outlet flow rate; ② Flow separation within the blade passage: When the airflow angle is too large, boundary layer separation easily occurs at the trailing edge of the blade suction surface, forming vortices and blocking the blade passage, resulting in flow loss and further reducing the fan outlet flow rate; ③ Vortex generation within the shroud: Uneven pressure distribution in the flow field between the impeller and the volute causes spiral flow when the airflow turns at large angles, triggering secondary flow and backflow, increasing flow resistance and noise. In existing technologies, to overcome the aforementioned shortcomings, some manufacturers have installed rectifiers inside the volute or at the impeller outlet to guide airflow, segment large-scale vortices, and suppress flow separation; or they have offset the impeller center relative to the volute center (eccentric design) to optimize the flow field pressure distribution between the impeller and the volute. However, while existing rectifiers can segment vortices, they increase flow losses; and while eccentric impeller designs can optimize the flow field, they easily lead to uneven volute tongue clearance, causing efficiency fluctuations and increased noise. Summary of the Invention

[0003] This invention provides a composite flow guiding device for the outlet of a multi-bladed centrifugal fan to overcome the aforementioned problems in the prior art. The composite flow guiding device for the outlet of this invention guides the airflow by setting an X-shaped flow guide at the outlet section of the volute, effectively suppressing flow separation, reducing flow loss, and thus increasing the fan outlet flow rate. Furthermore, the flow guide can adjust its circumferential attitude according to operating conditions, optimizing the airflow distribution at the impeller outlet, reducing airflow impact, and thus effectively reducing flow loss and improving fan operating efficiency. In addition, this invention sets multiple rectifier vanes on the impeller and creates micro-holes on the vanes, thereby utilizing the synergistic effect of the micro-hole structure and the flow guide to divide large-scale vortices into small-scale vortices, dispersing vortex energy and reducing broadband noise. Correspondingly, this invention also provides a multi-bladed centrifugal fan equipped with this composite flow guiding device.

[0004] For the outlet composite diversion device, the technical solution of this application is as follows:

[0005] A multi-blade centrifugal fan outlet composite flow guiding device includes a volute and an impeller disposed within the volute; a flow guide is provided at the outlet section of the volute; the flow guide is driven and connected to motor A, and its circumferential attitude can be adjusted under the drive of motor A; the flow guide is X-shaped and consists of two intersecting flow guide vanes; the impeller includes a mounting plate and a mounting ring distributed opposite each other, and a rectifier disposed between the mounting plate and the mounting ring; the rectifier consists of a set of rectifier vanes spaced apart along the circumference of the impeller; micro-holes are formed on the surface of the rectifier vanes; both ends of the rectifier vanes are fixedly connected to the mounting plate and the mounting ring respectively; a bushing for connecting the output shaft of motor B is provided in the middle of the mounting plate; both the flow guide vanes and the rectifier vanes are arc-shaped curved surfaces.

[0006] Compared with existing technologies, the multi-blade centrifugal fan outlet composite flow guiding device of this application can effectively improve aerodynamic efficiency and outlet flow rate, and reduce the operating noise of the multi-blade centrifugal fan through structural innovation and flow field optimization design. The outlet composite flow guiding device guides the airflow by setting an X-shaped flow guide at the outlet section of the volute, which can effectively suppress flow separation and reduce flow loss, thereby increasing the fan outlet flow rate. Moreover, the flow guide is connected to the motor, and during use, the circumferential attitude can be adjusted according to the operating conditions to optimize the airflow distribution at the impeller outlet, reduce airflow impact, and thus effectively reduce flow loss and improve the fan operating efficiency. In addition, this application sets multiple rectifiers on the impeller and opens micro-holes on the rectifiers, thereby utilizing the synergistic effect of the micro-hole structure and the flow guide to divide large-scale vortices into small-scale vortices, disperse vortex energy, reduce broadband noise, and improve the fan operating stability.

[0007] As an optimization, in the aforementioned multi-blade centrifugal fan outlet composite guide device, the two guide vanes are of different lengths, with the inner end of the longer guide vane pointing towards the volute and the inner end of the shorter guide vane pointing towards the impeller. This intersecting structure of different lengths avoids the airflow dead zone and aerodynamic resonance risks that are easily generated by symmetrical structures, optimizes the uniformity of the flow field at the volute outlet, and further suppresses airflow separation and vortex generation, making it highly practical.

[0008] Furthermore, the inner end of the guide vane is provided with a streamlined tip with a pointed angle. This helps to reduce obstruction and impact on the airflow at the impeller outlet, reducing airflow impact loss; it also avoids flow separation, vortices, and secondary flows at the end of the guide vane, further reducing aerodynamic noise.

[0009] Furthermore, the surface of the guide vane is coated with a superhydrophobic nano-coating. This superhydrophobic nano-coating possesses low surface energy and a micro / nano-level rough structure, which can form a stable gas film between the guide vane surface and the airflow, reducing the surface friction coefficient of the guide vane and thus decreasing airflow viscous resistance. Simultaneously, this gas film can also inhibit the accumulation and stagnation of low-energy fluids on the guide vane surface, reducing the risk of boundary layer separation and minimizing eddies and backflow.

[0010] As an optimization, in the aforementioned multi-blade centrifugal fan outlet composite flow guiding device, the porosity of the rectifier surface is 25%–40%, and the pore diameter of the micropores is 0.4–0.8 mm. This avoids the inability to achieve rectification and noise reduction effects due to excessively small micropore diameters or low porosity, while also preventing insufficient strength of the rectifier due to excessively large micropore diameters or high porosity.

[0011] Furthermore, the thickness of the rectifier is 1 / 9 to 1 / 12 of the thickness of the volute. This ensures that the rectifier has sufficient structural strength and rigidity when rotating at high speed, while also providing enough space between adjacent rectifiers for smooth airflow and ensuring aerodynamic efficiency.

[0012] As an optimization, in the aforementioned multi-blade centrifugal fan outlet composite flow guiding device, the rectifier blade includes a rectifier blade body and mounting portions located at both ends of the rectifier blade body; the mounting portions are welded to the outer surfaces of the mounting ring and the mounting plate; each of the two ends of the rectifier blade body, located on both sides, is provided with a limiting protrusion, which is located inside the mounting ring and the mounting plate, that is, the mounting ring and the mounting plate are respectively constrained between the corresponding mounting portions and the limiting protrusions. In this case, the connection is highly secure and the overall integrity is strong, avoiding the risk of the rectifier blade loosening or falling off, and ensuring high impeller reliability.

[0013] Furthermore, the mounting section consists of two spaced-apart mounting blocks, with an acute angle between the axes of the two mounting blocks. This reduces welding stress concentration, lowers the risk of welding deformation, and improves the overall structural stability of the impeller. Moreover, the acute angle arrangement of the two mounting blocks better adapts to the direction of the impeller's rotational force, resulting in a more uniform and smoother force transmission to the rectifier blades.

[0014] For multi-blade centrifugal fans, the technical solution of this application is as follows:

[0015] The multi-blade centrifugal fan adopts the aforementioned multi-blade centrifugal fan outlet composite flow guiding device of this application; during operation, the angle between the line connecting the center point of the flow guide and the center point of the impeller and the bisector of the acute angle formed by the two flow guide vanes is... Based on the real-time flow rate at the fan inlet Confirmed, details are as follows: ;in, The flow rate at the fan inlet is the rated flow rate. At that time, the fan outlet flow rate is maximized. Values, This represents the upper limit of the flow rate at the fan inlet. This is the lower limit of the flow rate at the fan inlet. , The flow rates at the fan inlet are respectively At that time, the fan outlet flow rate is maximized. Values.

[0016] Compared with existing technologies, the multi-blade centrifugal fan of this application is equipped with an outlet composite flow guide device with innovative structural design and optimized flow field design. During operation, the circumferential attitude of the flow guide can be adjusted in real time according to the operating conditions, thereby effectively improving aerodynamic efficiency and outlet flow rate, and reducing operating energy consumption and operating noise. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the multi-blade centrifugal fan in the embodiments of this application;

[0018] Figure 2 This is a schematic diagram of the outlet composite flow guiding device in the embodiment;

[0019] Figure 3 yes Figure 2 Front view of the outlet composite flow guiding device in the middle;

[0020] Figure 4 This is a schematic diagram of the impeller structure in an embodiment of this application;

[0021] Figure 5 yes Figure 4 A schematic diagram of the impeller after some rectifier vanes have been removed;

[0022] Figure 6 This is a schematic diagram of the rectifier in the embodiments of this application.

[0023] The labels in the attached diagram are as follows: 1-volute; 2-impeller; 21-mounting plate; 22-mounting ring; 23-rectifier; 231-rectifier body; 232-mounting part; 233-limiting protrusion; 24-shaft sleeve; 241-A flange; 25-B flange; 3-guide vane; 31-guide vane; 311-end; 4-A motor; 5-B motor. Detailed Implementation

[0024] The present application will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present application. Contents not described in detail in the following embodiments are all common knowledge in the art.

[0025] Example:

[0026] See Figure 1 and Figure 2 In this embodiment, the multi-blade centrifugal fan employs an outlet composite flow guiding device. The outlet composite flow guiding device includes a volute 1 and an impeller 2 housed within the volute 1. A flow guide 3 is provided at the outlet section of the volute 1. The flow guide 3 is connected to motor A 4 via a drive mechanism and can adjust its circumferential attitude under the drive of motor A 4 (a rotating shaft is provided in the middle of the flow guide 3, which is connected to the output shaft of motor A 4 via a coupling). The flow guide 3 is X-shaped and consists of two intersecting flow guide vanes 31 (the obtuse angle formed between the two flow guide vanes 31 is 120°). The impeller 2 includes... The impeller comprises a mounting plate 21 and a mounting ring 22 arranged in a relatively distributed manner, and a rectifier disposed between the mounting plate 21 and the mounting ring 22. The rectifier consists of 51 rectifier blades 23 evenly spaced along the circumference of the impeller 2. Micro-holes are formed on the surface of the rectifier blades 23. The two ends of the rectifier blades 23 are fixedly connected to the mounting plate 21 and the mounting ring 22, respectively. A bushing 24 is provided in the middle of the mounting plate 21. The bushing 24 is connected to the output shaft of the B motor 5, so that the mounting plate 21 can rotate under the drive of the B motor 5. Both the guide vane 31 and the rectifier blade 23 are arc-shaped curved surfaces.

[0027] The airflow disturbances, wakes, and separated flows generated during the rotation of impeller 2 easily form large-scale vortices. These vortices collide with the walls during flow, generating strong pressure pulsations, which in turn induce broadband aerodynamic noise. In this embodiment, by creating micro-holes on the rectifier plate 23, the large-scale vortices are broken, segmented, and guided by the micro-hole structure, decomposing them into vortices with lower energy and smaller scale, dissipating the internal energy of the vortices. Combined with the airflow guidance of the guide vane 3, airflow separation, collisions, and vortex regeneration can be reduced, thereby achieving the effect of dispersing vortex energy and reducing broadband noise. Experiments show that the micro-holes on the rectifier plate 23 can increase the number of vortices at the outlet of the volute 1, but reduce the intensity of individual vortices and reduce broadband noise.

[0028] In this embodiment, the two guide vanes 31 are of different lengths, with the inner end of the longer guide vane 31 pointing towards the volute 1 and the inner end of the shorter guide vane 31 pointing towards the impeller 2. The flow channel cross-section and airflow distribution in the outlet region of the volute 1 are asymmetrical. The asymmetrical structure of the two guide vanes 31 can adapt to the asymmetrical flow field at the outlet of the volute 1, achieving uniform airflow splitting and reducing flow blockage and eddy current losses.

[0029] In this embodiment, the inner end of the guide vane 31 is provided with a streamlined end 311 with a pointed angle. This helps to reduce the obstruction and impact on the airflow at the outlet of the impeller 2, and reduce airflow impact loss; moreover, it can also prevent the airflow from generating flow separation, vortices and secondary flow at the end of the guide vane 31, further reducing aerodynamic noise.

[0030] In this embodiment, the surface of the guide vane 31 is coated with a superhydrophobic nano-coating. The superhydrophobic nano-coating has low surface energy characteristics and a micro-nano multi-level rough structure on its surface. It can form a stable gas film between the surface of the guide vane 31 and the airflow, reducing the surface friction coefficient of the guide vane 31 and thus reducing the viscous resistance of the airflow. At the same time, the gas film can also inhibit the accumulation and stagnation of low-energy fluid on the surface of the guide vane 31, reduce the risk of boundary layer separation, and reduce the generation of eddies and backflow.

[0031] In this embodiment, the porosity of the surface of the rectifier plate 23 is 30%, and the pore diameter of the micropores is 0.5 mm (not shown in the figure). Therefore, while ensuring structural strength, it can achieve good vortex breaking and noise reduction effects, reducing airflow resistance and aerodynamic noise.

[0032] In this embodiment, the thickness of the rectifier 23 is 1 / 10 of the thickness of the volute 1. This ensures that the rectifier 23 has sufficient structural strength and rigidity during high-speed rotation, while also providing enough space between adjacent rectifiers 23 for smooth airflow and guaranteed aerodynamic efficiency. Furthermore, this specific thickness ratio facilitates stamping with commonly used materials and ensures the shape accuracy of the rectifier 23 (if it is too thin, it is prone to tearing or springback during stamping; if it is too thick, it is difficult to bend into the required complex curvature).

[0033] See Figures 4 to 6 In this embodiment, the rectifier 23 includes a rectifier body 231 and mounting portions 232 located at both ends of the rectifier body 231. The mounting portions 232 are welded to the outer surfaces of the mounting ring 22 and the mounting disk 21. At each of the two ends of the rectifier body 231, a limiting protrusion 233 is provided. The limiting protrusion 233 is located inside the mounting ring 22 and the mounting disk 21, meaning that the mounting ring 22 and the mounting disk 21 are respectively constrained between the corresponding mounting portions 232 and the limiting protrusions 233. This design ensures a high degree of connection strength and overall integrity, avoiding the risk of the rectifier loosening or falling off, and ensuring high reliability of the impeller 2. Furthermore, the mounting portion 232 consists of two spaced-apart mounting blocks, and the included angle between the axes of the two mounting blocks is an acute angle. This reduces welding stress concentration, lowers the risk of welding deformation, and improves the overall structural stability of the impeller 2. Furthermore, the acute-angled arrangement of the two mounting blocks better adapts to the rotational force direction of the impeller 2, resulting in a more uniform and smoother force transmission to the rectifier 23. Mounting holes are provided on the mounting plate 21 and mounting ring 22 for the corresponding mounting blocks to pass through. During assembly, the mounting blocks at both ends of the rectifier 23 are passed through the mounting holes on the mounting plate 21 and mounting ring 22, respectively. The mounting blocks are then bent to contact the outer surface of the mounting plate 21 or mounting ring 22, and then fixed by welding.

[0034] In this embodiment, the bushing 24 is provided with an A flange 241, which is located inside the mounting plate 21. Correspondingly, the outer side of the mounting plate 22 is provided with a B flange 25 that mates with the A flange 241. The impeller 2 can then be fixed to the inner wall of the volute 1 by bolts passing sequentially through the A flange 241, the mounting plate 21, the B flange 25, and the volute 1. This facilitates disassembly and assembly, and makes future maintenance and replacement easier.

[0035] See Figure 3 In this embodiment, when the guide vane 3 is in its initial position, the angle between the line connecting the center point of the guide vane 3 and the center point of the impeller 2, and the bisector of the acute angle formed by the two guide vanes 31, is 43° (i.e., In this embodiment, CFD numerical simulation experiments show that, at this angle, the flow rate at the inlet of the multi-blade centrifugal fan is the rated flow rate. At that time, the export flow is at its maximum.

[0036] During actual operation of the fan, the controller sends commands to motor A 4 according to different operating conditions, causing motor A 4 to drive the guide vane 3 to rotate and adjust its circumferential attitude. This changes the angle between the line connecting the center point of guide vane 3 and the center point of impeller 2 and the bisector of the acute angle formed by the two guide vanes 31. included angle Based on the real-time flow rate at the fan inlet Confirmed, details are as follows: ;in, This represents the upper limit of the flow rate at the fan inlet. This is the lower limit of the flow rate at the fan inlet. , The flow rates at the fan inlet are respectively At that time, the fan outlet flow rate is maximized. Values.

[0037] The real-time flow rate Q at the inlet can be obtained by the air volume sensor and the detection signal is transmitted to the controller.

[0038] The fan flow rate exceeds 1.15. Problems such as overload, decreased efficiency, and increased noise are prone to occur below 0.6. Problems such as rotational stall, surge, and sudden drop in efficiency are prone to occur. When implementing this invention, It can be 1.05-1.15 In this embodiment, 1.1 is used. ; It can be 0.6-0.7 In this embodiment, 0.6 is used. .

[0039] The foregoing general description of the invention and its specific embodiments should not be construed as limiting the technical solution of the invention. Those skilled in the art, based on the disclosure of this application, can add, reduce, or combine the disclosed technical features in the foregoing general description and / or embodiments without departing from the constituent elements of the invention, to form other technical solutions within the scope of protection of this application.

Claims

1. A composite flow guiding device for the outlet of a multi-bladed centrifugal fan, comprising a volute (1) and an impeller (2) disposed within the volute (1); characterized in that: The volute (1) is provided with a guide (3) at the outlet section; the guide (3) is connected to motor A (4) and can be adjusted in circumferential orientation under the drive of motor A (4); the guide (3) is X-shaped and consists of two intersecting guide vanes (31); the impeller (2) includes a mounting plate (21) and a mounting ring (22) distributed opposite to each other, and a rectifier located between the mounting plate (21) and the mounting ring (22); the rectifier consists of a set of rectifier vanes (23) distributed circumferentially along the impeller (2); micro-holes are provided on the surface of the rectifier vanes (23); the two ends of the rectifier vanes (23) are fixedly connected to the mounting plate (21) and the mounting ring (22) respectively; a bushing (24) for connecting the output shaft of motor B (5) is provided in the middle of the mounting plate (21); the guide vanes (31) and the rectifier vanes (23) are both arc-shaped curved surfaces.

2. The composite flow guiding device at the outlet of a multi-blade centrifugal fan according to claim 1, characterized in that: The two guide vanes (31) are of different lengths, with the inner end of the longer guide vane (31) pointing towards the volute (1) and the inner end of the shorter guide vane (31) pointing towards the impeller (2).

3. The composite flow guiding device at the outlet of a multi-blade centrifugal fan according to claim 2, characterized in that: The inner end of the guide vane (31) is provided with a streamlined end (311) with a pointed angle.

4. The composite flow guiding device at the outlet of a multi-blade centrifugal fan according to claim 3, characterized in that: The surface of the guide plate (31) is coated with a superhydrophobic nano-coating.

5. The composite flow guiding device for the outlet of a multi-blade centrifugal fan according to claim 1, characterized in that: The porosity of the surface of the rectifier (23) is 25% to 40%, and the pore size of the micropores is 0.4 to 0.8 mm.

6. The composite flow guiding device at the outlet of a multi-blade centrifugal fan according to claim 5, characterized in that: The thickness of the rectifier (23) is 1 / 9 to 1 / 12 of the thickness of the volute (1).

7. The composite flow guiding device for the outlet of a multi-bladed centrifugal fan according to claim 1, characterized in that: The rectifier (23) includes a rectifier body (231) and mounting portions (232) located at both ends of the rectifier body (231); the mounting portions (232) are welded to the outer surfaces of the mounting ring (22) and the mounting disk (21); at both ends of the rectifier body (231), a limiting protrusion (233) is provided on each side, and the limiting protrusion (233) is located on the inner side of the mounting ring (22) and the mounting disk (21).

8. The composite flow guiding device for the outlet of a multi-blade centrifugal fan according to claim 7, characterized in that: The mounting part (232) consists of two spaced mounting blocks, and the included angle between the axes of the two mounting blocks is an acute angle.

9. A multi-blade centrifugal fan, characterized in that: The multi-blade centrifugal fan outlet composite flow guiding device as described in claim 1 is adopted.

10. The multi-blade centrifugal fan according to claim 9, characterized in that: During operation, the angle between the line connecting the center point of the guide vane (3) and the center point of the impeller (2) and the bisector of the acute angle formed by the two guide vanes (31) is... Based on the real-time flow rate at the fan inlet Confirmed, details are as follows: ； in, The flow rate at the fan inlet is the rated flow rate. At that time, the fan outlet flow rate is maximized. Values, This represents the upper limit of the flow rate at the fan inlet. This is the lower limit of the flow rate at the fan inlet. , The flow rates at the fan inlet are respectively At that time, the fan outlet flow rate is maximized. Values.

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