Axial flow fan blade, axial flow fan and electric appliance

Abstract

The utility model discloses an axial flow fan blade, an axial flow fan and an electric appliance. The blade comprises a blade body connected with the hub and a fluid acting part arranged on at least one side of the blade body in the rotating direction of the hub, and the fluid acting part is arranged in a drooping mode relative to the side, facing the pressure face of the blade, of the blade body. The fluid acting part is used for restraining fluid from being separated from the suction surfaces of the blades when the axial flow fan blades rotate. According to the technical scheme, dynamic stall in the rotating process can be effectively improved, and noise is lowered.

Description

Technical Field

[0001] The utility model relates to the technical field of axial flow fans, in particular to an axial flow fan blade, an axial flow fan and an electrical appliance. Background Art

[0002] Axial flow fans are a type of fan widely used in the ventilation and home appliance industries, and are usually used in air conditioner outdoor units, refrigerator compressor compartments, microwave ovens, and electric fans. The blades of axial flow fans usually use open blades, which are composed of blades and hubs that are arranged uniformly or unevenly in the circumferential direction. The blade cross-sections of most axial flow fans use flow-direction equal-thickness airfoils, airfoils, or bionic airfoils, mainly for the purpose of reducing cross-sectional resistance or improving intake flow. The stall problem of axial flow fan blades during circumferential rotation has not been considered or improved. Once the blades of an axial flow fan stall, the noise will increase. Utility Model Content

[0003] The main purpose of the utility model is to provide an axial flow fan blade, which is intended to effectively improve the dynamic stall during the rotation process and reduce noise.

[0004] In order to achieve the above-mentioned purpose, the axial flow fan blade proposed by the utility model comprises:

[0005] Wheel hub; and

[0006] The blade includes a blade body connected to the hub, and a fluid action portion arranged on at least one side of the blade body in the rotation direction of the hub, the fluid action portion is arranged to droop relative to the blade body toward the pressure surface of the blade, and the fluid action portion is used to inhibit the separation of the fluid from the suction surface of the blade when the axial flow fan blade rotates.

[0007] In one embodiment, the fluid action portion extends from the hub to the blade tip of the blade; or the fluid action portion extends in a partial section between the hub and the blade tip.

[0008] In one embodiment, the fluid action portion is integrally formed with the blade body.

[0009] In one of the embodiments, the fluid action portion includes a leading edge hanging portion provided on the front side of the blade body in the rotation direction of the hub.

[0010] In one embodiment, at least a portion of the area between the front side edge of the blade body and the leading edge of the blade is bent relative to the blade body toward the pressure surface to form the leading edge drooping portion;

[0011] Alternatively, at least a portion of the area between the front side edge of the blade body and the leading edge of the blade is thickened relative to the blade body on the side facing the pressure surface to form the leading edge drooping portion;

[0012] Alternatively, a leading edge flap inclined toward one side of the pressure surface is provided at the leading edge of the blade, and the leading edge flap forms the leading edge drooping portion.

[0013] In one embodiment, in the spanwise direction of the blade extending from the hub toward the blade tip, the spanwise position at the hub is defined as 0, the spanwise position at the blade tip is defined as 1, and the spanwise position of the leading edge droop is within the interval [0, 1];

[0014] and / or, in the airfoil section of the blade, in the chord direction extending from the leading edge to the trailing edge of the blade, the chord position at the leading edge is defined as 0, the chord position at the trailing edge is defined as 1, and the droop position of the leading edge droop portion is within the interval [0, 1];

[0015] And / or, in the airfoil section of the blade, the leading edge droop angle of the blade is η, wherein 0°<η≤30°.

[0016] In one of the embodiments, the fluid action portion includes a trailing edge hanging portion arranged on the rear side of the blade body in the rotation direction of the hub.

[0017] In one embodiment, at least a portion of the area between the rear edge of the blade body and the trailing edge of the blade is bent relative to the blade body toward the pressure surface to form the trailing edge hanging portion;

[0018] Alternatively, at least a portion of the area between the rear edge of the blade body and the trailing edge of the blade is thickened relative to the blade body on the side facing the pressure surface to form the trailing edge drooping portion;

[0019] Alternatively, the trailing edge of the blade is provided with a trailing edge flap inclined toward one side of the pressure surface, and the trailing edge flap forms the trailing edge drooping portion.

[0020] In one embodiment, in the spanwise direction of the blade extending from the hub toward the blade tip, the spanwise position at the hub is defined as 0, the spanwise position at the blade tip is defined as 1, and the spanwise position of the trailing edge droop is within the interval [0, 1];

[0021] and / or, in the airfoil section of the blade, in the chord direction extending from the leading edge to the trailing edge of the blade, the chord position at the leading edge is defined as 0, the chord position at the trailing edge is defined as 1, and the droop position of the drooping portion of the trailing edge is within the interval [0, 1];

[0022] And / or, in the airfoil section of the blade, the trailing edge droop angle of the blade is ζ, wherein 0°<ζ≤30°.

[0023] The utility model also provides an axial flow fan, comprising the axial flow blades as described above, and a driving member drivingly connected to the axial flow blades, wherein the driving member is used to drive the axial flow blades to rotate.

[0024] The utility model also provides an electrical appliance, comprising the axial flow fan blade or axial flow fan as described above.

[0025] The axial flow fan blade of the technical solution of the utility model includes a hub and blades arranged on the circumferential side of the hub. Among them, the blade includes a blade body connected to the hub, and a fluid action part arranged on at least one side of the blade body in the rotation direction of the hub, and the fluid action part is drooped relative to the blade body on the side of the pressure surface of the blade. When the axial flow fan blade rotates, the fluid action part can improve the flow field morphology and suppress the separation of the fluid and the suction surface of the blade, so that most of the fluid can flow along the suction surface of the blade; in this way, dynamic stall caused by large-scale airflow separation on the suction surface of the blade can be avoided. The axial flow fan blade of the utility model can effectively improve the dynamic stall during rotation and reduce noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0027] Figure 1 It is a schematic diagram of the structure of a traditional axial flow fan blade;

[0028] Figure 2 This is a schematic structural diagram of an axial flow fan blade according to an embodiment of the utility model;

[0029] Figure 3 for Figure 2 Schematic diagram of the airfoil section of the blade of the mid-axial flow fan blade;

[0030] Figure 4 for Figure 3 Schematic diagram of the structure of the airfoil section of the middle blade near the leading edge

[0031] Figure 5 for Figure 3 A schematic diagram of the structure of the airfoil section of the middle blade close to the trailing edge;

[0032] Figure 6is a schematic diagram of an airfoil cross-section of an axial flow fan blade of another embodiment;

[0033] Figure 7 FIG. 1 is a grayscale schematic diagram of a partial structure of an axial flow fan blade according to an embodiment.

[0034] Description of Figure Numbers:

[0035]

[0036]

[0037] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0039] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0040] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the utility model, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the utility model.

[0041] Please refer to Figure 1, is a schematic diagram of the structure of a traditional axial flow fan blade 100'. Specifically, the axial flow fan blade 100' generally includes a hub 10' and a plurality of blades 20' arranged on the circumference of the hub 10'. The blade 20' has a leading edge 21' and a trailing edge 22' arranged opposite to each other in the rotation direction of the hub 10', and a blade top 23' arranged opposite to the circumference of the hub 10'. The leading edge 21', the trailing edge 22', the blade top 23' and the circumference of the hub 10' together enclose the overall outline of the blade 20'.

[0042] The cross-sectional form of traditional axial flow fan blades is generally an airfoil type, a constant thickness type or a bionic airfoil type. The streamlined cross-section has a larger lift-to-drag ratio and higher efficiency, and the bionic cross-section can also improve the leading edge noise. However, none of the above cross-sectional forms consider the dynamic stall problem of the blade during the circumferential rotation process. The dynamic stall phenomenon refers to a strong unsteady and nonlinear stall-delay flow phenomenon caused by large-scale airflow separation on the suction surface of the blade when the angle of attack of the blade changes periodically or changes rapidly and dynamically. The axial flow fans in household appliances usually work in an environment with uneven air intake height. At the same time, the blades bear a very high load under limited size, and stall problems are very likely to occur. Dynamic stall not only causes the blade's ability to do work to decrease, but also increases noise. Based on this, the utility model proposes an axial flow fan blade that can effectively improve dynamic stall and reduce noise.

[0043] The utility model provides an axial flow fan blade 100.

[0044] Please refer to Figure 2 and Figure 3 In one embodiment of the utility model, the axial flow fan blade 100 includes a hub 10 and a blade 20. The blade 20 includes a blade body 26 connected to the hub 10, and a fluid action portion 27 provided on at least one side of the blade body 26 in the rotation direction of the hub 10, the fluid action portion 27 is provided downwardly relative to the blade body 26 toward the pressure surface 24 of the blade 20, and the fluid action portion 27 is used to inhibit the fluid from separating from the suction surface 25 of the blade 20 when the axial flow fan blade 100 rotates.

[0045] Specifically, the axial flow fan blade 100 includes a hub 10 and a plurality of blades 20 arranged on the circumference of the hub 10, wherein the number of blades 20 can be set according to actual needs, as long as the entire fan blade can maintain balance during rotation. For example, the blades 20 can usually be set to three, five or more. The following mainly illustrates the structure of a single blade 20. The blade 20 has a leading edge 21 and a trailing edge 22 arranged relatively in the rotation direction of the hub 10, and a blade top 23 arranged relatively to the circumference of the hub 10. The leading edge 21, the trailing edge 22, the blade top 23 and the circumference of the hub 10 together enclose the overall outline of the blade 20. The blade 20 has a relative pressure surface 24 and a suction surface 25 along the axial direction of the hub 10. When the axial flow fan blade 100 rotates, a pressure difference is formed on both sides of the suction surface 25 and the pressure surface 24 of the blade 20, so that the blade 20 has a certain lift. The blade 20 includes a blade body 26 and a fluid action portion 27. The root of the blade body 26 is connected to the circumference of the hub 10. The blade body 26 is provided with a fluid action portion 27 on at least one side in the rotation direction of the hub 10. For example, a fluid action portion 27 (for example, a leading edge drooping portion 271) may be provided on the front side of the blade body 26; or a fluid action portion 27 (for example, a trailing edge 22 drooping portion) may be provided on the rear side of the blade body 26; or a fluid action portion 27 may be provided on the front side and the rear side of the blade 20, respectively. The fluid action portion 27 and the blade body 26 may be integrally formed, or the fluid action portion 27 and the blade body 26 may be separately formed and then assembled together by welding or fastener connection. The fluid action portion 27 is drooping relative to the blade body 26 on the side facing the pressure surface 24 of the blade 20. There are many specific ways to form the fluid action portion 27. For example, the fluid action portion 27 may be formed by bending the leading edge 21 and / or the trailing edge 22 of the blade 20 as an integral part. Alternatively, the fluid action portion 27 may be formed by thickening the leading edge 21 and / or the trailing edge 22 of the blade 20 relative to the side of the blade body 26 facing the pressure surface 24. Alternatively, other components (e.g., flaps) may be provided on the leading edge 21 and / or the trailing edge 22 of the blade 20 to form the fluid action portion 27.

[0046] The axial flow fan blade 100 of the technical solution of the utility model includes a hub 10 and a blade 20 arranged on the circumference of the hub 10. Among them, the blade 20 includes a blade body 26 connected to the hub 10, and a fluid action part 27 arranged on at least one side of the blade body 26 in the rotation direction of the hub 10, and the fluid action part 27 is drooped relative to the blade body 26 toward the pressure surface 24 of the blade 20. When the axial flow fan blade 100 rotates, the fluid action part 27 can improve the flow field morphology, inhibit the separation of the fluid and the suction surface 25 of the blade 20, so that most of the fluid can flow along the suction surface 25 of the blade 20; in this way, the dynamic stall caused by the large-scale airflow separation on the suction surface 25 of the blade 20 can be avoided. The axial flow fan blade 100 of the utility model can effectively improve the dynamic stall during the rotation process and reduce noise.

[0047] The extension length of the fluid action portion 27 in the span direction from the hub 10 to the blade tip 23 can be set according to actual needs. For example, in one embodiment, the fluid action portion 27 extends from the hub 10 to the blade tip 23 of the blade 20. In this way, the fluid action portion 27 has a sufficient span length and can act on the fluid in a larger range, thereby better improving dynamic stall and reducing noise. Of course, in some embodiments, the fluid action portion 27 can also be extended in a partial interval between the hub 10 and the blade tip 23 of the blade 20. For example, the fluid action portion 27 can extend from the hub 10 to a certain position between the hub 10 and the blade tip 23. Or, the fluid action portion 27 extends from a certain position between the hub 10 and the blade tip 23 to the blade tip 23. Or the fluid action portion 27 is located between the hub 10 and the blade tip 23, and the two ends of the fluid action portion 27 are spaced from the hub 10 and the blade tip 23 respectively. Furthermore, in some embodiments, when the spanwise length of the fluid action portion 27 is relatively short, a plurality of fluid action portions 27 may be disposed at intervals in the spanwise direction from the hub 10 to the blade tip 23 .

[0048] In one embodiment, the fluid action portion 27 is integrally formed with the blade body 26. In this way, the blade 20 is an integrally formed structure, which is convenient for production and manufacturing, and is conducive to improving the overall structural strength of the blade 20. At the same time, it can also avoid the blade 20 being spliced ​​by multiple parts and generating vibration noise during rotation, which is conducive to further reducing the noise of the axial flow fan blade 100 during rotation.

[0049] Please refer to Figure 3In one embodiment, the fluid action portion 27 includes a leading edge drooping portion 271 provided on the front side of the blade body 26 in the rotation direction of the hub 10. When the axial flow fan blade 100 rotates, the leading edge drooping portion 271 can suppress the separation of the fluid from the suction surface 25 of the blade 20, which can effectively improve dynamic stall and reduce noise. At the same time, when the maximum lift does not drop much, the maximum resistance can be significantly reduced, thereby improving the work efficiency of the blade 20.

[0050] There are various ways to form the front edge hanging portion 271 .

[0051] In one embodiment, at least a portion of the area between the front edge of the blade body 26 and the leading edge 21 of the blade 20 is bent relative to the blade body 26 toward the pressure surface 24 to form the leading edge drooping portion 271. Specifically, the leading edge drooping portion 271 can be bent relative to the blade body 26 toward the pressure surface 24 at the leading edge bending portion 2713, and the leading edge drooping portion 271 has a leading edge pressure surface 2711 and a leading edge suction surface 2712 relative to each other, and the leading edge pressure surface 2711 is arranged at an angle to the pressure surface 24 of the blade body 26.

[0052] In one embodiment, at least a portion of the area between the front edge of the blade body 26 and the leading edge 21 of the blade 20 is thickened relative to the blade body 26 on the side facing the pressure surface 24 to form the leading edge drooping portion 271. Specifically, the leading edge 21 of the pressure surface 24 of the blade 20 can be increased in thickness, while the leading edge 21 of the suction surface 25 of the blade 20 remains unchanged, thereby forming an effect of the leading edge 21 drooping.

[0053] like Figure 6 As shown, in one embodiment, the leading edge 21 of the blade 20 is provided with a leading edge flap inclined toward one side of the pressure surface 24, and the leading edge flap forms the leading edge drooping portion 271. For example, on the basis of the existing blade 20, a leading edge flap extending forward and drooping can be added to the leading edge 21 of the blade 20, so as to form a leading edge drooping effect. The leading edge flap can be a flat plate structure or a streamlined structure.

[0054] In one of the embodiments, in the spanwise direction of the blade 20 extending from the hub 10 toward the blade tip 23, the spanwise position at the hub 10 is defined as 0, the spanwise position at the blade tip 23 is defined as 1, and the spanwise position of the leading edge droop 271 is in the interval [0, 1]. That is, the leading edge droop 271 can be disposed near the hub 10, or the leading edge droop 271 can also be disposed near the blade tip 23, or the leading edge droop 271 can also be disposed at a position between the hub 10 and the blade tip 23. The spanwise length of the leading edge droop 271 can extend from the hub 10 to the blade tip 23. Or the leading edge droop 271 can also be extended in a partial interval between the hub 10 and the blade tip 23 of the blade 20. For example, the leading edge droop 271 can extend from the hub 10 to a position between the hub 10 and the blade tip 23. Alternatively, the leading edge drooping portion 271 extends from a certain position between the hub 10 and the blade tip 23 to the blade tip 23. Alternatively, the leading edge drooping portion 271 is located between the hub 10 and the blade tip 23, and the two ends of the leading edge drooping portion 271 are spaced from the hub 10 and the blade tip 23, respectively.

[0055] like Figure 3 As shown, in the axial flow impeller 100, the cross section of the blade 20 obtained by the intersection of the rotating body concentric with the hub 10 and the blade 20 is the airfoil cross section of the blade 20. The airfoil cross section shape of the blade 20 has a great influence on the performance of the blade 20.

[0056] In one of the embodiments, in the airfoil section of the blade 20, in the chordwise direction extending from the leading edge 21 to the trailing edge 22 of the blade 20, the chordwise position at the leading edge 21 is defined as 0, the chordwise position at the trailing edge 22 is defined as 1, and the drooping position of the leading edge drooping portion 271 is located in the interval [0, 1].

[0057] Specifically, in the airfoil section of the blade 20, the straight line connecting the leading edge 21 and the trailing edge 22 is the chord of the airfoil section, and the leading edge 21 is bent toward the pressure surface 24 from a certain position point on the chord (i.e., the leading edge bend 2713) to form a drooping effect of the leading edge 21. The chord length of the chord is recorded as C, and the position of the leading edge bend 2713 is the drooping position of the leading edge drooping portion 271, which is recorded as x_le / C, wherein x_le / C is between [0, 1]. Optionally, x_le / C is between [0, 0.3]. At this time, the drooping ratio of the leading edge 21 is moderate, which can play a good role in improving dynamic stall. For example, when the drooping position of the leading edge drooping portion 271 is 0.3, the length between the leading edge bend 2713 and the leading edge 21 is 30% of the chord length.

[0058] like Figure 4As shown, the front shape of the leading edge 21 droops is a dotted line, and becomes a solid line after rotating toward the pressure surface 24 at a certain position x_le / C on the chord line. The angle between the solid geometric center line and the dotted center line is the droop angle η of the leading edge 21. In one embodiment, in the airfoil section of the blade 20, the leading edge droop angle of the blade 20 is η, where 0°<η≤30°. In this way, the leading edge drooping portion 271 is inclined at a moderate angle relative to the blade body 26 toward the pressure surface 24, which can effectively improve dynamic stall and reduce noise. At the same time, when the maximum lift does not drop much, the maximum drag can be significantly reduced, thereby improving the work efficiency of the blade 20. For example, η can be designed to be 10°, 15°, 30°, etc. as needed.

[0059] like Figure 3 As shown, in one embodiment, the fluid action portion 27 includes a trailing edge drooping portion 272 disposed at the rear side of the blade body 26 in the rotation direction of the hub 10. The trailing edge drooping portion 272 can increase the dynamic lift, significantly improve the trailing edge flow field of the dynamic stall, and delay the occurrence of the dynamic stall.

[0060] There are many ways to form the trailing edge hanging portion 272 .

[0061] like Figure 3 As shown, in one embodiment, at least a portion of the area between the rear edge of the blade body 26 and the trailing edge 22 of the blade 20 is bent relative to the blade body 26 toward the pressure surface 24 to form the trailing edge drooping portion 272. Specifically, the trailing edge drooping portion 272 can be bent relative to the blade body 26 toward the pressure surface 24 at the trailing edge bending portion 2723, and the trailing edge drooping portion 272 has a trailing edge pressure surface 2721 and a trailing edge suction surface 2722 opposite to each other, and the trailing edge pressure surface 2721 is arranged at an angle with the pressure surface 24 of the blade body 26.

[0062] In one embodiment, at least a portion of the area between the rear edge of the blade body 26 and the trailing edge 22 of the blade 20 is thickened relative to the blade body 26 on the side facing the pressure surface 24 to form the trailing edge drooping portion 272. Specifically, the trailing edge 22 of the blade 20 can be thickened on the pressure surface 24 and beveled along the pressure surface 24 to form the trailing edge 22 drooping effect.

[0063] like Figure 6 As shown, in one embodiment, the trailing edge of the blade 20 is provided with a trailing edge flap inclined toward one side of the pressure surface 24, and the trailing edge flap forms the trailing edge drooping portion 272. For example, on the basis of the existing blade 20, a trailing edge flap extending forward and drooping can be added to the trailing edge 22 of the blade 20, thereby forming a drooping effect of the trailing edge 22. The trailing edge flap can be a flat plate structure or a streamlined structure.

[0064] In one embodiment, in the spanwise direction of the blade 20 extending from the hub 10 toward the blade tip 23, the spanwise position at the hub 10 is defined as 0, the spanwise position at the blade tip 23 is defined as 1, and the spanwise position of the trailing edge drooping portion 272 is in the interval [0, 1]. That is, the trailing edge drooping portion 272 can be disposed near the hub 10, or the trailing edge drooping portion 272 can also be disposed near the blade tip 23, or the trailing edge drooping portion 272 can also be disposed at a position between the hub 10 and the blade tip 23. The spanwise length of the trailing edge drooping portion 272 can extend from the hub 10 to the blade tip 23. Or the trailing edge drooping portion 272 can also be extended in a partial interval between the hub 10 and the blade tip 23 of the blade 20. For example, the trailing edge drooping portion 272 can extend from the hub 10 to a position between the hub 10 and the blade tip 23. Alternatively, the trailing edge drooping portion 272 extends from a certain position between the hub 10 and the blade tip 23 to the blade tip 23. Alternatively, the trailing edge drooping portion 272 is located between the hub 10 and the blade tip 23, and the two ends of the trailing edge drooping portion 272 are spaced from the hub 10 and the blade tip 23, respectively.

[0065] In one of the embodiments, in the airfoil section of the blade 20, in the chordwise direction extending from the leading edge 21 to the trailing edge 22 of the blade 20, the chordwise position at the leading edge 21 is defined as 0, the chordwise position at the trailing edge 22 is defined as 1, and the drooping position of the trailing edge drooping portion 272 is located in the interval [0, 1].

[0066] Specifically, if Figure 3 As shown, in the airfoil section of the blade 20, the straight line connecting the leading edge 21 and the trailing edge 22 is the chord of the airfoil section, and the trailing edge 22 is bent toward the pressure surface 24 from a certain position point on the chord (i.e., the trailing edge bend 2723) to form a drooping effect of the trailing edge 22. Wherein, the chord length of the chord is denoted as C, and the position of the trailing edge bend 2723 is the drooping position of the trailing edge drooping portion 272, which is denoted as x_te / C, wherein x_te / C is between [0, 1]. Optionally, x_te / C is between [0.7, 1]. At this time, the drooping ratio of the trailing edge 22 is moderate, which can play a better role in improving dynamic stall. For example, when the drooping position of the trailing edge drooping portion 272 is 0.7, the length between the trailing edge bend 2723 and the trailing edge 22 is 30% of the chord length.

[0067] like Figure 5As shown, the outer shape of the trailing edge 22 before drooping is a dotted line, and becomes a solid line after rotating toward the pressure surface 24 at a certain position x_te / C on the chord line, and the angle between the solid geometric center line and the dotted center line is the droop angle ζ of the trailing edge 22. In one embodiment, in the airfoil section of the blade 20, the trailing edge droop angle of the blade 20 is ζ, where 0°<ζ≤30°. In this way, the dynamic lift can be increased, the trailing edge flow field of the dynamic stall can be significantly improved, and the occurrence of the dynamic stall can be delayed. For example, η can be designed to be 10°, 15°, 30°, etc. as needed.

[0068] For details on the range of geometric parameters of leading edge or trailing edge droop, please refer to Table 1.

[0069] Table 1 Variation range of leading edge or trailing edge droop geometric parameters

[0070]

[0071] Optionally, the fluid action portion 27 includes a leading edge drooping portion 271 provided at the front side of the blade body 26 in the rotation direction of the hub 10, and a trailing edge drooping portion 272 provided at the rear side of the blade body 26. That is, both the leading edge 21 and the trailing edge of the blade 20 form a drooping effect toward the pressure surface 24. The combined drooping scheme of the leading edge 21 and the trailing edge 22 can combine the advantages of the two schemes, improve the lift-to-drag ratio during dynamic stall as a whole, improve efficiency, and reduce noise at the same time.

[0072] The utility model also provides an axial flow fan, which includes an axial flow fan blade 100 and a driving member drivingly connected to the axial flow fan blade 100, and the driving member is used to drive the axial flow fan blade 100 to rotate. The specific structure of the axial flow fan blade 100 refers to the above embodiment. Since the axial flow fan adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here one by one.

[0073] The utility model also provides an electrical appliance, including an axial flow fan blade 100 or an axial flow fan. The specific structure of the axial flow fan blade 100 or the axial flow fan refers to the above embodiment. Since the axial flow fan adopts all the technical solutions of all the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here. Among them, the electrical appliance includes but is not limited to an air conditioner outdoor unit, a refrigerator compressor cabin, a microwave oven, an electric fan, etc.

[0074] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An axial flow fan blade, characterized in that: include: Wheel hub; as well as The blade includes a blade body connected to the hub, and a fluid action portion arranged on at least one side of the blade body in the rotation direction of the hub, the fluid action portion is arranged to droop relative to the blade body toward the pressure surface of the blade, and the fluid action portion is used to inhibit the separation of the fluid from the suction surface of the blade when the axial flow fan blade rotates.

2. The axial flow fan blade according to claim 1, characterized in that: The fluid action portion extends from the hub to the blade tip of the blade; or the fluid action portion extends in a partial section between the hub and the blade tip.

3. The axial flow fan blade according to claim 1, characterized in that: The fluid action portion is integrally formed with the blade body.

4. The axial flow fan blade according to claim 1, characterized in that: The fluid action portion includes a leading edge hanging portion provided on the front side of the blade body in the rotation direction of the hub.

5. The axial flow fan blade according to claim 4, characterized in that: At least a portion of the area between the front side edge of the blade body and the leading edge of the blade is bent relative to the blade body toward the pressure surface to form the leading edge drooping portion; Alternatively, at least a portion of the area between the front side edge of the blade body and the leading edge of the blade is thickened relative to the blade body on the side facing the pressure surface to form the leading edge drooping portion; Alternatively, a leading edge flap inclined toward one side of the pressure surface is provided at the leading edge of the blade, and the leading edge flap forms the leading edge drooping portion.

6. The axial flow fan blade according to claim 4, characterized in that: In the spanwise direction of the blade extending from the hub toward the blade tip, the spanwise position at the hub is defined as 0, the spanwise position at the blade tip is defined as 1, and the spanwise position of the leading edge drooping portion is within the interval [0, 1]; and / or, in the airfoil section of the blade, in the chord direction extending from the leading edge to the trailing edge of the blade, the chord position at the leading edge is defined as 0, the chord position at the trailing edge is defined as 1, and the droop position of the leading edge droop portion is within the interval [0, 1]; And / or, in the airfoil section of the blade, the leading edge droop angle of the blade is η, wherein 0°<η≤30°.

7. The axial flow fan blade according to any one of claims 1 to 6, characterized in that: The fluid action portion includes a trailing edge hanging portion arranged at the rear side of the blade body in the rotation direction of the hub.

8. The axial flow fan blade according to claim 7, characterized in that: At least a portion of the area between the rear edge of the blade body and the trailing edge of the blade is bent relative to the blade body toward the pressure surface to form the trailing edge hanging portion; Alternatively, at least a portion of the area between the rear edge of the blade body and the trailing edge of the blade is thickened relative to the blade body on the side facing the pressure surface to form the trailing edge drooping portion; Alternatively, the trailing edge of the blade is provided with a trailing edge flap inclined toward one side of the pressure surface, and the trailing edge flap forms the trailing edge drooping portion.

9. The axial flow fan blade according to claim 7, characterized in that: In the spanwise direction of the blade extending from the hub toward the blade tip, the spanwise position at the hub is defined as 0, the spanwise position at the blade tip is defined as 1, and the spanwise position of the trailing edge drooping portion is within the interval [0, 1]; and / or, in the airfoil section of the blade, in the chord direction extending from the leading edge to the trailing edge of the blade, the chord position at the leading edge is defined as 0, the chord position at the trailing edge is defined as 1, and the droop position of the drooping portion of the trailing edge is within the interval [0, 1]; And / or, in the airfoil section of the blade, the trailing edge droop angle of the blade is ζ, wherein 0°<ζ≤30°.

10. An axial flow fan, characterized in that: It comprises an axial flow fan blade as claimed in any one of claims 1 to 9, and a driving member drivingly connected to the axial flow fan blade, wherein the driving member is used to drive the axial flow fan blade to rotate.

11. An electrical appliance, characterized in that: It comprises an axial flow fan blade as described in any one of claims 1 to 9 or an axial flow fan as described in claim 10.

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