Low-noise high-speed axial flow fan

Abstract

The application discloses a low-noise high-rotation-speed axial flow fan wheel, which comprises a fan wheel body and blades, a plurality of blades are equidistantly arranged on the outer side of the fan wheel body, a turn-up edge is arranged on the top edge of the blade and deviates from the pressure surface to the suction surface, a plurality of turn-up edge serrations are uniformly arranged on one side of the turn-up edge of the suction surface, a rib structure is arranged on the blade, the rib structure is circularly concave on the pressure surface of the blade and circularly convex on the suction surface of the blade, one end of the rib structure extends to the leading edge of the blade, a convex structure is formed at the inlet position of the blade, the trailing edge of the blade is provided with trailing edge serrations matched with the rib structure and the turn-up edge serrations, the rib structure on the surface of the blade extends to the leading edge of the blade, forms a convex structure at the leading edge of the blade, and combines the turn-up edge serrations on the turn-up edge of the blade top and the trailing edge serration structure deviated from the trailing edge of the blade to the rotation center of the fan wheel, so that the noise of the high-rotation-speed axial flow fan wheel can be reduced to the maximum extent.

Description

Technical Field

[0001] This invention belongs to the field of axial flow fan technology, specifically relating to a low-noise, high-speed axial flow impeller. Background Technology

[0002] Axial flow fans have a wide range of applications, such as electric fans and air conditioner outdoor unit fans. They are called "axial flow" because the gas flows parallel to the fan axis. Axial flow fans are typically used in applications requiring high flow rates but low pressure. An axial flow fan mainly consists of a fan impeller and a casing; its structure is simple, but its performance requirements are very high.

[0003] To address the issues of high noise levels and excessive stress on the blades of high-speed axial flow wind turbines, common approaches include adding biomimetic serrations to the trailing edge of the blade, adding folded wings to the blade tip, adding wave-like biomimetic structures to the leading edge of the blade, and arranging conventional ridge structures (one side concave and convex, the other flat) on the blade surface to solve the noise problem individually. Stress problems can be addressed individually by arranging reinforcing ribs on the blade. However, these measures are often simplistic and cannot simultaneously meet the practical needs of both noise reduction and stress reduction. Summary of the Invention

[0004] The purpose of this invention is to provide a low-noise, high-speed axial flow wind turbine. The blade inlet of this axial flow wind turbine has a protruding leading-edge noise reduction structure, the blade outlet has a toothed trailing-edge noise reduction serration structure that is biased towards the center of rotation of the wind turbine, the blade tip has a flanged and serrated structure, and the blade surface has a concave-convex rib-shaped flow guiding structure. This wind turbine reduces noise to the maximum extent through a comprehensive noise reduction structure, while its rib-shaped flow guiding structure can also act as a reinforcing rib, which can improve the structural strength and rigidity of the wind turbine blades.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a low-noise, high-speed axial flow wind turbine, comprising an impeller hub and blades. Multiple blades are evenly spaced on the outer side of the impeller hub, and each blade tip edge has a flange that deviates from the pressure surface towards the suction surface. Multiple flange serrations are evenly distributed on the suction surface side of the flange. The blades are provided with rib structures, which are concave in an arc shape on the pressure surface and convex in an arc shape on the suction surface. The rib structures serve as flow guides and reinforcing ribs. One end of the rib structure extends beyond the leading edge of the blade, forming a protruding structure at the blade inlet, which serves to guide flow and reduce noise by breaking vortices. The other end of the rib structure extends to the trailing edge of the blade, and the trailing edge of the blade has trailing edge serrations that cooperate with the rib structure and flange serrations, thereby minimizing the noise of the high-speed axial flow wind turbine.

[0006] The rib structure starts from the protruding structure at the blade inlet and gradually shifts towards the center of rotation as it extends towards the trailing edge of the blade. It can act as a reinforcing rib, improve the strength and stiffness of the blade, and enhance the load-bearing capacity of the wind turbine. The cross-section of the rib structure is an airfoil structure, which is obtained by offsetting the airfoil cross-section along the axial and radial directions to maximize aerodynamic performance.

[0007] Preferably, the shape of the flanged serrations is one of three shapes: wavy, triangular, or circular, which breaks the large vortex of fluid at the blade tip into smaller vortices, thus also achieving the effect of reducing noise at the blade tip.

[0008] Preferably, the trailing edge sawtooth shape is biased towards the center of the wind turbine rotation, and the angle between the sawtooth shape and the rotation axis is α, which is in the range of 5°≤α≤60°.

[0009] Preferably, the blade, flanged serrations, rib structure, protrusion structure, and trailing edge serrations are all integrally formed structures to ensure the structural robustness and stability.

[0010] Preferably, the tooth profile of the trailing edge serrations is biased toward the rotation center of the impeller hub.

[0011] Compared with the prior art, the beneficial effects of the present invention are:

[0012] This invention uses a rib structure on the blade surface that serves both as a guide for airflow and noise reduction, as well as a reinforcing rib, to extend out from the leading edge of the blade, forming a leading edge protrusion noise reduction structure. At the same time, it combines a blade tip noise reduction structure with serrated edges on the blade tip flange and a trailing edge noise reduction serrated structure with the trailing edge teeth angled toward the center of the wind turbine's rotation, which can minimize the noise of high-speed axial flow wind turbines.

[0013] The blades of this invention adopt a short and stout blade design, that is, the blades are short in the radial direction and long in the tangential direction; the blade airfoil adopts a mature airfoil, which improves strength and meets aerodynamic requirements; the rib structure can act as a reinforcing rib; since it is obtained by offsetting the airfoil section along the axial and radial directions, it does not add extra weight to the blade, while improving the vibration mode of the blade and enhancing the aerodynamic load-bearing capacity of the blade; the blade tip flange design also enhances the load-bearing capacity of the blade.

[0014] The blades employ a three-dimensional flow design to maximize forward curvature and sweep; the airfoil adopts a mature airfoil design to reduce boundary layer separation and lower noise from an aerodynamic perspective; the blades feature a rib structure with a concave pressure surface and a convex suction surface, which helps guide flow and reduce noise; the convex structure at the blade inlet, formed by the rib structure extending from the blade's leading edge, serves to guide flow and break up vortices, reducing noise; the serrated trailing edge of the blade also reduces noise at the trailing edge; the blade tip is flanged and serrated, which suppresses some backflow from the blade's pressure surface to its suction surface, while breaking up large vortices at the blade tip into smaller vortices, resulting in comprehensive noise reduction at the blade tip. Attached Figure Description

[0015] Figure 1 This is a three-dimensional structural diagram of the axial flow fan of the present invention;

[0016] Figure 2 This is a schematic diagram of the blade tip flanged and serrated structure of the present invention;

[0017] Figure 3 This is a partially enlarged view of the blade tip flange serrations of the present invention;

[0018] Figure 4 This is a diagram showing the distribution of the ribs of the present invention on the suction surface;

[0019] Figure 5 This is a schematic diagram showing the rib structure of the present invention on the blade surface;

[0020] Figure 6 This is a schematic diagram of an improved form of the directional curve of the ribs in this invention;

[0021] Figure 7 This is an enlarged schematic diagram of the protrusion structure of the present invention;

[0022] Figure 8 This is a schematic diagram of the serrated trailing edge of the blade of the present invention;

[0023] Figure 9 This is a schematic diagram showing the position of the fillet R on the wind turbine hub of the present invention;

[0024] In the diagram: 1. Flanged serrations, 2. Rib structure, 3. Protruding structure, 4. Tail edge serrations. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] Please see Figures 1 to 9This invention provides a technical solution: a low-noise, high-speed axial flow wind turbine, comprising an impeller hub and blades. Seven blades are evenly spaced on the outer side of the impeller hub. The inlet arc R of the impeller hub is 5.5mm. The impeller hub height is 25.4mm, and the hub outer diameter is 36mm. All blades have airfoil cross-sections, with an outer diameter of 56.4mm, a height of 27.5mm, and a minimum blade trailing edge thickness of 0.6mm. The flange height from the pressure surface to the suction surface is 0.6mm, and the height of the wave-shaped flange serration 1 on the flange is 0.2mm. The wavelength of the flange serration 1 is 0.6mm, which can suppress partial backflow from the pressure surface to the suction surface of the blade, and simultaneously break the large vortex at the blade tip into smaller vortices, thus achieving comprehensive noise reduction at the blade tip. Two rib structures 2, with a concave pressure surface and a convex suction surface, are distributed on the blade surface. The directional curve of the first rib structure 2 is half a distance from the center of rotation. The diameter is 20.5mm. The directional curve of the second rib structure 2 has a radius of 25mm from the center of rotation. The profile section of the rib structure 2 is obtained by moving the original airfoil profile 0.5mm axially towards the inlet side. The rib profile and other airfoil profiles overlap to form the basic shape of the blade with the rib structure 2. One end of the rib structure 2 extends beyond the leading edge of the blade, forming a protrusion structure 3 at the blade inlet. The distance from the first rib structure 2 to the leading edge of the blade is 0.56mm, and the distance from the second rib structure 2 to the leading edge of the blade is 0.67mm. This can play a role in guiding the flow and reducing noise by breaking vortices. There are three trailing edge serrations 4 at the trailing edge of the blade. The maximum length of the serration is 3mm, the minimum length of the serration is 1.6mm, the angle between the serration shape and the rotation axis is 34°, the maximum distance between the serrations is 1.7mm, and the minimum distance between the serrations is 1.5mm. This can play a role in reducing noise.

[0027] In this embodiment, preferably, the rib structure 2 starts from the protruding structure 3 at the blade inlet and gradually shifts towards the center of rotation as it extends toward the trailing edge of the blade. The cross-section of the rib structure 2 is an airfoil structure, and the rib structure 2 is obtained by offsetting the airfoil cross-section along the axial and radial directions.

[0028] In this embodiment, preferably, the blade, the flanged serration 1, the rib structure 2, the protruding structure 3, and the tail edge serration 4 are all integrally formed structures to ensure the structural robustness.

[0029] In this embodiment, preferably, the tooth profile of the trailing edge serration 4 is biased toward the rotation center of the impeller hub.

[0030] The directional curve of the rib structure 2 has two forms. The basic form of the directional curve is an arc centered on a point on the impeller rotation axis, extending from the leading edge to the trailing edge of the blade. The improved form of the directional curve is an arc extending from the leading edge to the trailing edge of the blade, forming an angle with the basic directional curve and gradually approaching the impeller rotation center. The rib is closest to the rotation center at the position closest to the trailing edge. In this invention, the basic form of the directional curve can satisfy the basic flow guiding function, while the rib structure with the improved directional curve has a better noise reduction effect. The improved directional curve of the rib structure 2 forms an angle β with the basic directional curve, and the range of this angle is β≤30°.

[0031] The working principle and usage process of this invention: The blades of this invention adopt a short and stout blade design, that is, the blades are short in the radial direction and long in the tangential direction; the blade airfoil adopts a mature airfoil, which improves strength and meets aerodynamic requirements; the rib structure 2 can act as a reinforcing rib; since it is obtained by offsetting the airfoil section along the axial and radial directions, it does not add extra weight to the blade, while improving the vibration mode of the blade and enhancing the aerodynamic load-bearing capacity of the blade; the blade tip flange design also enhances the load-bearing capacity of the blade; the blade adopts a three-dimensional flow design to maximize forward curvature and... Forward sweep; the blade adopts a mature airfoil design to reduce boundary layer separation and reduce noise from an aerodynamic perspective; the blade is designed with rib structures 2, which are concave on the pressure surface and convex on the suction surface, and can play a role in guiding flow and reducing noise; the convex structure 3 formed by the rib structure 2 extending from the leading edge of the blade at the blade inlet can play a role in guiding flow and breaking vortices to reduce noise; the trailing edge serrations 4 of the blade play a role in reducing noise at the trailing edge; the blade tip is flanged and has flanged serrations 1, which can suppress part of the backflow from the blade pressure surface to the blade suction surface, and at the same time break the large vortex at the blade tip into small vortices, playing a comprehensive role in reducing noise at the blade tip.

[0032] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-noise, high-speed axial flow wind turbine, comprising an impeller hub and blades, characterized in that: The impeller hub has multiple blades evenly spaced on its outer side, and the blade tip edge has a flange that is biased from the pressure surface to the suction surface. Multiple flange serrations (1) are evenly arranged on the suction surface side of the flange. The blade has a rib structure (2). The rib structure (2) is concave in an arc shape on the pressure surface of the blade and convex in an arc shape on the suction surface of the blade. One end of the rib structure (2) extends out of the leading edge of the blade and forms a convex structure (3) at the blade inlet. The other end of the rib structure (2) extends to the trailing edge of the blade. The trailing edge of the blade has trailing edge serrations (4) that cooperate with the rib structure (2) and the flange serrations (1). The rib structure (2) starts from the protruding structure (3) at the blade inlet and gradually shifts towards the rotation center as it extends towards the trailing edge of the blade. The cross section of the rib structure (2) is an airfoil structure. The rib structure (2) is obtained by offsetting the airfoil cross section along the axial and radial directions. The trailing edge sawtooth (4) is biased towards the rotation center of the wind turbine. The angle between the sawtooth and the rotation axis is α, and the range of this angle is 5°≤α≤60°.

2. The low-noise, high-speed axial flow impeller according to claim 1, characterized in that: The shape of the flanged saw teeth (1) is one of three shapes: wavy, triangular, or circular.

3. The low-noise, high-speed axial flow impeller according to claim 1, characterized in that: The blade, the flanged serration (1), the rib structure (2), the protruding structure (3), and the tail edge serration (4) are all integrally formed structures.

4. The low-noise, high-speed axial flow impeller according to claim 1, characterized in that: The tooth profile of the trailing edge sawtooth (4) is biased toward the rotation center of the impeller hub.

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