Noise reduction type double-impeller axial centrifugal fan

Abstract

The invention relates to the technical field of fans, in particular to a noise reduction type double-impeller axial centrifugal fan which comprises a first-stage air inlet duct, a first-stage impeller, a first-stage air duct, a second-stage air inlet duct, a second-stage impeller, a second-stage air duct and a driving part. The first-stage air inlet duct, the first-stage impeller, the driving part, the second-stage air inlet duct, the second-stage impeller and the second-stage air duct are sequentially mounted in the first-stage air duct in series; the first-stage impeller comprises first-stage blades, the second-stage impeller comprises second-stage blades, and the inlet edge of each second-stage blade is of a beveled structure; the first-stage air duct comprises a first-stage guide vane, and the second-stage air duct comprises a second-stage guide vane. The axial flowing time of air flow is longer than that of an original fan, the energy transfer time is effectively prolonged, pressure fluctuation is dispersed, the air flow pulsation frequency is reduced, the noise frequency spectrum shifts to the low frequency, the noise intensity is controlled, and the technical problem that the noise is large when an existing locomotive fan runs is solved.

Description

Technical Field

[0001] This invention relates to the field of fan technology, and in particular to a noise-reducing dual-impeller axial centrifugal fan. Background Technology

[0002] The main application of cooling fans is to provide cooling air for the traction motors of electric locomotives and to ventilate and dissipate heat from heat-generating equipment. When the locomotive is running, the traction motor provides the power required for forward movement, and it generates a large amount of heat during operation. The cooling fan rotates at high speed, drawing in cool air from the roof and side walls of the locomotive. After being pressurized by the impeller, the air is blown along a dedicated pipeline to the traction motor at the bottom of the locomotive, providing forced cooling ventilation and quickly carrying away the heat into the atmosphere, thereby achieving the purpose of cooling the traction motor.

[0003] A locomotive's engine room typically requires 4-6 traction fans. A single traditional traction fan produces approximately 102 dB(A) of noise, and the noise increases by 6-8 dB(A) when 4-6 fans are running simultaneously. To comply with the "source control" principle of the "Supervision and Management Measures for the Prevention and Control of Noise Pollution from Railway Locomotives and Rolling Stock," the traction motor cooling fans, as auxiliary equipment, must work together to control overall noise. The owner has stipulated that the traction fan noise should not exceed 98 dB(A). Therefore, the original traction fan noise requirements are no longer sufficient, necessitating a low-noise cooling fan to address these technical issues. Summary of the Invention

[0004] The main objective of this invention is to provide a noise-reducing dual-impeller axial centrifugal fan, which aims to solve the technical problem of high noise levels during operation of existing locomotive fans.

[0005] To achieve the above objectives, the present invention proposes a noise-reducing dual-impeller axial centrifugal fan, comprising a primary air inlet duct, a primary impeller, a primary air casing, a secondary air inlet duct, a secondary impeller, a secondary air casing, and a drive component. The primary air inlet duct, the primary impeller, the drive component, the secondary air inlet duct, the secondary impeller, and the secondary air casing are sequentially connected in series within the primary air casing. The primary impeller includes primary blades, the secondary impeller includes secondary blades, and the inlet edge of the secondary blades has a beveled structure. The primary air casing includes a primary guide vane with a primary beveled angle at its inlet, and the secondary air casing includes a secondary guide vane with a secondary beveled angle at its inlet.

[0006] The noise-reducing dual-impeller axial centrifugal fan of the present invention is further improved in that the oblique cutting angle of the oblique cutting structure is between 0° and 20°, the outlet angle of the second-stage blade is between 38° and 45°, and the inlet angle of the second-stage blade is between 30° and 35°.

[0007] The noise-reducing dual-impeller axial centrifugal fan of the present invention is further improved in that the first-stage blade is an arc-shaped blade, the outlet angle of the first-stage blade is between 32° and 40°, and the inlet angle of the blade is between 18° and 21°.

[0008] The noise-reducing dual-impeller axial centrifugal fan of the present invention is further improved in that the first-stage oblique angle and the second-stage oblique angle are both between 5° and 15°, and the inlet angle of the first-stage guide vane and the second-stage guide vane are both between 20° and 50°.

[0009] The noise-reducing dual-impeller axial centrifugal fan of the present invention is further improved in that the primary air duct also includes a primary outer cylinder, a primary inner cylinder and a mounting plate. The primary inner cylinder is installed inside the primary outer cylinder, the mounting plate is fixed inside the inner cylinder, the drive component is installed on the mounting plate, the primary guide vane is installed on the outer wall of the primary inner cylinder, and the primary inner cylinder has a conical structure with the conical structure forming an angle of 3° to 12° with the axis.

[0010] The noise-reducing dual-impeller axial centrifugal fan of the present invention is further improved in that the secondary air duct also includes a secondary outer cylinder and a secondary inner cylinder. The secondary inner cylinder is installed inside the secondary outer cylinder, and the secondary guide vanes are installed on the outer wall of the secondary inner cylinder. The secondary inner cylinder has a conical structure, and the conical structure forms an angle of 3° to 12° with the axis.

[0011] The noise-reducing dual-impeller axial centrifugal fan of the present invention is further improved in that the number of primary guide vanes is between 11 and 17, and the number of primary guide vanes and the number of primary impeller blades are relatively prime numbers; the number of secondary guide vanes is between 17 and 23, and the number of secondary guide vanes and the number of secondary impeller blades are relatively prime numbers.

[0012] The noise-reducing dual-impeller axial centrifugal fan of the present invention is further improved in that the primary air inlet duct includes a straight flange, a blind hole nut, a contraction section and an expansion section. The blind hole flange is fixed to the straight flange, the contraction section is fixed to the middle of the straight flange, and the expansion section is fixedly connected to the rear of the contraction section.

[0013] The noise-reducing dual-impeller axial centrifugal fan of the present invention is further improved in that the secondary air inlet duct includes a contraction arc section, a conical arc section and an expansion arc section, and the conical arc section is fixedly connected between the contraction arc section and the expansion arc section.

[0014] The noise-reducing dual-impeller axial centrifugal fan of the present invention is further improved in that the first-stage impeller also includes a first-stage front impeller, a first-stage rear impeller, and a first-stage impeller core. The first-stage blades are installed between the first-stage front impeller and the first-stage rear impeller, and the first-stage impeller core is installed at the center of the first-stage rear impeller.

[0015] The technical solution of the present invention has the following beneficial effects: This invention relates to a noise-reducing dual-impeller axial centrifugal fan. The series-connected dual impellers (first-stage and second-stage impellers) and dual guide vane structure (first-stage and second-stage air ducts) allow the airflow to first be pressurized by the first-stage impeller and rectified by the first-stage guide vanes, then pressurized by the second-stage impeller and rectified by the second-stage guide vanes. This results in a longer axial flow time compared to traditional fans, effectively extending energy transfer time, dispersing pressure fluctuations, reducing airflow pulsation frequency, shifting the noise spectrum to lower frequencies, and controlling noise intensity. This solves the technical problem of high noise levels in existing locomotive fans. The use of the dual-stage impeller in this invention requires reducing the motor speed to ensure motor reliability. While the reduction in speed and the increase in diameter are inversely related, this invention ensures a decrease in circumferential velocity, significantly reducing fan noise. Fan noise is proportional to the 5th to 6th power of the airflow circumferential velocity. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is an exploded view of the noise-reducing dual-impeller axial centrifugal fan of the present invention; Figure 2 This is a front view of the first-stage impeller of the noise-reducing dual-impeller axial centrifugal fan of the present invention; Figure 3 for Figure 2 Sectional view of line AA in the middle; Figure 4 This is a front view of the secondary impeller of the noise-reducing dual-impeller axial centrifugal fan of the present invention; Figure 5 for Figure 2 Sectional view of the middle BB line; Figure 6 This is a side view of the primary air inlet duct of the noise-reducing dual-impeller axial centrifugal fan of the present invention; Figure 7 This is a side view of the secondary air inlet duct of the noise-reducing dual-impeller axial centrifugal fan of the present invention; Figure 8 This is a schematic diagram of the assembly gap between the primary air inlet and the primary impeller of the noise-reducing dual-impeller axial centrifugal fan of the present invention. Figure 9 for Figure 8 A magnified view of the C-ring; Figure 10This is a perspective view of the primary air duct of the noise-reducing double-impeller axial centrifugal fan of the present invention; Figure 11 This is an axial sectional view of the primary air duct of the noise-reducing double-impeller axial centrifugal fan of the present invention; Figure 12 for Figure 11 Sectional view of the DD line; Figure 13 This is a perspective view of the secondary air duct of the noise-reducing double-impeller axial centrifugal fan of the present invention; Figure 14 This is an axial cross-sectional view of the secondary air duct of the noise-reducing double-impeller axial centrifugal fan of the present invention.

[0018] Explanation of icon numbers: 1-First-stage air inlet duct, 11-Straight flange, 12-Blind hole nut, 13-Contraction section, 14-Expansion section, 2-First-stage impeller, 21-First-stage front impeller disc, 22-First-stage blade, 23-First-stage wheel core, 24-First-stage rear impeller disc, 3-First-stage air duct, 31-First-stage outer cylinder, 32-First-stage guide vane, 33-Junction box, 34-Reinforcing rib, 35-Mounting plate, 36-First-stage inner cylinder, 4-Second-stage impeller, 41-Second-stage front impeller disc, 42-Second-stage blade, 43-Second-stage wheel core, 44-Second-stage rear impeller disc, 5-Second-stage air duct, 51-Second-stage outer cylinder, 52-Second-stage guide vane, 53-Wind baffle ring, 54-Second-stage inner cylinder, 55-Bearing seat mounting plate, 6-Drive component, 7-Bearing seat, 8-Second-stage air inlet duct, 81-Contraction arc section, 82-Conical arc section, 83-Expansion arc section. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0021] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0022] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0024] When the locomotive is running, the traction motor provides the necessary forward power. During operation, it emits a lot of heat. A noise-reducing double-impeller axial centrifugal fan rotates at high speed, drawing in cool air from the roof side wall. After being pressurized by the impeller and rectified by the air duct, the high-pressure airflow flows out from the fan outlet and then blows along the special ventilation duct at the bottom of the locomotive to the traction motor, forcibly cooling and ventilating it. This quickly carries away the heat and blows it into the atmosphere, thereby achieving the purpose of cooling the traction motor.

[0025] like Figures 1-14 As shown, this invention proposes a noise-reducing dual-impeller axial centrifugal fan, comprising a primary air inlet duct 1, a primary impeller 2, a primary air duct 3, a secondary air inlet duct 8, a secondary impeller 4, a secondary air duct 5, and a drive component 6. The primary air inlet duct 1, the primary impeller 2, the drive component 6, the secondary air inlet duct 8, the secondary impeller 4, and the secondary air duct 5 are sequentially connected in series within the primary air duct 3. The primary impeller 2 includes primary blades 22, and the secondary impeller 4 includes secondary blades 42, the inlet edge of which is obliquely cut. The primary air duct 3 includes primary guide vanes 32, the inlet of which is provided with a primary oblique angle, and the secondary air duct 5 includes secondary guide vanes 52, the inlet of which is provided with a secondary oblique angle.

[0026] When the noise-reducing dual-impeller axial centrifugal fan of this invention is working, the airflow first passes through the first-stage impeller 2 for work and pressurization. After being rectified by the first-stage guide vanes 32, it flows into the second-stage impeller 4 for further work and pressurization. The second-stage guide vanes 52 then rectify the airflow, and finally the airflow is blown onto the traction motor for forced ventilation and cooling. The first and second-stage impellers 4 adopt a series connection structure. The aerodynamic principle of this structure is that the fan flow rate remains constant while the pressure is doubled. The series-connected first and second-stage impellers 4 each bear the pressure load that was originally borne by one impeller. The distribution of the pressure load on the two impellers can be allocated as needed based on the flow field simulation results and structural constraints. The pressure ratio can be designed as 5:5 / 4:6 / 6:4 / 7:3 or more combinations as required. To optimize the fan noise, according to the extreme value theory, this invention implements a 5:5 distribution between the first and second-stage impellers 4. The aerodynamic structure of the impeller and guide vanes is parametrically modeled using Expressions in NX software (an integrated CAD / CAE / CAM digital product development system). This model is then transferred to ANSYS Workbench (a simulation software) to build an intelligent simulation optimization process, optimizing the structural parameters to meet fan performance requirements. Simultaneously, the dual-impeller design, by appropriately increasing the impeller inlet and outlet diameters and reducing the motor speed, simultaneously reduces both the inlet airflow velocity and the outlet circumferential velocity, thus lowering noise levels. This invention, based on parametric modeling optimization, presents a dual-impeller cooling fan that meets the technical requirements of low noise and high efficiency, with a fan flow rate of 1.4 m³ / h. 3 / s, pressure not less than 3600Pa, sound power noise not greater than 98dB(A).

[0027] Preferably, such as Figure 2 and Figure 3 As shown, the oblique cutting angle of this oblique structure is between 0° and 20°, the outlet angle of the second-stage blade 42 is between 38° and 45°, and the inlet angle of the second-stage blade 42 is between 30° and 35°. The oblique cutting angle is represented by γ, the outlet angle of the second-stage blade 42 is represented by β2A, and the inlet angle of the second-stage blade 42 is represented by β1A. The oblique cutting structure can improve the uneven airflow phenomenon at the blade inlet bend. The setting of the oblique cutting angle makes the blade inlet diameter gradually increase along the blade height direction, so that the airflow enters the impeller with as little impact as possible. Similarly, the radial clearance δ (single side) between the inlet diameter of the second-stage impeller 4 and the end of the air inlet duct is maintained at 2~4mm, and the axial overlap depth h is maintained at 3~5mm. The second-stage impeller 4 pressurizes the gas from the first-stage impeller 2 a second time to reach the pressure required by the fan. In this embodiment, the outlet diameter D1 of the second-stage impeller 4 blades is 620mm~640mm, the inlet diameter D2 of the blades is 304mm~336mm, the airflow outlet height H of the impeller is 60mm~70mm, and the number of blades is 14~16.

[0028] Preferably, such as Figure 4 and Figure 5As shown, the first-stage blade 22 is an arc-shaped plate blade with an outlet angle between 32° and 40° and an inlet angle between 18° and 21°. The outlet diameter of the first-stage blade 22 of the first-stage impeller 2 is 610mm to 630mm, the inlet diameter is 281mm to 311mm, and the airflow outlet height is 82mm to 92mm to ensure sufficient flow rate. Figure 8 and Figure 9 As shown, the radial clearance δ (on one side) between the inlet diameter of the first-stage impeller 2 and the end of the air inlet duct is maintained at 2~4mm, and the axial overlap depth h is maintained at 3~5mm. The arc-shaped blades have excellent aerodynamic performance, and the inlet and outlet angles of the blades can be flexibly adjusted according to aerodynamic performance and flow field conditions. In this embodiment, the number of first-stage blades 22 is 8~12. Although the second-stage impeller 4 and the first-stage impeller 2 both bear half the pressure of the original impeller (1800Pa:1800Pa), their geometric parameters differ due to the different airflow angles during intake.

[0029] Preferably, such as Figure 11 and Figure 12 As shown, both the primary and secondary oblique cut angles are between 5° and 15°, and the inlet angles of both the primary guide vane 32 and the secondary guide vane 52 are between 20° and 50°. The primary oblique cut angle uses θ. 11 This indicates that the secondary bevel angle is θ. 21 This indicates that the inlet angle of the first-stage guide vane 32 adopts θ. 13 This indicates that the inlet angle of the second-stage guide vane 52 adopts θ. 23 express.

[0030] Preferably, such as Figure 10 and Figure 11 As shown, the primary air duct 3 also includes a primary outer duct 31, a primary inner duct 36, and a mounting plate 35. The primary inner duct 36 is installed inside the primary outer duct 31, and the mounting plate 35 is fixed inside the inner duct. The drive component 6 is installed on the mounting plate 35, and the primary guide vane 32 is installed on the outer wall of the primary inner duct 36. The primary inner duct 36 has a conical structure, and the conical structure forms an angle of 3° to 12° with the axis, expressed as θ. 12 The outer periphery of the first-stage outer cylinder 31 is provided with multiple reinforcing ribs 34 along the axial direction to increase strength. In this embodiment, the drive unit 6 is a motor. The functions of the first-stage air duct 3 are: firstly, to support the motor and connect to the air intake pipe at the bottom of the locomotive; and secondly, to rectify the high-speed airflow from the first-stage impeller 2, converting some of the gas dynamic pressure energy into static pressure energy and axially discharging the airflow. The first-stage air duct 3 also includes a junction box 33 for connecting wires. The structural dimensions of the first-stage guide vane 32 are closely related to the wind pressure, and the radius R of the arc of the first-stage guide vane 32 is... 12The length is 220mm~350mm. The above five structural parameters θ... 11 θ 12 θ 13 R 12 Parametric modeling is performed in NX with Z1 to enable multi-objective optimization design during subsequent CFD (Computational Fluid Dynamics) calculations, seeking the best-matching aerodynamic parameter values. For ease of assembly, the secondary air inlet 8 is welded inside the primary air duct 3, specifically located below the primary guide vane 32. The secondary air inlet 8 can also be assembled independently using bolt connections.

[0031] Preferably, such as Figure 13 and Figure 14 As shown, the secondary air duct 5 also includes a secondary outer duct 51 and a secondary inner duct 54. The secondary inner duct 54 is installed inside the secondary outer duct 51, and the secondary guide vane 52 is installed on the outer wall of the secondary inner duct 54. The secondary inner duct 54 has a conical structure, and the conical structure forms an angle of 3° to 12° with the axis, using θ. 22 The noise-reducing dual-impeller axial centrifugal fan also includes a bearing housing 7, and a bearing housing mounting plate 55 for mounting the bearing housing 7 is provided inside the secondary inner cylinder 54. A baffle ring 53 is also provided at the front end of the secondary inner cylinder 54. The function of the secondary air duct 5 is to perform secondary rectification of the airflow at the outlet of the secondary impeller 4, transforming the radially ejected high-speed airflow into axial flow along the guide vane inlet, while further increasing the fan static pressure, extending the energy transfer time, and dispersing the influence of pressure fluctuations. Similarly, the radius of curvature R22 of the secondary guide vane 52 is 200mm~400mm. Likewise, the five structural parameters θ of the aforementioned secondary guide vane 52... 21 θ 22 θ 23 R 22 Parametric modeling of Z2 and Z2 is performed in NX to enable multi-objective optimization design during subsequent CFD calculations, seeking the best matching aerodynamic parameter values.

[0032] Preferably, the number of primary guide vanes 32 is between 11 and 17, and the number of primary guide vanes 32 is a prime number relative to the number of blades of the primary impeller 2; the number of secondary guide vanes 52 is between 17 and 23, and the number of secondary guide vanes 52 is a prime number relative to the number of blades of the secondary impeller 4.

[0033] Preferably, such as Figure 6As shown, the primary air inlet duct 1 includes a straight flange 11, blind hole nuts 12, a contraction section 13, and an expansion section 14. The blind hole flange is fixed to the straight flange 11, the contraction section 13 is fixed to the middle of the straight flange 11, and the expansion section 14 is fixedly connected to the rear of the contraction section 13. The primary air inlet duct 1 and the secondary air inlet duct 8 function to guide the airflow at the impeller inlet, forming a funnel shape. The arc at the tail of the air inlet duct is optimally matched with the impeller inlet, allowing the airflow to enter the impeller without impact and reducing impact vortices. The primary air inlet duct 1 is connected to the primary air duct 3 by bolts, smoothly guiding the airflow into the primary impeller 2. Several blind hole nuts 12 are used to connect to the ventilation ducts of the vehicle body.

[0034] Preferably, such as Figure 7 As shown, the secondary air inlet duct 8 includes a contracting arc section 81, a conical arc section 82, and an expanding arc section 83. The conical arc section 82 is fixedly connected between the contracting arc section 81 and the expanding arc section 83. The secondary air inlet duct 8 is welded to the outlet section of the primary air duct 3 (the secondary air inlet duct 8 can also be connected by bolts). The secondary air inlet duct 8 collects the airflow rectified by the primary guide vanes 32 and evenly guides it into the secondary impeller 4 along the arc.

[0035] Preferably, the first-stage impeller 2 further includes a first-stage front impeller 21, a first-stage rear impeller 24, and a first-stage impeller core 23. The first-stage blades 22 are installed between the first-stage front impeller 21 and the first-stage rear impeller 24, and the first-stage impeller core 23 is installed at the center of the first-stage rear impeller 24. The second-stage impeller 4 has the same structure as the first-stage impeller 2, including a second-stage front impeller 41, second-stage blades 42, a second-stage rear impeller 44, and a second-stage impeller core 43. Both the second-stage impeller 4 and the first-stage impeller 2 are backward-curved centrifugal impellers. These impellers are characterized by high efficiency and low noise, and are simple to manufacture and have low production costs. The function of the first-stage impeller 2 and the second-stage impeller 4 is to perform work on the airflow, raising the airflow to a sufficient pressure after passing through the impellers to overcome the resistance of the traction motor ventilation system and provide ventilation and heat dissipation. They are one of the key components of the fan. Similarly, viewed along the air inlet and outlet directions, the first-stage impeller 2 and the second-stage impeller 4, connected in series, each bear half the pressure of the original impeller (pressure ratio 5:5), and the flow rate remains unchanged.

[0036] The use of the two-stage impeller (first-stage impeller 2 and second-stage impeller 4) in this invention reduces the motor speed from 3500 rpm to 1750 rpm to ensure motor reliability. After the speed reduction, the impeller diameter needs to be appropriately increased from 470 mm to 620 mm to ensure aerodynamic performance. The reduction in speed and the increase in diameter are mutually exclusive, but this invention ensures that the circumferential linear velocity decreases from 86.1 m / s to 56.8 m / s, which can greatly reduce the fan noise. The fan noise is proportional to the 5th to 6th power of the airflow circumferential linear velocity.

[0037] As the impeller diameter increases, the inlet diameter also needs to increase. The inlet diameter increases from 280mm to 320mm, while the airflow velocity decreases from 22.7m / s to 17.4m / s, effectively reducing inlet airflow noise.

[0038] The noise-reducing dual-impeller axial centrifugal fan of the present invention features a series of dual impellers (first-stage impeller 2 and second-stage impeller 4) + a dual guide vane structure (first-stage air duct 3 and second-stage air duct 5). This allows the airflow to be pressurized by the first-stage impeller 2 and rectified by the first-stage guide vane 32, and then pressurized by the second-stage impeller 4 and rectified by the second-stage guide vane 52. The airflow travels axially for a longer time than the original fan, effectively extending the energy transfer time, dispersing pressure fluctuations, reducing the airflow pulsation frequency, shifting the noise spectrum to lower frequencies, controlling the noise intensity, and solving the technical problem of high noise during operation of existing locomotive fans. The use of a two-stage impeller in this invention reduces the motor speed from 3500 rpm to 1750 rpm to ensure motor reliability. To maintain aerodynamic performance after the speed reduction, the impeller diameter needs to be appropriately increased from 470 mm to 620 mm. The reduction in speed and the increase in diameter are mutually exclusive, but this solution ensures that the circumferential linear velocity decreases from 86.1 m / s to 56.8 m / s, which greatly reduces fan noise. Fan noise is proportional to the 5th to 6th power of the airflow circumferential linear velocity.

[0039] After parametric modeling and D0E multi-objective parameter optimization, eight sets of optimal guide vane parameters were obtained for the guide vanes and inner cylinder, forming eight implementation examples. When the flow rate Q = 1.4 m³ / s... 3 At / s, the fan pressure P and noise power L of different embodiments WA See the table below. The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A noise-reducing dual-impeller axial centrifugal fan, characterized in that, The system includes a primary air inlet duct (1), a primary impeller (2), a primary air duct (3), a secondary air inlet duct (8), a secondary impeller (4), a secondary air duct (5), and a drive unit (6). The primary air inlet duct (1), the primary impeller (2), the drive unit (6), the secondary air inlet duct (8), the secondary impeller (4), and the secondary air duct (5) are sequentially connected in series within the primary air duct (3). The primary impeller (2) includes a primary blade (22), and the secondary impeller (4) includes a secondary blade (42). The inlet edge of the secondary blade (42) is obliquely cut. The primary air duct (3) includes a primary guide vane (32), and the inlet of the primary guide vane (32) is provided with a primary oblique angle. The secondary air duct (5) includes a secondary guide vane (52), and the inlet of the secondary guide vane (52) is provided with a secondary oblique angle.

2. The noise-reducing dual-impeller axial centrifugal fan as described in claim 1, characterized in that, The oblique cutting angle of the oblique structure is between 0° and 20°, the exit angle of the secondary blade (42) is between 38° and 45°, and the inlet angle of the secondary blade (42) is between 30° and 35°.

3. The noise-reducing dual-impeller axial centrifugal fan as described in claim 1, characterized in that, The first-stage blade (22) is an arc-shaped blade, and the exit angle of the first-stage blade (22) is between 32° and 40°, and the inlet angle of the blade is between 18° and 21°.

4. The noise-reducing dual-impeller axial centrifugal fan as described in claim 1, characterized in that, The first-level oblique angle and the second-level oblique angle are both between 5° and 15°, and the inlet angles of the first-level guide vane (32) and the second-level guide vane (52) are both between 20° and 50°.

5. The noise-reducing dual-impeller axial centrifugal fan as described in claim 1, characterized in that, The primary air duct (3) also includes a primary outer duct (31), a primary inner duct (36), and a mounting plate (35). The primary inner duct (36) is installed inside the primary outer duct (31), the mounting plate (35) is fixed inside the inner duct, the driving component (6) is installed on the mounting plate (35), and the primary guide vane (32) is installed on the outer wall of the primary inner duct (36). The primary inner duct (36) has a conical structure, and the conical structure forms an angle of 3° to 12° with the axis.

6. The noise-reducing dual-impeller axial centrifugal fan as described in claim 1, characterized in that, The secondary air duct (5) also includes a secondary outer duct (51) and a secondary inner duct (54). The secondary inner duct (54) is installed inside the secondary outer duct (51), and the secondary guide vane (52) is installed on the outer wall of the secondary inner duct (54). The secondary inner duct (54) has a conical structure, and the conical structure forms an angle of 3° to 12° with the axis.

7. The noise-reducing dual-impeller axial centrifugal fan as described in claim 1, characterized in that, The number of primary guide vanes (32) is between 11 and 17, and the number of primary guide vanes (32) is a prime number relative to the number of blades of the primary impeller (2); the number of secondary guide vanes (52) is between 17 and 23, and the number of secondary guide vanes (52) is a prime number relative to the number of blades of the secondary impeller (4).

8. The noise-reducing dual-impeller axial centrifugal fan as described in claim 1, characterized in that, The primary air inlet duct (1) includes a straight flange (11), a blind hole nut (12), a contraction section (13), and an expansion section (14). The blind hole flange is fixed to the straight flange (11), the contraction section (13) is fixed to the middle part of the straight flange (11), and the expansion section (14) is fixedly connected to the rear part of the contraction section (13).

9. The noise-reducing double-impeller axial centrifugal fan as described in claim 1, characterized in that, The secondary air intake duct (8) includes a contraction arc section (81), a conical arc section (82), and an expansion arc section (83), with the conical arc section (82) fixedly connected between the contraction arc section (81) and the expansion arc section (83).

10. The noise-reducing dual-impeller axial centrifugal fan as described in claim 1, characterized in that, The first-stage impeller (2) also includes a first-stage front impeller (21), a first-stage rear impeller (24) and a first-stage wheel core (23). The first-stage blades (22) are installed between the first-stage front impeller (21) and the first-stage rear impeller (24), and the first-stage wheel core (23) is installed at the center of the first-stage rear impeller (24).

Images