Fan blade, fan impeller and centrifugal fan

Abstract

The invention provides a fan blade, a fan impeller and a centrifugal fan, and relates to the technical field of centrifugal fans, the fan blade comprises a suction wall surface, a pressure wall surface, a front edge, a rear edge, a blade top and a blade root, and the suction wall surface and the pressure wall surface extend in the length direction of the blade. The front edge is gradually heightened in the axial direction, and the rear edge is kept unchanged and then gradually lowered; the chord length is gradually reduced from the blade root to the blade top, the distance from the front edge point of the blade top to the circle center of the impeller is gradually increased, and the distance from the rear edge point to the circle center of the impeller is unchanged in the blade root area and gradually reduced in the blade top area. The front edge of each blade is an air inlet side, the air inlet angle is gradually increased in the axial direction, the rear edge of each blade is an air outlet side, and the air outlet angle is kept unchanged and then decreased in the axial direction. The geometrical shapes, chord lengths, air inlet angles, air outlet angles and the like of the front edges and the rear edges of the fan blades are optimized, so that airflow flowing is improved, turbulent flow and vortex are reduced, the pneumatic performance of the centrifugal fan is improved, noise is lowered, and the stability of the fan is enhanced.

Description

Technical Field

[0001] The present application relates to the technical field of centrifugal fans, and in particular to a fan blade, a fan impeller and a centrifugal fan. Background Art

[0002] With the acceleration of modern industry and the advancement of urbanization, ventilation systems are becoming increasingly widely used. Centrifugal fans, as a key component of ventilation systems, play an important role in indoor ventilation, and their aerodynamic performance is key to the overall operating efficiency of the system. Therefore, optimizing the aerodynamic performance of centrifugal fans is an important direction of technical research.

[0003] The air intake and exhaust directions of a centrifugal fan are perpendicular to each other. The airflow inside the centrifugal fan needs to undergo an axial-to-radial conversion and axial acceleration before leaving the fan. The airflow initially entering the fan presents a uniform axial velocity. Affected by the pressure gradient formed by the negative pressure zone created by the rotation of the impeller near the impeller, the airflow will gradually convert from axial velocity to radial velocity before entering the impeller. However, due to the limited attraction of the negative pressure zone to the airflow and the influence of the axial velocity, most of the airflow is accelerated out of the impeller through the section close to the impeller disc side. The impeller section close to the wheel cover side presents a more complex flow field, which affects the overall aerodynamic efficiency of the fan.

[0004] Due to cost requirements, most centrifugal fan blades are designed with a common arc shape and remain consistent in the axial direction. This design causes the blades near the wheel cover to generate more vortices, which in turn affects aerodynamic efficiency. A single arc blade makes it difficult to effectively control the flow field, and due to the differences in the internal flow field in the axial direction, the shape of the blades near the wheel cover needs to be improved to achieve better aerodynamic performance. Traditional blade designs exhibit more large vortices due to the large number of internal vortices, especially in the flow field on the wheel cover side, which in turn produces stronger low-frequency noise. Summary of the Invention

[0005] In view of this, the present application proposes a fan blade, a fan impeller and a centrifugal fan, which solves the problems of multiple vortices on the wheel cover side of the centrifugal fan, low aerodynamic efficiency and high low-frequency noise in the prior art by optimizing the shape of the fan blade.

[0006] The technical solution of this application is achieved as follows: In one aspect, the present application provides a wind turbine blade, comprising: The suction wall and the pressure wall, both of which extend along the length of the fan blade; The chord length of the fan blade gradually decreases from the blade root to the blade tip. The distance from the leading edge point to the center of the impeller gradually increases from the blade root to the blade tip, and the distance from the trailing edge point to the center of the impeller first remains unchanged and then gradually decreases from the blade root to the blade tip. The leading edge of the fan blade is the air inlet side, and the air inlet angle of the air inlet side gradually increases along the axial direction. The trailing edge of the fan blade is the air outlet side, and the air outlet angle of the air outlet side first remains unchanged and then gradually decreases along the axial direction.

[0007] On the basis of the above technical solution, preferably, the suction wall surface is a convex surface, and the pressure wall surface is a concave surface.

[0008] On the basis of the above technical solution, preferably, the distance from the leading edge point at the blade tip to the center of the impeller varies in the range of 115.43 mm to 125.43 mm, and the distance from the trailing edge point at the blade tip to the center of the impeller varies in the range of 144.51 mm to 148.51 mm. On the basis of the above technical solution, preferably, the chord length of the fan blade varies in the range of 28 mm to 36 mm.

[0009] On the basis of the above technical solution, preferably, the range of the air inlet angle is 75°~80°, and the range of the air outlet angle is 154°~170°.

[0010] On the basis of the above technical solution, preferably, the axial distance between the height change demarcation point of the leading edge and the height change demarcation point of the trailing edge and the impeller disc ranges from 62 mm to 93 mm.

[0011] On the basis of the above technical solution, preferably, the axial length ratio of the height maintaining section of the trailing edge on the impeller disc side to the height reducing section on the impeller cover side is 1:1.5~1:2.

[0012] In the second aspect, the present application discloses a fan impeller, comprising an impeller disc, an impeller cover and the fan blades as described in the first aspect, wherein the fan blades are evenly fixed between the impeller disc and the impeller cover along the circumferential direction, the length direction of each fan blade is parallel to the axial direction of the fan impeller, and the leading edge of the fan blade is closer to the rotation center of the fan impeller than the trailing edge.

[0013] In the third aspect, the present application discloses a centrifugal fan, comprising a drive motor, a volute and the fan impeller described in the second aspect, the volute having an air inlet on its front side and an air outlet on its side wall, the fan impeller being arranged in the volute and coaxially with the air inlet, with the impeller cover facing the air inlet, the drive motor being located on the side of the volute away from the air inlet, and the output shaft of the drive motor being coaxially fixedly connected to the impeller disc.

[0014] Compared with the prior art, this application has the following beneficial effects: (1) The fan blade disclosed in this application has a small chord length feature at the top of the blade on the wheel cover side and a large chord length feature at the blade root on the disk side, and the chord length of the blade gradually decreases in the direction of the blade height. Under this structural design, the chord length of the impeller blade on the wheel cover side is reduced, the inlet angle is increased, and the outlet angle is reduced, which improves the complex flow of the airflow on the wheel cover side, effectively weakens the secondary flow of the airflow on the wheel cover side, and reduces the flow loss of the airflow in this part. The chord length of the blade on the disk side is increased to meet the acceleration effect of the impeller on the airflow. By changing the geometric shape of the leading edge and the trailing edge, adjusting the chord length of the blade top and the blade root, optimizing the inlet angle and the outlet angle, etc., the airflow is made smoother, turbulence and vortex are reduced, the aerodynamic performance is improved, the noise is reduced, and the working stability of the fan is enhanced.

[0015] (2) By setting the precise distance range from the leading edge and trailing edge to the center of the impeller, the way the airflow enters and leaves the fan blade can be precisely controlled. This precise distance range setting helps to achieve a smooth transition of the airflow and reduces the disturbance and instability of the airflow on the blade surface. Setting the leading and trailing edges within this distance range ensures the uniformity of the airflow when flowing on the blade surface, reduces the influence of adverse factors such as vortex and turbulence, thereby reducing fan noise and improving the fan's aerodynamic efficiency.

[0016] (3) By setting the range of the fan blade chord length variation, the design achieves precise control of the airflow and optimizes the distribution of the airflow on the blade surface. By appropriately varying the chord length, the fan blade can effectively reduce the generation of vortices and turbulence, improve aerodynamic efficiency, reduce noise levels, and improve fan stability.

[0017] (4) By optimizing the angles at which air enters and leaves the fan blades, the smoothness of the airflow is ensured, aerodynamic losses are reduced, and the aerodynamic efficiency of the fan is improved. This design not only improves the fan's airflow guidance and discharge capabilities, but also effectively reduces the fan's noise level and eddy current losses, enhancing the fan's stability and reliability.

[0018] (5) By properly setting the axial distance between the leading and trailing edge height change points and the impeller disc, the airflow velocity and pressure distribution in different areas of the blade can be effectively adjusted. These changes allow the airflow to pass smoothly through the blade, reducing efficiency losses caused by uneven airflow, thereby improving the overall performance of the fan.

[0019] (6) By ensuring that the length of the height reduction area is greater than the length of the height maintenance area, the airflow can be discharged gradually and smoothly. This design helps to reduce the generation of airflow separation and vortex, improve aerodynamic efficiency, reduce noise, and enhance the stability and adaptability of the fan under different working conditions. At the same time, the ratio design of the height maintenance area and the height reduction area at the trailing edge of the blade directly affects the airflow discharge characteristics of the fan. By designing a reasonable ratio, it can ensure that the airflow is smoother when flowing at the end of the blade, reduce the generation of airflow separation and vortex, thereby improving the aerodynamic efficiency and the overall performance of the fan. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0021] Figure 1 A schematic diagram of the three-dimensional structure of the fan blade disclosed in this application; Figure 2 A front view of the fan blade disclosed in this application; Figure 3 A schematic diagram of the side structure of the fan blade disclosed in this application; Figure 4 This is a schematic diagram of the distribution of fan blades on the impeller disc disclosed in this application; Figure 5 This is a schematic diagram of the overall structure of the centrifugal impeller disclosed in this application; Figure 6 This is a schematic diagram of the internal structure of the centrifugal impeller disclosed in this application; Figure 7 This is a schematic diagram of the overall structure of the centrifugal fan disclosed in this application; Reference numerals: 10. Fan blade; 101. Suction wall; 102. Pressure wall; 103. Leading edge; 104. Trailing edge; 105. Blade tip; 106. Blade root; p, leading edge point; q, trailing edge point; 107, Inlet side; 108, Outlet side; 20. Inlet angle; 30. Outlet angle; 40. Fan impeller; 401. Impeller disc; 402. Impeller cover; 50. Centrifugal fan; 501. Drive motor; 502. Volute; 5021. Air inlet; 5022. Air outlet. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0023] Since traditional centrifugal fan blades usually adopt a structure with consistent shape in the axial direction, and in addition to the axial and radial flows caused by acceleration, there is also obvious axial flow inside the centrifugal fan, and the flow fields at different axial positions show large differences, it is necessary to improve the centrifugal fan blades in the axial direction.

[0024] Specifically, the air intake and exhaust directions of a centrifugal fan are perpendicular to each other, and the airflow inside the centrifugal fan needs to undergo an axial-to-radial conversion and axial acceleration before leaving the fan. The airflow initially entering the fan presents a uniform axial velocity. Affected by the pressure gradient formed by the negative pressure zone created by the rotation of the impeller near the impeller, the airflow will gradually convert from axial velocity to radial velocity and enter the impeller. However, due to the limited attraction of the negative pressure zone to the airflow and the influence of the axial velocity, most of the airflow is accelerated out of the impeller through the section close to the impeller disc side. The impeller section close to the wheel cover side presents a more complex flow field, which affects the overall aerodynamic efficiency of the fan.

[0025] This application optimizes the structure of the fan blades and effectively reduces the airflow loss on the wheel cover side through a variable chord length blade design with improved leading and trailing edge profiles. By improving the airflow path, the variable chord length blades can more effectively guide the airflow while ensuring effective outflow on the wheel disc side, thereby improving the aerodynamic efficiency of the fan.

[0026] Specifically, the embodiment of the present application discloses a fan blade, which can be applied to a small single-suction centrifugal impeller. Figure 1 As shown, combined Figure 2-4 The wind turbine blade 10 disclosed in this embodiment includes a suction wall 101 , a pressure wall 102 , a leading edge 103 , a trailing edge 104 , a blade root 106 and a blade tip 105 .

[0027] The suction wall 101 and the pressure wall 102 are disposed opposite each other and extend along the length of the fan blade 10, forming the two primary aerodynamic surfaces of the fan blade 10. The suction wall 101 is a convex surface formed on the inner side of the fan blade 10, responsible for guiding airflow into the fan impeller 40; the pressure wall 102 is a concave surface formed on the outer side of the fan blade 10, responsible for guiding airflow out of the impeller.

[0028] Based on the boundary layer control principle in fluid mechanics, the suction wall 101 (convex surface) accelerates the airflow through curvature to form a low-pressure area; the pressure wall 102 (concave surface) decelerates and pressurizes the airflow, forming a pressure gradient field. The two extend along the length direction to form a continuous airflow channel, ensuring that the airflow forms a stable attached flow on the blade surface, providing a basic flow channel structure for subsequent variable chord length design.

[0029] The fan blade 10 includes a blade root 106 and a blade tip 105. The blade root 106 is the edge connecting the fan blade 10 to the impeller disk 401, and the blade tip 105 is the edge connecting the fan blade 10 to the impeller shroud 402. In this embodiment, the chord length of the fan blade 10 gradually decreases from the blade root 106 to the blade tip 105. With this configuration, the large-chord blade root 106 can increase the lateral chord length of the impeller disk 401 to increase circulation, enhance the main flow channel work capacity, and significantly improve the lateral static pressure performance of the impeller disk 401. The small-chord blade tip 105 can reduce the lateral chord length of the impeller shroud 402 to reduce the Reynolds number, promote laminar flow maintenance, and effectively reduce frictional resistance and secondary flow losses.

[0030] This blade has a long-chord blade root 106 on the impeller disc 401 side, and the chord length on the impeller disc 401 side is increased compared to the original structure. This design maintains the fan's ability to provide primary radial and axial acceleration performance during operation. Combined with the small-chord blade on the impeller shroud 402 side, it improves the fan's overall aerodynamic efficiency.

[0031] In this embodiment, the leading edge 103 and the trailing edge 104 define the key boundaries of the airflow inlet and outlet. The leading edge 103 has a plurality of leading edge points p along its axial direction, and the trailing edge 104 has a plurality of trailing edge points q along its axial direction. Figure 1 Only the leading edge point p and the trailing edge point q at the blade tip 105 are shown.

[0032] The distance from the leading edge point p to the impeller center gradually increases from the blade root 106 to the blade tip 105. This configuration causes the leading edge 103 of the fan blade 10 to gradually move away from the impeller center as the axial position increases, improving the airflow's entry pattern. This increased distance from the leading edge point p allows airflow to flow more smoothly into the blade, reducing friction and instability between the airflow and the blade surface, thereby improving the blade's aerodynamic efficiency.

[0033] The distance from the trailing edge point q to the impeller center remains constant from the blade root 106 to the blade tip 105 before gradually decreasing. This segmented control of the trailing edge distance achieves dual aerodynamic optimization effects through the coordinated design of maintaining a constant trailing edge distance in the blade root region (segment DE) and decreasing it in the blade tip region (segment EF). This achieves dual aerodynamic optimization effects: A stable trailing edge thickness and pressure recovery gradient are maintained in the blade root region, ensuring a smooth airflow transition and maintaining work capacity. Simultaneously, the gradually decreasing trailing edge distance accelerates airflow discharge in the blade tip region, enhancing the centrifugal effect and suppressing the endwall lateral pressure gradient, effectively reducing secondary flow losses and wake vortex intensity. This "lower stability and upper drier" segmented control strategy ensures aerodynamic stability on the disc side while optimizing flow separation characteristics on the shroud side, achieving matched flow control effects at different radial blade positions.

[0034] The leading edge 103 of the fan blade 10 forms the air inlet side 107. The inlet angle 20 of the air inlet side 107 gradually increases along the axial direction. This gradual increase in inlet angle 20 helps optimize the airflow's entry path and reduces unstable flow caused by sudden angle changes. Increasing inlet angle 20 also facilitates airflow into the blade, reducing aerodynamic losses in the inlet direction and improving the fan's aerodynamic performance.

[0035] The trailing edge 104 of the fan blade 10 forms the outlet side 108. The outlet angle 30 of the outlet side 108 initially remains constant along the axial direction and then gradually decreases. This change in outlet angle 30 helps optimize the outflow direction of the airflow. The gradually decreasing outlet angle 30 of the fan blade 10 helps accelerate the airflow at the blade outlet, reducing turbulence and vortex formation. By controlling the outlet angle 30, the airflow can exit the blade smoothly, avoiding aerodynamic losses caused by an inappropriate angle, thereby improving the performance of the entire fan.

[0036] The fan blade 10 disclosed in the present application has a small chord length feature at the blade tip 105 on the shroud side and a large chord length feature at the blade root 106 on the disc side, and the blade chord length gradually decreases in the blade height direction. Under this structural design, the chord length of the impeller blade on the shroud side is reduced, the inlet angle is increased, and the outlet angle is reduced, which improves the complex flow of the airflow on the shroud side, effectively weakens the secondary flow of the airflow on the shroud side, and reduces the flow loss of the airflow in this part. The chord length of the blade on the disc side is increased to meet the acceleration effect of the impeller on the airflow. By changing the geometric shape of the leading edge 103 and the trailing edge 104, adjusting the chord length of the blade tip 105 and the blade root 106, optimizing the inlet angle 20 and the outlet angle 30, etc., the airflow is made smoother, turbulence and vortex are reduced, the aerodynamic performance is improved, the noise is reduced, and the working stability of the fan is enhanced.

[0037] In some embodiments, the distance from the leading edge point p to the impeller center ranges from 115.43 mm to 125.43 mm. This distance directly affects the way airflow enters the blade, and adjusting this distance can optimize the flow pattern over the blade. The variation within this range demonstrates that the designer effectively guides the airflow by precisely controlling the geometric position of the leading edge 103. Adjusting this distance helps optimize airflow distribution, reduce interference and vortices during intake, and improve aerodynamic efficiency.

[0038] The distance from the trailing edge point q to the impeller center ranges from 144.51 mm to 148.51 mm. Variations in this distance affect the outflow of air from the outlet side 108 of the fan blade 10. This range demonstrates that the position of the blade's trailing edge 104 controls the smooth transition of airflow. Adjusting the position of the trailing edge point q can reduce the generation of eddies and turbulence, optimize the way airflow leaves the blade, reduce aerodynamic losses, and improve overall fan performance.

[0039] By setting the precise distance range from the leading edge point p and the trailing edge point q to the center of the impeller, the way the airflow enters and leaves the fan blade 10 can be precisely controlled. This precise distance range setting helps to achieve a smooth transition of the airflow and reduces the disturbance and instability of the airflow on the blade surface. The setting of the leading edge 103 and the trailing edge 104 within this distance range ensures the uniformity of the airflow as it flows on the blade surface, reduces the influence of adverse factors such as eddies and turbulence, thereby reducing fan noise and improving the aerodynamic efficiency of the fan. The fan can maintain high performance under different operating conditions, especially exhibiting excellent aerodynamic characteristics under low-load and high-load conditions.

[0040] In some embodiments, the chord length of the wind turbine blade 10 ranges from 28 mm to 36 mm. Chord length, the linear distance from the leading edge 103 to the trailing edge 104, determines the blade's geometry and the flow path of airflow through the blade. Variations in chord length have a significant impact on aerodynamic performance, particularly at different locations on the wind turbine blade 10 (such as the blade root 106 and blade tip 105). Appropriate adjustment of chord length can effectively control airflow velocity and pressure distribution across the blade, as well as its impact on the blade surface.

[0041] The chord length of the blade gradually decreases from the blade root 106 to the blade tip 105, with the chord length being greater at the blade root 106 and smaller at the blade tip 105. The gradual decrease in chord length helps improve the distribution of airflow over the blade surface, reduce aerodynamic losses at the tip of the fan blade 10, and optimize the flow pattern of the airflow.

[0042] By adjusting the chord length of the fan blade 10 within a certain range, the design achieves precise control of airflow and optimizes the distribution of airflow across the blade surface. By appropriately varying the chord length, the fan blade 10 can effectively reduce the generation of eddies and turbulence, improving aerodynamic efficiency while also lowering noise levels and enhancing fan stability.

[0043] The design of a larger chord length at the blade root 106 helps to improve the air handling capacity of the blade in the area close to the impeller, while the design of a smaller chord length at the blade tip 105 helps to reduce terminal vortex, reduce airflow separation, and improve airflow flow, thereby optimizing the overall aerodynamic performance of the fan.

[0044] In some embodiments, the air inlet angle 20 ranges from 75° to 80°. The air inlet angle 20 refers to the angle formed by the airflow relative to the windward surface of the blade. In the design of the fan blade 10, the air inlet angle 20 determines the angle and speed of the airflow entering the blade. A smaller air inlet angle 20 (closer to 75°) generally helps reduce resistance to airflow entering the blade and improves the airflow guidance effect. The angle of airflow entering the fan blade 10 is closely related to the contact angle of the blade surface. A reasonable air inlet angle 20 helps to smooth the airflow and reduce unnecessary aerodynamic losses.

[0045] Within the range of 75° to 80°, the airflow entry angle is moderate, which can not only maintain a high airflow guidance capability, but also avoid large disturbances caused by the airflow entering, providing higher aerodynamic efficiency.

[0046] The outlet angle 30 ranges from 154° to 170°. The outlet angle 30 refers to the angle between the fan blades 10 and the outflow direction of the airflow, determining the direction and speed of the airflow leaving the blades. A larger outlet angle 30 (closer to 170°) allows the airflow to exit at a wider angle, which helps improve the fan's exhaust efficiency and reduce vortexes at the end. However, an excessively large outlet angle 30 can also lead to airflow instability. Therefore, precise adjustment of the outlet angle 30 degrees is necessary to ensure efficient airflow and optimize overall fan performance.

[0047] Within the range of 154° to 170°, the outflow angle of the airflow can effectively balance the speed and pressure of the airflow, ensure smooth discharge of the airflow, reduce airflow backflow or airflow separation, and improve the energy efficiency and stability of the fan.

[0048] By optimizing the angles at which air enters and exits the fan blades 10, smooth airflow is ensured, aerodynamic losses are reduced, and the fan's aerodynamic efficiency is improved. This design not only improves the fan's airflow guidance and exhaust capabilities, but also effectively reduces noise levels and eddy current losses, enhancing the fan's stability and reliability.

[0049] As some embodiments, the position range of the height change demarcation point of the leading edge 103 and the height change demarcation point of the trailing edge 104 in the axial direction of the impeller is 62 mm to 93 mm.

[0050] The height change points of the leading edge 103 and trailing edge 104 are the specific locations where the blade's leading edge 103 and trailing edge 104 begin to significantly change in their axial shape. These changes directly affect the airflow characteristics, particularly how it flows through different regions of the blade, particularly the root 106. By precisely controlling the locations of these change points, the overall performance of the blade can be optimized while maintaining efficient aerodynamic performance.

[0051] By properly setting the axial distance between the height change points of the leading edge 103 and the trailing edge 104 and the impeller disk 401, the airflow velocity and pressure distribution in different areas of the blade can be effectively adjusted. These changes allow the airflow to pass smoothly through the blade, reducing efficiency losses caused by uneven airflow, thereby improving the overall performance of the fan.

[0052] In this embodiment, for illustration, the two endpoints of the leading edge 103 are A and C, the height change demarcation point of the leading edge 103 is B, the two endpoints of the trailing edge 104 are D and F, and the height change demarcation point of the trailing edge 104 is E.

[0053] In the axial direction of the blade, the distance from the leading edge point p to the impeller center gradually increases in the AC section; the distance from the trailing edge point q to the impeller center remains unchanged in the DE section and gradually decreases in the EF section.

[0054] In addition, the chord length of the blade remains unchanged on the side close to the impeller disk 401, that is, in the AB and CD sections, and gradually decreases in the BC and EF sections, with the range of change being 28 mm to 36 mm.

[0055] In some embodiments, the ratio of the length of the height-maintaining region to the length of the height-reducing region in the axial direction of the trailing edge 104 is 1:1.5 to 1:2. In this embodiment, the trailing edge 104 of the wind blade 10 exhibits a height-varying characteristic, including a height-maintaining region and a height-reducing region. The height-maintaining region refers to the portion of the trailing edge 104 of the wind blade 10 where its height remains relatively constant within a certain axial range, specifically embodied in segment DE. The height-reducing region refers to the portion of the blade trailing edge 104 where its height gradually decreases, specifically embodied in segment EF.

[0056] The shorter height retention zone means the airflow decreases more gradually at the blade tip, allowing the airflow to exit the blade without sudden changes. This design helps reduce drastic changes in the airflow, avoiding the risk of vortices and airflow separation, thereby improving the fan's aerodynamic efficiency. The longer height reduction zone allows the airflow to exit the blade tip more smoothly, ensuring a smoother transition and enhancing the aerodynamic performance of the fan blade 10.

[0057] By ensuring that the length of the height reduction area is greater than the length of the height maintenance area, a gradual and smooth discharge of airflow can be achieved. This design helps reduce airflow separation and the generation of vortices, improves aerodynamic efficiency, reduces noise, and enhances the stability and adaptability of the fan under different operating conditions. At the same time, the ratio design of the height maintenance area and the height reduction area of the blade trailing edge 104 directly affects the airflow discharge characteristics of the fan. By designing a reasonable ratio, the airflow can be ensured to flow more smoothly at the blade tip, reducing airflow separation and vortex generation, thereby improving aerodynamic efficiency and the overall performance of the fan.

[0058] This application also discloses a fan impeller 40, see the attached Figure 5 and 6 As shown, it includes an impeller disc 401, an impeller cover 402 and the fan blades 10 disclosed in the above embodiment. The fan blades 10 are evenly fixed between the impeller disc 401 and the impeller cover 402 along the circumferential direction. The length direction of each fan blade 10 is parallel to the axial direction of the fan impeller 40, and the leading edge 103 of the fan blade 10 is closer to the rotation center of the fan impeller 40 than the trailing edge 104.

[0059] The fan blades 10 are evenly distributed along the circumference of the impeller disc 401 and the impeller cover 402, which helps balance the aerodynamic performance of the fan and avoid vibration and noise caused by uneven blade distribution. The even distribution also ensures that the airflow flows evenly across the entire impeller surface, improving the stability and efficiency of the fan.

[0060] The leading edge 103 of the fan blade 10 is closer to the center of rotation than the trailing edge 104, which means that the angle of the blade and the airflow guidance angle are more suitable for the initial stages of rotation and flow. When the airflow enters from the leading edge 103 of the blade and flows along the surface of the blade, it can accelerate the flow over a shorter path, reducing energy loss caused by airflow lag. In addition, because the leading edge 103 of the blade is closer to the center of rotation of the fan impeller 40 than the trailing edge 104, the blade can more effectively guide the airflow into the fan impeller 40 and reduce the disturbance of the airflow. The design of the leading edge 103 closer to the center of rotation allows the airflow to pass through the surface of the blade more evenly, thereby reducing the separation and vortex effects of the flow and improving the aerodynamic efficiency of the fan.

[0061] This application also discloses a centrifugal fan 50, see the attached Figure 7 As shown, it includes a drive motor 501, a volute 502 and the fan impeller 40 disclosed in the above embodiment. The volute 502 is provided with an air inlet 5021 on the front side, and an air outlet 5022 on the side wall. The fan impeller 40 is arranged in the volute 502 and is coaxially arranged with the air inlet 5021, and the impeller cover 402 faces the air inlet 5021. The drive motor 501 is located on the side of the volute 502 away from the air inlet 5021, and the output shaft of the drive motor 501 is coaxially fixedly connected to the impeller disc 401.

[0062] The design of volute 502 effectively guides and accelerates the airflow entering the fan. The air inlet 5021 is located on the front side of volute 502, while the air outlet 5022 is located on the side wall of volute 502. This layout helps the airflow gradually turn as it passes through volute 502, thereby increasing the airflow pressure and promoting its discharge.

[0063] The aerodynamic performance of the fan impeller 40 determines the efficiency of airflow guidance and the overall operating efficiency of the fan. By designing variable-chord blades with improved leading and trailing edge 104 profiles, energy loss can be reduced, aerodynamic performance, and fan efficiency enhanced. This application provides the following experimental data demonstrating the excellent aerodynamic and noise performance of the centrifugal fan.

[0064] The blade structures with different leading edge and trailing edge distances from the impeller center were established, and accordingly they were combined into fan impellers and centrifugal fans.

[0065] Table 1. Physical parameters of blades with different configurations

[0066] The aerodynamic and noise characteristics of the blades under different parameter configurations were calculated, and the aerodynamic and noise performance parameters of the blades under different parameter configurations were extracted, as shown in the following table.

[0067] Table 2. Performance parameters of blades with different configurations

[0068] The above experimental data show that the single-suction centrifugal fan impeller with variable-chord length blades with improved leading and trailing edge profiles has excellent aerodynamic and noise performance. Table 2 shows that the aerodynamic and noise performance are better than those of the original blade structure. Compared with the traditional blade, the flow rate is increased by 1.19%, the efficiency is increased by 0.39%, and the noise is reduced by 5.51 dB, which further improves the aerodynamic and noise performance of contemporary centrifugal fans.

[0069] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A fan blade, characterized in that: include: The suction wall and the pressure wall, both of which extend along the length of the fan blade; The chord length of the fan blade gradually decreases from the blade root to the blade tip. The distance from the leading edge point to the center of the impeller gradually increases from the blade root to the blade tip, and the distance from the trailing edge point to the center of the impeller first remains unchanged and then gradually decreases from the blade root to the blade tip. The leading edge of the fan blade is the air inlet side, and the air inlet angle of the air inlet side gradually increases along the axial direction. The trailing edge of the fan blade is the air outlet side, and the air outlet angle of the air outlet side first remains unchanged and then gradually decreases along the axial direction.

2. The fan blade according to claim 1, wherein: The suction wall surface is a convex surface, and the pressure wall surface is a concave surface.

3. The fan blade according to claim 2, wherein: The distance from the leading edge point to the center of the impeller varies in the range of 115.43 mm to 125.43 mm, and the distance from the trailing edge point to the center of the impeller varies in the range of 144.51 mm to 148.51 mm.

4. The fan blade according to claim 2, wherein: The chord length of the fan blades varies in the range of 28 mm to 36 mm.

5. The fan blade according to claim 2, wherein: The range of the wind inlet angle is 75°~80°, and the range of the wind outlet angle is 154°~170°.

6. The fan blade according to claim 2, wherein: The axial distance between the height change demarcation point of the leading edge and the height change demarcation point of the trailing edge and the impeller disc ranges from 62 mm to 93 mm.

7. The fan blade according to claim 6, wherein: In the axial direction of the trailing edge, the ratio of the length of the height-maintaining region to the length of the height-reducing region is 1:1.5 to 1:

2.

8. A fan impeller, comprising an impeller disc, an impeller cover, and the fan blade according to any one of claims 1 to 7, characterized in that: The fan blades are evenly fixed between the impeller disc and the impeller cover along the circumferential direction, the length direction of each fan blade is parallel to the axial direction of the fan impeller, and the leading edge of the fan blade is closer to the rotation center of the fan impeller than the trailing edge.

9. A centrifugal fan comprising a drive motor, a volute, and the fan impeller according to claim 8, characterized in that: The volute is provided with an air inlet on the front side and an air outlet on the side wall. The fan impeller is arranged in the volute and is coaxial with the air inlet, with the impeller cover facing the air inlet. The drive motor is located on the side of the volute away from the air inlet, and the output shaft of the drive motor is coaxially fixedly connected to the impeller disc.

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