A heat dissipation device for a wind power generator

Abstract

The application discloses a heat dissipation device of a wind driven generator and belongs to the technical field of heat dissipation of a wind driven generator set. The heat dissipation device comprises a hub, a plurality of main fan blades which are arranged on the outer side wall of the hub in a circumferential direction of the hub, a plurality of fan ring plates which are arranged on the outer side of the hub in the circumferential direction of the hub, and the fan ring plates are arranged to be movable in the radial direction of the hub. The heat dissipation device further comprises an air inlet rectification area, a main working acceleration area and an outer ring pressure expansion area. When the fan ring plates move in the radial direction, the flow cross sections of the three areas can be synchronously adjusted. The application realizes dynamic regulation and control of the air flow channel through radial adjustment of the fan ring plates, and further fine adjustment is realized in cooperation with the telescopic wind baffle. The weight of the fan blades is obviously reduced, the air volume is improved, the noise is reduced, and the technical problems that the bearings of the heat dissipation fan of the existing wind driven generator are damaged due to the excessive weight of the fan blades and the maintenance is difficult are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of wind turbine generator heat dissipation technology, and specifically to an axial flow heat dissipation device for a wind turbine generator top heat dissipation system. Background Technology

[0002] During operation, wind turbines generate a large amount of heat in their generator section, requiring forced cooling by a cooling fan. Existing wind turbines generally use top-mounted axial-flow cooling fans, whose blades are typically made of cast iron or steel. A single blade can weigh up to 50 kilograms, and the entire fan assembly (including the motor, end caps, etc.) weighs approximately 250 kilograms.

[0003] In actual operation, due to the excessive mass of the fan blades, the enormous centrifugal force generated by prolonged high-speed rotation causes the generator end cover bearings to bear extremely high radial loads, leading to wear and damage. Once the end cover bearings fail, the generator rotor will experience axial movement, causing motor overload and triggering the fan power supply switch to trip, with the system reporting a "generator cooling fan thermal relay trip" fault. Furthermore, because the fan motor is located on top of the generator, the maintenance space is limited, and replacing a single fan blade assembly requires at least six maintenance personnel working together, resulting in lengthy repair times and severely impacting the availability and power generation revenue of the wind turbine.

[0004] Existing technologies include solutions that use lightweight materials (such as aluminum alloys) to replace cast iron. However, simple material replacement cannot solve the structural strength problem of fan blades under high-speed rotation. Furthermore, lightweight fan blades often require a larger blade area to achieve the same cooling airflow at the same rotational speed, which introduces new dynamic balance and noise issues. In addition, the blade spacing and airflow channels of existing cooling fans are fixed structures, which cannot be adjusted in real time according to changes in operating conditions (such as wind speed, generator load, ambient temperature, etc.), making it difficult to continuously optimize cooling efficiency. Therefore, there is an urgent need for a new type of wind turbine cooling device that can effectively reduce weight, ensure airflow, reduce noise, and has adaptive adjustment capabilities. Summary of the Invention

[0005] This invention aims to solve the technical problem of bearing damage and maintenance difficulties caused by excessively heavy fan blades in existing wind turbine cooling fans, while achieving dynamic adjustment of the airflow channel to further improve heat dissipation efficiency and reduce noise.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A heat dissipation device for a wind turbine includes:

[0008] Wheel hub;

[0009] Multiple main fan blades are spaced apart along the circumference of the hub on the outer side wall of the hub;

[0010] Multiple fan-shaped ring plates are spaced apart on the outer side of the hub along the circumference of the hub, and the fan-shaped ring plates are configured to be movable radially along the hub.

[0011] Multiple auxiliary fan blades are spaced apart along the circumference of the fan ring plate on the outer side wall of the fan ring plate;

[0012] The auxiliary fan blades and the main fan blades are arranged alternately along the axial direction of the hub;

[0013] An air intake rectification area is formed between the outer ring of the hub and the inner ring wall of the fan ring plate;

[0014] The pressure surface of the main fan blade, the suction surface of the auxiliary fan blade, and the outer ring of the fan ring plate form the main power acceleration zone;

[0015] The suction surface of the main fan blade, the pressure surface of the auxiliary fan blade, and the outer ring of the fan ring plate form an outer ring pressure diffusion zone;

[0016] When the fan ring plate moves radially, it can simultaneously adjust the flow cross-section of the intake rectification zone, the main power acceleration zone, and the outer ring diffuser zone.

[0017] Furthermore, it also includes an electric telescopic rod, one end of which is connected to the wheel hub or fixed bracket, and the other end is connected to the fan ring plate, for driving the fan ring plate to move radially.

[0018] Furthermore, the main fan blade is provided with a blade groove, and a retractable windshield is provided in the blade groove; the retractable windshield includes a plurality of bent flaps connected in sequence, each bent flap is provided with a folding cavity, and a folding spring for actively folding the bent flap is provided in the folding cavity.

[0019] Furthermore, the retractable windshield can switch between an extended state and a retracted state: in the extended state, the retractable windshield extends into the main power acceleration zone to change the flow cross-section of the zone; in the retracted state, the retractable windshield is housed within the blade slot.

[0020] Furthermore, an electromagnet is provided at the end of the retractable windshield away from the blade slot; the electromagnet is de-energized when the fan ring plate moves radially, so that the retractable windshield retracts to the opening position of the blade slot under the action of the flap spring; after the fan ring plate moves to the target position, the electromagnet is energized and magnetically attracted to the metal surface of the main fan blade, so that the retractable windshield remains in the extended state.

[0021] Furthermore, the outer surface of the electromagnet is wrapped with a flexible material layer, which is used to adapt to the curvature of the main fan blade at different radial positions when the electromagnet is attracted.

[0022] Furthermore, the flexible material layer is a rubber layer or a silicone layer.

[0023] Furthermore, multiple fan ring plates are arranged circumferentially along the hub and combined on the periphery of the hub to form an annular isolation structure. The annular isolation structure is used to isolate the outer ring diffuser area from the intake rectification area and the main power acceleration area.

[0024] Furthermore, the main fan blade is at least partially made of metal material for use in conjunction with the electromagnet for adsorption; the fan ring plate and the secondary fan blade are made of non-metallic material to reduce the overall weight.

[0025] Furthermore, the hub has a polygonal groove in its central shaft hole for positioning in conjunction with a polygonal boss on the generator output shaft.

[0026] Beneficial effects:

[0027] 1. This invention, by arranging long and short blades in an alternating pattern and combining it with a radially movable fan-shaped plate, divides the space between adjacent blades into three independent functional areas, thereby achieving dynamic adjustment of the airflow channel:

[0028] In the intake rectification zone, the annular gap between the fan ring plate and the hub effectively guides airflow smoothly into the impeller inner ring, preventing airflow blockage near the hub, significantly reducing intake resistance, and increasing the effective flow area. CFD simulations have verified that, at the same rotational speed, this structure can increase intake flow by 8% to 12%.

[0029] In the main power acceleration zone, the pressure surface of the main blade and the suction surface of the secondary blade are arranged opposite each other. The secondary blade can actively break up the large-scale eddies that fall off in the wake of the main blade, suppress boundary layer separation, and enable the airflow to achieve higher kinetic energy conversion efficiency on the blade surface. Experiments show that the aerodynamic efficiency in this region is more than 15% higher than that of the traditional equal-length blade structure.

[0030] The outer diffuser zone features a structure where the suction surface of the main fan blades and the pressure surface of the auxiliary fan blades are arranged opposite each other, forming a constraint structure similar to a "virtual blade tip." This effectively prevents leakage flow at the tip of the main fan blades, reducing airflow loss, and simultaneously homogenizes the outlet airflow velocity distribution, thus reducing turbulence noise. Actual measurement data shows that this structure can reduce the overall fan noise by 3 to 5 dB(A).

[0031] 2. Dynamic Adjustment Capability: Driven radially by an electric telescopic rod, the fan ring plate can simultaneously change the flow cross-section of the three zones. This allows the cooling device to optimize airflow distribution in real time based on changes in generator load, ambient temperature, wind speed, and other operating conditions, ensuring it always operates within the optimal cooling efficiency range. Combined with the fine adjustment of the retractable windshield, a wider range of flow control can be achieved.

[0032] 3. Lightweight design: Since the fan ring plate and auxiliary fan blades share part of the aerodynamic load, the stress on the main fan blades is optimized. With the use of non-metallic materials, the total mass of the fan blades can be reduced to less than 40% of the original cast iron design. This fundamentally solves the problem of bearing damage caused by excessive fan blade weight. It is expected to reduce the fan failure rate by more than 70% and shorten maintenance downtime to 1 / 3 of the original. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the present invention.

[0034] Figure 2 for Figure 1 Top view.

[0035] Figure 3 This is a schematic diagram of a single sector ring plate.

[0036] Figure 4 This is a structural diagram of a retractable windshield.

[0037] In the diagram: 1. Fan hub, 10. Main fan blade, 11. Fan ring plate, 12. Secondary fan blade, 13. Electric telescopic rod, 14. Blade groove, 15. Telescopic windshield, 16. Bending blade, 17. Folding cavity, 18. Folding spring, 19. Electromagnet, 20. Outer ring diffusion zone, 21. Main power acceleration zone, 22. Intake rectification zone. Detailed Implementation

[0038] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings.

[0039] Example 1

[0040] Reference Figures 1 to 4This embodiment provides a heat dissipation device for a wind turbine, including a hub 1, five main fan blades 10, five fan ring plates 11, and five auxiliary fan blades 12. The main fan blades 10 are evenly distributed around the circumference of the hub 1, and the root of each main fan blade 10 is fixedly connected to the outer wall of the hub 1. The fan ring plates 11 are arc-shaped plate structures, and the five fan ring plates 11 are arranged around the circumference of the hub 1, forming a ring-shaped isolation structure around the periphery of the hub 1. The fan ring plates 11 are configured to move radially along the hub 1, and each fan ring plate 11 is connected to the hub 1 or a fixed bracket via an electric telescopic rod 13, which drives the fan ring plate 11 to move radially. The auxiliary fan blades 12 are evenly arranged around the circumference of the fan ring plates 11 on the outer wall of the fan ring plates 11, and the number of auxiliary fan blades 12 is equal to the number of main fan blades 10, arranged in a staggered manner in the axial direction, i.e., each auxiliary fan blade 12 is located in the middle of two adjacent main fan blades 10.

[0041] The intake rectification zone 22 is formed between the outer ring of the hub 1 and the inner ring wall of the fan ring plate 11. This area is an annular gap, and its function is to guide outside air smoothly into the inner ring of the impeller, avoiding vortex losses caused by airflow blockage near the hub. When the fan ring plate 11 moves radially outward, the radial width of this zone increases, and the intake volume increases; conversely, when it moves inward, the intake volume decreases. Its radial width is preferably 5% to 15% of the hub radius.

[0042] The main power acceleration zone 21 is formed between the pressure surface (concave surface) of the main fan blade 10, the suction surface (convex surface) of the secondary fan blade 12, and the outer ring of the fan ring plate 11. The pressure surface of the main fan blade is the main power surface, where the airflow is accelerated and obtains high pressure. The suction surface of the secondary fan blade faces the pressure surface of the main fan blade, which can actively cut and break up the large-scale vortices that fall off in the wake of the main fan blade, suppress boundary layer separation, and thus improve aerodynamic efficiency. Its circumferential arc length is preferably 30% to 60% of the chord length of the main fan blade.

[0043] The outer diffuser zone 20 is formed between the suction surface (convex surface) of the main fan blade 10, the pressure surface (concave surface) of the auxiliary fan blade 12, and the outer ring of the fan ring plate 11. The suction surface of the main fan blade and the pressure surface of the auxiliary fan blade are arranged opposite to each other, forming a constraint structure similar to a "virtual blade tip," which effectively prevents leakage flow at the blade tip of the main fan blade, reduces airflow loss, and at the same time, uniformizes the outlet airflow velocity distribution, reducing turbulence noise. Its radial length is preferably 10% to 30% of the radial height of the auxiliary fan blade.

[0044] When the fan ring plate 11 moves radially, it can simultaneously adjust the flow cross-section of the intake rectification zone 22, the main power acceleration zone 21 and the outer ring diffuser zone 20, thereby achieving dynamic optimization of airflow distribution.

[0045] Furthermore, the retractable windshield structure includes a blade groove 14 on the main fan blade 10, within which a retractable windshield 15 is installed. The retractable windshield 15 comprises multiple sequentially connected folding flaps 16, each folding flap 16 having a folding cavity 17 containing a folding spring 18 for actively retracting the folded flap 16. An electromagnet 19 is located at the end of the retractable windshield 15 furthest from the blade groove 14. The outer surface of the electromagnet 19 is covered with a rubber layer (flexible material layer) to adapt to the curvature of the main fan blade 10 at different radial positions when the electromagnet 19 is attracted.

[0046] When the fan ring plate 11 moves radially, the electromagnet 19 is de-energized, and the retractable windshield 15 retracts to the opening position of the blade slot 14 under the action of the flap spring 18 to avoid interference with the fan ring plate 11. After the fan ring plate 11 moves to the target position, the electromagnet 19 is energized and magnetically attracted to the metal surface of the main fan blade 10, so that the retractable windshield 15 is kept in the extended state and extends into the main power acceleration zone 21 to change the flow cross section of the zone.

[0047] The main fan blade 10 is made of cold-rolled steel sheet (SPCC) through stamping and has a galvanized anti-corrosion treatment to ensure reliable magnetic attraction with the electromagnet 19; the fan ring plate 11 and the auxiliary fan blade 12 are made of glass fiber reinforced nylon 66 (PA66+GF30) through injection molding to reduce the overall weight; the hub 1 is made of cast iron. The total weight of the entire fan blade assembly is 95kg, which is 62% lighter than the original cast iron design (250kg).

[0048] Durability testing was conducted at the rated speed of 1500 rpm. After 2000 hours of continuous operation, no abnormal wear was observed on the bearing end cover, the fan power supply current remained stable, and no overload tripping faults occurred. Noise testing showed that under the same airflow conditions, the fan noise of this embodiment was 72 dB(A), while the noise of the original cast iron fan was 78 dB(A), a reduction of 6 dB(A). Airflow can be adjusted within a range of ±15% under different loads by adjusting the radial movement of the fan ring plate.

[0049] Performance Verification: After replacing the original cooling fan of a 2MW wind turbine with the cooling device of this embodiment, the on-site operating data is as follows:

[0050] Generator winding temperature: decreased by an average of 3.5℃;

[0051] Fan motor current fluctuation range: reduced from ±8% to ±2%;

[0052] Annual number of failures: decreased from an average of 2.3 times / year to 0.4 times / year;

[0053] The working hours for a single repair have been reduced from 6 people x 4 hours to 2 people x 2 hours.

[0054] Example 2:

[0055] The difference between this embodiment and Embodiment 1 is that:

[0056] Number of blades: There are 3 main fan blades (10) and 3 auxiliary fan blades (12), and 3 fan ring plates (11). It is suitable for wind turbines with smaller power (such as units below 1MW) or other industrial heat dissipation scenarios.

[0057] Material selection: The main fan blade 10 is made of martensitic stainless steel (410 stainless steel) by stamping; the fan ring plate 11 and the auxiliary fan blade 12 are made of glass fiber reinforced nylon 66 (PA66+GF30) by injection molding; and the hub 1 is made of aluminum alloy die casting. The total weight of the entire fan blade assembly is 48kg.

[0058] Zone parameters: Intake rectification zone 22 radial width is 8% of the hub radius; main power acceleration zone 21 circumferential arc length is 35% of the main fan blade chord length; outer ring diffuser zone 20 radial length is 25% of the auxiliary fan blade radial height.

[0059] Performance data: Rated speed 1800rpm; Maximum air volume 4200m³ / h (comparable to traditional cast iron 3-blade fans); Noise 68dB(A) (5dB(A) lower than traditional structures); Bearing life prediction: Based on accelerated life testing, the bearing life can reach more than 8 years, which is about 3 times longer than traditional structures.

[0060] Applicable scenarios: This embodiment is particularly suitable for offshore wind power or humid environments that are sensitive to weight and have high requirements for corrosion resistance.

[0061] Example 3:

[0062] The difference between this embodiment and Embodiment 1 is that:

[0063] Number of blades: There are 7 main fan blades (10) and 7 auxiliary fan blades (12), and 7 fan ring plates (11). It is suitable for large wind turbines (such as units above 5MW) or heat dissipation scenarios with extremely high air volume requirements.

[0064] Material selection: The main fan blade 10 is made of electrical pure iron or low carbon steel plate by stamping; the fan ring plate 11 and the auxiliary fan blade 12 are made of carbon fiber reinforced epoxy resin prepreg by molding; and the hub 1 is made of titanium alloy CNC machined parts. The total weight of the entire fan blade assembly is 112kg, which is 72% lighter than the cast iron solution of the same specifications (approximately 400kg).

[0065] Zoning parameters: Intake rectification zone 22 radial width is 12% of the hub radius; main power acceleration zone 21 circumferential arc length is 55% of the main fan blade chord length; outer ring diffuser zone 20 radial length is 15% of the auxiliary fan blade radial height.

[0066] Structural reinforcement design: Due to the strong anisotropy of carbon fiber material, a titanium alloy reinforcing bushing is added at the connection between the secondary fan blade 12 and the fan ring plate 11 to prevent fatigue cracking caused by stress concentration.

[0067] Performance data: Rated speed 1200rpm (for large-diameter impellers, the speed is appropriately reduced to control the tip linear velocity); Maximum air volume 18500m³ / h (22% higher than the cast iron solution of the same specification); Noise 75dB(A) (4dB(A) lower than the traditional structure); Fatigue life tested for 1 million cycles of load, no cracks or delamination were found on the blades.

[0068] Example 4:

[0069] The difference between this embodiment and Embodiment 1 is that:

[0070] Blade configuration: 5 main fan blades (10), 3 secondary fan blades (12), and 3 fan ring plates (11). This means that fan ring plates and secondary fan blades are not installed in every main fan blade interval; rather, a set of fan ring plates and secondary fan blades is installed every one or two main fan blade intervals.

[0071] Zoning characteristics: In the intervals with fan ring plates, the definitions of the intake rectification zone 22, the main power acceleration zone 21, and the outer ring diffuser zone 20 are exactly the same as in Example 1; in the intervals without fan ring plates, only the intake rectification zone 22 (naturally formed between the hub and the root of the main fan blade) is retained, and the main power acceleration zone and the outer ring diffuser zone are merged into a conventional airflow channel.

[0072] Design motivation: In some cost-sensitive applications, appropriately reducing the number of fan ring plates and secondary fan blades can reduce mold costs and assembly complexity while ensuring most of the performance improvement.

[0073] Performance data: Rated speed 1500rpm; Maximum air volume 6600m³ / h (reduced by about 5% compared to Example 1, but still more than 10% higher than the conventional structure); Noise 73dB(A) (increased by 2dB(A) compared to Example 1, but still reduced by 5dB(A) compared to the conventional structure); Total weight 78kg (further reduced by 7kg compared to Example 1).

[0074] Applicable scenarios: This embodiment represents a compromise between performance and cost, and is suitable for the wind power operation and maintenance retrofit market where cost-effectiveness is a high priority.

[0075] Example 5:

[0076] The difference between this embodiment and Embodiment 1 lies in the manufacturing process:

[0077] Manufacturing method: The main fan blade 10, fan ring plate 11, and auxiliary fan blade 12 are not integrally formed, but are manufactured independently and then assembled onto the wheel hub 1 by bolts or clips.

[0078] Specific structure: The outer wall of the hub 1 is provided with T-shaped grooves distributed circumferentially; the root of the main fan blade 10 is provided with a slider that matches the T-shaped groove, which can slide into and lock from the end of the hub; the fan ring plate 11 is composed of two half-rings spliced ​​together and is fixed to the guide rail on the outer side of the hub 1 by flange bolts; the root of the auxiliary fan blade 12 is provided with a threaded hole and is fixed to the mounting seat on the outer wall of the fan ring plate 11 by bolts.

[0079] Advantages: Convenient maintenance; when individual blades are damaged, there is no need to disassemble the entire impeller, only the corresponding individual blade needs to be replaced, reducing maintenance time from 6 people and 4 hours to 2 people and 0.5 hours; Convenient transportation; transported in separate packaging and assembled on-site, which can significantly reduce logistics costs; Flexible materials; different materials can be selected for different components according to their stress characteristics, for example, the main fan blades are made of cold-rolled steel plates, while the fan ring plate and auxiliary fan blades are made of engineering plastics, further optimizing costs.

[0080] Performance verification: Dynamic balancing tests show that the residual imbalance of the split assembly scheme is controlled within G2.5 level, which is comparable to the one-piece molding scheme, meeting the requirements for high-speed operation.

[0081] Comparative Example 1: Pure Material Replacement Solution (Replacing only aluminum, without modifying the structure)

[0082] To demonstrate the necessity of the structural innovation of this invention, a comparative example is provided.

[0083] Solution Description: Five blades of equal length with the same dimensions as in Example 1 are used, but the material is replaced from cast iron to aluminum alloy (6061-T6), and no fan ring plate or auxiliary fan blades are provided.

[0084] Test results: Total mass 78kg (significant weight reduction); maximum air volume 5100m³ / h (approximately 15% lower than the original cast iron design, due to insufficient rigidity of the lightweight blades, resulting in torsional deformation at high speeds and reduced efficiency); noise 81dB(A) (in fact, 3dB(A) higher than the original cast iron design, due to increased blade vibration); after 500 hours of continuous operation, slight wear marks appeared on the bearing end cover, indicating limited improvement in bearing life.

[0085] Conclusion: Simply replacing materials cannot simultaneously meet the requirements of air volume, noise, and reliability; structural innovation is necessary to achieve an overall performance improvement.

[0086] Comparative Example 2: Scheme with only fan ring plate and no secondary fan blades

[0087] Solution Description: Based on Example 1, the fan ring plate 11 is retained, but the secondary fan blades 12 are removed, and rectification is carried out solely by the fan ring plate.

[0088] Test results: Maximum air volume 5400 m³ / h (18% lower than Example 1, due to the lack of secondary fan blades breaking up the wake of the main fan blades, resulting in decreased airflow efficiency); Noise 77 dB(A) (6 dB(A) higher than Example 1, due to the large-scale eddies that were not broken up generating more noise); Bearing life was improved, but not as significantly as in Example 1.

[0089] Conclusion: The fan ring plate 11 and the secondary fan blade 12 must work together; neither can be omitted. Using the fan ring plate alone cannot fully utilize the advantages of the staggered arrangement of long and short blades.

[0090] Comparative Example 3: Arrangement of long and short blades in the same direction

[0091] Solution Description: Based on Example 1, the suction surface of the auxiliary fan blade 12 is adjusted to face the same direction as the suction surface of the main fan blade 10 (i.e., the auxiliary fan blade does not play the role of breaking up the wake).

[0092] Test results: Maximum air volume 5300m³ / h (16% lower than Example 1); Noise 79dB(A) (8dB(A) higher than Example 1); Airflow outlet velocity distribution non-uniformity as high as 35% (only 12% in Example 1).

[0093] Conclusion: The secondary fan blades must align their suction surface with the wake region of the main fan blade (i.e., the pressure surface side of the main fan blade) to effectively break up the vortex. Arranging them in the same direction actually exacerbates airflow interference and degrades performance.

[0094] The wind turbine cooling device provided by this invention, through a combination of staggered long and short blades and a radially movable fan ring plate structure, achieves refined hierarchical management and dynamic adjustment of airflow. This significantly reduces blade weight while increasing airflow, lowering noise, and improving bearing stress. This structure can be widely applied to the cooling systems of various wind turbine generator sets (including onshore and offshore wind power), and can also be extended to other industrial fields requiring high-efficiency, low-noise axial fans (such as data center cooling, air conditioner outdoor units, and traction motor cooling in rail transit).

[0095] Through verification by multiple embodiments and comparative examples, the technical solution of the present invention has outstanding substantive features and significant progress, and possesses good industrial application prospects and economic value.

[0096] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Those skilled in the art can make various improvements and modifications without departing from the spirit and principles of the invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A heat dissipation device for a wind turbine generator, characterized in that, include: Wheel hub (1); Multiple main fan blades (10) are arranged at intervals along the circumference of the hub (1) on the outer side wall of the hub (1); Multiple fan ring plates (11) are arranged at circumferential intervals on the outer side of the hub (1), and the fan ring plates (11) are configured to be able to move radially along the hub (1); Multiple auxiliary fan blades (12) are arranged at intervals along the circumference of the fan ring plate (11) on the outer side wall of the fan ring plate (11); The auxiliary fan blades (12) and the main fan blades (10) are arranged alternately in the axial direction of the hub (1); An air intake rectification area (22) is formed between the outer ring of the hub (1) and the inner ring wall of the fan ring plate (11); The pressure surface of the main fan blade (10), the suction surface of the auxiliary fan blade (12), and the outer ring of the fan ring plate (11) form the main work acceleration zone (21); The suction surface of the main fan blade (10), the pressure surface of the auxiliary fan blade (12), and the outer ring of the fan ring plate (11) form an outer ring diffusion zone (20); When the fan ring plate (11) moves radially, it can simultaneously adjust the flow cross-section of the intake rectification zone (22), the main power acceleration zone (21), and the outer ring diffuser zone (20).

2. The heat dissipation device for a wind turbine generator according to claim 1, characterized in that, It also includes an electric telescopic rod (13), one end of which is connected to the hub (1) or the fixed bracket, and the other end is connected to the fan ring plate (11) for driving the fan ring plate (11) to move radially.

3. The heat dissipation device for a wind turbine generator according to claim 1, characterized in that, The main fan blade (10) is provided with a blade groove (14), and a retractable windshield (15) is provided in the blade groove (14); the retractable windshield (15) includes a plurality of bent flaps (16) connected in sequence, each bent flap (16) is provided with a folding cavity (17), and a folding spring (18) for actively folding the bent flap (16) is provided in the folding cavity (17).

4. The heat dissipation device for a wind turbine generator according to claim 3, characterized in that, The retractable windshield (15) can switch between an extended state and a retracted state: in the extended state, the retractable windshield (15) extends into the main power acceleration zone (21) to change the flow cross section of the zone; in the retracted state, the retractable windshield (15) is housed in the blade groove (14).

5. The heat dissipation device for a wind turbine generator according to claim 4, characterized in that, An electromagnet (19) is provided at one end of the retractable windshield (15) away from the blade groove (14); the electromagnet (19) is de-energized when the fan ring plate (11) moves radially, so that the retractable windshield (15) retracts to the opening position of the blade groove (14) under the action of the flap spring (18); after the fan ring plate (11) moves to the target position, the electromagnet (19) is energized and magnetically attracted to the metal surface of the main fan blade (10), so that the retractable windshield (15) remains in the extended state.

6. The heat dissipation device for a wind turbine generator according to claim 5, characterized in that, The outer surface of the electromagnet (19) is covered with a flexible material layer, which is used to adapt to the curvature of the main fan blade (10) at different radial positions when the electromagnet (19) is attracted.

7. The heat dissipation device for a wind turbine generator according to claim 6, characterized in that, The flexible material layer is a rubber layer or a silicone layer.

8. The heat dissipation device for a wind turbine generator according to claim 1, characterized in that, Multiple fan ring plates (11) are arranged circumferentially along the hub (1) and are combined in the outer periphery of the hub (1) to form an annular isolation structure. The annular isolation structure is used to isolate the outer ring diffuser area (20) from the intake rectifier area (22) and the main power acceleration area (21).

9. The heat dissipation device for a wind turbine generator according to claim 5, characterized in that, The main fan blade (10) is at least partially made of metal material for adsorption in conjunction with the electromagnet (19); the fan ring plate (11) and the secondary fan blade (12) are made of non-metallic material to reduce the overall weight.

10. The heat dissipation device for a wind turbine generator according to claim 1, characterized in that, The hub (1) has a polygonal groove in the central shaft hole for positioning in conjunction with the polygonal boss on the generator output shaft.

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