A multi-wing forward centrifugal fan with binary blade diversification

Abstract

The application relates to the field of ventilation and cooling technology of rail transit vehicles, in particular to a multi-wing forward centrifugal fan with diversified binary blades, which comprises an air inlet, a casing, an impeller, a shaft sleeve and a motor, the air inlet is connected to the inlet end of the casing, the motor is connected to the outlet end of the casing, the impeller is contained in the casing, one end of the impeller is connected to the motor through the shaft sleeve, and the ratio of the air inlet gas inlet diameter to the air outlet diameter of the air inlet ranges from 1.12 to 1.3; the impeller comprises an impeller front disc, an impeller rear disc, blades and a shaft sleeve, the blades are connected between the impeller front disc and the impeller rear disc, the impeller rear disc is connected to the driving shaft of the motor through the shaft sleeve, and the impeller front disc is gradually expanded and formed by arc segment rotation; the ratio of the impeller height to the casing width ranges from 0.55 to 0.8. The application has the advantages of high practicability and high value by optimizing the structural design, improving the aerodynamic performance and structural strength of the fan, and effectively reducing the noise.

Description

Technical Field

[0001] This application relates to the field of ventilation and cooling technology for rail transit vehicles, specifically to a binary blade optimization design technology for a multi-blade forward centrifugal fan applied to the ventilation and cooling system of a traction motor in rail transit vehicles. Background Technology

[0002] As rail transit vehicles continue to develop towards high speed and heavy load, the traction motor, as the core power equipment of the vehicle, is experiencing an increasing heat load during operation. The ventilation and cooling system is a key component in ensuring the insulation life and operational reliability of the traction motor, and its performance directly affects the overall efficiency and operational safety of the motor. In existing technologies, multi-bladed forward-curved centrifugal fans are widely used in ventilation and cooling systems of rail transit vehicles due to their advantages such as compact structure, high flow coefficient, and smooth noise spectrum. Their core working principle involves generating centrifugal force through the rotation of forward-mounted multi-bladed blades, thereby pressurizing and transporting gas. The binary blades, as the core aerodynamic component of this type of fan, directly determine the aerodynamic performance and operational stability of the fan, including total pressure, efficiency, flow range, etc., based on their profile design, number of blades, outlet angle, and chord length distribution. However, current multi-bladed forward-curved centrifugal fans suffer from technical shortcomings such as low efficiency, high energy consumption, and excessive noise, making it difficult to meet the urgent requirements of next-generation traction systems for "high efficiency, energy saving, and environmental protection." In terms of aerodynamic performance, the existing fan impeller aerodynamic design is not well-matched with the volute flow channel structure, resulting in significant airflow separation and vortices within the flow channel, causing energy loss. Regarding noise control, the coupling effect of airflow disturbance and structural vibration leads to excessive fan operating noise, affecting the overall acoustic environment of the vehicle. Furthermore, with the tightening of energy conservation and environmental protection policies and the upgrading of end products, the market has put forward higher requirements for wind turbines, including higher efficiency (reducing energy consumption), wider operating conditions (adapting to stable operation in multiple flow ranges), and lower noise (reducing aerodynamic and mechanical noise). Therefore, conducting optimized design of multi-bladed forward centrifugal fans with diversified binary blades to achieve synergistic optimization of aerodynamic performance, structural design and noise level has become a key technical issue to ensure the performance upgrade of rail transit vehicle power systems. Utility Model Content

[0003] The purpose of this application is to provide a multi-bladed forward centrifugal fan with two blades to solve the problems of general aerodynamic performance, unreasonable structural design and excessive noise in the existing technology.

[0004] The embodiments of this application can be implemented through the following technical solutions: A multi-bladed forward centrifugal fan with two blades includes an air inlet, a casing, an impeller, a shaft sleeve, and a motor. The air inlet is connected to the inlet end of the casing, the motor is connected to the outlet end of the casing, the impeller is housed in the casing, and one end of the impeller is connected to the motor through the shaft sleeve. The air inlet includes an air inlet flange, an air inlet neck section, and an air inlet mounting flange that are smoothly connected in sequence. The air inlet diameter is... air inlet and outlet diameter The ratio ranges from 1.12 to 1.3; The impeller includes a front impeller disc, a rear impeller disc, blades, and a bushing. The blades are connected between the front impeller disc and the rear impeller disc. The rear impeller disc is coaxially connected to the drive shaft of the motor through the bushing. The front impeller disc is in a gradually expanding shape formed by rotating an arc segment. Impeller height With the width of the casing The ratio ranges from 0.55 to 0.8.

[0005] Furthermore, the housing includes a front panel, a side panel, and a rear panel. The front panel and the rear panel each have an opening extending through their axial direction in the middle. The side panel is connected between the front panel and the rear panel, together forming a housing structure that is closed on all four sides and has an axially extending flow channel in the middle. The air inlet is installed at the opening of the front panel. Effective outlet length of the casing With the width of the casing The ratio ranges from 1 to 1.3.

[0006] Furthermore, the side plate includes a volute plate, a first relief plate, and a second relief plate. The volute plate is an arc-shaped panel with two notches facing the front side plate. The first relief plate and the second relief plate are both flat plate structures and are respectively located at the two notches of the front side plate. One end of the first relief plate and the second relief plate are smoothly connected to the volute plate, and the other end is connected to the front side plate. The front side plate has a cross-section at the connection point with the first relief plate and the second relief plate. Two interface flanges are respectively connected to the first relief plate and the second relief plate. Along the axial direction of the centrifugal fan, the interface flanges are exposed to the outside through the cross-section of the front side plate.

[0007] Furthermore, the profile of the worm plate at the rear side plate is composed of the rear side plate worm line, the rear side plate worm tongue, and the rear side plate exit line; the profile of the worm plate at the front side plate is composed of the front side plate worm line, the front side plate worm tongue, and the front side plate exit line; both the front side plate worm tongue and the rear side plate worm tongue are arc structures, and the arc radius of the front side plate worm tongue is larger than the arc radius of the rear side plate worm tongue.

[0008] Furthermore, the worm gear of the front side plate coincides with the worm gear trajectory of the rear side plate, and the length of the worm gear of the rear side plate is greater than that of the worm gear of the front side plate. The exit line of the front side plate coincides with the exit line trajectory of the rear side plate, and the length of the exit line of the rear side plate is greater than that of the exit line of the front side plate.

[0009] Furthermore, the angle between the front side plate volute tongue and the rear side plate volute tongue... The value range is 3° to 8°.

[0010] Furthermore, the volute portion of the housing is provided with two different airfoil-shaped heads instead of the traditional volute arc. The convex surface of the airfoil is tangent to the exit line of the housing, and the concave surface is tangent to the volute line.

[0011] Furthermore, the air inlet throat diameter of the air inlet neck section air inlet and outlet diameter The ratio ranges from 0.95 to 0.99, and the throat diameter height... Height of air inlet The ratio ranges from 0.36 to 0.5.

[0012] Furthermore, the front disc inlet diameter With the outer diameter of the front disc The ratio ranges from 0.75 to 0.82; The height of the inlet end of the impeller front disc With impeller height The ratio ranges from 0.1 to 0.3.

[0013] Furthermore, the impeller rear plate is a flat plate, and the diameter of the rear plate is... With the outer diameter of the front disc The ratio is 0.9 to 1.

[0014] The embodiments of this application provide a multi-bladed forward centrifugal fan with two blades and multiple winglets, which has at least the following beneficial effects: (1) The total pressure of the optimized fan at each operating point is 5.74% higher than that of the original fan, the total pressure efficiency is increased by about 5%, and the high efficiency range is further expanded, which can more efficiently meet the power output requirements of the new generation traction system and meet the core requirements of "high efficiency and energy saving". (2) The total pressure efficiency curve changes smoothly, and the aerodynamic stability under rated air volume and total pressure conditions is significantly improved, which can effectively reduce the risk of fluctuations during operation and extend the service life of the fan. (3) The operating noise at each working point is reduced by 5.7 to 9.7 dB(A) compared with the original fan, which greatly optimizes the operating environment and fully meets the urgent requirements of "environmental protection"; (4) It can directly replace the original fan without adjusting the installation space and related adaptation structure. While solving the problems of insufficient flow and flow field interference caused by limited axial space, it perfectly adapts to the comprehensive performance requirements of the new generation traction system for the fan to be "high efficiency, energy saving and environmental protection", and has extremely high application value. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of a binary blade multi-blade forward centrifugal fan according to this application. Figure 2a This is a partial side sectional schematic diagram of a multi-bladed forward centrifugal fan with two blades according to this application. Figure 2b This is a magnified view of a portion of the overlap between the air inlet and the impeller. Figure 3 This is a schematic diagram of the air inlet structure in this application; Figure 4 This is a schematic diagram of the casing structure in this application; Figure 5 This is a schematic diagram of the housing structure in this application after the front side panel has been removed. Figure 6 This is a schematic diagram of the volute portion of the fan casing in this application; Figure 7 This is a schematic diagram of the fan casing outlet from the perspective of this application; Figure 8 This is a schematic diagram of the velocity curve of the fan casing in this application; Figure 9 This is a schematic diagram of the overall structure of an impeller according to this application; Figure 10 This is a partial side sectional view of an impeller according to this application; Figure 11 This is a schematic diagram of the forming line of the blade in this application; Figure 12 This is a schematic diagram of the blade tilt angle and blade exit edge adjustment in this application; Figure 13 This is a schematic diagram of the airfoil blade manufactured by casting in this application; Figure 14 This is a schematic diagram of the intersection lines between the blade and different cross sections in this application; Figure 15 This application contains a schematic diagram of the fan flow-pressure curve. Figure 16 This application includes a schematic diagram of the fan flow efficiency curve; Figure 17 This application presents a schematic diagram of the fan flow rate and noise curve.

[0016] Numbers in the diagram 1. Air inlet; 2. Housing; 3. Impeller; 4. Shaft sleeve; 5. Motor; 6. Protective net; 7. Connecting parts; 101, Air inlet flange; 102, Air inlet neck section; 103, Air inlet mounting flange; 201, Front side plate; 202, Side plate; 203, Rear side plate; 204, Outlet flange; 205, Interface flange; 206, Reinforcing rib; 2051, Spiral plate; 2052, First clearance plate; 2053, Second yield plate; 2051-1, Rear side plate worm line; 2051-2, Rear side plate worm tongue; 2051-3, Rear side plate exit line; 2051-4, Front side plate worm line; 2051-5, Front side plate worm tongue; 2051-6, Front side plate exit line. Detailed Implementation

[0017] The present application will now be further described based on preferred embodiments and with reference to the accompanying drawings.

[0018] Furthermore, for ease of understanding, various components on the drawings have been enlarged or reduced, but this is not intended to limit the scope of protection of this application.

[0019] Singular forms of words also include plural meanings, and vice versa.

[0020] In the description of the embodiments of this application, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use, they are only for the convenience of describing this application and simplifying the description, and 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 a limitation on this application. In addition, in the description of this application, in order to distinguish different units, the terms "first," "second," etc. are used in this specification, but these are not limited by the manufacturing order, nor should they be construed as indicating or implying relative importance. Their names may differ in the detailed description and claims of this application.

[0021] The vocabulary used in this specification is for illustrative purposes and is not intended to limit the scope of this application. It should also be noted that, unless otherwise expressly specified and limited, the terms "set," "connected," and "linked" 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 via an intermediate medium; or they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of these terms in this application.

[0022] like Figure 1, Figure 2a As shown, a multi-bladed forward centrifugal fan with two blades includes an air inlet 1, a housing 2, an impeller 3, a bushing 4, and a motor 5. The air inlet 1 is located at one end of the impeller 3, and the other end of the impeller 3 is connected to the motor 5 through the bushing 4. The drive shaft of the motor 5 is coaxially arranged with the axis of the impeller 3. The housing 2 is fitted around the outside of the impeller 3. The two ends of the housing 2 are connected to the air inlet and the motor 5 respectively through connectors 7 to form a closed and continuous airflow channel.

[0023] During operation, after the motor 5 starts, it drives the impeller 3 to rotate synchronously through the bushing 4. The negative pressure generated by the rotation of the impeller 3 causes outside air to be smoothly drawn into the impeller 3 from the air inlet 1. After the airflow enters, it undergoes centrifugal motion along the blade channel under the push of the binary multi-dimensional blades 303 of the impeller 3, and is simultaneously endowed with kinetic energy and pressure energy. Finally, under the action of pressure difference, it is efficiently transported to the designated outlet along the flow channel of the casing 2, completing the complete airflow cycle of intake-pressurization-delivery.

[0024] In some preferred embodiments, such as Figure 2a As shown, the air inlet 1 includes an air inlet flange 101, an air inlet neck section 102, and an air inlet mounting flange 103 arranged in sequence. A protective net 6 is installed at the inlet end of the air inlet flange 101 to block foreign objects from entering the fan and protect core components such as the impeller and motor. The air inlet mounting flange 103 is fixedly connected to the casing 2 to form a sealed and stable airflow channel, guiding outside air to flow smoothly into the impeller, while ensuring the reliability of the connection between the air inlet and the casing and preventing airflow leakage.

[0025] In some preferred embodiments, such as Figure 3 As shown, the air inlet neck section 102 is formed by rotating 1 to 3 arc segments. One end of the air inlet neck section 102 is tangent to the air inlet flange 101, and the beginning and end of each arc segment are tangent to each other, forming a smooth transition curved surface structure.

[0026] In some preferred embodiments, the inner diameter of the inlet end face of the inlet flange 101, i.e., the diameter of the circular opening of this port along the direction perpendicular to the inlet axis, is defined as the inlet diameter. The inner diameter of the outlet end face of the inlet mounting flange 103, that is, the diameter of the circular opening at this port along the direction perpendicular to the inlet axis, is defined as the inlet outlet diameter. Air inlet diameter air inlet and outlet diameter The ratio ranges from 1.12 to 1.3, and it is used to guide airflow to flow smoothly along curved surfaces without impact, avoiding eddies and impact losses caused by sudden changes in airflow.

[0027] In some preferred embodiments, the diameter of the section at the lowest point of the concave surface formed by the arc segment of the air inlet neck 102 along the direction perpendicular to the air inlet axis is defined as the air inlet throat diameter. air inlet throat diameter air inlet and outlet diameter The ratio ranges from 0.95 to 0.99, and it is used to ensure stable airflow velocity and improve intake efficiency while widening the intake channel.

[0028] In some preferred embodiments, the distance from the lowest point of the concave arc segment of the inlet neck section 102 to the end face of the outlet flange 103 along the inlet axis is defined as the throat height. The straight-line distance between the inlet end face of the inlet flange 101 and the outlet end face of the inlet mounting flange 103 along the inlet axis is defined as the inlet height. Throat height Height of air inlet The ratio range is 0.36 to 0.5. Through the above settings, the throat diameter of the air inlet is placed at the optimal position for airflow introduction, guiding the airflow to flow smoothly along the curved surface of the neck section, providing a uniform and stable inflow for the impeller 3, and synergistically improving the intake efficiency and the stability of the fan operation.

[0029] Based on the smooth airflow introduction design of the air inlet 1, in order to further optimize the aerodynamic performance of the whole machine and reduce noise, this application also optimizes the casing 2 in a coordinated structure.

[0030] In some preferred embodiments, such as Figure 4 As shown, the housing 2 includes a front side plate 201, a side plate 202, a rear side plate 203, an outlet flange 204, an interface flange 205, and a reinforcing rib 206. The front side plate 201 and the rear side plate 203 each have an opening extending along their axial direction in the middle. The side plate 202 is connected between the front side plate 201 and the rear side plate 203, together forming a housing structure that is closed on all sides and has an axially extending flow channel in the middle. The air inlet 1 is installed at the opening of the front side plate 201. The interface flange 205 is connected to the side plate 202. The reinforcing rib 206 is connected between the outlet flange and the front side plate 201 and / or the rear side plate 203 to enhance the strength of the overall structure.

[0031] In some preferred embodiments, the side plate 202 includes a volute plate 2051, a first clearance plate 2052, and a second clearance plate 2053. The volute plate 2051 is an arc-shaped panel with two notches facing the front side plate 201. The first clearance plate 2052 and the second clearance plate 2053 are both flat plate structures and are respectively disposed at the two notches of the front side plate 201. One end of the first clearance plate 2052 and the second clearance plate 2053 is smoothly connected to the volute plate 2051, and the other end is connected to the front side plate 201. The front side plate 201 is cut at the connection point with the first clearance plate 2052 and the second clearance plate 2053. The two interface flanges 205 are respectively connected to the first clearance plate 2052 and the second clearance plate 2053, so that the interface flanges 205 can be exposed through the cut surface of the front side plate 201 along the axial direction of the centrifugal fan for easy installation.

[0032] In some preferred embodiments, such as Figure 5 As shown, the profile of the worm plate 2051 at the rear side plate 203 is composed of the rear side plate worm line 2051-1, the rear side plate worm tongue 2051-2, and the rear side plate exit line 2051-3, with each adjacent line segment connected tangentially; the profile of the worm plate 2051 at the front side plate 201 is composed of the front side plate worm line 2051-4, the front side plate worm tongue 2051-5, and the front side plate exit line 2051-6, with each adjacent line segment also connected tangentially.

[0033] In some preferred embodiments, the worm gear 2051 is formed by connecting the profile lines at the front side plate 201 and the rear side plate 203. The worm line 2051-4 of the front side plate coincides with the worm line 2051-1 of the rear side plate, and the length of the worm line 2051-1 of the rear side plate is greater than that of the worm line 2051-4 of the front side plate. The exit line 2051-6 of the front side plate coincides with the exit line 2051-3 of the rear side plate, and the length of the exit line 2051-3 of the rear side plate is greater than that of the exit line 2051-6 of the front side plate.

[0034] In some preferred embodiments, both the front side plate volute 2051-5 and the rear side plate volute 2051-2 are arc-shaped structures, and the radius of the arc of the front side plate volute 2051-5 is larger than the radius of the arc of the rear side plate volute 2051-2. For example... Figure 7 As shown, the angle in the vertical direction between the geometric center lines (or the curvature center axis of the arc segment) of the front side plate volute tongue 2051-5 and the rear side plate volute tongue 2051-2, which are perpendicular to the rear side plate, and the volute tongue, is defined as the tilt angle. The angle formed by the side plate volute tongue 2051-5 and the rear side plate volute tongue 2051-2 The value range is 3° to 8°, such as Figure 8 As shown, by designing the gap difference between the impeller and the volute tongue in the width direction and the inclined structure of the volute tongue, the uniform frequency of dynamic and static interference between the impeller and the volute tongue can be effectively broken, thereby reducing noise.

[0035] In some preferred embodiments, such as Figure 6 As shown, the volute tongue portion of the housing 2 can be replaced by two different airfoil heads instead of the traditional volute tongue arc. The convex surface of the airfoil is tangent to the exit line of the housing 2, and the concave surface is tangent to the volute line. This design can significantly reduce the aerodynamic losses of the traditional volute tongue arc portion and further optimize the flow field characteristics.

[0036] The velocity variation curve of the medium within the space enclosed by the cylindrical surface of the impeller outer diameter and the casing is as follows: Figure 8 As shown in the figure, "Original" represents the velocity variation curve before optimization, and "New" represents the velocity variation curve after optimization. The horizontal axis represents the flow channel development length from the volute tongue to the fan outlet, and the vertical axis represents the medium velocity at the corresponding cross-section. The curve characteristics show that the medium velocity is the highest at the volute tongue and the lowest at the outlet. After optimization, the medium velocity at the volute tongue is reduced by half compared to before optimization, while the velocity at the outlet remains the same. Furthermore, the curvature change of the optimized velocity curve is smoother, and the overall velocity level is lower. Under the premise that the fan outlet position and size remain unchanged, the casing achieves a maximized and continuously smooth profile design within a limited space, ultimately achieving the goal of minimizing the medium velocity inside the casing. The lower the medium velocity, the lower the aerodynamic loss, the higher the fan efficiency, and the lower the operating noise.

[0037] Meanwhile, to ensure that the installation position and interface size of the connecting flange remain unchanged and do not affect the overall installation space, two clearance plates are provided on the side plate of the casing. These clearance plates adopt a flat plate structure, which is simple to process and manufacture; numerical comparison calculations have verified that the presence or absence of clearance plates has an impact on the overall performance of the fan that is controlled within 1%, and has almost no impact on the fan's operating effect.

[0038] In addition, the efficiency of the fan is also limited by the axial installation space. The axial dimension is limited, and the length of the bushing 4 extending into the impeller is too large, which seriously affects the flow capacity of the medium. In order to reduce the interference of the bushing 4 on the flow field, the structure of the impeller 3 is optimized. The specific optimization design is as follows.

[0039] In some preferred embodiments, such as Figure 9 , Figure 10 As shown, the impeller 3 includes an impeller front plate 301, an impeller rear plate 302, blades 303 and a bushing 4. The blades 303 are connected between the impeller front plate 301 and the impeller rear plate 302. The impeller rear plate 302 is coaxially connected to the drive shaft of the motor 5 through the bushing 4 to ensure that the motor can drive the impeller to rotate synchronously and smoothly after starting.

[0040] In some preferred embodiments, the impeller front disc 301 is formed by rotating an arc segment, and one side of it is provided with a small-diameter port adapted to the air inlet. This port has a smooth, gradually widening design along the airflow direction, and its overall outline conforms to the airflow guide trajectory, forming a trumpet-shaped structure of "small-end air inlet, gradually widening guide". The small-diameter port of the impeller front disc 301 is the inlet, and the outwardly widening large-diameter port is the guide port. The diameter of the inlet is defined as the front disc inlet diameter. The diameter of the flow guide port is defined as the diameter of the outer edge of the front disc. The front disc inlet diameter With the outer diameter of the front disc The ratio ranges from 0.75 to 0.82 and is used to optimize the airflow introduction path and reduce inlet impact loss.

[0041] In some preferred embodiments, the axial length from the guide port to the inlet is equal to the inlet height. The axial length from the inlet end of the impeller front plate 301 to the impeller rear plate 302 is equal to the impeller height. The height of the inlet end of the impeller front disc 301 With impeller height The ratio ranges from 0.1 to 0.3, which is used to widen the effective flow cross section inside the impeller 3 within a limited axial space, reduce the interference of the bushing on the flow field, and improve the flow capacity and flow field stability of the impeller 3.

[0042] Through the above structural design, the arc-shaped impeller front disc 301 possesses multiple technical advantages: First, it can guide airflow along the arc surface to achieve smooth speed changes and turns, avoiding abrupt changes in airflow state, significantly reducing intake impact loss and eddy current loss, and improving airflow efficiency; Second, the arc profile can effectively buffer the direct impact between the airflow and the front disc surface, weakening the intensity of airflow disturbance, thereby suppressing the generation of turbulent noise. This advantage is more prominent under high-speed conditions, helping the fan achieve low-noise operation; Third, it can optimize the airflow angle of attack distribution at the blade inlet, allowing the airflow to adhere and flow evenly along the blade inlet, avoiding local airflow separation, which not only broadens the stable operating range of the fan but also greatly enhances its anti-surge capability, ensuring reliable operation of the fan under different operating conditions.

[0043] In some preferred embodiments, the impeller height With the outer diameter of the front disc The ratio ranges from 0.45 to 0.55, which allows for wider flow channels and matching of fan pressure characteristics within a limited axial space, while avoiding airflow stagnation or insufficient flow.

[0044] In some preferred embodiments, the impeller rear plate 302 is a flat plate, and the diameter of the impeller rear plate 302 is defined as the rear plate diameter. The diameter of the rear disc With the outer diameter of the front disc The ratio is 0.9 to 1, which is used to maximize the flow cross section, ensure the blade is under balanced stress and avoid airflow deviation, and improve the flow field stability and pressure transmission efficiency.

[0045] In some preferred embodiments, such as Figure 11 As shown, the blade 303 is formed by stretching a circular arc. The angle between the tangent at the inlet end of the blade 303 and the tangent in the impeller rotation direction is defined as the blade inlet angle. The inlet angle of the blade 303 The angle between the tangent at the exit end of the blade 303 and the tangent in the impeller rotation direction is defined as the blade exit angle, which is 45°-70°. The exit angle of the blade 303 The inlet diameter is defined as the radius of the arc along the axis perpendicular to the impeller's rotation axis at the inlet end of blade 303, which is 152° to 168°. The inlet diameter of the blade 303 With the outer diameter of the front disc The ratio ranges from 0.35 to 0.42. The radius of the arc along the axis perpendicular to the impeller rotation axis at the outlet end of the blade 303 is defined as the blade outlet diameter. The outlet diameter of blade 303 With the outer diameter of the front disc The ratio ranges from 0.48 to 0.49, and it is used to achieve smooth airflow introduction, full work and efficient output in structures with limited axial dimensions, while taking into account the flow capacity, pressure performance and operational stability of the fan.

[0046] In some preferred embodiments, the blades 303 are arranged in an inclined manner, keeping the maximum diameter at the impeller front disc 301 unchanged. Figure 12 As shown, the angle between the generatrix of the blade 303 and the impeller axis is defined as the blade tilt angle. The blade tilt angle of the blade 303 The value range is 82°-88°. The exit edge of the blade 303 adopts a composite cutting edge design of "large wave edge + small wave tooth": the large wave is distributed with 1 to 2 wavelengths in the width direction of the blade, and the ratio of its amplitude to wavelength is 0.05 to 0.07; the small wave is distributed with 10 to 15 wavelengths in the width direction of the blade, and the ratio of its amplitude to wavelength is 0.9 to 1.1.

[0047] Large wavy teeth are used to adjust the blade exit edge, minimizing the velocity difference between the same volute cross-section segments based on the internal flow field diagram. Small wavy teeth break up large-scale vortices detached from the trailing edge, suppressing airflow separation and weakening the generation and propagation of vortex noise, achieving the dual goals of "noise reduction + efficiency improvement". Sawtooths cut large vortices into multiple smaller vortices, reducing vortex intensity, lowering flow resistance, and improving fan efficiency; vortex shedding is one of the main sources of aerodynamic noise in fans, and smaller vortices have higher frequencies and more dispersed energy, avoiding frequencies sensitive to the human ear. At the same time, the sawtooth structure can disrupt the coherence of noise, achieving a noise reduction effect; the guiding effect of the sawtooth tips can improve the airflow adhesion state on the blade surface, reduce the separation zone area, and improve the fan's stable operating range and anti-surge capability.

[0048] like Figure 13 As shown, if the casting process is adopted, the blade cross section should preferably adopt a non-uniform thickness airfoil thickening design, in which the toothed part at the tail is kept of uniform thickness, while the concave toothed part is thinned to form a fishtail-like structure, which takes into account both structural strength and airflow adaptability.

[0049] The wind turbine blades in this application are comparable in manufacturing difficulty to binary blades, yet possess diverse attributes: such as... Figure 14 As shown, any cross-section parallel to the back disk along the blade width direction exhibits differences in its intersection line with the blade in terms of inlet angle, outlet angle, inlet diameter, outlet diameter, intersection line length, and blade thickness. This allows for precise adaptation to complex flow fields, achieving a comprehensive improvement in "wide operating conditions, high efficiency, low noise, and high stability." These multi-faceted characteristics mitigate problems such as inlet airflow impact, mid-section turbulence separation, and outlet vortex shedding, resulting in a more uniform distribution of velocity and pressure fields within the impeller flow channel. This reduces local vortex losses, thereby improving the overall energy conversion efficiency. Simultaneously, it disperses vortex shedding frequencies, preventing the superposition of single-frequency noise and reducing the impact noise between the airflow and the blade.

[0050] In some preferred embodiments, the number of blades 303 is 24 to 36, to avoid insufficient pressure due to too few blades and flow channel blockage due to too many blades.

[0051] Preferably, the number of blades 303 is 32, which takes into account both flow efficiency and pressure performance, and can suppress airflow interference noise between blades, thus adapting to the complex flow field requirements of multi-blade systems.

[0052] In some preferred embodiments, the length of the housing 2 along the axis of rotation is defined as the housing width. impeller height With the width of the casing The ratio ranges from 0.55 to 0.8, which avoids impeller height... Too small a cross-section leads to a reduction in the flow passage, exacerbating the insufficient flow caused by excessive shaft extension, and also preventing... Excessive size will interfere with the inner wall of the casing 2 or exceed the axial installation limit. At the same time, reasonable diffusion space is reserved for the airflow discharged from the impeller 3 to reduce the airflow transition impact loss. In conjunction with the low-loss profile design of the casing 2, aerodynamic efficiency and operational stability are ensured in confined space.

[0053] like Figure 5 As shown, the portion of the outlet flange 204 along its inner length through which airflow passes is called the effective outlet length of the casing. Effective exit length of the casing With the width of the casing The ratio ranges from 1 to 1.3, providing ample diffusion space for the airflow, enabling a smooth conversion of kinetic energy into pressure energy, and reducing aerodynamic losses at the outlet.

[0054] like Figure 2b As shown, Figure 2b This is a magnified view of the part where the air inlet and the impeller overlap. The overlap is a butt joint, meaning that the air inlet is not inserted into the impeller and the air inlet and the impeller do not overlap axially. The overlap gap is the minimum gap between the air inlet and the impeller, which is 2 to 5 mm.

[0055] The following optimized effects were obtained from the performance and noise test results: like Figure 15 As shown, the horizontal axis represents flow rate, and the vertical axis represents total pressure. Pressure increases to varying degrees at each operating point. Figure 16 As shown, the horizontal axis represents flow rate, and the vertical axis represents total pressure efficiency. Efficiency improved to varying degrees at each operating point, and the changes were stable, indicating more stable operation. Figure 17 As shown, the horizontal axis represents flow rate, and the vertical axis represents noise. Noise levels at each operating point are reduced to varying degrees. After optimization, the total pressure of the fan at each operating point is increased by 5.74%, the total pressure efficiency is increased by about 5%, the high-efficiency range is expanded, and the noise level during full-curve operation is reduced by 5.7–9.7 dB(A). The aerodynamic stability under rated airflow and total pressure conditions is significantly improved.

[0056] The specific embodiments of this application have been described in detail above. For those skilled in the art, several improvements and modifications can be made to this application without departing from the principle of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A multi-bladed forward centrifugal fan with two blades, comprising an air inlet (1), a casing (2), an impeller (3), a bushing (4), and a motor (5), wherein the air inlet (1) is connected to the inlet end of the casing (2), the motor (5) is connected to the outlet end of the casing (2), the impeller (3) is housed within the casing (2), and one end of the impeller (3) is connected to the motor (5) via the bushing (4), characterized in that: The air inlet (1) includes an air inlet flange (101), an air inlet neck section (102), and an air inlet mounting flange (103) that are smoothly connected in sequence. The air inlet diameter is... air inlet and outlet diameter The ratio ranges from 1.12 to 1.3; The impeller (3) includes an impeller front plate (301), an impeller rear plate (302), blades (303) and a bushing (4). The blades (303) are connected between the impeller front plate (301) and the impeller rear plate (302). The impeller rear plate (302) is coaxially connected to the drive shaft of the motor (5) through the bushing (4). The impeller front plate (301) is gradually expanding in the shape formed by the rotation of an arc segment. Impeller height With the width of the casing The ratio ranges from 0.55 to 0.

8.

2. The binary blade multi-blade forward centrifugal fan according to claim 1, characterized in that: The housing (2) includes a front side plate (201), a side plate (202), and a rear side plate (203). The front side plate (201) and the rear side plate (203) are provided with openings that run through their axes in the middle. The side plate (202) is connected between the front side plate (201) and the rear side plate (203) to form a housing structure that is closed on all sides and has an axial flow channel in the middle. The air inlet (1) is installed at the opening of the front side plate (201). Effective outlet length of the casing With the width of the casing The ratio ranges from 1 to 1.

3.

3. The binary blade multi-blade forward centrifugal fan according to claim 2, characterized in that: The side panel (202) includes a spiral plate (2051), a first relief plate (2052), and a second relief plate (2053). The spiral plate (2051) is an arc-shaped panel with two notches facing the front side panel (201). The first relief plate (2052) and the second relief plate (2053) are both flat plate structures and are respectively located at the two notches of the front side panel (201). One end of the first relief plate (2052) and the second relief plate (2053) The first end is smoothly connected to the worm plate (2051), and the other end is connected to the front side plate (201). The front side plate (201) is used to connect with the first relief plate (2052) and the second relief plate (2053) with a cross-section. Two interface flanges (205) are respectively connected to the first relief plate (2052) and the second relief plate (2053). Along the axial direction of the centrifugal fan, the interface flanges (205) are exposed to the outside through the cross-section of the front side plate (201).

4. The binary blade multi-blade forward centrifugal fan according to claim 3, characterized in that: The profile of the worm plate (2051) at the rear side plate (203) is composed of the rear side plate worm line (2051-1), the rear side plate worm tongue (2051-2), and the rear side plate exit line (2051-3). The profile of the worm plate (2051) at the front side plate (201) is composed of the front side plate worm line (2051-4), the front side plate worm tongue (2051-5), and the front side plate exit line (2051-6). Both the front side plate worm tongue (2051-5) and the rear side plate worm tongue (2051-2) are arc structures, and the arc radius of the front side plate worm tongue (2051-5) is greater than that of the rear side plate worm tongue (2051-2).

5. The binary blade multi-blade forward centrifugal fan according to claim 4, characterized in that: The trajectories of the front side plate worm line (2051-4) and the rear side plate worm line (2051-1) coincide, and the length of the rear side plate worm line (2051-1) is greater than that of the front side plate worm line (2051-4). The trajectories of the front side plate exit line (2051-6) and the rear side plate exit line (2051-3) coincide, and the length of the rear side plate exit line (2051-3) is greater than that of the front side plate exit line (2051-6).

6. The binary blade multi-blade forward centrifugal fan according to claim 5, characterized in that: The angle between the front side plate volute (2051-5) and the rear side plate volute (2051-2) The value range is 3° to 8°.

7. The binary blade multi-blade forward centrifugal fan according to claim 4, characterized in that: The volute of the housing (2) is replaced by two different airfoil heads instead of the traditional volute arc. The convex surface of the airfoil is tangent to the exit line of the housing (2), and the concave surface is tangent to the volute line.

8. The binary blade multi-blade forward centrifugal fan according to claim 1, characterized in that: The air inlet throat diameter of the air inlet neck section (102) air inlet and outlet diameter The ratio ranges from 0.95 to 0.99, and the throat diameter height... Height of air inlet The ratio ranges from 0.36 to 0.

5.

9. The binary blade multi-blade forward centrifugal fan according to claim 1, characterized in that: Front disc inlet diameter With the outer diameter of the front disc The ratio ranges from 0.75 to 0.82; The inlet height of the impeller front disc (301) With impeller height The ratio ranges from 0.1 to 0.

3.

10. The binary blade multi-blade forward centrifugal fan according to claim 9, characterized in that: The impeller back plate (302) is a flat plate, and the diameter of the back plate is... With the outer diameter of the front disc The ratio is 0.9 to 1.

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