Axial flow fan blade and air conditioner outdoor unit

Abstract

The utility model provides a kind of axial flow fan blade and air conditioner outdoor unit, axial flow fan blade includes hub and multiple blades, blade includes inner edge, outer edge, leading edge and trailing edge, inner edge is connected with hub, outer edge is set away from hub;Leading edge is located at the windward side of blade, trailing edge is located at the leeward side of blade;Trailing edge includes the inner side section of being set close to inner edge, inner side section is equipped with sawtooth structure;Sawtooth structure includes multiple sawteeth, at least part of sawteeth in multiple sawteeth is first bending structure;By setting sawtooth structure in trailing edge inner side section, the concentrated eddy current flowing through this area can be effectively scattered, broken into multiple smaller scale, lower energy micro eddy current, the generation of low-frequency eddy current noise is inhibited from noise source;Trailing edge also includes the outer side section of being set close to outer edge, outer side section is equipped with second bending structure;Effectively increase the equivalent working area of blade outside, so as to ensure that the overall air volume output of fan blade remains unchanged, can optimize the flow field of blade tip.

Description

Technical Field

[0001] This utility model belongs to the field of refrigeration equipment technology, and in particular relates to an axial flow fan blade and an outdoor air conditioning unit. Background Technology

[0002] Axial fan blades are a key component of outdoor air conditioning units, and their aerodynamic performance and noise level directly affect the energy efficiency and user experience of the entire unit. With the continuous advancement of national energy conservation and emission reduction policies and the increasing demands of users for comfort, the development of high-efficiency, low-noise axial fan blades has become an urgent need for the industry.

[0003] In existing axial flow fan blades, a serrated structure is set in most areas near the trailing edge and outer edge of the blade to reduce noise. However, the outer edge of the blade is the main working area for generating air volume and air pressure. Setting a serrated structure here reduces the effective working area, resulting in a significant reduction in the air volume output of the fan blade and affecting the overall performance of the machine. In addition, the outer edge of the axial flow fan blade is usually designed with a bending structure. The bending structure generates a large vortex, which not only increases the kinetic energy loss of the fluid, but also leads to an increase in the power consumption of the fan and an increase in noise. Utility Model Content

[0004] In view of this, the present invention provides an axial flow fan blade and an outdoor air conditioning unit to solve the problems of existing axial flow fan blades having a serrated structure near the outer edge of the blade, which reduces the working area of ​​the blade and leads to a reduction in the air volume of the fan blade, and having a bending structure on the outer edge of the blade, which generates a large vortex, resulting in the loss of wind kinetic energy, increased fan power consumption and noise.

[0005] This utility model provides an axial flow fan blade, including a hub and multiple blades, wherein the multiple blades are arranged at intervals along the circumference of the hub; each blade includes an inner edge, an outer edge, a leading edge, and a trailing edge, wherein the inner edge is connected to the hub, and the outer edge is disposed away from the hub; the leading edge is located on the windward side of the blade, and the trailing edge is located on the leeward side of the blade, and both the leading edge and the trailing edge are connected to the inner edge and the outer edge, respectively. The trailing edge includes an inner section, which is disposed close to the inner edge; The inner section is provided with a serrated structure, which includes a plurality of serrations, which are spaced apart along the extension direction of the inner section; at least a portion of the plurality of serrations are in the form of a first bending structure, which is bent from the pressure surface of the blade to the suction surface of the blade.

[0006] Alternatively, the first bending structure may be arc-shaped.

[0007] Further optionally, the bending radius of the first bending structure is the same at all points along the radial direction of the hub; The bending radius of the first bending structure is Ra, and Ra satisfies: 13mm≤Ra≤15mm.

[0008] Further optionally, the projected area of ​​the first bending structure in the axial direction of the hub is S; along the radial direction of the hub, from the inside to the outside, S gradually increases.

[0009] Further optionally, the tooth height of the saw teeth is H1, and the minimum height of the first bending structure is h; H1 and h satisfy: 0.15≤h / H1≤0.8.

[0010] Further optionally, each of the saw teeth has a tooth tip, and the tooth tips of a plurality of saw teeth are connected in sequence to form a tooth tip connecting line; In each of the blades, the line connecting the tooth tips curves from the trailing edge to the leading edge.

[0011] Further optionally, the serrated structure further includes a plurality of grooves, and the grooves and serrations are arranged alternately along the extension direction of the inner segment; The depth of the tooth groove is H2, and H2 satisfies: 4mm≤H2≤6mm.

[0012] Alternatively, the bottom of the tooth groove has an arc-shaped structure.

[0013] Further optionally, the bottom of the tooth groove includes a first arc segment, a second arc segment, and a third arc segment arranged sequentially and connected; the radius of the first arc segment and the third arc segment is r1, and the radius of the second arc segment is r2; The values ​​of r1 and r2 satisfy: 1mm≤r1≤1.5mm, 1mm≤r2≤1.5mm.

[0014] Further optionally, the trailing edge further includes an outer segment disposed close to the outer edge; the outer segment is provided with a second bending structure.

[0015] Alternatively, the second bending structure is bent from the pressure surface of the blade to the suction surface of the blade.

[0016] Further optionally, the second bending structure is arc-shaped; the bending radius of the second bending structure is the same at all points along the radial direction of the hub; The bending radius of the second bending structure is Rb, and Rb satisfies: 13mm≤Rb≤15mm.

[0017] Further optionally, the outer segment includes a first outer sub-segment and a second outer sub-segment, the first outer sub-segment being located between the inner segment and the second outer sub-segment and connecting the inner segment and the second outer sub-segment; The outline of the first outer sub-segment and the line connecting the tooth tip are tangentially connected to form a continuous curve; in each blade, the curve bends from the trailing edge to the leading edge.

[0018] Further optionally, the end of the inner segment near the inner edge and the end of the first outer sub-segment away from the inner edge are connected to form an end connection line; The distance from a point on the curve to the line connecting the end is Ha; along the radial direction of the hub, from the inside to the outside, Ha first increases and then decreases.

[0019] Further optionally, the distance between the end of the serrated structure away from the inner edge and the axis of the hub is R1, and the distance between the end of the first outer sub-segment away from the inner edge and the axis of the hub is R2; R1 and R2 satisfy: 0.8≤R1 / R2≤0.9.

[0020] Further optionally, the radius of the axial flow fan blade is R, and the distance between the end of the sawtooth structure away from the inner edge and the axis of the hub is R1; R1 and R satisfy: 0.5≤R1 / R≤0.65.

[0021] This utility model also provides an outdoor unit for an air conditioner, including a housing and an axial flow fan blade as described in any of the above claims, wherein the axial flow fan blade is disposed inside the housing.

[0022] Compared with the prior art, the main advantages of this utility model are: (1) Effectively reduce aerodynamic noise: By setting a sawtooth structure on the inner side of the trailing edge, the concentrated vortex flowing through this area can be effectively dispersed and broken into multiple micro vortices with smaller scale and lower energy, thereby suppressing the generation of low- and medium-frequency vortex noise from the source of noise and achieving a significant noise reduction effect; Experiments show that the axial flow fan blade with this design can reduce noise by about 0.9 dB(A) while maintaining the same air volume. (2) Maintaining the aerodynamic performance of the blades: By limiting the serrated structure for noise reduction to the inner section near the hub, interference with the main working area on the outer side of the blades is avoided, thereby ensuring the equivalent working area and working capacity on the outer side of the blades. This allows the overall air volume and air pressure output of the blades to be maintained, overcoming the defect of air volume reduction caused by the traditional serrated structure on the outer edge. Experiments show that the blades can reduce the power of the fan by about 10% while maintaining the air volume. (3) Optimize the flow field and reduce power consumption: The first bending structure of the sawtooth structure itself helps to guide the airflow, optimize the flow field of the trailing edge of the blade, especially the inner region, weaken the vortex intensity, reduce the kinetic energy loss of the fluid, thereby reducing the torque required to drive the axial flow blade to rotate, and realizing the reduction of the operating power of the fan. Attached Figure Description

[0023] To more clearly illustrate the embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0024] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the implementation conditions of this utility model. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that this utility model can produce, should still fall within the scope of the technical content disclosed in this utility model.

[0025] Figure 1 A schematic diagram of the axial flow fan blade embodiment provided by this utility model; Figure 2a , Figure 2b , Figure 2c and Figure 2d This is a schematic diagram of the main structure of an embodiment of the axial flow fan blade provided by this utility model; Figure 3 for Figure 2d Enlarged view of point A in the middle; Figure 4 for Figure 2d Sectional view at point BB; Figure 5 for Figure 2d Sectional view at CC; Figure 6 To compare the pressure cloud map of the pressure surface after simulation of the axial flow fan blade provided by this utility model and the axial flow fan blade in the prior art; Figure 7 To compare the pressure cloud map of the suction surface after simulating the axial flow fan blade provided by this utility model and the axial flow fan blade in the prior art; Figure 8 The power comparison curves after simulation of the axial flow fan blade provided by this utility model and the axial flow fan blade in the prior art are shown. Figure 9 The noise comparison curves are shown after simulation of the axial flow fan blade provided by this utility model and the axial flow fan blade in the prior art. In the picture: 1-Blade; 11-Inner edge; 12-Outer edge; 13-Leading edge; 14-Tailing edge; 141-Inner section; 142-Outer section; 1421-First outer sub-segment; 1422-Second outer sub-segment; 15-Serrated structure; 151-Serve; 152-Groove; 1521-First arc segment; 1522-Second arc segment; 1523-Third arc segment; 16-Second bending structure; 171-Pressure surface; 172-Suction surface; 2-Wheel hub; 31 - Line connecting the tooth tip; 32 - Outline; 33 - Line connecting the end. Detailed Implementation

[0026] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0027] The terminology used in the embodiments of this utility model is for the purpose of describing particular embodiments only and is not intended to limit the utility model. The singular forms “a,” “said,” and “the” used in the embodiments of this utility model and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise; “multiple” generally includes at least two, but does not exclude the inclusion of at least one.

[0028] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0029] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0030] In existing axial flow fan blades, a serrated structure is set in most areas of the trailing edge and near the outer edge of the blade to reduce noise; however, the outer edge of the blade is the main working area for generating air volume and air pressure. Setting a serrated structure here reduces the effective working area, resulting in a significant reduction in the air volume output of the fan blade and affecting the overall performance of the machine. In addition, the outer edge of the axial flow fan blade is usually designed with a bending structure. The bending structure generates a large vortex, which not only increases the kinetic energy loss of the fluid, but also leads to an increase in the power consumption of the fan and an increase in noise. This utility model creatively provides an axial flow fan blade, including a hub and multiple blades. Each blade includes an inner edge, an outer edge, a leading edge, and a trailing edge. The inner edge is connected to the hub, and the outer edge is located away from the hub. The leading edge is located on the windward side of the blade, and the trailing edge is located on the leeward side of the blade. The trailing edge includes an inner section located near the inner edge, and the inner section has a serrated structure. The serrated structure includes multiple serrations, and at least some of the serrations have a first bending structure. By setting a serrated structure on the inner section of the trailing edge, the concentrated vortex flowing through this area can be effectively dispersed and broken into multiple micro-vortices with smaller scale and lower energy, thus suppressing the generation of mid-to-low frequency vortex noise from the source of noise. The first bending shape of the serrated structure itself helps to guide the airflow, optimize the flow field at the trailing edge of the blade, especially in the inner region, weaken the vortex intensity, reduce the kinetic energy loss of the fluid, and reduce the torque required to drive the axial flow blade to rotate.

[0031] like Figures 1 to 9 As shown, this embodiment provides an axial flow fan blade, including a hub 2 and multiple blades 1, which are spaced apart circumferentially along the hub 2. Each blade 1 includes an inner edge 11, an outer edge 12, a leading edge 13, and a trailing edge 14. The inner edge 11 is connected to the hub 2, and the outer edge 12 is located away from the hub 2. The leading edge 13 is located on the windward side of the blade 1, and the trailing edge 14 is located on the leeward side of the blade 1. Both the leading edge 13 and the trailing edge 14 are connected to the inner edge 11 and the outer edge 12, respectively. The trailing edge 14 includes an inner segment 141, which is disposed close to the inner edge 11; The inner section 141 is provided with a serrated structure 15, which includes a plurality of serrations 151. The plurality of serrations 151 are spaced apart along the extending direction of the inner section 141, and at least some of the serrations 151 have a first bending structure; preferably, the plurality of serrations 151 have the same structure. Thus, by adopting the axial flow fan blade provided by this utility model, the power and noise of the fan can be reduced while ensuring the air volume remains unchanged; the sawtooth structure 15 can disrupt the formation of vortices at the trailing edge 14, reduce airflow separation, thereby reducing the aerodynamic noise and structural vibration generated during the operation of the axial flow fan blade; the first bending structure further optimizes the airflow near the trailing edge 14, making the airflow transition more smoothly, reducing turbulence intensity, and improving the operating stability of the axial flow fan blade; the combination of the sawtooth structure 15 and the first bending structure improves aerodynamic efficiency while maintaining the basic function of the axial flow fan blade, making it suitable for various working conditions.

[0032] The bending direction of the first bending structure is explained below. The first bending structure bends from the pressure surface 171 of the blade 1 to the suction surface 172 of the blade 1. The curvature direction of the first bending structure is opposite to the curvature direction of the pressure surface of the blade 1, and the curvature of the first bending structure is positive. That is, the pressure surface of the blade 1 bends in the first direction, and the first bending structure bends in the second direction, and the first direction and the second direction are opposite. Thus, the bending direction of the first bending structure helps to guide the high-pressure airflow of the pressure surface 171 to the suction surface 172, promotes airflow adhesion, reduces boundary layer separation, thereby reducing energy loss and noise; by improving the pressure balance between the pressure surface 171 and the suction surface 172, the lift characteristics of the axial flow fan are enhanced, and the aerodynamic efficiency and air volume output are improved.

[0033] The structure and dimensions of the first bending structure are described below. The first bending structure is arc-shaped. Along the radial direction of hub 2, the bending radius of the first bending structure is the same at all points. The bending radius of the first bending structure is Ra, and Ra satisfies: 13mm≤Ra≤15mm; Thus, the arc-shaped first bend structure reduces local resistance when airflow passes through, avoids vortices caused by sharp edges, and makes airflow more continuous; the specific bend radius range (13mm≤Ra≤15mm) has been experimentally verified to effectively reduce noise while maintaining good aerodynamic performance and avoid efficiency loss due to excessive bending.

[0034] It should be noted that the first bending structure can also be in the form of other spline curves, and the curvature direction of the first bending structure is opposite to the curvature direction of the pressure surface of blade 1.

[0035] The following describes the projected area of ​​the first bending structure. The projected area of ​​the first bending structure in the axial direction of the hub 2 is S. Along the radial direction of the hub 2, from the inside to the outside, S gradually increases. The sawtooth bending structure located on the side with the largest radial direction of the hub 2 has the largest projected area in the axial direction of the hub 2. Thus, the gradual design of the projected area of ​​the first bending structure conforms to the change in radial airflow velocity of blade 1, enabling the first bending structure to effectively control airflow at different radii, reducing root eddies and tip losses; by optimizing stress distribution, stress concentration at the blade root is reduced, enhancing the fatigue life and operational safety of the axial flow fan blade.

[0036] The following describes the tooth height of sawtooth 151 and the height of the first bending structure. The tooth height of sawtooth 151 is H1, and the minimum height of the first bending structure is h. H1 and h satisfy: 0.15≤h / H1≤0.8. This ensures the dimensional matching of the sawtooth 151 and the first bending structure, enabling the sawtooth 151 to effectively break up large-scale eddies, while the first bending structure further refines the eddies, jointly reducing noise and vibration; preventing airflow interference or structural failure caused by excessive or insufficient bending height, thus ensuring the reliability and efficiency of the wind turbine.

[0037] The following describes the sawtooth structure 15. Each sawtooth 151 has a tooth tip, and the tooth tips of multiple sawtooth 151 are connected in sequence to form a tooth tip connection line 31. In each blade 1, the tooth tip line 31 bends from the trailing edge 14 to the front edge 13; Thus, the curved shape of the tooth tip connection 31 is more in line with the airflow streamline, reducing the impact and separation of the airflow, and further reducing noise and drag; this curved design makes the sawtooth structure 15 more effectively disperse sound wave energy, improve acoustic performance, especially in reducing mid-to-high frequency noise.

[0038] Furthermore, the serrated structure 15 also includes a plurality of grooves 152, and the grooves 152 and the serrations 151 are arranged alternately along the extension direction of the inner section 141; The depth of tooth groove 152 is H2, and H2 satisfies: 4mm≤H2≤6mm; Thus, by setting a specific depth of groove 152, which works in conjunction with sawtooth 151, the breaking scale of the vortex can be controlled more precisely, decomposing larger, energy-concentrated vortices into smaller, more stable vortices, thereby more effectively reducing mid-to-high frequency aerodynamic noise. This specific depth range (4mm-6mm) has been optimized to achieve the best balance between effective noise reduction and maintaining the structural strength of blade 1. If the depth of groove 152 is too small, the noise reduction effect will be insignificant; if the depth of groove 152 is too large, it will excessively weaken the trailing edge material, affecting the structural rigidity and service life of blade 1.

[0039] The specific structure of tooth groove 152 is described below. The bottom of tooth groove 152 has an arc-shaped structure. Thus, the arc-shaped groove bottom avoids the stress concentration problem that is easily caused by the sharp V-shaped groove bottom, significantly improves the fatigue strength of the bottom of the toothed groove 152, reduces the risk of blade 1 cracking from the bottom of the toothed groove 152 under long-term alternating load, and improves the reliability and durability of the axial flow fan blade; the arc-shaped groove bottom shape is more in line with the fluid dynamics characteristics, which allows the airflow to turn and flow more smoothly in the toothed groove 152, reducing the small eddies and additional noise caused by the airflow hitting the sharp corners.

[0040] Furthermore, the bottom of the tooth groove 152 includes a first arc segment 1521, a second arc segment 1522 and a third arc segment 1523 arranged sequentially and connected; the radius of the first arc segment 1521 and the third arc segment 1523 is r1, and the radius of the second arc segment 1522 is r2. r1 and r2 satisfy: 1mm≤r1≤1.5mm, 1mm≤r2≤1.5mm; Thus, by combining the first arc segment 1521, the third arc segment 1523 (radius r1), and the second arc segment 1522 (radius r2), a composite arc structure profile that better conforms to the ideal aerodynamic streamline is formed; this guides the airflow to undergo a more controlled and smooth acceleration and deceleration process within the toothed groove 152, further suppressing boundary layer separation and vortex generation; this multi-arc smooth transition design can distribute stress more evenly than a single arc, minimizing the stress peak in the groove bottom region, and further enhancing the fatigue resistance of the sawtooth structure 15 under harsh working conditions; the given radius range (1mm-1.5mm) is a proven preferred solution that simultaneously meets the processability and the above performance requirements.

[0041] In addition, the trailing edge 14 also includes an outer section 142, which is located close to the outer edge 12. The outer section 142 is provided with a second bending structure 16. On the one hand, it effectively increases the equivalent working area on the outer side of the blade, thereby ensuring that the overall air volume output of the blade remains unchanged. On the other hand, it can optimize the flow field at the blade tip, guide the airflow to leave more smoothly, significantly reduce the intensity and scale of the vortex on the outer side of the trailing edge, especially in the blade tip region, and reduce the fluid kinetic energy loss caused by this. This reduces the torque required to drive the blade to rotate, thereby directly converting into a decrease in the power of the fan.

[0042] The bending direction of the second bending structure 16 will be explained below. The second bending structure 16 bends from the pressure surface 171 of the blade 1 to the suction surface 172 of the blade 1. Thus, in the high-speed rotating blade tip region, the high-pressure airflow on the pressure surface 171 has a strong tendency to overflow laterally towards the suction surface 172, forming a strong blade tip vortex; the bending direction of the second bending structure 16 can guide this lateral overflow, making it flow more smoothly towards the suction surface 172, thereby greatly weakening the intensity and size of the blade tip vortex; by suppressing the blade tip vortex, the induced drag caused by the vortex is reduced, the effective lift of the blade 1 is improved, thereby improving the overall aerodynamic efficiency of the blade.

[0043] The structure and dimensions of the second bending structure 16 are described below. The second bending structure 16 is arc-shaped. Along the radial direction of the hub 2, the bending radius of the second bending structure 16 is the same at all points. The second bending structure has a bending radius of Rb, which satisfies the following condition: 13mm≤Rb≤15mm; Thus, the arc-shaped bend works perfectly with the aforementioned airflow guiding function, avoiding new airflow separation caused by sudden bends and ensuring that the high-pressure airflow can smoothly "climb" over the trailing edge. For the high-velocity characteristics of the outer section 142, this specific bend radius range (13mm≤Rb≤15mm) has been proven to be the most effective range for suppressing tip vortices. Too small a radius may cause airflow stripping, while too large a radius will result in insufficient guiding effect. This ensures that while significantly reducing tip noise, it will not have a negative impact on the blade head and airflow.

[0044] It should be noted that the second bending structure 16 can also be in the form of other spline curves, and the curvature direction of the first bending structure 16 is opposite to the curvature direction of the pressure surface of the blade 1.

[0045] In addition, the outer segment 142 also includes a first outer sub-segment 1421, which is disposed near the inner segment 141, and a second outer sub-segment 1422 is disposed near the outer edge 12; the first outer sub-segment 1421 is located between the inner segment 141 and the second outer sub-segment 1422, and the first outer sub-segment 1421 connects the inner segment 141 and the second outer sub-segment 1422; The outline 32 of the first outer sub-segment 1421 and the tooth tip line 31 are tangently connected to form a continuous curve; in each blade 1, the curve bends from the trailing edge 14 to the front edge 13. Thus, through the key feature of "tangential connection", it is ensured that when the airflow flows from the sawtooth structure 15 region of the inner section 141 to the bending region of the outer section 142, there will be no abrupt change in direction or flow separation. This smooth transition avoids the generation of new vortices and airflow disturbances at the joint, thereby eliminating potential noise sources and reducing flow losses. The continuous curve design makes the load transfer of the trailing edge 14 of the blade 1 more uniform, avoids stress concentration caused by discontinuity of the profile, and improves the structural reliability and fatigue life of the blade 1 (especially in the critical transition region).

[0046] Preferably, both the first outer sub-segment 1421 and the second outer sub-segment 1422 are provided with a second bending structure 16.

[0047] The overall structure of the first outer sub-segment 1421 and the inner sub-segment 141 is described below. The end of the inner sub-segment 141 near the inner edge 11 and the end of the first outer sub-segment 1421 away from the inner edge 11 are connected to form the end connection line 33. The distance from the point on the curve to the end line 33 is Ha; along the radial direction of hub 2, from the inside to the outside, Ha first increases and then decreases; Thus, Ha increases first and then decreases, essentially defining a trailing edge profile curve that bulges towards the trailing edge 14, resembling an "airfoil." This streamlined trailing edge shape can better guide and control the airflow flowing along the blade span, making it fit the trailing edge surface more closely, thereby effectively suppressing vortex shedding across the entire trailing edge 14 span. This specific curve shape is the result of aerodynamic optimization, which can match the twist angle and chord length distribution of the blade itself, reducing noise while minimizing airflow resistance, achieving a global improvement in the aerodynamic efficiency of the blade.

[0048] That is, along the radial direction of the blade from the inside to the outside, the inner section 141, the first outer sub-section 1421 and the second outer sub-section 1422 are arranged and connected in sequence. The inner section 141 is provided with a serrated structure 15, which includes multiple serrations 151. The multiple serrations 151 are arranged evenly in sequence along the extension direction of the inner section 141; some serrations 151 have a first bending structure; the outer section 142 is provided with a second bending structure 16. Furthermore, the distance between the end of the serrated structure 15 away from the inner edge 11 and the axis of the hub 2 is R1, and the distance between the end of the first outer sub-segment 1421 away from the inner edge 11 and the axis of the hub 2 is R2. R1 and R2 satisfy: 0.8 ≤ R1 / R2 ≤ 0.9; Thus, this proportional relationship scientifically divides the effective range of the sawtooth structure 15 (inner section) and the aerodynamic optimization zone (first outer sub-segment 1421 and second outer sub-segment 1422) which is mainly composed of bent structures. It ensures that the sawtooth structure 15 is applied in the blade root region where the vortex intensity is high and noise reduction is most sensitive, while avoiding the structural stiffness reduction problem that may be caused by excessively extending the sawtooth structure 15 to the middle of the blade 1. This proportional range ensures a smooth and effective connection between the sawtooth structure region and the smooth transition region, so that the two different aerodynamic control methods can play their roles in their respective optimal regions and work together to achieve the overall performance goal.

[0049] The dimensions of the sawtooth structure 15 are described below. The radius of the axial flow fan blade is R, and the distance between the end of the sawtooth structure 15 away from the inner edge 11 and the axis of the hub 2 is R1. R1 and R satisfy: 0.5≤R1 / R≤0.65. Thus, this proportion, on a scale of the entire blade, clearly defines that the serrated structure 15 should cover the area from the hub 2 to approximately 50% to 65% of the blade span; this range is based on a deep understanding of the noise source distribution of axial fans: the blade root area is an important noise source, but beyond a certain range, the noise reduction benefit diminishes and may negatively impact efficiency; this proportion ensures that noise reduction measures are applied to the most effective area; this feature provides a universal, optimized design guideline for the design of axial fan blades of different sizes, ensuring that a balance is achieved between significant noise reduction effects and reliable structural performance based on this axial fan blade.

[0050] Simulation analyses were conducted on the axial flow fan blade provided by this invention and those in the prior art. Figure 6 To compare the pressure contour maps of the pressure surfaces of the axial flow fan blade provided by this invention and those of existing axial flow fan blades after simulation, Figure 7 To compare the pressure cloud map of the suction surface of the axial flow fan blade provided by this utility model and that of the axial flow fan blade in the prior art after simulation; by Figure 6 It can be seen that after adopting the axial flow fan blade provided by this utility model, the pressure on the pressure surface 171 is reduced, especially at the second bending structure 16, the pressure on the pressure surface 171 is significantly reduced, the pressure gradient on the pressure surface 171 is increased, and the work capacity of the axial flow fan blade is improved; Figure 7 It can be seen that after adopting the axial flow fan blade provided by this utility model, the pressure on the suction surface 172 is reduced, and the pressure difference between the suction surface 172 and the pressure surface 171 is reduced. This can prevent the outer edge 12 from generating large vortices, prevent the airflow from generating large kinetic energy loss, thereby avoiding excessive power consumption of the fan and also preventing the fan from generating large noise during operation. Through the second bending structure 16, the air volume reduction that may be caused by the reduction of the working area of ​​the fan blade due to the sawtooth structure 15 can be compensated, ensuring that the air volume of the axial flow fan blade remains unchanged before and after the change. At the same time, the bending structure and the sawtooth structure can control the vortex of the trailing edge airflow, thereby reducing the vortex noise of the fan blade.

[0051] To further demonstrate the actual effect of the axial flow fan blade provided by this utility model, experimental tests were conducted on the axial flow fan blade provided by this utility model and the axial flow fan blade in the prior art. The test results are shown in the table below.

[0052] At the same rotational speed, the airflow of the axial flow fan blade provided by this invention is basically equivalent to that of the axial flow fan blades in the prior art, which is consistent with the conclusions of simulation analysis. Compared with the axial flow fan blades in the prior art, the axial flow fan blade provided by this invention reduces power by 9%~11% and noise by 0.7~0.9 dB(A) at the same airflow. The experimental test data are converted into curves, as shown below. Figure 8 and Figure 9 As shown, the technical effect of the axial flow fan blade provided by this utility model is more clearly demonstrated; by adding a sawtooth structure and a bending structure, the power of the fan can be reduced while ensuring the air volume remains unchanged, and the noise of the rotating vortex of the fan blade can be reduced at the same time.

[0053] This embodiment also provides an outdoor air conditioning unit, including a casing and any of the above-mentioned axial flow fan blades, wherein the axial flow fan blades are disposed inside the casing.

[0054] Example 2 Unlike Embodiment 1, the serrated structure of the inner section is eliminated, and the entire trailing edge 14 is designed with a bending structure. Thus, by adopting a uniform bending structure across the entire trailing edge 14 of blade 1, a continuous and consistent airflow guidance mechanism is provided for all airflow along the radial direction of blade 1 from hub 2 to blade tip. This design eliminates abrupt changes in airflow patterns caused by different structures of trailing edge 14 (such as partial serrations or partial bends), allowing the airflow on the entire swept surface to leave trailing edge 14 more smoothly and synchronously, thereby effectively reducing overall aerodynamic drag and improving the aerodynamic efficiency and operational stability of axial fan blades under a wide range of operating conditions. Compared to creating a precise serrated structure 15 at the root, the continuous bending structure used throughout the trailing edge 14 greatly simplifies the design and manufacturing complexity of the mold; this structure is easier to form in one step through processes such as injection molding, reducing the difficulty of quality control and potential scrap rate in the production process, thereby significantly improving production efficiency and manufacturing consistency, reducing the unit production cost, and making it more conducive to large-scale industrial manufacturing. The serrated structure 15 inherently interrupts the trailing edge and creates potential stress concentration points at the root of the teeth. By eliminating the serrations 151 and replacing them with a continuous trailing edge 14 bending structure, the structural continuity of the trailing edge 14 of the blade 1 is ensured, avoiding the risk of fatigue cracks caused by stress concentration in discontinuous structures under high-speed rotation. This makes the overall structural strength of the blade 1 higher, the dynamic balance better, and improves the mechanical reliability and service life of the wind turbine blade. The bending structure effectively suppresses the generation and development of vortices on the trailing edge 14 by guiding the smooth flow from the pressure surface 171 to the suction surface 172. Applying this structure to the entire trailing edge 14 means that the intensity of vortex shedding in the three key areas of the blade root, middle and tip can be weakened simultaneously. This unified design can achieve more comprehensive and balanced suppression of aerodynamic noise across the entire working range (especially caused by tip vortices and middle vortices), providing a more balanced broadband noise reduction solution. At the same time, it avoids the reduction of the working area of ​​the serrated structure, and the air volume can be increased by increasing the bending area of ​​the bending structure.

[0055] Exemplary embodiments of this disclosure have been specifically shown and described above. It should be understood that this disclosure is not limited to the detailed structures, arrangements, or implementations described herein; rather, this disclosure is intended to cover various modifications and equivalent arrangements contained within the spirit and scope of the appended claims.

Claims

1. An axial flow fan blade, characterized in that, The device includes a hub (2) and multiple blades (1), with the multiple blades (1) spaced apart circumferentially along the hub (2); each blade (1) includes an inner edge (11), an outer edge (12), a leading edge (13), and a trailing edge (14), the inner edge (11) being connected to the hub (2), and the outer edge (12) being located away from the hub (2); the leading edge (13) is located on the windward side of the blade (1), and the trailing edge (14) is located on the leeward side of the blade (1), and both the leading edge (13) and the trailing edge (14) are connected to the inner edge (11) and the outer edge (12); The trailing edge (14) includes an inner segment (141) disposed close to the inner edge (11); The inner section (141) is provided with a serrated structure (15), the serrated structure (15) includes a plurality of serrations (151), the plurality of serrations (151) are spaced apart along the extension direction of the inner section (141); at least some of the plurality of serrations (151) are in the form of a first bending structure, the first bending structure is bent from the pressure surface (171) of the blade (1) to the suction surface (172) of the blade (1).

2. The axial flow fan blade according to claim 1, characterized in that, The first bending structure is arc-shaped.

3. The axial flow fan blade according to claim 2, characterized in that, Along the radial direction of the hub (2), the bending radius of the first bending structure is the same at all points; The bending radius of the first bending structure is Ra, and Ra satisfies: 13mm≤Ra≤15mm.

4. The axial flow fan blade according to claim 2, characterized in that, The projected area of ​​the first bending structure on the axial direction of the hub (2) is S; along the radial direction of the hub (2), from the inside to the outside, S gradually increases.

5. The axial flow fan blade according to claim 2, characterized in that, The tooth height of the sawtooth (151) is H1, and the minimum height of the first bending structure is h; H1 and h satisfy: 0.15≤h / H1≤0.

8.

6. The axial flow fan blade according to claim 1, characterized in that, Each of the saw teeth (151) has a tooth tip, and the tooth tips of multiple saw teeth (151) are connected in sequence to form a tooth tip line (31); In each of the blades (1), the tooth tip line (31) bends from the trailing edge (14) toward the leading edge (13).

7. The axial flow fan blade according to claim 1, characterized in that, The serrated structure (15) further includes a plurality of grooves (152), and the grooves (152) and the serrations (151) are arranged alternately along the extension direction of the inner section (141); The depth of the tooth groove (152) is H2, and H2 satisfies: 4mm≤H2≤6mm.

8. The axial flow fan blade according to claim 7, characterized in that, The bottom of the groove (152) has an arc-shaped structure.

9. The axial flow fan blade according to claim 8, characterized in that, The groove bottom of the toothed groove (152) includes a first arc segment (1521), a second arc segment (1522) and a third arc segment (1523) arranged and connected in sequence; the radius of the first arc segment (1521) and the third arc segment (1523) is r1, and the radius of the second arc segment (1522) is r2. The values ​​of r1 and r2 satisfy: 1mm≤r1≤1.5mm, 1mm≤r2≤1.5mm.

10. The axial flow fan blade according to claim 1, characterized in that, The trailing edge (14) further includes an outer segment (142), which is disposed close to the outer edge (12); the outer segment (142) is provided with a second bending structure (16).

11. The axial flow fan blade according to claim 10, characterized in that, The second bending structure (16) bends from the pressure surface (171) of the blade (1) to the suction surface (172) of the blade (1).

12. The axial flow fan blade according to claim 11, characterized in that, The second bending structure (16) is arc-shaped; along the radial direction of the hub (2), the bending radius of the second bending structure (16) is the same at all points; The bending radius of the second bending structure (16) is Rb, and Rb satisfies: 13mm≤Rb≤15mm.

13. The axial flow fan blade according to claim 10, characterized in that, The outer segment (142) includes a first outer sub-segment (1421) and a second outer sub-segment (1422), wherein the first outer sub-segment (1421) is located between the inner segment (141) and the second outer sub-segment (1422) and connects the inner segment (141) and the second outer sub-segment (1422). The outline (32) of the first outer sub-segment (1421) and the tooth tip line (31) are tangentially connected and form a continuous curve; in each blade (1), the curve bends from the trailing edge (14) to the leading edge (13).

14. The axial flow fan blade according to claim 13, characterized in that, The end of the inner segment (141) near the inner edge (11) and the end of the first outer sub-segment (1421) away from the inner edge (11) are connected to form an end connection line (33); The distance from a point on the curve to the line (33) connecting the ends is Ha; along the radial direction of the hub (2), from the inside to the outside, Ha first increases and then decreases.

15. The axial flow fan blade according to claim 13, characterized in that, The distance between the end of the sawtooth structure (15) away from the inner edge (11) and the axis of the hub (2) is R1, and the distance between the end of the first outer sub-segment (1421) away from the inner edge (11) and the axis of the hub (2) is R2. R1 and R2 satisfy: 0.8≤R1 / R2≤0.

9.

16. The axial flow fan blade according to claim 13, characterized in that, The radius of the axial flow fan blade is R, and the distance between the end of the sawtooth structure (15) away from the inner edge (11) and the axis of the hub (2) is R1; R1 and R satisfy: 0.5≤R1 / R≤0.

65.

17. An outdoor unit for an air conditioner, characterized in that, It includes a housing and an axial flow fan blade as described in any one of claims 1 to 16, wherein the axial flow fan blade is disposed within the housing.

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