Axial flow fan blade and fan

Abstract

This utility model relates to the field of fan technology, and discloses an axial flow fan blade and a fan. The axial flow fan blade includes: a fan blade body, the trailing edge of which is provided with a serrated structure; the outer diameter of the fan blade body is D1, and the radius of the circumference of the starting end a of the serrated structure is r. a The radius of the circumference of the end b of the sawtooth structure is r. b And satisfy the relation 0 < r b <r a <D1 / 2, r b ≥0.4D1 / 2. The sawtooth structure can cut the large-scale vortex at the tail into smaller-scale vortices, weakening the intensity of the tail vortex, thereby reducing pressure pulsation intensity and aerodynamic noise; the sawtooth structure is distributed on the trailing edge of the blade body with a circumference r. b and r a Between, satisfying 0 < r b <r a <D1 / 2, ensuring stable shedding of tip vortices, reducing noise, while ensuring the mechanical strength of the sawtooth structure and preventing fatigue fracture; r b With a diameter of ≥0.4D1 / 2, large-scale vortices can be effectively cut at the tail of the blades to form small-scale vortices, thus effectively reducing noise.

Description

Technical Field

[0001] This utility model relates to the field of fan technology, specifically to an axial flow fan blade and a fan. Background Technology

[0002] During fan operation, if the actual angle of attack exceeds a critical value when airflow enters the blades, the airflow cannot adhere to the blade surface, causing the boundary layer to detach from the suction surface. This detached airflow forms a low-pressure vortex region behind the blades, known as a separation vortex. This vortex structure is unstable and periodically detaches, leading to pressure pulsations and generating discrete noise and broadband turbulent noise. The shedding of separation vortices not only increases the aerodynamic load on the fan but also results in significant fan noise, negatively impacting the user experience. Utility Model Content

[0003] In view of this, the present invention provides an axial flow fan blade and fan to solve the problem of increased aerodynamic load and noise of the fan due to the shedding of the separation vortex.

[0004] In a first aspect, this utility model provides an axial flow fan blade, comprising:

[0005] The blade body has a serrated structure at its trailing edge;

[0006] The outer diameter of the wind turbine blade body is D1, and the radius of the circumference of the starting end a of the serrated structure is r. a The radius of the circumference of the end b of the sawtooth structure is r. b And satisfy the relation 0 < r b <r a <D1 / 2, r b ≥0.4D1 / 2.

[0007] Beneficial effects: The serrated structure can cut the large-scale vortex at the tail into smaller vortices, weakening the intensity of the tail vortex and thus reducing pressure pulsation and aerodynamic noise. Furthermore, the serrated structure on the blade body reduces the blade area, improving the outflow efficiency without reducing work capacity, resulting in a corresponding decrease in overall load. The serrated structure is distributed on the trailing edge of the blade body with a circumference r. b and r a Between, satisfying 0 < r b <r aThe radius of the serrated structure is set to be greater than or equal to 0.4D1 / 2, ensuring a certain distance between the tip of the serrated structure and the blade tip, and a certain distance between the end of the serrated structure and the blade root. The blade tip is the main area for tip vortex generation; if the serrated structure is too close to the blade tip, it will interfere with the stable shedding of the tip vortex, increasing the vortex intensity and leading to increased noise. The blade root connects to the hub and bears the maximum centrifugal force and bending stress; if the serrated structure is too close to the blade root, stress concentration points are likely to form at the root of the serrated structure, accelerating fatigue crack propagation. The radius of the circumference of the end of the serrated structure is set to be greater than or equal to 0.4D1 / 2, ensuring that it is not too close to the blade root and also ensuring the radial extension length of the serrated structure, guaranteeing the tooth pitch. This allows the serrated structure to effectively cut large-scale vortices into small-scale vortices at the tail of the blade, effectively reducing noise.

[0008] In one alternative implementation, r a ≤0.9D1 / 2.

[0009] Beneficial effects: The radius of the circumference of the starting end of the sawtooth structure is set to be less than or equal to 0.9D1 / 2, which is not too close to the blade tip and also ensures the tooth pitch of the sawtooth. This allows the sawtooth structure to fully cut large-scale vortices at the tail of the blade to form small-scale vortices, effectively reducing noise.

[0010] In one optional embodiment, the blade tip chord length of the wind turbine body is L, the tooth height of the serrated structure is h, and the condition h = (5% ~ 10%)·L is satisfied.

[0011] Beneficial effects: The tip chord length is L, which is the line connecting the windward edge point P and the trailing edge point Q of the tip. If the tooth height is less than 5%L, the tooth height is small, the degree of breaking vortex is insufficient, and it cannot meet the requirement of reducing load. If the tooth height is greater than 10%L, the trailing edge area is reduced too much, the work capacity is weakened, and the air volume is lost. The tooth height h satisfies h = (5%~10%)·L, which can meet the requirements of breaking vortex and avoid the situation of air volume loss caused by excessive reduction of trailing edge area.

[0012] In one optional embodiment, the tooth pitch of the sawtooth structure is w, and w≥h.

[0013] Beneficial effects: The tooth pitch is greater than or equal to the tooth height, and the entire sawtooth exhibits a large tooth pitch, which has a better effect on breaking up large-scale vortices, and can also improve outflow efficiency and reduce aerodynamic load.

[0014] In one optional embodiment, the angle between the extensions of the tooth profiles of two adjacent serrations of the serrated structure is θ. Let the angle near the blade tip of the blade body be θ1, and let the angle near the blade root of the blade body be θn, satisfying θ1≤θ2≤θ3···≤θn, where n is the number of serrations.

[0015] Beneficial effects: From the tip of the blade towards the root, the angle θ between the extensions of the tooth profiles of two adjacent serrations gradually increases, i.e., θ1 < θ2 < θ3 ... < θn. As the angle increases progressively, the working capacity of the airflow weakens towards the blade root. Therefore, the serration area can be appropriately increased towards the blade root to reduce wake vortices without excessive airflow loss. When θ1 = θ2 = θ3 ... = θn, the manufacturing process of the serrated structure is simple, effectively controlling costs.

[0016] In one alternative implementation, the angle θ ≤ 80°.

[0017] Beneficial effects: If the included angle θ is too large, it may cause excessive reduction in area, decrease mechanical strength, easily cause fatigue fracture, and affect the life of the wind turbine blade.

[0018] In one optional embodiment, a noise reduction structure is provided on the suction surface of the fan blade body.

[0019] Beneficial effects: The noise reduction structure disrupts the originally smooth surface of the flavor body's suction surface, inducing the separation of the boundary layer airflow in advance, causing the large-scale vortex with concentrated energy to be dispersed into smaller vortices with lower energy; in addition, when the sound wave energy passes through the noise reduction structure, it is converted into heat energy dissipation under the action of friction, further absorbing mid-to-high frequency noise.

[0020] In one optional implementation, the noise reduction structure includes:

[0021] At least two pits are distributed on the suction surface of the fan blade body.

[0022] Beneficial effects: The uneven surface formed by at least two pits causes sound waves to be reflected and scattered multiple times during propagation, extending the propagation path of sound waves on the suction surface; the sound wave energy is converted into heat energy dissipation through friction at the pits, further absorbing mid-to-high frequency noise; the uneven structure can disrupt the originally smooth surface of the suction surface of the wind turbine blade, inducing the separation of the boundary layer airflow in advance, so that the large-scale vortex with concentrated energy is dispersed into small vortices with lower energy, thereby effectively reducing noise.

[0023] Secondly, this utility model also provides a fan, comprising:

[0024] Wheel hub;

[0025] In any of the above-mentioned axial flow fan blades, at least three of the fan blade bodies are distributed on the outer periphery of the hub.

[0026] Beneficial effects: Since the fan includes the axial flow fan blade of this utility model, it has the same technical effect as the axial flow fan blade. The sawtooth structure can cut the large-scale vortex at the tail of the fan blade body into small-scale vortices, weaken the intensity of the tail vortex, thereby reducing the pressure pulsation intensity and aerodynamic noise. Moreover, after setting the sawtooth structure, the fan blade area is reduced, and its outflow efficiency is improved and the fan load is reduced while ensuring that the work capacity is not weakened.

[0027] In one alternative implementation, the number of the fan blades is odd.

[0028] Beneficial effects: Using an odd number of blades disperses vibration energy, prevents the superposition of vibration energy during rotation, avoids resonance when the rotation speed reaches the system's natural frequency, significantly reduces noise, and avoids fatigue fracture. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of this utility model, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 This is a front view of a fan according to an embodiment of the present utility model;

[0031] Figure 2 for Figure 1 Schematic diagram of the region between the starting end a and the ending end b of the sawtooth structure;

[0032] Figure 3 for Figure 1 A schematic diagram of the main dimensional parameters;

[0033] Figure 4 This is a structural diagram of a wind turbine blade body according to an embodiment of the present utility model, showing the main dimensional parameters of the serrated structure;

[0034] Figure 5 This is a partially enlarged view of a sawtooth structure according to an embodiment of the present invention, showing the angle θ.

[0035] Figure 6 This is a schematic diagram of the suction surface of the fan according to an embodiment of the present invention;

[0036] Figure 7 Comparison of vorticity between wind turbine blades with and without serrated structures.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1. Wind blade body;

[0039] 11. Serrated structure; 111. Tooth tip; 112. Tooth groove; 113. Tooth profile line;

[0040] 12. Dents;

[0041] 2. Wheel hub. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. 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.

[0043] In the description of this utility model, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0044] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0045] The following is combined with Figures 1 to 7 The following describes embodiments of the present invention.

[0046] According to embodiments of the present invention, on the one hand, such as Figures 1-3 As shown, an axial fan blade is provided, comprising:

[0047] The fan blade body 1 has a serrated structure 11 at its trailing edge;

[0048] The outer diameter of the blade body 1 is D1, and the radius of the circumference of the starting end a of the serrated structure 11 is r. a The radius of the circumference of the end b of the sawtooth structure 11 is r. b And satisfy the relation 0 < r b <r a <D1 / 2, r b ≥0.4D1 / 2.

[0049] The serrated structure 11 can cut the large-scale vortex at the tail into smaller-scale vortices, weakening the intensity of the tail vortex and thus reducing pressure pulsation intensity and aerodynamic noise. Furthermore, by setting the serrated structure 11 on the blade body 1, the blade area is reduced, improving the outflow efficiency without weakening the work capacity, resulting in a corresponding decrease in the overall load. Moreover, the serrated structure 11 is distributed on the trailing edge of the blade body 1 with a circumference r. b and r a Between, satisfying 0 < r b <r a The radius of the serrated structure 11 is set to be greater than or equal to 0.4D1 / 2, ensuring that the tip of the serrated structure 11 is a certain distance from the blade tip, and the end of the serrated structure 11 is also a certain distance from the blade root. The blade tip is the main area for tip vortex generation. If the serrated structure 11 is too close to the blade tip, it will interfere with the stable shedding of the tip vortex, thus increasing the vortex intensity and leading to increased noise. The blade root connects to the hub 2 and bears the maximum centrifugal force and bending stress. If the serrated structure 11 is too close to the blade root, it is easy to form a stress concentration point at the root of the serrated structure 11, accelerating the propagation of fatigue cracks. The radius of the circumference of the end of the serrated structure 11 is set to be greater than or equal to 0.4D1 / 2, which is not too close to the blade root and also ensures the radial extension length of the serrated structure 11 and the tooth pitch. This allows the serrated structure 11 to fully cut large-scale vortices at the tail of the blade to form small-scale vortices, effectively reducing noise.

[0050] In some embodiments, r a ≤0.9D1 / 2.

[0051] The radius of the circumference of the starting end of the sawtooth structure 11 is set to be less than or equal to 0.9D1 / 2, which is not too close to the blade tip and also ensures the tooth pitch of the sawtooth, so that the sawtooth structure 11 can fully cut the large-scale vortex at the tail of the blade to form a small-scale vortex, effectively reducing noise.

[0052] In some embodiments, the blade tip chord length of the wind turbine body 1 is L, the tooth height of the serrated structure 11 is h, and the condition h = (5% ~ 10%)·L is satisfied.

[0053] The leaf tip chord length is L, such as Figure 4As shown, the tip chord length is the line connecting the windward edge point P and the trailing edge point Q. If the tooth height is less than 5%L, the tooth height is too small, the degree of breaking vortex is insufficient, and it cannot meet the requirement of reducing load. If the tooth height is greater than 10%L, the trailing edge area is reduced too much, the work capacity is weakened, and the air volume is lost. The tooth height h satisfies h = (5%~10%)·L, which can meet the requirements of breaking vortex and avoid the situation of air volume loss caused by excessive reduction of trailing edge area.

[0054] In some embodiments, the tooth pitch of the sawtooth structure 11 is w, and w ≥ h.

[0055] With a tooth pitch greater than or equal to the tooth height, the entire sawtooth exhibits a large tooth pitch, which is effective in breaking up large-scale vortices, improving outflow efficiency, and reducing aerodynamic load.

[0056] It should be noted that in this utility model, the tooth profile line 113 is defined as the line connecting the tooth tip 111 and the tooth groove 112 of the sawtooth. The angle θ between the extensions of the tooth profile lines 113 of two adjacent sawtooths is shown in [reference needed]. Figure 5 .

[0057] In some embodiments, the angle between the extensions of the tooth profile lines 113 of two adjacent teeth of the sawtooth structure 11 is θ, see [reference]. Figure 4 and Figure 5 Let θ1 be the included angle at the tip of the blade near the body of the wind turbine 1, and let θn be the included angle at the root of the blade near the body of the wind turbine 1, satisfying θ1≤θ2≤θ3···≤θn, where n is the number of serrations.

[0058] From the tip of the blade body 1 towards the blade root, the angle θ between the extended lines of the tooth profiles 113 of two adjacent serrations gradually increases, i.e., θ1 < θ2 < θ3 ... < θn. The working capacity of the airflow weakens near the blade root. Therefore, the serration area can be appropriately increased towards the blade root to reduce the wake vortex without losing too much airflow. When θ1 = θ2 = θ3 ... = θn, the manufacturing process of the serration structure 11 is simple and can effectively control costs.

[0059] Of course, in some other embodiments, the included angle θ of the extension lines of the tooth profile lines 113 of two adjacent serrations can also be partially equal from the tip of the leaf to the direction closer to the root of the leaf. The angle can be selected and set as needed in specific applications.

[0060] In some embodiments, the angle θ ≤ 80°.

[0061] If the included angle θ is too large, it may cause the area to be reduced too much, the mechanical strength to decrease, and fatigue fracture to occur easily, affecting the life of the wind turbine blade.

[0062] In some embodiments, such as Figure 4 and Figure 5As shown, the tooth tips 111 and tooth grooves 112 of the sawtooth structure 11 are both arc-shaped, which can reduce the energy loss of airflow.

[0063] In some embodiments, a noise reduction structure is provided on the suction surface of the fan blade body 1.

[0064] The noise reduction structure disrupts the originally smooth surface of the suction surface of the blade body 1, inducing the separation of the boundary layer airflow in advance, causing the large-scale vortex with concentrated energy to be dispersed into small vortices with lower energy; in addition, when the sound wave energy passes through the noise reduction structure, it is converted into heat energy dissipation under the action of friction, further absorbing mid-to-high frequency noise.

[0065] In some embodiments, such as Figure 6 As shown, the noise reduction structure includes:

[0066] At least two pits 12 are distributed on the suction surface of the fan blade body 1.

[0067] The uneven surface formed by at least two pits 12 causes sound waves to be reflected and scattered multiple times during propagation, extending the propagation path of sound waves on the suction surface; the sound wave energy is converted into heat energy dissipation through friction at the pits 12, further absorbing mid-to-high frequency noise; the uneven structure can destroy the originally smooth surface of the suction surface of the blade body 1, inducing the separation of the boundary layer airflow in advance; the large-scale vortex with concentrated energy is dispersed into small vortices with lower energy, thereby effectively reducing noise.

[0068] According to an embodiment of the present invention, another aspect provides a fan, comprising:

[0069] Wheel hub 2;

[0070] Axial flow fan blades, with at least three fan blade bodies 1 distributed on the outer periphery of the hub 2.

[0071] Since the fan includes the axial flow fan blade of this utility model, it has the same technical effect as the axial flow fan blade. The sawtooth structure 11 can cut the large-scale vortex at the tail of the fan blade body 1 into small-scale vortices, weaken the intensity of the tail vortex, thereby reducing the pressure pulsation intensity and aerodynamic noise. Moreover, after setting the sawtooth structure 11, the fan blade area is reduced, and its outflow efficiency is improved and the fan load is reduced while ensuring that the work capacity is not weakened.

[0072] In some embodiments, the number of wind blade bodies 1 is odd.

[0073] The number of blades 1 is odd. The asymmetrical layout of odd-numbered blades disperses vibration energy, prevents the superposition of vibration energy during rotation, avoids resonance when the rotation speed reaches the system's natural frequency, significantly reduces noise, and avoids fatigue fracture.

[0074] In this embodiment, there are three fan blade bodies 1, and the fan rotates clockwise. The diameter of the fan blade is D1, the diameter of the hub 2 is D2, and the radius of the circumference of the outermost starting end a of the serrated structure 11 is r. a The radius of the circle containing the innermost end b of the sawtooth structure 11 is r. b Therefore, the serrations are distributed at the trailing edge of the blade, r b ~r a Between. This is mainly due to the distance between the serrated structure 11 and the leaf tip and root; it cannot be too close to the leaf tip and root, while being too far away would reduce the distribution range of the serrated structure 11. Therefore, it is necessary to control the distribution of the serrations at the trailing edge. Where r a ≤0.9D1 / 2, r b ≥0.4D1 / 2, and r a >r b .

[0075] Define the blade tip chord length as L (i.e., the line connecting the windward edge point P and the trailing edge point Q of the blade tip), the tooth pitch of the serrated structure 11 at the trailing edge as w, the tooth height of the serrations as h, and the angle between the extensions of the tooth profile lines 113 of two adjacent teeth as θ, where the tooth height h = (5%~10%)L, the tooth pitch w ≥ h, and the angle between the extensions of the tooth profile lines 113 of two adjacent teeth as θ1≤θ2≤θ3···≤θn≤80°, where n is the number of serrations. In this embodiment, the number of serrations is 3, but it is not limited to 3. The tooth pitch and tooth height can be controlled according to the blade diameter to change the number of serrations. The entire serration exhibits the characteristics of large tooth pitch and tooth height (relative to small serrations). When the tooth height h is less than 5%L, the tooth height of the serrations is shallow, the degree of vortex breaking is insufficient, and it cannot meet the requirements for reducing load. When the tooth height h is greater than 10%L, the trailing edge area is reduced too much, the work capacity is weakened, and the airflow is lost. The closer to the blade root, the more the angle θ can be increased, i.e., θ1 < θ2 < θ3 ... < θn, with the angle θ increasing step by step. As the airflow's work capacity weakens closer to the blade root, the serration area can be appropriately increased to reduce the wake vortex without losing too much airflow.

[0076] In one embodiment, D1 = 197.3 mm, D2 = 66 mm; r b =40mm, r a =90mm; tooth pitch w1=17.8mm, w2=19mm, w3=21mm; tooth height h1=9.6mm, h2=10.1mm, h3=10.2mm.

[0077] The serrated structure 11 reduces the working area of ​​the trailing edge to some extent, thus reducing airflow. Therefore, the serrations cannot be too large; if the serrations are too small, the trailing edge dissipation is not obvious, and the noise reduction effect is not significant. Therefore, the size of the trailing edge serrations of the fan blade must be reasonably designed according to the diameter of the blade and the trailing edge area. When the airflow flows from the windward edge to the trailing edge, the large-scale vortex of the trailing vortex is broken, reducing dissipation and improving airflow efficiency. The serrations at the tail also appropriately reduce the ineffective working area of ​​the blade, thus reducing the overall aerodynamic load while reducing noise.

[0078] Figure 7 A comparison of vortex volume between a wind turbine blade without a serrated structure in related technologies and the wind turbine blade with a serrated structure in this invention is presented. As shown in the red box in the figure, the serrated structure at the trailing edge can enhance the mixing between the low-speed flow and the mainstream in the wake region, expand the wake region area, and make the velocity distribution in the wake region more uniform. The serrated structure widens the wake region and accelerates the breaking up of large eddies, diffusing vortex energy to the spanwise and vertical directions, so that the velocity pulsation in the three directions exhibits different diffusion patterns. The turbulent pulsation attenuation rate increases along the flow direction, thus weakening the turbulent pulsation.

[0079] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by this application.

Claims

1. An axial flow fan blade, characterized in that, include: The blade body (1) has a serrated structure (11) at its trailing edge; The outer diameter of the blade body (1) is D1, and the circumference of the starting end a of the serrated structure (11) is r. a The radius of the circumference of the end b of the sawtooth structure (11) is r. b And satisfy the relation 0 < r b <r a <D1 / 2, r b ≥0.4D1 / 2.

2. The axial flow fan blade according to claim 1, characterized in that, r a ≤0.9D1 / 2。 3. The axial flow fan blade according to claim 1, characterized in that, The blade tip chord length of the blade body (1) is L, and the tooth height of the sawtooth structure (11) is h, and the condition h = (5% ~ 10%)·L is satisfied.

4. The axial flow fan blade according to claim 3, characterized in that, The tooth pitch of the sawtooth structure (11) is w, and w≥h.

5. The axial flow fan blade according to claim 1, characterized in that, The angle between the extension lines of the tooth profile lines (113) of two adjacent saw teeth of the sawtooth structure (11) is θ. Let the angle near the tip of the blade body (1) be θ1, and let the angle near the root of the blade body (1) be θn, satisfying θ1≤θ2≤θ3···≤θn, where n is the number of saw teeth.

6. The axial flow fan blade according to claim 5, characterized in that, Angle θ≤80°.

7. The axial flow fan blade according to any one of claims 1 to 6, characterized in that, The suction surface of the fan blade body (1) is provided with a noise reduction structure.

8. The axial flow fan blade according to claim 7, characterized in that, The noise reduction structure includes: At least two pits (12) are distributed on the suction surface of the fan blade body (1).

9. A fan, characterized in that, include: Wheel hub (2); According to any one of claims 1 to 8, at least three of the blade bodies (1) are distributed on the outer periphery of the hub (2).

10. The fan according to claim 9, characterized in that, The number of the wind turbine blades (1) is odd.

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