Plate-type semi-airfoil blade impeller of ventilation axial flow fan

Abstract

The plate-type half-wing blade impeller of the ventilation axial flow fan comprises a hub and a plurality of blades, and a central axis z is arranged at the axis of the hub; blade roots of the multiple blades are welded to the periphery of the hub around the central axis z, and an impeller structure is formed. Any blade is provided with a suction wall surface and a pressure wall surface, the suction wall surface is provided with a bulge structure and forms a suction surface bulge, the pressure wall surface is internally provided with a pressure surface inner wall, and the pressure wall surface is also provided with a pressure surface wing-shaped outer wall. The technical problems that in the prior art, a blade in an axial flow fan is low in operation efficiency and serious in energy loss, and the working efficiency of the blade is invisibly reduced are solved.

Description

Technical Field

[0001] The invention relates to the technical field of blades, and in particular to a plate-type semi-winglet blade impeller for a ventilation axial flow fan. Background Art

[0002] The working principle of axial flow fans is based on the flow of air in the axial direction. When the motor drives the impeller to rotate, the blades are arranged at a certain angle and speed, exerting thrust on the inhaled air to make it flow in the axial direction. The thrust of the blades converts the mechanical energy into the kinetic energy of the fluid, and further converts the kinetic energy into pressure energy through components such as guide vanes and diffusers, thereby realizing the transportation of gas. Axial flow fans are widely used in various fields due to their advantages such as high efficiency, energy saving and low noise.

[0003] In Chinese patent application document CN117167323A, "a trailing edge noise reduction structure for the blade tip of an axial flow fan blade" is proposed. The device includes a fan body, a fan blade, and a trailing edge noise reduction structure. The trailing edge noise reduction structure is located at the trailing edge of the blade tip of the fan blade, and the bottom is flush with the leeward side of the trailing edge of the fan blade, and extends along the edge of the blade tip; wherein the front end part of the trailing edge noise reduction structure is an integral whole with the fan blade, and the rear end part of the trailing edge noise reduction structure is suspended outside the trailing edge of the fan blade, and the airflow can flow through the inner cavity of the trailing edge noise reduction structure that runs through the front and back; when the fan rotates, the fan blades rotate, squeeze and cut the airflow, generating a certain amount of rotational noise. During the rotation of the fan blades, the trailing edge noise reduction structure can guide the wake flow at the fan blade tip, suppress the flow of the blade tip separation vortex, reduce the aerodynamic loss at the axial flow fan blade tip, and reduce the tip vortex clearance noise at the same time;

[0004] Although the above-mentioned comparative documents have made partial improvements to the structure of the blades, giving them a certain noise reduction effect, the existing axial flow fan blades still have the disadvantages of low efficiency, high power consumption, and poor flow guidance performance during actual use. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned technical deficiencies and provide a plate-type semi-winglet blade impeller for a ventilation axial flow fan to solve the technical problem that the blades in the axial flow fan in the prior art have low operating efficiency and serious energy loss, which invisibly reduces the working efficiency of the blades.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a ventilation axial flow fan plate-type semi-wing blade impeller, comprising:

[0008] A wheel hub, wherein a central axis z is arranged at the axis center of the wheel hub;

[0009] A plurality of blades; the roots of the plurality of blades are welded to the outer periphery of the hub around the central axis z to form an impeller structure; a suction wall and a pressure wall are respectively provided on any one of the blades, a convex structure is provided on the suction wall to form a suction surface convexity, a pressure surface inner wall is provided inside the pressure wall, and a pressure surface airfoil outer wall is also provided on the pressure wall.

[0010] In some embodiments, the blade is a plate-type semi-wing blade, and a leading edge and a trailing edge are also provided on the blade. The blade plate thickness from the leading edge to the trailing edge is the same, and the thickness is 2 mm.

[0011] In some embodiments, a flow-guiding structure with a blade root expansion angle is provided at the blade root of the blade.

[0012] In some embodiments, a rounded corner structure is provided at the upper end of the hub.

[0013] In some embodiments, the blade is provided with an airfoil cutoff length s, and the axial cross-sectional chord length L and the angle of attack α of the blade from the blade root to the blade tip are different.

[0014] In some embodiments, the chord length L has a value range of 140 mm < L < 187 mm.

[0015] In some embodiments, the attack angle α has a value range of 20°<α<47°.

[0016] In some embodiments, the airfoil cutoff length s has a value range of 0.5L≤s≤0.8L.

[0017] Compared with the prior art, the present invention provides a ventilation axial flow fan plate-type semi-wing blade impeller. The axial flow blade based on the wing in the present application avoids the performance limitation problem of the same flow conduction capacity on the windward and wind outlet surfaces of the plate-type fan blades due to the structure, thereby improving the stability of the impeller rotation; secondly, the plate-type cross-section semi-wing blade adopts a hollow structure, which solves the lightweight problem of the wing blade due to its solid structure, thereby reducing the energy loss of the axial flow fan system; furthermore, the plate-type semi-wing blade directly uses a straight plate of equal thickness, and the opening structure on the air outlet side omits the welding process, thereby simplifying the processing cost problem of the plate-type full-wing blade and the solid wing blade; reducing the resistance of the blade rotating and colliding with the incoming wind, allowing the airflow to enter the working area of ​​the blade more smoothly, reducing the energy consumed by the impeller to overcome the wind resistance, improving the work efficiency and work capacity of the fan, and thereby improving the efficiency of the axial flow fan. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is an overall schematic diagram of a plate-type semi-winglet blade impeller of a ventilation axial flow fan provided by an embodiment of the present invention;

[0019] Figure 2 It is an airfoil profile diagram of a plate-type semi-airfoil blade impeller of a ventilation axial flow fan provided by an embodiment of the present invention;

[0020] Figure 3 It is a schematic diagram of the truncation length dimensions of the airfoil of the plate-type semi-airfoil blade impeller of the ventilation axial flow fan provided by an embodiment of the present invention;

[0021] Figure 4 It is a schematic diagram of the chord length of the plate-type semi-winglet blade impeller of the ventilation axial flow fan provided by an embodiment of the present invention;

[0022] Figure 5 It is a schematic diagram of the attack angle marking of the plate-type semi-winglet blade impeller of the ventilation axial flow fan provided by an embodiment of the present invention;

[0023] Figure 6 It is a schematic diagram of a discrete two-dimensional curve of a plate-type semi-winglet blade impeller of a ventilation axial flow fan provided by an embodiment of the present invention;

[0024] Figure 7 It is a velocity cloud diagram of a plate-type semi-winglet blade impeller of a ventilation axial flow fan provided by an embodiment of the present invention and an original blade impeller;

[0025] Figure 8 It is a surface pressure cloud diagram of a plate-type semi-winglet blade impeller of a ventilation axial flow fan and an original blade impeller provided by an embodiment of the present invention.

[0026] Explanation of the reference numerals: 1. hub; 11. fillet structure; 2. blade; 21. blade root; 22. suction wall; 221. suction surface bulge; 23. pressure wall; 231. pressure surface inner wall; 232. pressure surface airfoil outer wall; 24. leading edge; 25. expansion angle; 26. trailing edge. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] In order to solve the technical problem that the blades in the axial flow fan in the prior art have low operating efficiency and serious energy loss, which invisibly reduces the working efficiency of the blades, the present invention provides a plate-type semi-winglet blade impeller for a ventilation axial flow fan, which can improve the working efficiency of the blades and reduce the energy loss generated during the use of the axial flow fan.

[0029] It should be noted that the ventilation axial flow fan plate type semi-wing blade impeller described in the present invention is used for but not limited to the fan field, etc. For the convenience of explanation, in the present invention, only the application of the ventilation axial flow fan plate type semi-wing blade impeller in the fan field is used as an example for explanation, and the principle of applying the ventilation axial flow fan plate type semi-wing blade impeller in other types of equipment is essentially the same as the principle applied in the fan field, which will not be repeated here.

[0030] See also Figure 1 , Figure 1 The present invention is a schematic structural diagram of a plate-type semi-wing-shaped blade impeller for a ventilation axial flow fan in an embodiment of the present invention, which comprises a hub 1 and a plurality of blades 2. A central axis z is arranged at the axis center of the hub 1; blade roots 21 of the plurality of blades 2 are welded to the outer periphery of the hub 1 around the central axis z to form an impeller structure; a suction wall 22 and a pressure wall 23 are respectively arranged on any blade 2, a convex structure is arranged on the suction wall 22 to form a suction surface convexity 221, a pressure surface inner wall 231 is arranged inside the pressure wall 23, and a pressure surface wing-shaped outer wall 232 is also arranged on the pressure wall 23.

[0031] In the present embodiment, the axial flow blade 2 based on the airfoil in the present application avoids the problem of limited performance of the same flow guiding capacity on the windward and wind outlet surfaces of the plate-type fan blade 2 due to the structure, thereby improving the stability of the impeller rotation; secondly, the plate-type cross-section semi-airfoil blade 2 adopts a hollow structure, which solves the lightweight problem of the airfoil blade 2 due to its solid structure, thereby reducing the energy loss of the axial flow fan system; furthermore, the plate-type semi-airfoil blade 2 directly uses a straight plate of equal thickness, and the welding process is omitted in the opening structure on the air outlet side, thereby simplifying the processing cost problem of the plate-type full-airfoil blade 2 and the solid airfoil blade 2; utilizing the flow guiding effect of the airfoil and the expansion angle 25, a higher relative velocity of the incoming wind can be provided compared with other fan impellers, reducing the resistance of the blade 2 rotating and colliding with the incoming wind, allowing the airflow to enter the working area of ​​the blade 2 more smoothly, reducing the energy consumed by the impeller to overcome the wind resistance, improving the work efficiency and work capacity of the fan, and thereby improving the efficiency of the axial flow fan.

[0032] In one embodiment, see Figure 1 and Figure 2 In order to improve the working efficiency of the blade 2, the blade 2 is a plate-type semi-wing blade, and a leading edge 24 and a trailing edge 26 are also provided on the blade 2. The blade plate thickness of the blade 2 from the leading edge 24 to the trailing edge 26 is the same, and the thickness is 2 mm. A guide structure with an expansion angle 25 is provided at the root 21 of the blade 2, and a rounded structure 11 is provided at the upper end of the hub 1.

[0033] In this embodiment, the hub 1 is used to connect the motor main shaft and fix the plate-type semi-wing blade 2; the suction surface protrusion 221 can optimize the inlet diversion and reduce the loss on the one hand, and can increase the air intake and achieve efficiency improvement on the other hand; the trailing edge 26 is an irregular arc, which can improve the fluid flow of the trailing edge 26 and reduce energy loss; the blade root 21 is connected and fixed to the hub 1 by welding, which can improve the stability of the blade 2 and ensure stable and reliable operation; the expansion angle 25 of the blade root 21 can improve the incoming flow direction, and can provide a higher incoming wind relative speed than other fan impellers, reduce the resistance of the blade 2 rotating and hitting the incoming wind, so that the airflow enters the working area of ​​the blade 2 more smoothly, reduces the energy consumed by the impeller to overcome the wind resistance, and improves the work efficiency and work capacity of the fan, thereby improving the efficiency of the axial flow fan; the windward fillet structure 11 at the upper end of the hub 1 can evenly disperse the incoming flow, reduce stress concentration, and guide the future flow more to the surface of the blade 2 to achieve high power of the fan.

[0034] In one embodiment, see Figure 3 - Figure 8 Compared with ordinary axial flow fans, under the same air volume and wind pressure conditions, the blade 2 of the present application has advantages. The blade 2 is provided with an airfoil cutoff length s. The cross-sectional chord length L and the angle of attack α of the blade 2 along the axial direction from the blade root 21 to the blade tip are different. The value range of the chord length L is 140mm<L<187mm, the value range of the angle of attack α is 20°<α<47°, and the value range of the airfoil cutoff length s is 0.5L≤s≤0.8L.

[0035] In this embodiment, the blade 2 in the device can reduce the tip circumferential speed and reduce the noise generated when cutting the air. Compared with the ordinary axial flow fan, under the same air volume and air pressure conditions, the noise generated is smaller; in addition, the blade 2 in the present application adopts a plate-type semi-airfoil shape, which enables it to more accurately control the direction and speed of the airflow, and increase the stability and reliability of the entire axial flow fan during operation; Table 1 shows the coordinate data of the airfoil, which is accurate and reliable;

[0036]

[0037] Table 1

[0038] Combining the advantages of the airfoil structure, the lower wall of the plate-type airfoil is intercepted (the interception range is 0.3L-0.7L) based on the chord length L to form a plate-type semi-airfoil blade 2 structure, which can realize the function of the airfoil blade 2, and the weight is further reduced, the energy loss is reduced, and the energy-saving effect is better achieved; wherein the chord length of the plate-type semi-airfoil blade 2 is L, and the blade 2 is scaled based on the chord length L. Since the semi-airfoil cross-sectional size range between the blade root 21 connected to the impeller hub 1 and the blade tip away from the hub 1 is 120mm-200mm; the midpoint of the chord length is coincided with the coordinate origin, and after coincidence, the blade 2 is rotated with this point as the origin, and the inclination angle α is the angle between the chord length and the horizontal line, and the value range is 10°-50°.

[0039] The chord length of the plate-type semi-airfoil blade 2 is L. The semi-airfoil blade 2 is scaled based on the chord length L, and a plurality of plate-type semi-airfoil sections are formed. The sections are arranged in a staggered manner at a certain angle rotated clockwise. The purpose of using a straight plate at the blade root 21 is to generate an expansion angle 25, improve the flow guidance effect at the blade root 21, and reduce energy loss; the fourth section is arranged in parallel with the third section, and the smooth transition between the fourth section and the third section can control the tip curve and improve the performance of the blade 2. The original blade and the new plate-type semi-airfoil blade 2 are numerically simulated to ensure the consistency of the inlet flow and the motor speed. According to the simulation results, it is found that the power consumption of the new plate-type semi-airfoil is reduced by 8% compared with the original blade, and the ventilation efficiency is improved by 11.95%. The root of the original blade is connected to the vertical side of the hub 1. After the incoming wind is disturbed by the pressure surface, the flow hits the hub 1 to weaken the kinetic energy, and changes the flow direction, which interferes with the flow trend of the subsequent incoming wind, resulting in turbulent airflow at the edge of the hub 1 and reducing the overall air output of the impeller. Efficiency. At the same time, affected by the obstruction of the hub 1, the speed change of the incoming wind at this location affects the force on the blade 2. The geometric structure of the root of the blade 2 bulges in the direction of rotation, resulting in an increase in the reverse torque of the impeller of the original single-plate blade 2, thereby overcoming the reverse torque and consuming more energy to do work. The root of the plate-type semi-airfoil blade 2 reduces the area of ​​the incoming wind hitting the hub 1 due to the diversion effect of the expansion angle 25 structure, and reduces the energy loss caused by the incoming wind hitting the hub 1. At the same time, the expansion angle 25 structure guides the incoming wind into the hollow structure of the semi-airfoil leading edge 24, and impacts the windward leading edge 24 of the blade 2. Because the direction of the incoming wind introduced into the hollow structure has a positive influence on the direction of rotation of the impeller, the incoming wind guided by the root assists the impeller to rotate; therefore, the expansion angle 25 structure at the root of the plate-type semi-airfoil blade 2 can reduce the effect of the hub 1 on blocking the incoming wind and interfering with the flow trend, change the incoming wind direction to the semi-airfoil hollow structure, assist the impeller to work, and reduce the impeller reverse torque and energy consumption.

[0040] In one embodiment, see Figure 8Compared with ordinary axial flow fans, the pressure distribution on the suction surface of the original blade varies greatly, but the pressure on the leading edge and near the tip of the original blade is relatively small, resulting in a large flow velocity at the tip of the blade. Under the centrifugal influence of the rotation of the impeller, the incoming wind is easily thrown out to the outside of the impeller and flows into the tip gap, causing aerodynamic friction and impeller vibration, resulting in high aerodynamic noise and low life of the axial flow fan; the pressure at the tip of the original blade pressure surface and the pressure at the tip of the suction surface have a large difference. According to the cantilever structure characteristics of the original blade with the shortest chord length of the tip section and the farthest distance between the tip and the hub, the tip of the blade is prone to large deformation; there is a pressure change on the end face on the same side of the original hub and the pressure surface. After the incoming wind flows through this place, there is no wall interference to produce a convergence effect to change the flow direction of the incoming wind, which affects the overall wind pressure of the fan. The plate-type semi-airfoil has a large suction The force surface is affected by the flow guidance of the leading edge 24, so that the pressure distribution is relatively uniform, so the possibility of blade 2 causing large deformation and stress concentration is small, which has the effect of optimizing and improving the service life and aerodynamic performance of blade 2; the pressure difference between the suction surface and the pressure surface of the plate-type semi-airfoil blade 2 close to the tip is relatively the largest, but because the plate-type semi-airfoil is a double-layer structure, combined with the structure of the leading edge 24 of the semi-airfoil, it has the effect of dispersing the force, so even if the tip pressure difference of the plate-type semi-airfoil blade 2 is relatively the largest, it still has the effect of resisting deformation; according to the flow guidance effect of the expansion angle 25 structure, the cross-section of the hub 1 does not produce a gathering effect, part of the incoming wind enters the hollow structure of the semi-airfoil to assist the impeller, and the rest of the flow is guided out of the impeller, which makes the hub 1 less affected by the wind pressure, so the plate-type semi-airfoil has the effect of reducing power consumption and improving efficiency.

[0041] In order to better understand the present invention, the following Figures 1 to 8The technical scheme of the present invention is described in detail: a plurality of blades 2 are connected to the outer periphery of the hub 1 along the circumferential direction of the central axis z, and the blade roots 21 of the blades 2 are welded to the outer periphery of the hub 1, wherein the hub 1 is used to connect the motor main shaft and fix the plate-type semi-wing blades 2; a suction surface protrusion 221 is provided on the blade 2, and the suction surface protrusion 221 can optimize the inlet diversion, reduce the loss and increase the air intake at the same time, thereby improving the efficiency; the irregular arc-shaped trailing edge 26 can improve the fluid flow of the trailing edge 26 and reduce energy loss; the expansion angle 25 can improve the incoming flow direction, and can provide a higher incoming wind relative speed than other fan impellers, reduce the resistance of the blades 2 rotating and hitting the incoming wind, and make the airflow enter the working area of ​​the blades 2 more smoothly, reduce the energy consumed by the impeller to overcome the wind resistance, improve the work efficiency of the fan, and thereby improve the efficiency of the axial flow fan; the windward fillet structure 11 at the upper end of the hub 1 can evenly disperse the incoming flow and reduce stress concentration, In the future, more flow will be directed to the surface of blade 2 to achieve high power of the fan, wherein blade 2 can reduce the tip circumferential speed and reduce the noise generated when cutting the air. Compared with ordinary axial flow fans, under the same air volume and pressure conditions, the noise generated is smaller. In addition, the special shape of the airfoil blade 2 enables it to more accurately control the direction and speed of the airflow, increase the stability and reliability of the entire axial flow fan during operation, and reduce the weight of the blade 2. By taking the chord length L as a reference, the lower wall of the plate-type airfoil is intercepted (the interception range is 0.3L-0.7L) to form a plate-type semi-airfoil blade 2 structure. Since the semi-airfoil section size range from the blade root 21 connected to the hub 1 of the semi-airfoil impeller to the blade tip away from the hub 1 is 120mm-200mm; the midpoint of the chord length is overlapped with the coordinate origin, and after the overlap, the point is used as the origin to rotate the blade 2. The inclination angle α is the angle between the chord length and the horizontal line, and the value range is 10°-50°;

[0042] The root of the original blade is connected to the vertical side of the original hub. After the incoming wind is disturbed by the pressure surface, the flow hits the original hub to weaken the kinetic energy and change the flow direction, interfering with the flow trend of the subsequent incoming wind, causing the airflow at the edge of the original hub to be turbulent and reducing the overall air outlet efficiency of the impeller. At the same time, affected by the obstruction of the original hub, the speed change of the incoming wind at this point affects the force of the original fan blade. The root geometric structure of the original blade bulges in the direction of rotation, resulting in an increase in the impeller reverse torque of the original blade, thereby consuming more energy to overcome the reverse torque. The root of the plate-type semi-airfoil blade 2 has a 25° expansion angle. The structure guides the flow, reduces the area of ​​the incoming wind hitting the hub 1, and reduces the energy loss caused by the incoming wind hitting the hub 1. At the same time, the expansion angle 25 structure guides the incoming wind into the hollow structure of the semi-airfoil leading edge 24, and impacts the windward leading edge 24 of the blade 2. Because the incoming wind direction introduced into the hollow structure has a positive influence on the rotation direction of the impeller, the incoming wind guided at the root assists the impeller to rotate. Therefore, the expansion angle 25 structure at the root of the plate-type semi-airfoil blade 2 can reduce the hub 1's blocking and interference with the flow trend of the incoming wind, change the incoming wind direction to the semi-airfoil hollow structure, assist the impeller to work, and reduce the impeller's reverse torque and energy consumption;

[0043] The pressure distribution on the suction surface of the original blade changes greatly, but the pressure at the leading edge and near the tip of the original blade is relatively small, resulting in a large flow velocity at the tip of the blade. Under the centrifugal influence of the impeller rotation, the incoming wind is easily thrown out to the outside of the impeller and flows into the tip gap, causing aerodynamic friction and impeller vibration, resulting in high aerodynamic noise and low life of the axial flow fan; the pressure difference between the tip of the original blade pressure surface and the tip of the suction surface is relatively large. According to the cantilever structure characteristics of the original blade tip with the shortest chord length and the tip farthest from the original hub, the tip of the blade is prone to large deformation;

[0044] There is a pressure change on the end face on the same side of the original hub and the pressure surface. After the incoming wind flows through this place, there is no wall interference to produce a convergence effect to change the flow direction of the incoming wind, which affects the overall wind pressure of the fan. The suction surface of the plate-type semi-airfoil is affected by the diversion of the leading edge 24, so that the pressure distribution is relatively uniform. Therefore, the possibility of large deformation and stress concentration of the blade 2 is relatively small, which has an optimization and improvement effect on the service life and aerodynamic performance of the blade 2. The pressure difference between the suction surface and the pressure surface of the plate-type semi-airfoil blade 2 close to the tip is relatively the largest, and the plate-type semi-airfoil is a double-layer structure. Combined with the semi-airfoil leading edge 24 structure, it has the effect of dispersing force. Therefore, even if the tip pressure difference of the plate-type semi-airfoil blade 2 is relatively the largest, it still has an anti-deformation effect; according to the diversion effect of the expansion angle 25 structure, the cross-section of the hub 1 does not produce a convergence effect, and part of the incoming wind enters the hollow structure of the semi-airfoil to assist the impeller in working, and the rest of the diversion flows out of the impeller, which makes the hub 1 less affected by the wind pressure.

[0045] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A ventilation axial flow fan plate-type semi-wing blade impeller, characterized in that: include: A wheel hub, wherein a central axis z is arranged at the axis center of the wheel hub; A plurality of blades; the roots of the plurality of blades are welded to the outer periphery of the hub around the central axis z to form an impeller structure; a suction wall and a pressure wall are respectively provided on any one of the blades, a convex structure is provided on the suction wall to form a suction surface convexity, a pressure surface inner wall is provided inside the pressure wall, and a pressure surface airfoil outer wall is also provided on the pressure wall.

2. The ventilation axial flow fan plate-type semi-wing blade impeller according to claim 1, characterized in that: The blade is a plate-type semi-wing-shaped fan blade, and a leading edge and a trailing edge are also provided on the blade. The blade plate thickness from the leading edge to the trailing edge is the same, and the thickness is 2 mm.

3. The ventilation axial flow fan plate-type semi-wing blade impeller according to claim 1, characterized in that: A flow guiding structure with a blade root expansion angle is arranged at the blade root of the blade.

4. The ventilation axial flow fan plate-type semi-wing blade impeller according to claim 1, characterized in that: The upper end of the hub is provided with a rounded corner structure.

5. The ventilation axial flow fan plate-type semi-wing blade impeller according to claim 1, characterized in that: The blade is provided with an airfoil cutoff length s, and the axial cross-sectional chord length L and the attack angle α of the blade from the blade root to the blade tip are different.

6. The ventilation axial flow fan plate-type semi-wing blade impeller according to claim 5, characterized in that: The value range of the chord length L is 140 mm<L<187 mm.

7. The plate-type semi-wing blade impeller of a ventilation axial flow fan according to claim 5, characterized in that: The value range of the attack angle α is 20°<α<47°.

8. The plate-type semi-wing blade impeller of a ventilation axial flow fan according to claim 5, characterized in that: The airfoil cutoff length s has a value range of 0.5L≤s≤0.8L.

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