Axial flow fan blade and fan

Abstract

The application provides an axial flow fan blade, comprising a hub, a plurality of blades are arranged on the hub at intervals, the blade comprises a trailing edge part towards the leeward direction and a leading edge part towards the windward direction, the leading edge part and the trailing edge part are arc curves, so as to reduce the centrifugal force of the fluid in the boundary layer of the blade, thereby reducing the energy loss of the blade. The application also provides a fan. The axial flow fan blade and the fan provided by the application reduce the centrifugal force of the fluid in the boundary layer of the blade by arranging the blade as a curved cambered profile structure, effectively inhibit the blade tip stall of the blade, thereby reducing the energy loss of the blade tip part, and improving the efficiency of the blade. The middle part of the blade surface is wider than the root part and the tip part in area, the effective working area of the blade surface is increased, the performance of the blade is improved, and the air volume of the fan blade is increased; the middle part of the suction surface of the blade is thickened, which is beneficial to improving the strength of the fan blade, improving the bending resistance, and preventing deformation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fans, and particularly relates to an axial flow fan blade and a fan. BACKGROUND

[0002] With the improvement of living standards, people have increasing demands for the function and performance diversity of fans. Most of the floor fans are equipped with five-blade fan blades at present. Due to the symmetrical structure of the even-numbered fan blades, the axial tension generated during the operation of the fan blades is more likely to cause fatigue fracture and vibration of the fan blades.

[0003] People prefer fans that provide a comfortable experience. The more fan blades, the more stable the air supply, and the better the air supply effect. Although the load is increased, the more fan blades can cut the wind into smaller pieces, making the blown wind softer. The air supply of a seven-blade fan is more comfortable than that of a five-blade fan, and the noise reduction effect is better.

[0004] However, the current axial seven-blade fan has many problems: the fan blades are prone to deformation during long-term operation, and the wind volume decays obviously; the middle part of the blade does little work. Therefore, there is an urgent need to design a new type of axial fan blade to improve the anti-deformation strength of the fan blade. SUMMARY

[0005] The main purpose of the present application is to provide an axial fan blade and a fan, improve the anti-deformation strength of the fan blade, improve the air supply flow divergence of the traditional fan blade, enhance the air supply effect, and improve the air supply volume of the blade.

[0006] To achieve the above-mentioned purpose, the specific technical scheme of the axial fan blade and the fan of the present application is as follows:

[0007] The present application provides an axial fan blade, which comprises a hub, a plurality of blades are arranged on the hub at intervals, the blade comprises a trailing edge part facing the leeward direction and a leading edge part facing the windward direction, and the leading edge part and the trailing edge part are arc curves to reduce the centrifugal force of the fluid in the boundary layer of the blade, thereby reducing the energy loss of the blade.

[0008] As a preferred embodiment provided by the present application, the blade comprises a tip part, and the trailing edge part and the tip part are connected in sequence to form an arc curve.

[0009] As a preferred embodiment provided by the present application, the blade comprises a tip part, and the trailing edge part and the tip part are connected in sequence to form an arc curve.

[0010] As a preferred embodiment provided by the present application, the trailing edge part to the tip part and the tip part of the blade form a streamlined arc line, and the sweep degree of the streamlined arc line is set to be small at the blade root part, large at the tip part, and small again at the tip part.

[0011] As a preferred embodiment provided by the present application, the leading edge part is tangent to the center line of the blade, and the trailing edge part is tangent to the center line of the blade to form a diameter of a circle, the diameter of the circle is from small to large, and then from large to small.

[0012] As a preferred embodiment provided by the present application, the blade area formed by the trailing edge part and the blade tip part connected in sequence is smaller.

[0013] As a preferred embodiment provided by the present application, the part of the blade and the hub in contact is provided as a blade root part, the blade root part and the trailing edge part are connected in sequence, and the blade root part converges to the leading edge part.

[0014] As a preferred embodiment provided by the present application, the radial width of the trailing edge part is greater than the radial width of the blade root part and the radial width of the blade tip part.

[0015] As a preferred embodiment provided by the present application, the blade includes a suction surface and a pressure surface, and the middle part of the suction surface is provided with a protrusion.

[0016] As a preferred embodiment provided by the present application, the radial width of the blade tip part is greater than the radial width of the blade root part.

[0017] As a preferred embodiment provided by the present application, the included angle of the arc lines of the leading edge part and the blade tip part is provided as 40°-50°.

[0018] As a preferred embodiment provided by the present application, the maximum radius of the fan blade is provided as R, the connecting line of the middle point of the blade tip part and the concentric circle of the cylindrical surface of the hub is L1, the connecting line of the middle point of the blade root part and the center of the hub is L2, the connecting line of the intersection point of the middle line of the airfoil and the cylindrical surface with a radius of r and the center of the hub is L3, the included angle between L2 and L3 is the net bending angle A1 of the blade, when the ratio of r / R is 0.3-0.9, the value range of the net bending angle A1 of the blade is 0.2°-25.4°.

[0019] As a preferred embodiment provided by the present application, the connecting line of the intersection point C of the leading edge part of the blade and the cylindrical surface with a radius of r and the center point is L4, the included angle of the tangent line L5 of the tangent point of the leading edge and L4 is the bending angle A2 of the leading edge, when the ratio of r / R is 0.3-0.9, the value range of the bending angle A2 of the leading edge is 16.5°-39.7°.

[0020] As a preferred embodiment provided by the present application, the connecting line of the intersection point D of the trailing edge part of the blade and the cylindrical surface with a radius of r and the center point is L6, the included angle of the tangent line L7 of the tangent point of the trailing edge and L6 is the bending angle A3 of the trailing edge, when the ratio of r / R is 0.3-0.9, the value range of the bending angle A3 of the trailing edge is 9.7°-60.2°.

[0021] As the preferred embodiment provided by the present application, the angle between the rotating plane of the fan blade and the chord line b of the blade cross section obtained by cutting a different cylinder surface with a radius of r concentric with the hub cylinder surface is the blade installation angle Q, when the ratio of r / R is 0.3 to 0.9, the blade installation angle Q is in the range of 34.5° to 12.7°.

[0022] As the preferred embodiment provided by the present application, the blade installation angle decreases from the blade root portion to the blade tip portion.

[0023] The present application also provides a fan comprising the axial fan blade as described above.

[0024] The axial fan blade and the fan provided by the present application have the following advantages:

[0025] The axial fan blade and the fan provided by the present application, by setting the blade into the curved camber line structure, reduce the centrifugal force of the fluid in the boundary layer of the blade, effectively suppress the blade tip stall, thereby reducing the energy loss of the blade tip portion and improving the blade efficiency. The middle portion of the blade surface is wider than the blade root portion and the blade tip portion, increases the effective working area of the blade surface, improves the blade performance, and increases the air volume of the fan blade. The middle portion of the suction surface of the blade is thickened, which is beneficial to improve the strength of the fan blade, improve the bending resistance, and prevent deformation. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The overall structure of the axial fan blade provided by the present application Figure 1 ;

[0027] Figure 2 The overall structure of the axial fan blade provided by the present application Figure 2 ;

[0028] Figure 3 The partial structure of the axial fan blade provided by the present application Figure 1 ;

[0029] Figure 4 The partial structure of the axial fan blade provided by the present application Figure 2 ;

[0030] Figure 5 The side view of the axial fan blade provided by the present application

[0031] Figure 6 The partial cross section of the axial fan blade provided by the present application Figure 1 ;

[0032] Figure 7 The partial cross section of the axial fan blade provided by the present application Figure 2 ;

[0033] Figure 8Partial cross section of the axial flow fan blade provided by the present application Figure 3 ;

[0034] Figure 9 Overall structure schematic diagram of the axial flow fan blade provided by the present application and the axial flow fan blade in the prior art.

[0035] Marked description in the figure:

[0036] 1, hub; 2, blade; 21, leading edge part; 22, trailing edge part; 23, blade root part; 24, blade tip part; 25, blade tip part; 26, pressure surface; 27, suction surface; 28, blade cross section; 281, first cross section; 282, second cross section; 3, trailing edge curve. DETAILED DESCRIPTION

[0037] The technical solutions of the present application will be described clearly and completely below in combination with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application. In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0038] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0039] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0040] For example, Figure 1 and Figure 2As shown, the axial flow fan blade provided by the embodiment of the present application comprises a hub 1, a plurality of blades 2 are arranged on the hub 1 at intervals, a part of the blade 2 in contact with the hub 1 is arranged as a blade root part 23, a part of the blade 2 away from the blade root part 23 is arranged as a blade tip part 24, a trailing edge part 22 is arranged between the blade root part 23 and the blade tip part 24, a blade tip part 25 is connected to the blade tip part 24, the blade tip part 25 is arranged as the top end of the blade 2, a leading edge part 21 is arranged between the blade tip part 25 and the blade root part 23, and a chord line of the blade tip part 24 is a line between opposite ends of the blade tip part 24. The trailing edge part 22 and the leading edge part 21 are arranged as arc curves, and the bending degree of the trailing edge part 22 is greater than that of the leading edge part 21. The curved arc design can reduce the centrifugal force of the fluid in the boundary layer of the blade 2, effectively suppress the stall of the blade tip part 24 of the blade 2, thereby reducing the energy loss of the blade tip part 24 of the blade 2 and improving the efficiency of the blade 2.

[0041] Of course, it can be understood that, as an alternative embodiment, since the trailing edge part 22 is arranged as a circular arc line with a large bending degree, the trailing edge part 22 can completely replace the blade tip part 24, and in some embodiments, the bending degree of the trailing edge part 22 can be increased to be directly connected to the blade tip part 25, so that the blade 2 forms a circular arc trailing edge part 22. The area of the blade 2 connected by the trailing edge part 22 and the blade tip part 25 is reduced, the deformation of the fan blade during long-term operation is reduced, the curved arc design can reduce the centrifugal force of the fluid in the boundary layer of the blade 2, effectively suppress the stall of the blade tip part 24 of the blade 2, thereby reducing the energy loss of the blade tip part 24 and improving the efficiency of the blade 2, while also reducing the weight of the blade 2.

[0042] In the specific use process of the above-mentioned axial flow fan blade, a plurality of blades 2 are arranged at equal intervals on the hub 1. Specifically, the number of blades 2 can be three, five or seven or more, but the number of blades 2 is always an odd number. Since the symmetrical structure of the even number of blades 2 produces axial tension during fan operation, it is more likely to cause fan fatigue fracture and vibration. Therefore, the odd number of blades 2 scheme is preferred, thereby avoiding the symmetrical arrangement of the blades 2, which causes the centrifugal force, wind resistance and other symmetrical distribution of the blades 2 during the rotation of the axial flow impeller, thereby causing the axial flow impeller to be prone to deformation. The number of blades 2 is designed according to different application scenarios. As a preferred embodiment, the number of blades 2 provided by the embodiment of the present application is seven, which improves the anti-deformation strength of the fan blade, improves the air flow divergence of the traditional fan blade, enhances the air supply effect, improves the air supply volume of the blade 2, improves the anti-deformation strength of the fan blade, and ensures that the fan blade has large air volume, comfortable noise and stable and soft air supply under low load.

[0043] As Figure 3 to Figure 8As shown, the embodiment provided by the present application comprises a blade tip 25 connected to the leading edge 21, so that the blade tip 25 is curved towards the windward direction. The trailing edge 22 to the blade tip 24 and the blade tip 25 of the blade 2 form a streamlined curve, and the degree of sweep of the streamlined curve is set to be small to large and then large to small from the blade root 23 to the blade tip 25. The embodiment provided by the present application is a swept blade 2, which has a complex three-dimensional spatial structure in addition to the twist along the spanwise direction of the blade 2, and also has an inclination (sweep) along the circumferential rotation direction and an inclination (sweep) along the flow direction between the blade tip and the blade root of the blade 2.

[0044] At present, the swept blade 2 has been widely used in turbomachinery. A large number of experimental researches and numerical calculations show that reasonable blade 2 sweep can change the radial component of the force acting on the blade 2, control the pressure gradient distribution on the surface of the blade 2, reduce flow loss, and achieve the purpose of improving the aerodynamic performance of the turbomachinery. The research on the swept blade 2 mainly focuses on the sweep of the blade tip 24 and the blade root 23.

[0045] As a preferred embodiment, the degree of sweep of the embodiment provided by the present application is set to be small to large and then large to small.

[0046] Further, the diameter of the circle formed by the tangency of the leading edge 21 to the center line of the blade 2 and the tangency of the trailing edge 22 to the center line of the blade 2 is set to be small to large and then large to small. The diameter of the circle is consistent with the change trend of the degree of sweep of the curve.

[0047] Further, compared with the conventional blade 2, the trailing edge 22 and the blade tip 24 of the blade 2 are an arc, the area of the blade surface at the connection between the trailing edge 22 and the blade tip 24 is reduced, and the deformation of the fan blade during long-term operation is reduced. The curved arc design can reduce the centrifugal force of the fluid in the boundary layer of the blade 2, effectively suppress the stall of the blade tip 24 of the blade 2, thereby reducing the energy loss of the blade tip 24 of the blade 2 and improving the efficiency of the blade 2.

[0048] Further, the part of the blade 2 in contact with the hub 1 is set as the blade root 23, the blade root 23 and the trailing edge 22 are sequentially connected, and the blade root 23 converges towards the leading edge 21, which is conducive to reducing the weight of the blade 2, reducing the load of the motor, and thereby reducing the cost of the motor.

[0049] Further, the width of the trailing edge 22 along the radial direction is greater than the width of the blade root 23 along the radial direction and the width of the blade tip 24 along the radial direction, which increases the effective working area of the surface of the blade 2, improves the performance of the blade 2, and improves the air volume of the fan blade.

[0050] Further, the blade 2 comprises a suction surface 27 and a pressure surface 26, and the middle part of the suction surface 27 is provided with a protrusion, and the middle part of the suction surface 27 is thickened, which is beneficial to improve the strength of the blade and improve the bending resistance and prevent deformation.

[0051] Further, the front edge part 21 is provided with a concave large-angle arc line, and the radial width of the blade top part 24 is greater than the radial width of the blade root part 23, which can effectively inhibit and reduce the formation and separation of the blade surface vortex, and achieve the purpose of noise reduction.

[0052] Further, the included angle of the arc lines of the front edge part 21 and the blade top part 24 is set to 40°-50°, and the blade tip angle is designed, which can effectively reduce the blade tip vortex and the front edge separation vortex, thereby achieving the purpose of reducing the aerodynamic noise. If the α angle is too small, it cannot be molded, and if the α angle is too large, the blade tip working area is reduced.

[0053] As shown in Figure 2 The specific embodiments provided by the application are shown, the ratio of the hub 1 is 0.26, R=197.5, the number of blades is selected to be 7, and α is 45.3°. The axial flow blade mainly comprises a hub 1 and a plurality of annular distribution blades 2 connected to the side wall around the hub 1. The blade 2 mainly comprises a front edge part 21, a rear edge part 22, a blade root part 23, a blade top part 24, a blade tip part 25, a pressure surface 26, a suction surface 27 and a blade cross section 28.

[0054] The ratio of the diameter d of the blade hub 11 to the outer diameter D of the blade is selected to be 0.25-0.35 in the embodiments of the application.

[0055] Further, the maximum radius of the blade is set to R, the midpoint of the blade top part 24 and the cylindrical surface concentric circle of the hub 1, the midpoint of the circular arc of the blade cross section 28 cut by the cylindrical surface with a radius of r, the connecting line of the blade root part chord midpoint and the hub 1 center is L2, and the connecting line of the intersection point of the airfoil median line L1 and the cylindrical surface with a radius of r and the hub 1 center is L3; the included angle between L2 and L3 is the net bending angle A1 of the blade 2, and when the ratio of r / R is 0.3-0.9, the value range of the net bending angle A1 of the blade 2 is 0.2°-25.4°.

[0056] As a preferred embodiment provided by the application, the connecting line of the intersection point C of the leading edge of the blade 2 and the center point of the cylindrical surface with a radius of r is L4, and the included angle between the tangent line L5 of the tangent point of the leading edge and L4 is the leading edge bending angle A2, and when the ratio of r / R is 0.3-0.9, the value range of the leading edge bending angle A2 is 16.5°-39.7°.

[0057] As the preferred embodiment provided by the present application, the intersection point D of the cylindrical surface with radius r and the leading edge of the blade 2 is connected to the center point, the tangent line L7 of the tangent point of the leading edge and the angle between L6 is the leading edge bending angle A3, when the ratio of r / R is 0.3 to 0.9, the value range of the leading edge bending angle A3 is 9.7° to 60.2°.

[0058] As the preferred embodiment provided by the present application, the intersection point D of the cylindrical surface with radius r and the leading edge of the blade 2 is connected to the center point, the tangent line L7 of the tangent point of the leading edge and the angle between L6 is the leading edge bending angle A3, when the ratio of r / R is 0.3 to 0.9, the value range of the leading edge bending angle A3 is 9.7° to 60.2°.

[0059] As the preferred embodiment provided by the present application, the intersection point D of the cylindrical surface with radius r and the leading edge of the blade 2 is connected to the center point, the tangent line L7 of the tangent point of the leading edge and the angle between L6 is the leading edge bending angle A3, when the ratio of r / R is 0.3 to 0.9, the value range of the leading edge bending angle A3 is 9.7° to 60.2°.

[0060] As the preferred embodiment provided by the present application, the intersection point D of the cylindrical surface with radius r and the leading edge of the blade 2 is connected to the center point, the tangent line L7 of the tangent point of the leading edge and the angle between L6 is the leading edge bending angle A3, when the ratio of r / R is 0.3 to 0.9, the value range of the leading edge bending angle A3 is 9.7° to 60.2°. As the preferred embodiment provided by the present application, the intersection point D of the cylindrical surface with radius r and the leading edge of the blade 2 is connected to the center point, the tangent line L7 of the tangent point of the leading edge and the angle between L6 is the leading edge bending angle A3, when the ratio of r / R is 0.3 to 0.9, the value range of the leading edge bending angle A3 is 9.7° to 60.2°. As the preferred embodiment provided by the present application, the intersection point D of the cylindrical surface with radius r and the leading edge of the blade 2 is connected to the center point, the tangent line L7 of the tangent point of the leading edge and the angle between L6 is the leading edge bending angle A3, when the ratio of r / R is 0.3 to 0.9, the value range of the leading edge bending angle A3 is 9.7° to 60.2°.

[0061] Preferably, the intersection point C of the cylindrical surface with radius r and the leading edge of the blade 2 is connected with the center point O as L4, and the included angle between the tangent line L5 of the tangent point of the leading edge and L4 is the leading edge bending angle A2. The corresponding values of the leading edge bending angle A2 at different r / R ratio cross sections are 16.5°, 10.6°, 4.7°, 1.4°, 7.0°, 12.6°, 17.9°, 23.3°, 28°, 31.7°, 34.7°, 37.2°, 39.7°. The technical scheme limits the sweep degree of the leading edge of the blade 2, the large-angle leading edge sweep scheme is adopted in the embodiment provided by the application, the sweep degree of the leading edge gradually increases from the blade root 23 to the blade tip 24, the backflow existing in the leading edge of the impeller can be eliminated, and the flow loss and flow blockage are reduced. Secondly, the leading edge sweep blade 2 can inhibit the shedding of vortex flow on the surface of the blade 2, reduce the wideband noise of the blade 2, and improve the sound quality.

[0062] Preferably, the intersection point D of the cylindrical surface with radius r and the trailing edge of the blade 2 is connected with the center point O as L6, and the included angle between the tangent line L7 of the tangent point of the trailing edge and L6 is the trailing edge bending angle A3. The corresponding values of the trailing edge bending angle A3 at different r / R ratio cross sections are 9.7°, 13.5°, 16.7°, 19.6°, 22.3°, 25.1°, 28.2°, 32°, 36.8°, 42.3°, 48.1°, 54.1°, 60.2°. The embodiment provided by the application limits the sweep degree of the trailing edge of the blade 2, and the large-angle trailing edge sweep can effectively inhibit the shedding of vortex flow on the trailing edge of the blade 2, thereby reducing the noise of the blade 2.

[0063] Preferably, the included angle between the tangent line b of the blade cross section 28 obtained by the different cylindrical surfaces with radius r concentric with the cylindrical surface of the hub 1 and the tangent line of the tangent point of the blade 2 is the installation angle Q of the blade 2. The corresponding values of the installation angle Q of the blade 2 at different r / R ratio cross sections are 34.5°, 32.1°, 30.5°, 27.9°, 25.9°, 23.8°, 21.8°, 19.8°, 17.9°, 16.3°, 14.9°, 13.8°, 12.7°. The technical scheme limits the installation angle Q of the blade 2 at different cross sections, and the installation angle gradually decreases from the blade root 23 to the blade tip 24, the installation angle of the blade root 23 is large, the strength of the blade can be effectively guaranteed, the installation angle of the blade tip 24 gradually decreases, and the overall load of the blade 2 can be effectively reduced, thereby reducing the pressure of the motor.

[0064] The axial flow fan provided by the embodiment has a wide air supply range, the air converges at a certain position and diffuses outward, the wind field is wider, the air volume is larger, and the air feeling is softer and more comfortable. Meanwhile, the axial flow impeller in the above embodiment can effectively reduce the "humming sound" when rotating at a high speed, and improve the sound quality.

[0065] like Figure 9 As shown in the figure, the shape of the non-blade 2 of the axial flow impeller in the above embodiment is compared with that of the conventional blade 2. As can be seen from the figure, the curvature of the trailing edge 22 is set as a circular arc transition section.

[0066] The performance comparison data of the axial flow impeller in the above embodiment and the traditional fan with five blades 2 are shown in the table below:

[0067]

[0068] The test data in the table above shows that the axial flow impeller has a significant improvement in overall performance, with an increase of 4 air volume, a speed increase of 50 R / s, and a power increase of 2W. The overall energy efficiency ratio of the axial flow impeller has increased.

[0069] Furthermore, the blade 2 is provided with a blade cross-section 28, which includes a first cross-section 281 and a second cross-section 282. The first cross-section 281 and the second cross-section 282 are connected in sequence, such that the second cross-section 282 extends to the sidewall of the first cross-section 281. This makes the center of the suction surface 27 of the blade 2 protrude.

[0070] The fan in one embodiment of the present invention includes the axial flow impeller of any of the above embodiments. Specifically, the fan further includes a rotating component for driving the axial flow impeller to rotate. Further, the rotating component is disposed on the hub 1, wherein the rotating component is a motor.

[0071] The present invention also provides another embodiment of a fan, including the axial flow blades described above, wherein the fan is a floor-standing circulating fan. In other embodiments, the fan may be other types of fans.

[0072] The axial flow fan blade and fan provided by this invention, by setting the blade 2 to a curved arc profile structure, reduces the centrifugal force of the fluid within the boundary layer of the blade 2, effectively suppressing blade tip stall, thereby reducing energy loss at the blade tip 24 and improving blade efficiency. The middle part of the blade surface is wider than the root 23 and the tip 24, increasing the effective working area of ​​the blade 2 surface, thus improving blade performance and increasing airflow. The thickened central convexity of the suction surface 27 of the blade 2 helps to improve blade strength, enhance bending resistance, and prevent deformation. The width of the blade tip 24 is greater than that of the root 23, which can effectively suppress and reduce the formation and detachment of vortices on the blade surface, achieving noise reduction. A sharp angle α is provided between the leading edge 21 and the tip 24 of the blade 2, with the angle α ranging from 40° to 50°. The sharp angle design of the blade tip can effectively reduce the generation of tip vortices and leading edge separation vortices, thereby reducing aerodynamic noise.

[0073] Those skilled in the art will appreciate that the features of the various embodiments can be combined with each other, as means within the scope of the application and form different embodiments. For example, in the claims, any of the claimed embodiments can be used in any combination.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An axial flow fan blade, characterized in that, It includes a hub with multiple blades spaced apart. Each blade has a trailing edge facing the leeward direction and a leading edge facing the windward direction. The leading and trailing edges are arc-shaped curves to reduce the centrifugal force of the fluid in the blade boundary layer, thereby reducing blade energy loss. The leaf blade consists of a leaf tip, a trailing edge, and a leaf tip that are connected in sequence to form an arc-shaped curve with the trailing edge and leaf tip. The blade includes a tip, and the tip and leading edge are connected so that the tip is bent toward the windward direction; The trailing edge of the blade to the top and tip forms a streamlined arc, and the degree of sweep of the streamlined arc is set to gradually increase from the root to the tip, and then decrease again. The diameter of the circle formed by the tangency of the leading edge and the trailing edge to the center line of the leaf gradually increases and then decreases again. The degree of curvature of the leading edge gradually increases from the leaf root to the leaf tip.

2. The axial flow fan blade according to claim 1, characterized in that, The leaf area gradually decreases as the leaf is formed by connecting the posterior margin to the top of the leaf.

3. The axial flow fan blade according to claim 1, characterized in that, The part where the blade contacts the hub is set as the blade root, and the blade root and the trailing edge are connected in sequence, with the blade root converging towards the front edge.

4. The axial flow fan blade according to claim 3, characterized in that, The radial width of the trailing edge is greater than the radial width of the leaf root and the radial width of the leaf tip.

5. The axial flow fan blade according to claim 1, characterized in that, The blades include a suction surface and a pressure surface, with a protrusion in the center of the suction surface.

6. The axial flow fan blade according to claim 3, characterized in that, The radial width of the leaf tip is greater than the radial width of the leaf root.

7. The axial flow fan blade according to claim 1, characterized in that, The angle between the leading edge and the arc at the tip of the blade is set to 40° to 50°.

8. The axial flow fan blade according to claim 3, characterized in that, The maximum radius of the blade is set to R. The line connecting the midpoint of the blade tip and the midpoint of the cross-sectional arc of the blade cut by different cylindrical surfaces with radius r, which are concentric circles of the cylindrical surface of the hub, is L1. The line connecting the midpoint of the chord at the blade root and the center of the hub is L2. The line connecting the intersection of the airfoil centerline L1 and the cylindrical surface with radius r and the center of the hub is L3. The angle between L2 and L3 is the blade net bending angle A1. When the ratio of r / R is 0.3 to 0.9, the value of the blade net bending angle A1 ranges from 0.2° to 25.4°.

9. The axial flow fan blade according to claim 1, characterized in that, The line connecting the intersection point C of the cylindrical surface with radius r and the leading edge of the blade to the center point is L4. The angle between the tangent line L5 at the tangent point of the leading edge and L4 is the leading edge bending angle A2. When the ratio of r / R is 0.3 to 0.9, the leading edge bending angle A2 ranges from 16.5° to 39.7°.

10. The axial flow fan blade according to claim 1, characterized in that, The line connecting the intersection point D of the cylindrical surface with radius r and the trailing edge of the blade to the center point is L6. The angle between the tangent L7 and L6 at the intersection point is the trailing edge bending angle A3. When the ratio of r / R is 0.3 to 0.9, the trailing edge bending angle A3 ranges from 9.7° to 60.2°.

11. The axial flow fan blade according to claim 1, characterized in that, The angle between the rotating plane of the wind turbine blade and the chord b of the blade cross-section obtained by different cylindrical surfaces of radius r concentric with the hub cylindrical surface is the blade installation angle Q. When the ratio of r / R is 0.3 to 0.9, the blade installation angle Q ranges from 34.5° to 12.7°.

12. The axial flow fan blade according to claim 3, characterized in that, The blade installation angle decreases sequentially from the blade root to the blade tip.

13. A fan, characterized in that, Includes the axial flow fan blades as described in any one of claims 1-12.

Images