Axial fan blade and air conditioner

Abstract

The present application provides an axial flow fan blade and an air conditioner. The axial flow fan blade comprises a hub (1) and blades (2), wherein a plurality of blades (2) are arranged along the circumference of the hub (1), and along the radial direction of the hub (1), the pressure surface (25) of the blade (2) comprises a positive curvature surface segment (251) and a negative curvature surface segment (252), wherein the positive curvature surface segment (251) and the negative curvature surface segment (252) have a smooth transition, wherein the positive curvature surface segment (251) is arranged on a side of the blade (2) close to an outer edge (23), and the negative curvature surface segment (252) is arranged on a side of the blade (2) close to an inner edge (24). According to the axial flow fan blade of the present application, a balance between air volume, power and noise can be achieved, thereby improving the performance of the axial flow fan blade.

Description

Technical Field

[0001] The present application relates to the technical field of air conditioning, and in particular to an axial flow fan blade and an air conditioner. Background Art

[0002] With the continuous upgrading of the national energy conservation and emission reduction policies, air conditioners, as the "main force" of power consumption in life, have put forward higher requirements for the energy efficiency ratio of products. It is imperative to continuously improve their performance while reducing power consumption. The outdoor unit of the air conditioner has several major power-consuming modules: motor, controller, compressor, etc. Among them, the power consumption of the motor is not only related to its own manufacturing process, but also the aerodynamic performance of the fan blade is a major influencing factor. A well-designed fan blade can reduce the power required by the motor while reducing the noise value while maintaining the air volume performance, thereby improving the overall energy efficiency ratio of the air conditioner.

[0003] The axial flow fan blades currently used in air conditioner outdoor units on the market generally need to have the following characteristics:

[0004] 1. The air volume is large enough to meet the system heat dissipation requirements;

[0005] 2. Low operating power, reduced power loss and motor load;

[0006] 3. Low noise, in compliance with relevant noise laws and regulations.

[0007] There is a relationship of mutual influence and mutual restraint between the three indicators of air volume, power and noise. For example, if a sufficiently large air volume is required, the axial flow fan blades themselves need to do more work to provide power, which means that the power of the fan blades will be greater when they are running; at the same time, a large air volume also means that the airflow is faster and more violent, which brings more obvious wind noise and the running noise of the axial flow fan blades is greater. The known technology lacks an axial flow fan blade that can balance the relationship between the three and achieve large air volume, low power and low noise operation. Summary of the invention

[0008] Therefore, the technical problem to be solved by the present application is to provide an axial flow fan blade and an air conditioner, which can achieve a balance between air volume, power and noise, and improve the performance of the axial flow fan blade.

[0009] In order to solve the above problems, the present application provides an axial flow fan blade, including a hub and blades, wherein the multiple blades are arranged along the circumference of the hub, and along the radial direction of the hub, the pressure surface of the blade includes a positive curvature surface segment and a negative curvature surface segment, and there is a smooth transition between the positive curvature surface segment and the negative curvature surface segment. The positive curvature surface segment is arranged on the side of the blade close to the outer edge, and the negative curvature surface segment is arranged on the side of the blade close to the inner edge.

[0010] Preferably, the blade also includes a leading edge and a trailing edge, the intersection of the outer edge and the leading edge is the blade tip, the intersection of the outer edge and the trailing edge is the blade tail, the blade is surrounded by the leading edge, the inner edge, the trailing edge and the outer edge, and the inner edge is located at the junction of the blade and the hub; and / or the area of ​​the negative curvature surface segment is greater than the area of ​​the positive curvature surface segment.

[0011] Preferably, on a plane perpendicular to the central axis of the hub, the maximum width of the positive curvature surface segment in the radial direction ranges from 10 mm to 30 mm.

[0012] Preferably, on the cross section passing through the central axis of the hub and intersecting the outer edge and inner edge of the blade, the length of the line ab between the intersection point b of the inner edge and the cross section and the highest point a of the positive curvature surface segment is L, and the distance between the lowest point c of the negative curvature surface segment on the cross section and the line ab is H, K=H / L, 0.05≤K≤0.15.

[0013] Preferably, along the direction approaching the trailing edge, the K value increases; and / or, along the direction approaching the trailing edge, the H value increases.

[0014] Preferably, H≥5mm.

[0015] Preferably, an angle α is formed between a tangent line at any point on the outer edge and a plane perpendicular to the central axis of the hub, and α increases along the direction from the blade tip to the blade tail.

[0016] Preferably, α is smallest at the blade tip and largest at the blade tail.

[0017] Preferably, the value of α at the blade tip is α1, 0°<α1≤10°; and / or the value of α at the blade tail is α2, 60°≤α2≤70°.

[0018] Preferably, the root installation angle of the blade is β=42±5°.

[0019] Preferably, the chord lines at both ends of the outer edge of the blade are outer edge chord lines, the chord lines at both ends of the inner edge of the blade are inner edge chord lines, and the chord length of the outer edge chord line is more than 3 times the chord length of the inner edge chord line.

[0020] Preferably, the trailing edge is provided with a sawtooth section, and the sawtooth section is provided with a sawtooth notch.

[0021] Preferably, the depths of the serrated notches are the same, the number of the serrated notches is 5 or more, the depth is 3 mm or more, the tooth pitch is 5 mm or more, and the length of the serrated segment accounts for more than 1 / 2 of the length of the trailing edge.

[0022] Preferably, the trailing edge of the blade is recessed toward the side where the leading edge is located.

[0023] Preferably, a plurality of pits are distributed on the suction surface of the blade, and the number of pits on a single blade is greater than 30.

[0024] Preferably, the pit is in a spherical, cylindrical, pyramidal or rectangular parallelepiped shape.

[0025] According to another aspect of the present application, an air conditioner is provided, comprising an axial flow fan blade, wherein the axial flow fan blade is the above-mentioned axial flow fan blade.

[0026] The axial flow fan blade provided by the present application includes a hub and a blade, wherein a plurality of blades are arranged along the circumference of the hub, and along the radial direction of the hub, the pressure surface of the blade includes a positive curvature surface segment and a negative curvature surface segment, and the positive curvature surface segment and the negative curvature surface segment have a smooth transition, the positive curvature surface segment is arranged on the side of the blade close to the outer edge, and the negative curvature surface segment is arranged on the side of the blade close to the inner edge. The axial flow fan blade adopts a negative curvature surface segment on the radial inner side, which can produce a wind gathering effect, transport the low-energy fluid on both sides of the blade to the middle of the blade, increase the wind gathering effect, reduce the operating power, and increase the air volume. The positive curvature surface segment is adopted on the radial outer side, which can reduce the vortex generated at the outer edge of the blade, thereby reducing the operating noise of the axial flow fan blade. The structure combining the positive curvature surface segment and the negative curvature surface segment can make the blade structure more in line with the fluid characteristics, achieve a balance between air volume, power and noise, and effectively improve the working efficiency and performance of the axial flow fan blade while increasing the air volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a three-dimensional structural diagram of an axial flow fan blade according to an embodiment of the present application;

[0028] Figure 2 This is a schematic cross-sectional view of an axial flow fan blade according to an embodiment of the present application;

[0029] Figure 3 This is a schematic diagram of the angle structure of the outer edge of an axial flow fan blade at the blade tip according to an embodiment of the present application;

[0030] Figure 4 This is a schematic diagram of the angle structure of the outer edge of an axial flow fan blade at the blade tail according to an embodiment of the present application;

[0031] Figure 5 This is a schematic diagram of the installation angle structure of an axial flow fan blade according to an embodiment of the present application;

[0032] Figure 6 This is a schematic diagram of the structure of an axial flow fan blade according to an embodiment of the present application;

[0033] Figure 7 A surface static pressure distribution diagram obtained by performing fluid CFD simulation on a first type of wind blade in the known technology;

[0034] Figure 8 A surface static pressure distribution diagram obtained by performing fluid CFD simulation on a second type of wind blade in the known technology;

[0035] Fig. 9 A surface static pressure distribution diagram obtained by performing fluid CFD simulation on the third type of wind blade in the known technology;

[0036] Fig.10 A surface static pressure distribution diagram obtained by performing fluid CFD simulation on a first type of wind blade in the known technology;

[0037] Fig.11 A comparison chart of the air volume, power and efficiency of three axial flow fan blades of the prior art and the axial flow fan blade of the embodiment of the present application;

[0038] Fig.12 1. The fluid line diagrams at the leading edge of two known blades and the blade of the embodiment of the present application;

[0039] Fig.13 The following are the installation angle-wind volume curve and the installation angle-power curve of the blades in the embodiment of the present application.

[0040] The reference numerals are as follows:

[0041] 1. Hub; 2. Blade; 21. Leading edge; 22. Trailing edge; 221. Sawtooth notch; 23. Outer edge; 231. Blade tip; 232. Blade tail; 24. Inner edge; 241. Inner edge chord; 25. Pressure surface; 251. Positive curvature surface segment; 252. Negative curvature surface segment; 26. Suction surface; 261. Pit. DETAILED DESCRIPTION

[0042] See also Figures 1 to 13 As shown, according to an embodiment of the present application, the axial flow fan blade includes a hub 1 and blades 2, and a plurality of blades 2 are installed on the outer periphery of the hub 1 and arranged along the circumferential direction of the hub 1. Along the radial direction of the hub 1, the pressure surface 25 of the blade 2 includes a positive curvature surface segment 251 and a negative curvature surface segment 252, and there is a smooth transition between the positive curvature surface segment 251 and the negative curvature surface segment 252. The positive curvature surface segment 251 is arranged on the side of the blade 2 close to the outer edge 23, and the negative curvature surface segment 252 is arranged on the side of the blade 2 close to the inner edge 24.

[0043] The blade 2 also includes a leading edge 21 and a trailing edge 22. The intersection of the outer edge 23 and the leading edge 21 is a blade tip 231, and the intersection of the outer edge 23 and the trailing edge 22 is a blade tail 232. The blade 2 is surrounded by the leading edge 21, the inner edge 24, the trailing edge 22 and the outer edge 23. The inner edge 24 is located at the junction of the blade 2 and the hub 1.

[0044] The axial flow fan blade adopts a negative curvature surface segment 252 on the radial inner side, which can produce a wind gathering effect, transport the low-energy fluid on both sides of the blade 2 to the middle of the blade 2, thereby increasing the wind gathering effect, reducing the operating power, and increasing the air volume. The positive curvature surface segment 251 is adopted on the radial outer side, which can reduce the eddy current generated at the outer edge of the blade 2, thereby reducing the operating noise of the axial flow fan blade. The structure combining the positive curvature surface segment 251 and the negative curvature surface segment 252 can make the blade structure more in line with the fluid characteristics, achieve a balance between air volume, power and noise, and effectively improve the working efficiency and performance of the axial flow fan blade while increasing the air volume.

[0045] For a single blade, in each embodiment of the present application, the edge portion on the windward side is the leading edge 21, the edge portion on the leeward side is the trailing edge 22, the orthographic projection of the central axis of the hub 1 in a plane perpendicular to the central axis is the center point, and a circle is drawn with the above-mentioned center point as the center through a certain point, and the circumferential direction is the circumferential direction; the direction of the line connecting this point and the above-mentioned center point is the radial direction.

[0046] The blade 2 includes a relative pressure surface 25 and a suction surface 26. The pressure surface 25 faces the wind outlet side of the axial flow fan blade, and the suction surface 26 faces the wind inlet side of the axial flow fan blade. When the fan blade is working, the pressure surface 25 mainly bears positive pressure, and the suction surface 26 mainly bears negative pressure.

[0047] The radial curvature of the positive curvature surface segment 251 is a positive number, that is, it is radially "convex", and the radial curvature of the negative curvature surface segment 252 is a negative number, that is, it is radially "concave", and the area of ​​the negative curvature surface segment 252 is greater than the area of ​​the positive curvature surface segment 251.

[0048] In one embodiment, on a plane perpendicular to the central axis of the hub 1, the maximum width of the positive curvature surface segment 251 in the radial direction ranges from 10 mm to 30 mm, so that the width of the positive curvature surface segment 251 can be limited, and then the proportion of the positive curvature surface segment 251 on the pressure surface of the blade 2 can be limited, preventing the area of ​​the positive curvature surface segment 251 from being too large to squeeze the area of ​​the negative curvature surface segment 252, thereby ensuring that the axial flow fan blade provides a larger air volume.

[0049] On the cross section that passes through the central axis of the hub 1 and intersects the outer edge 23 and the inner edge 24 of the blade 2, the length of the line ab between the intersection b of the inner edge 24 and the cross section and the highest point a of the positive curvature surface segment 251 is L, and the distance between the lowest point c of the negative curvature surface segment 252 on the cross section and the line ab is H, K=H / L, 0.05≤K≤0.15. A K value that is too small will cause the airflow to be unfocused and the air outlet efficiency to be reduced. A K value that is too large will cause the airflow angle to change, forming a turbulent airflow, which is not conducive to the increase of air volume. Moreover, under the same diameter, due to the increase in arc length, the weight of the fan blade increases greatly, which increases the power consumption of the motor, thereby reducing efficiency. In a large number of CFD simulations and experiments, the optimal solution for air volume, power, and noise is sought, that is, 0.05≤K≤0.15.

[0050] The K value increases in a direction approaching the trailing edge 22 of the blade 2 .

[0051] The value of H increases gradually in a direction approaching the trailing edge 22 of the blade 2 .

[0052] In one embodiment, H≥5 mm, that is, the concave depth of the pressure surface 25 of the blade 2 on the above cross section is ≥5 mm.

[0053] The H value determines the depth of the pressure surface 25 of the blade 2 relative to the wind outlet side, and the K value determines the radial blade shape and radial concave curvature of the blade 2. The L value of the same blade 2 is roughly constant, so the larger the H value at different positions of the same blade, the larger the K value.

[0054] In the present application, the K value increases as the cross section is closer to the trailing edge of the blade 2, and this structure is conducive to forming a C-shaped pressure distribution on the pressure surface 25 of the blade 2. When the blade 2 is working, after the airflow enters from the leading edge 21, as the radial concavity increases, the wind gathering effect is enhanced, and the blade 2 transports the low-energy fluid on both sides to the middle of the blade 2, which is carried away by the mainstream fluid, reducing the radial flow of the airflow, reducing flow losses, and improving work efficiency. Under the same power condition, the air volume is effectively increased.

[0055] See also Figures 7 to 10 As shown, it is a surface static pressure distribution diagram obtained by fluid CFD simulation of fan blades with different K values ​​in the known technology and the fan blade of the present application.

[0056] It can be seen from the static pressure distribution on the blade surface that the pressure centers of the pressure surface and suction surface of blade 1 are relatively concentrated, with the peak values ​​located at about 70% of the outer edge (from the tip to the trailing edge), and the positive pressure area on the pressure surface accounts for about 75% of the entire pressure surface area.

[0057] The peak value of blade 2 is also located at about 70% of the outer edge (from the blade tip to the trailing edge), and the positive pressure area of ​​the pressure surface accounts for about 75% of the entire pressure surface area.

[0058] The pressure center of the fan blade 3 is not obvious, and the positive pressure area of ​​the pressure surface accounts for about 60% of the entire pressure surface area.

[0059] The pressure centers of the blade pressure and suction surfaces of the axial flow fan blade designed in this application are most concentrated, with the peak value located at about 70% of the position from the blade tip to the trailing edge; the positive pressure area of ​​the pressure surface accounts for about 80% of the entire pressure surface area, indicating that the effective work done by the axial flow fan blade is more, and the area ratio occupied by the area within the same pressure range is higher, which means that the axial flow fan blade has a stronger work-doing capacity. The CFD simulation results are roughly consistent with the measured results.

[0060] like Fig.11 As shown, this is a comparison chart of the measured values ​​of air volume, power and efficiency of the four axial flow fan blades. It can be seen that the blade shape of the axial flow fan blade designed in the embodiment of the present application has the highest work efficiency, that is, the air volume is higher at the same power.

[0061] An angle α is formed between a tangent line at any point on the outer edge 23 and a plane perpendicular to the central axis of the hub 1 , and α increases along the direction from the blade tip 231 to the blade tail 232 .

[0062] α is smallest at the blade tip 231 and largest at the blade tail 232 .

[0063] The value of α at the blade tip 231 is α1, 0°<α1≤10°.

[0064] The value of α at the blade tail 232 is α2, 60°≤α2≤70°.

[0065] In the embodiment of the present application, the inclination angle at the blade tip 231 is small in order to allow the airflow to smoothly enter the working area of ​​the blade at a certain airflow angle, reduce the climbing effect of the airflow at the inlet, and minimize the inlet impact loss as much as possible; α gradually increases in order to gradually strengthen the working effect of the blade 2 on the airflow, increase the working efficiency, and increase the air volume.

[0066] like Fig.12 As shown, it is a fluid CFD simulation diagram of the blades of two known axial flow fan blades and the blades of the axial flow fan blade of the embodiment of the present application. It can be found that the fluid "climbing" phenomenon at the leading edge of the blade of the known axial flow fan blade is more serious. The "climbing" phenomenon will cause the negative pressure area near the leading edge air inlet of the fan blade pressure surface to increase. The negative pressure area will do negative work on the overall performance of the fan blade, consume more air volume, and consume more power. The leading edge inclination and concavity of the axial flow fan blade of the embodiment of the present application can effectively reduce this negative effect and reduce the inlet impact loss.

[0067] The line connecting the leading edge 21 and the trailing edge 22 is a chord line, and the angle between the chord line and a plane perpendicular to the central axis of the hub is an installation angle β. The root installation angle of the blade 2 is β=42±5°.

[0068] When the installation angle is too small, the blade 2's ability to do work on the airflow is greatly reduced, and the efficiency is low. When the installation angle is too large, airflow separation often occurs on the suction surface 26 of the blade 2, thereby forming a separation zone. Since the gas energy in the separation zone is relatively low, the axial flow fan blade increases the cross-sectional airfoil resistance, increases the rotational torque of the blade 2, increases the input power, and reduces the air volume of the axial flow fan blade; and the fluid in the separation zone forms a large number of vortices, which is very likely to generate high vortex noise.

[0069] See also Fig.13 The figure shows the relationship between the installation angle, air volume and power after adjusting the blade installation angle. It can be seen from the figure that within a certain range, the fan air volume and power increase with the increase of the installation angle, and the power and the installation angle have a linear relationship. When the installation angle exceeds 50°, the fan enters a stall state, and the air volume and power drop suddenly. In the air volume increase stage, as the installation angle increases, the increase in air volume gradually decreases.

[0070] Taking into account the degree of concavity of the entire blade shape and the inclination angle of the outer edge, and the relationship between air volume and power, in order to seek maximum work efficiency, the blade root installation angle of the axial flow fan blade in the embodiment of the present application is set to β=42±5°.

[0071] The chord lines at both ends of the outer edge 23 of the blade 2 are outer edge chord lines, and the chord lines at both ends of the inner edge 24 of the blade 2 are inner edge chord lines 241. The chord length of the outer edge chord line is more than 3 times the chord length of the inner edge chord line 241, thereby making full use of the high air flow velocity at the outer circumference and improving the working capacity of the blade.

[0072] In one embodiment, the trailing edge 22 is provided with a sawtooth section, and the sawtooth section is provided with a sawtooth notch 221 .

[0073] The depth of the sawtooth notches 221 is the same, the number of the sawtooth notches 221 is more than 5, the depth is more than 3 mm, the tooth pitch is more than 5 mm, and the length of the sawtooth segment accounts for more than 1 / 2 of the length of the trailing edge 22 .

[0074] The shape of the sawtooth notch 221 can be V-shaped, U-shaped, semicircular, square, etc.

[0075] The trailing edge 22 of the blade 2 is recessed toward the side where the leading edge 21 is located.

[0076] The serrated notch 221 at the trailing edge can effectively reduce the noise value. According to CFD simulation analysis, there are rotating vortices in the flow area of ​​the trailing edge. This is mainly due to the large difference in speed and pressure between the pressure surface 25 and the suction surface 26 at the trailing edge 22, which forms a pressure difference. The vortex noise is related to the vortex at the trailing edge 22.

[0077] The maximum peak value of the trailing edge vorticity with the sawtooth notch 221 appears at the point where the sawtooth tips converge, effectively reducing the distribution area of ​​the vorticity peak value, thereby reducing vortex noise. The noise value test under the same conditions shows that compared with the known axial flow fan blade, the fan blade with the sawtooth notch 221 at the trailing edge of this embodiment reduces the noise by about 2dB.

[0078] At the same time, the sawtooth notch 221 can also reduce the overall weight of the fan blade, reduce the operating power, and improve the working efficiency of the fan blade with little impact on the air volume.

[0079] A plurality of pits 261 are distributed on the suction surface 26 of the blade 2, and the number of the pits 261 on a single blade 2 is more than 30. The depth of the pits is between 0.5 and 2 mm, and needs to be adjusted accordingly according to the size and thickness of the blade 2.

[0080] The pit 261 is in the shape of a sphere, a column, a pyramid or a cuboid. The column shape can be a cylindrical shape or a prism shape.

[0081] During operation, the back side (i.e., the suction side) of the axial flow fan blade will inevitably generate eddy currents, which in turn generates eddy current noise, which has a negative impact on the operating noise value and sound quality. In this application, many pits 261 with relatively uniform sizes and intervals are set on the suction side of the axial flow fan blade. The CFD simulation results show that the pits 261 can disperse and slow down the pressure difference on the suction side, weaken the eddy current effect on the suction side, and reduce the eddy current noise. At the same time, the uneven surface also has the effect of absorbing noise. The noise value test under the same conditions shows that, compared with the blade with a smooth suction side, the honeycomb pits set on the suction side can effectively reduce the noise by about 1dB.

[0082] At the same time, the honeycomb-shaped pits, similar to the sawtooth notches, can also reduce the overall weight of the fan blades, reduce operating power, and improve the work efficiency of the fan blades with little impact on the air volume.

[0083] According to an embodiment of the present application, the air conditioner includes an axial flow fan blade, which is the axial flow fan blade mentioned above.

[0084] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0085] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application. The above are only preferred implementations of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present application, and these improvements and variations should also be regarded as the protection scope of the present application.

Claims

1. An axial flow fan blade, characterized in that: The invention comprises a hub (1) and blades (2), wherein a plurality of blades (2) are arranged along the circumferential direction of the hub (1), and along the radial direction of the hub (1), a pressure surface (25) of the blade (2) comprises a positive curvature surface segment (251) and a negative curvature surface segment (252), wherein a smooth transition is formed between the positive curvature surface segment (251) and the negative curvature surface segment (252), wherein the positive curvature surface segment (251) is arranged on a side of the blade (2) close to an outer edge (23), and the negative curvature surface segment (252) is arranged on a side of the blade (2) close to an inner edge (24); The blade (2) further comprises a leading edge (21) and a trailing edge (22); the intersection of the outer edge (23) and the leading edge (21) is a blade tip (231); the intersection of the outer edge (23) and the trailing edge (22) is a blade tail (232); the blade (2) is surrounded by the leading edge (21), the inner edge (24), the trailing edge (22) and the outer edge (23); the inner edge (24) is located between the blade (2) and the hub (1) ); on a cross section passing through the central axis of the hub (1) and intersecting the outer edge (23) and the inner edge (24) of the blade (2), the length of a line ab between the intersection point b of the inner edge (24) and the cross section and the highest point a of the positive curvature surface segment (251) is L, and the distance between the lowest point c of the negative curvature surface segment (252) on the cross section and the line ab is H, K=H / L, 0.05≤K≤0.

15.

2. The axial flow fan blade according to claim 1, characterized in that: On a plane perpendicular to the central axis of the hub (1), the maximum width of the positive curvature surface segment (251) in the radial direction ranges from 10 mm to 30 mm.

3. The axial flow fan blade according to claim 1, characterized in that: The K value increases along a direction approaching the trailing edge (22); and / or the H value increases along a direction approaching the trailing edge (22).

4. The axial flow fan blade according to claim 3, characterized in that: H≥5mm.

5. The axial flow fan blade according to claim 1, characterized in that: An angle α is formed between a tangent line at any point on the outer edge (23) and a plane perpendicular to the central axis of the hub (1), and the angle α increases along a direction from the blade tip (231) to the blade tail (232).

6. The axial flow fan blade according to claim 5, characterized in that: The value of α at the blade tip (231) is α1, 0°<α1≤10°; and / or the value of α at the blade tail (232) is α2, 60°≤α2≤70°.

7. The axial flow fan blade according to claim 1, characterized in that: The root installation angle of the blade (2) is β=42±5°.

8. The axial flow fan blade according to claim 1, characterized in that: The chord lines at both ends of the outer edge (23) of the blade (2) are outer edge chord lines, the chord lines at both ends of the inner edge (24) of the blade (2) are inner edge chord lines (241), and the chord length of the outer edge chord line is more than three times the chord length of the inner edge chord line (241).

9. The axial flow fan blade according to claim 1, characterized in that: The rear edge (22) is provided with a sawtooth segment, and the sawtooth segment is provided with a sawtooth notch (221).

10. The axial flow fan blade according to claim 9, characterized in that: The sawtooth notches (221) have the same depth, the number of the sawtooth notches (221) is more than 5, the depth is more than 3 mm, the tooth pitch is more than 5 mm, and the ratio of the length of the sawtooth segment to the length of the rear edge (22) is more than 1 / 2.

11. The axial flow fan blade according to claim 1, characterized in that: The trailing edge (22) of the blade (2) is recessed toward the side where the leading edge (21) is located.

12. The axial flow fan blade according to claim 1, characterized in that: A plurality of pits (261) are distributed on the suction surface (26) of the blade (2), and the number of the pits (261) on a single blade (2) is more than 30.

13. The axial flow fan blade according to claim 12, characterized in that: The pit (261) is in the shape of a sphere, a column, a pyramid or a cuboid.

14. The axial flow fan blade according to claim 1, characterized in that: The area of ​​the negative curvature surface segment (252) is greater than the area of ​​the positive curvature surface segment (251).

15. An air conditioner, comprising an axial flow fan blade, characterized in that: The axial flow fan blade is the axial flow fan blade according to any one of claims 1 to 14.

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