Backward centrifugal wind wheel

Abstract

The backward centrifugal wind wheel comprises a wheel cover, a wheel disc and a plurality of blades, and the blades are arranged between the wheel cover and the wheel disc at equal intervals; an air inlet is formed in the center of the wheel cover; an air outlet is formed between adjacent blades; the wheel disc comprises a wheel disc center part and a plurality of wheel disc wing parts, and a hollow part is formed between every two adjacent wheel disc wing parts; the blade top is connected with the wheel cover, the blade front edge is close to the air inlet, the blade tail edge is close to the air outlet, and the blade roots of the blades are connected with the wheel disc wing parts in a one-to-one correspondence mode. Under the axial projection of the wind wheel, the projection area of the hollow part and the projection area of the air inlet are at least partially overlapped. The hollow part is ingeniously arranged on the wheel disc, on one hand, the problems that a traditional integrally-formed wind wheel is difficult to demould and a mould is complex are solved, and low-cost and high-efficiency integrated production is achieved; and on the other hand, the excellent wing-shaped design of the blades is reserved, it is ensured that the wind wheel has excellent aerodynamic performance, and the dual requirements for efficient production and excellent performance of the backward centrifugal wind wheel in the field are really met.

Description

Technical Field

[0001] This invention relates to the field of centrifugal impeller technology, and more particularly to a backward centrifugal impeller. Background Technology

[0002] As a core component in ventilation, air conditioning, refrigeration, and various fluid machinery, the performance and manufacturing process of backward centrifugal impellers directly affect the overall energy efficiency and production cost of the machine. Currently, backward centrifugal impellers on the market mainly consist of a disc, a cover, and multiple backward blades distributed between the two.

[0003] In existing manufacturing technologies, backward centrifugal wind turbines typically employ a modular assembly structure to achieve better aerodynamic performance. This production method involves separately manufacturing the impeller, impeller cover, and each blade using injection molding or stamping processes. Then, dozens of blades are assembled and fixed between the impeller and impeller cover using secondary processing methods such as snap-fitting, ultrasonic welding, or gluing. While this modular production method reduces reliance on single molds to some extent, its drawbacks are also significant: firstly, the individual production and inventory management of numerous components, coupled with numerous assembly processes, leads to low overall production efficiency, making it difficult to meet the market demand for large-scale, rapid delivery; secondly, multi-component assembly structures inevitably have assembly tolerances, which can easily cause vibration and noise due to loosening or fatigue at the joints during long-term operation. Furthermore, uneven transitions at the joints can interfere with airflow, affecting the aerodynamic stability of the wind turbine.

[0004] To address the issue of low production efficiency, some manufacturers in the industry have attempted to directly manufacture backward-curved centrifugal wind turbines using one-piece molding technology. However, because backward-curved blades typically have complex curved surfaces and tilt angles, conventional one-piece demolding processes must consider draft angles. This often results in simplification of the blade profile or uneven thickness distribution, making it impossible to maintain optimal aerodynamic airfoil design. Therefore, while existing one-piece demolding production methods achieve rapid manufacturing, they often come at the cost of sacrificing fluid performance, leading to significant inferiorities in key performance indicators such as airflow, air pressure, and noise control compared to traditional assembled wind turbines.

[0005] In summary, existing production methods for backward centrifugal wind turbines all have shortcomings. Modular production is inefficient and costly, while integrated demolding production is not high-performing and cannot meet the industry's dual demands for efficient production and excellent performance of wind turbines. Therefore, developing a backward centrifugal wind turbine that can achieve simple and efficient integrated demolding production and has good blade performance has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] In response to the problems raised in the background art, the purpose of this invention is to propose a backward centrifugal impeller that solves the limitation that the integral molding of the backward centrifugal impeller in the prior art inevitably leads to performance compromise.

[0007] To achieve this objective, the present invention adopts the following technical solution: A backward centrifugal impeller includes a wheel cover, a wheel disk, and a plurality of blades, wherein the blades are installed between the wheel cover and the wheel disk, and the plurality of blades are equidistantly arranged around the impeller's rotation axis L; The wheel cover has an air inlet at its center, and an air outlet is formed between adjacent blades; The blade is wing-shaped and includes a leaf root, a leaf tip, a leading edge of the leaf, and a trailing edge of the leaf. The roulette wheel includes a central part and several wing parts. The wing parts are evenly arranged circumferentially on the outer edge of the central part of the roulette wheel, and a hollow part is formed between adjacent wing parts. The number of blades is the same as the number of disc wings; The blade tip is connected to the wheel cover, the leading edge of the blade is close to the air inlet, the trailing edge of the blade is close to the air outlet, and the blade roots of several blades are respectively connected to several wheel disc wings one by one. Under the axial projection of the wind turbine, the projection area of ​​the hollow part at least partially overlaps with the projection area of ​​the air inlet.

[0008] Preferably, the number of blades is z, where 5 ≤ z ≤ 11.

[0009] Preferably, the maximum outer diameter of the wheel is smaller than the maximum outer diameter of the wheel cover.

[0010] Preferably, the wheel disc wing includes a first curve, a second curve, and a connecting section; The connecting section is connected to the center of the wheel; One end of the first curve is connected to one end of the connecting segment, and the other end of the first curve extends in a direction away from the wind turbine rotation axis L; One end of the second curve is connected to the other end of the connecting segment, and the other end of the second curve is connected to the other end of the first curve; The first curve is connected to the leaf root; The ends of two adjacent connecting segments are connected by a transition arc segment, which is formed on the outer edge of the center of the disk and is recessed toward the direction of the wind turbine rotation axis L.

[0011] Preferably, the wrap angle of the transition arc segment is α, where, .

[0012] Preferably, the wheel further includes a raised edge, which is located on one side of the second curve of the wheel wing.

[0013] Preferably, the wheel further includes reinforcing ribs, which are disposed on the surface of the wheel away from the blades; The reinforcing rib includes a radial extension and a flange extension; The radial extension is located at the center of the wheel, and the radial extension extends radially along the center of the wheel; The flange extension is located on the wheel disc wing and extends along the extension directions of the first curve and the second curve.

[0014] Preferably, the shape of the second curve is any one of a straight line, an arc, an S-shape, or a wave shape.

[0015] Preferably, the overlapping line of the leaf trailing edge is any one of a straight line, an arc, or an S-shape.

[0016] Preferably, the leaf tip edge is serrated.

[0017] Compared with the prior art, one of the above technical solutions has the following beneficial effects: By cleverly setting hollow sections on the impeller, the problems of difficult demolding and complex molds of traditional one-piece molded wind turbines are solved, achieving low-cost and high-efficiency integrated production. On the other hand, the excellent airfoil design of the blades is retained, ensuring that the wind turbine has excellent aerodynamic performance, truly meeting the dual requirements of efficient production and excellent performance of backward centrifugal wind turbines in this field. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of an embodiment of the present invention; Figure 2 This is a schematic diagram from another angle of one embodiment of the present invention; Figure 3 yes Figure 1 Top view; Figure 4 yes Figure 1 Side view; Figure 5 This is a schematic diagram of another embodiment of the present invention.

[0019] Among them: air inlet 01, air outlet 02, wheel cover 1, wheel 2, wheel center 21, wheel wing 22, first curve 221, second curve 222, transition arc 223, hollow part 23, reinforcing rib 24, radial extension part 241, wing extension part 242, convex edge part 25, blade 3, blade root 31, blade tip 32, blade leading edge 33 and blade trailing edge 34. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0021] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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. Therefore, they should not be construed as limitations on this invention.

[0022] Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," and "third" may explicitly or implicitly include one or more of that feature.

[0023] It should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] The following is in conjunction with the appendix Figures 1 to 5 The technical solution of the present invention will be further illustrated through specific embodiments.

[0025] A backward centrifugal impeller includes a wheel cover 1, a wheel disk 2, and a plurality of blades 3, wherein the blades 3 are installed between the wheel cover 1 and the wheel disk 2, and the plurality of blades 3 are equidistantly arranged around the impeller rotation axis L; The wheel cover 1 has an air inlet 01 at its center, and an air outlet 02 is formed between adjacent blades 3; The blade 3 is wing-shaped and includes a leaf root 31, a leaf tip 32, a leading edge 33, and a trailing edge 34. The roulette wheel 2 includes a central part 21 and a plurality of wing parts 22. The plurality of wing parts 22 are evenly arranged circumferentially on the outer edge of the central part 21, and a hollow part 23 is formed between adjacent wing parts 22. The number of blades 3 is the same as the number of disc wings 22; The blade tip 32 is connected to the wheel cover 1, the blade leading edge 33 is close to the air inlet 01, the blade trailing edge 34 is close to the air outlet 02, and the blade roots 31 of several blades 3 are respectively connected to several wheel disc wings 22 in a one-to-one correspondence. Under the axial projection of the wind turbine, the projection area of ​​the hollow part 23 at least partially overlaps with the projection area of ​​the air inlet 01.

[0026] This invention significantly simplifies the mold structure for integrally molded wind turbines by providing a hollow portion 23 on the wheel 2, reducing production difficulty and cost. Specifically, the wheel 2 includes a central portion 21 and several wheel wing portions 22 evenly distributed around the outer periphery of the central portion 21. The hollow portion 23 formed between adjacent wheel wing portions 22 at least partially overlaps with the projection area of ​​the air inlet 01 under axial projection. This allows an unobstructed through area between the hollow portion 23 and the air inlet 01 when the wind turbine is viewed along its axial direction. During the injection molding process of the wind turbine, the mold core can be axially inserted using this through area, eliminating the need for independent lateral core-pulling sliders for the complex flow channels between each blade, as is required in existing technologies. Traditional one-piece molding molds often require dozens of intersecting core-pulling modules in the axial and radial directions. In this solution, since the hollow part 23 provides space for the mold to pass through, the mold slider can be demolded simply by combining along the axial and radial directions. This greatly reduces the number of sliders and the complexity of the mold, thereby reducing the mold manufacturing cost, shortening the mold opening and closing cycle, and improving production efficiency.

[0027] Furthermore, this invention achieves simple and efficient demolding while simultaneously improving the aerodynamic performance of the wind turbine. The blade 3 adopts an airfoil design, including a blade root 31, blade tip 32, blade leading edge 33, and blade trailing edge 34. The leading edge 33 is close to the air inlet 01, and the trailing edge 34 is close to the air outlet 02. This design ensures that the blade 3 has excellent aerodynamic characteristics. Due to the simplified mold structure, there is no need to excessively simplify the blade's curved surface or increase the draft angle to accommodate a complex core-pulling mechanism. Therefore, the blade 3 can maintain an optimal airfoil design, resulting in low flow resistance and low energy loss during the airflow process from the air inlet 01, through the surface of the blade 3, and finally out of the air outlet 02. This leads to better performance in key indicators such as airflow, air pressure, and noise control. Compared to the traditional approach of sacrificing performance due to demolding limitations in one-piece molded wind turbines, this invention achieves a harmonious balance between structural design and aerodynamic performance.

[0028] Furthermore, the number of blades 3 is the same as the number of rotor blades 22, and they are connected one-to-one, ensuring a reliable connection between the blade roots and the rotor. The blade roots 31 are connected to the rotor blades 22, enhancing the overall structural strength and operational stability of the wind turbine. The rotor blades 22 are evenly distributed circumferentially on the outer edge of the center 21 of the rotor, resulting in a uniform mass distribution and excellent dynamic balance performance of the entire wind turbine during high-speed rotation, reducing vibration and noise caused by mass eccentricity.

[0029] Furthermore, the hollowed-out section 23 also brings the additional benefits of reducing the weight of the impeller and saving raw materials. While ensuring the connection strength between the impeller disc 2 and the cover 1, the hollowed-out structure effectively reduces the amount of material used in the impeller disc 2 and lowers the moment of inertia of the impeller. This not only helps to reduce the load on the drive motor and improve the system energy efficiency, but also reduces the vibration and noise during the operation of the whole machine.

[0030] In summary, this invention, by cleverly incorporating a hollowed-out portion 23 on the impeller 2, overcomes the limitation of existing technologies where "one-piece molding inevitably leads to performance compromises." On one hand, it solves the problems of difficult demolding and complex molds in traditional one-piece molded wind turbines, achieving low-cost and high-efficiency integrated production. On the other hand, it retains the excellent airfoil design of the blades 3, ensuring that the wind turbine has excellent aerodynamic performance, truly meeting the dual requirements of efficient production and superior performance of backward centrifugal wind turbines in this field.

[0031] Furthermore, the number of blades 3 is z, where 5 ≤ z ≤ 11.

[0032] In terms of structural strength, the appropriate selection of the number of blades 3 is closely related to the arrangement of the hollowed-out portions 23 of the wheel 2. Several hollowed-out portions 23 are provided on the wheel 2, located between adjacent wheel wing portions 22, and at least partially overlap with the air inlet 01 under axial projection. The number of blades 3 is the same as the number of wheel wing portions 22, directly determining the number and distribution density of wheel wing portions 22 and hollowed-out portions 23. When the number of blades is greater than 11, it means that more wheel wing portions 22 need to be provided on the wheel 2, and the number of hollowed-out portions 23 between adjacent wheel wing portions 22 also increases accordingly. To ensure sufficient hollowed-out area for mold passage, the circumferential dimension of each hollowed-out portion 23 will be forced to increase, or more material needs to be removed from the outer edge of the wheel center portion 21 to form a sufficient number of hollowed-out areas. In either case, the connection area between the wheel center portion 21 and the wheel wing portions 22 will become too narrow, resulting in excessive material removal and significantly weakening the overall rigidity of the wheel 2. When the impeller rotates at high speed, excessively large or densely distributed perforations can easily lead to stress concentration in the impeller 2 under centrifugal force, resulting in deformation or even cracking, which seriously affects the structural reliability and service life of the product. By controlling the number of blades 3 to less than 11, the size design of the perforated part 23 is ensured to meet the mold passage requirements while retaining sufficient material to maintain the structural strength of the impeller 2, thus achieving an optimized balance between lightweight and structural rigidity.

[0033] Furthermore, the maximum outer diameter of the wheel 2 is smaller than the maximum outer diameter of the wheel cover 1.

[0034] Firstly, regarding mold design and demolding process, by setting the maximum outer diameter of the wheel 2 to be smaller than that of the wheel cover 1, better spatial conditions are created for the core-pulling action of the mold. Specifically, during the one-piece injection molding process, because the outer edge of the wheel 2 is recessed relative to the wheel cover 1, the mold slider used to form the blade 3 and the structure of the wheel 2 does not need to pass over the obstruction of the outer edge of the wheel 2 when it is pulled out radially, reducing the risk of interference between the slider and the molded part. Combined with the hollow part 23 on the wheel 2, the mold slider can slide out more smoothly radially, further simplifying the mold opening and closing action, reducing mold wear, and extending the mold service life. Thus, while achieving efficient production, the dimensional accuracy and surface quality of the molded product are guaranteed.

[0035] Secondly, in terms of aerodynamic performance, this dimensional relationship facilitates the implementation of equal circulation design, effectively suppressing the uneven airflow velocity at the rotor outlet. When the maximum outer diameter of the rotor disk 2 is smaller than the maximum outer diameter of the cover 1, the blades 3 exhibit a gradually contracting distribution trend along the axial direction from the cover 1 to the rotor disk 2. This structure makes the change in the flow channel cross-sectional area more consistent with the equal circulation control law during the airflow from the inlet 01 to the outlet 02. Specifically, through equal circulation control, the difference in outlet velocity between the rotor side (blade root 31) and the cover side (blade tip 32) can be effectively suppressed, avoiding flow separation or high-speed jet phenomena in the blade tip region caused by blade root overload. This not only reduces eddy current losses caused by large velocity gradients but also significantly improves the flow field uniformity at the rotor outlet, thereby improving aerodynamic efficiency while reducing discrete noise induced by outlet pulsation. At the same time, the uniform outlet velocity distribution also helps improve the matching between the rotor and the downstream flow channel or volute, reducing energy losses within the system and further improving overall performance.

[0036] Furthermore, the wheel wing 22 includes a first curve 221, a second curve 222, and a connecting section; The connecting segment is connected to the center part 21 of the wheel; One end of the first curve 221 is connected to one end of the connecting segment, and the other end of the first curve 221 extends in a direction away from the wind turbine rotation axis L. One end of the second curve 222 is connected to the other end of the connecting segment, and the other end of the second curve 222 is connected to the other end of the first curve 221; The first curve 221 is connected to the leaf root 31; The ends of two adjacent connecting segments are connected by a transition arc segment 223, which is formed on the outer edge of the center portion 21 of the disk and is recessed toward the direction of the wind turbine rotation axis L.

[0037] In terms of structural strength, the connection between the first curve 221 and the blade root 31, and the convergence of the first curve 221 and the second curve 222 at the far end, form a support structure for the blade 3. Specifically, one end of the first curve 221 is connected to the center part 21 of the rotor disk via a connecting section, and its other end extends away from the rotor axis L and connects to the other end of the second curve 222; at the same time, the first curve 221 is also directly connected to the blade root 31. This arrangement ensures that the blade root 31 is not simply attached to the rotor disk airfoil 22, but is supported by the first curve 221. When the rotor rotates at high speed, the centrifugal load on the blade 3 can be evenly transmitted to the first curve through the blade root, and then distributed to the entire rotor disk airfoil and the center part of the rotor disk via the first curve, avoiding the concentrated accumulation of stress at the connection between the blade root 31 and the rotor disk, effectively preventing blade root cracking, and significantly improving the structural reliability and service life of the rotor.

[0038] Secondly, the ends of two adjacent connecting sections are connected by a concave transition arc segment 223 facing the rotation axis of the impeller, which forms a smooth stress-relieving structure on the outer edge of the impeller center 21. The concave shape of the transition arc segment 223 makes the connection area between the impeller center 21 and each impeller blade 22 no longer a sharp corner, but a smooth arc transition. This smooth transition can evenly distribute the stress transmitted from the impeller blade 22 to the impeller center 21, avoiding stress concentration at the connection point, and further enhancing the overall structural strength of the impeller. At the same time, the setting of the transition arc segment 223 also increases the connection area between the impeller center 21 and the impeller blade 22, improving the tensile strength and fatigue resistance of the connection area.

[0039] To further explain, in terms of aerodynamic performance, the curved design of the rotor blade 22 helps optimize the flow field distribution on the rotor surface. The first curve 221 extends away from the rotor's rotation axis, and the second curve 222 merges with it to form the blade profile, resulting in a smooth curved surface in the transition area between the blade root and the rotor. Compared to traditional right-angle or straight-line transitions, this curved transition effectively guides the airflow smoothly through the blade root region, reducing flow separation and vortex losses caused by abrupt structural changes, thereby improving the rotor's aerodynamic efficiency to some extent. Simultaneously, the concave transition arc 223 at the outer edge of the rotor's center 21 further optimizes the airflow direction on the rotor surface, preventing airflow stagnation at the rotor edge and helping to reduce rotor operating noise.

[0040] Furthermore, the envelope angle of the transition arc segment 223 is α, where, .

[0041] Regarding the mold release process, when the wrap angle α is greater than 1°, the recessed area of ​​the transition arc 223 has sufficient circumferential dimensions, allowing the mold slider to be smoothly pulled out axially (i.e., in the direction perpendicular to the plane of the wheel) without the need for a complex radial core-pulling mechanism. This axial release method significantly simplifies the mold opening and closing actions, reduces the number of sliders, lowers mold manufacturing costs, and improves production efficiency. If the wrap angle α is too small or even close to zero, the recessed area becomes too narrow, and the mold core cannot effectively extend in, forcing the use of a more complex core-pulling structure and increasing production difficulty.

[0042] The upper limit of the wrap angle α is limited to That is, not greater than half the angle between adjacent blades, effectively avoiding flow field deterioration caused by excessive reduction in the area of ​​the central part 21 of the disk. The transition arc segment 223, as the concave structure on the outer edge of the central part 21 of the disk, has its wrap angle directly determining the remaining area of ​​the central part 21 of the disk. When the wrap angle α is too large, exceeding... When the area of ​​the central part 21 of the rotor is within a certain range, it means that the outer edge of the central part 21 of the rotor is excessively cut off, and the effective area of ​​the central part 21 of the rotor is significantly reduced. This will weaken the structural strength of the rotor 2 and affect the reliability of the wind turbine when rotating at high speed. On the other hand, the reduction in the area of ​​the central part 21 of the rotor will change the flow path of the airflow before entering the blade 3, which may cause the inlet airflow to form a flow dead zone or local vortex between the central part 21 of the rotor and the root of the blade, destroying the uniformity of the flow field, thereby reducing the aerodynamic efficiency of the wind turbine and increasing noise. This scheme controls the wrap angle α within a certain range. Within this range, the central part 21 of the wheel retains sufficient solid area, which maintains the integrity of the structure and provides a smooth transition area for airflow, avoiding flow loss caused by geometric abrupt changes.

[0043] Furthermore, the reasonable range of values ​​for the wrap angle α is synergistically related to the number of blades z. When the number of blades is small, A larger value allows the transition arc 223 to have a relatively large wrap angle; when the number of blades is large, this upper limit value is reduced accordingly to prevent excessive concavity from affecting the strength of the rotor. This design, which is linked to the number of blades, allows the wind turbine to maintain an optimized balance between structural strength and aerodynamic performance under different specifications.

[0044] Furthermore, the wheel 2 also includes a raised edge 25, which is located on one side of the second curve 222 of the wheel wing 22.

[0045] The protruding edge 25 effectively extends the diffuser channel of the wind turbine, significantly enhancing the diffusion effect. Specifically, when the airflow exits from the channel between the blades 3 and enters the outlet 02 region, the protruding edge 25 is located on one side of the rotor blade section on the second curve 222, effectively forming a local extension structure near the outlet of the blades 3. This structure ensures that after leaving the blade trailing edge 34, the airflow does not immediately enter the open volute or downstream space, but instead passes through a transition channel defined by the protruding edge 25. According to fluid dynamics principles, as the airflow flows in the gradually expanding channel, the dynamic pressure gradually transforms into static pressure, thereby achieving energy recovery. The presence of the protruding edge 25 prolongs this diffusion process, allowing for more complete airflow pressure recovery and improving the aerodynamic efficiency of the wind turbine. Simultaneously, this gradual diffusion transition also helps reduce vortex losses and airflow pulsation caused by the sudden expansion of the channel cross-section, thereby reducing the operating noise of the wind turbine.

[0046] Furthermore, the addition of the raised edge 25 is equivalent to adding a reinforcing structure to the edge of the wheel disc wing 22. One side of the second curve 222 was originally the free edge of the wheel disc wing 22. The presence of the raised edge 25 enhances the rigidity and deformation resistance of this area, enabling the wheel disc 2 to better maintain shape stability when rotating at high speed and reducing radial expansion deformation caused by centrifugal force.

[0047] Furthermore, the wheel 2 also includes a reinforcing rib 24, which is disposed on the surface of the wheel 2 away from the blade 3; The reinforcing rib 24 includes a radial extension 241 and a flange extension 242; The radial extension 241 is located at the center portion 21 of the wheel, and the radial extension 241 extends radially along the center portion 21 of the wheel. The flange extension 242 is located on the wheel wing 22 and extends along the extension directions of the first curve 221 and the second curve 222.

[0048] The radial extension 241 and the flange extension 242 together form a continuous reinforcing network, achieving synergistic reinforcement of the central region and the wing region of the rotor disk. The radial extension 241 radiates outward from the center of the rotor disk, while the flange extension 242 extends along the first curve 221 and the second curve 222. The two naturally converge at the connection point, forming a continuous reinforcing structure. This design transforms the rotor disk 2 from a passively load-bearing single component into an actively guided and uniformly distributed load through the reinforcing ribs 24. When the wind turbine is in operation, both concentrated stress from the center of the rotor disk and localized loads from the blade roots can be efficiently transferred and dispersed through this reinforcing network, significantly improving the overall structural strength and fatigue resistance of the rotor disk.

[0049] The reinforcing rib 24 is located on the surface of the rotor 2 away from the blades 3. This arrangement achieves structural reinforcement while completely avoiding interference with aerodynamic performance. The flow channels between the blades 3 and the surface of the rotor 2 facing the blades 3 are critical areas for airflow. Any structural protrusion could disrupt the uniformity of the flow field. By placing the reinforcing rib 24 on the back of the rotor 2, the side of the rotor facing the blades remains smooth and flat. Airflow can flow smoothly across the rotor surface into the blade flow channels without generating additional vortex losses or flow resistance due to the reinforced structure. This ensures that the aerodynamic efficiency of the wind turbine remains unaffected while improving structural strength.

[0050] Furthermore, the shape of the second curve 222 can be any one of a straight line, an arc, an S-shape, or a wave shape.

[0051] When the second curve 222 adopts a straight-line shape, it presents the simplest geometric features. This design is characterized by its ease of manufacturing and mold forming. The straight-line contour makes the edges of the disc wing 22 neat and uniform. During injection molding, the machining difficulty of the mold cavity is low, and the demolding resistance is small, which helps to improve production efficiency. At the same time, the straight-line shape is suitable for applications with relatively conventional aerodynamic performance requirements. It can achieve stable and reliable mass production while ensuring the basic structural strength, making it a conventional design choice that balances performance and economy.

[0052] When the second curve 222 adopts an arc shape, the transition between the rotor blade 22 and the blade is optimized. The arc-shaped profile presents a smooth curvature, allowing the edge of the rotor blade 22 to connect with the blade with a smooth curved surface, avoiding stress concentration caused by geometric abrupt changes. This smooth transition not only enhances the structural strength of the rotor blade and reduces the risk of blade root cracking, but also facilitates smooth airflow along the root region of the blade pressure surface, reducing local vortex losses and improving the aerodynamic efficiency of the wind turbine.

[0053] When the second curve 222 adopts an S-shaped design, it combines multiple advantages brought by curve variations. The S-shaped curve is composed of inverted curved segments, which can achieve more complex geometric transitions within a limited space. From a structural strength perspective, the S-shaped curve increases the bending stiffness of the blade edge 22, giving it better resistance to deformation under centrifugal loads. From an aerodynamic performance perspective, the undulating changes of the S-shaped curve can subtly guide the airflow in the blade area, helping to regulate local pressure distribution, suppress flow separation, and thus further improve the operational stability of the wind turbine.

[0054] When the second curve adopts a wave-shaped design, it exhibits unique advantages in improving the acoustic quality of the wind turbine. The wave-shaped profile presents a periodic undulating characteristic, a structure similar to a sawtooth noise reduction mechanism. This mechanism can cut the large-scale, regular vortices generated when airflow passes over the blades into several small-scale, irregular vortices. Large-scale vortices are often the main source of discrete noise, with concentrated energy and a single frequency, easily generating harsh peak noise. In contrast, small-scale vortices have dispersed energy and a wide frequency distribution, effectively reducing noise peaks and making the sound of the wind turbine run more mellow and smooth. At the same time, the wave-shaped profile increases the contact area between the rotor blades and the airflow, which helps to further dissipate vortex energy and reduce aerodynamic noise at its source.

[0055] Furthermore, the overlapping line of the leaf trailing edge 34 can be any one of a straight line, an arc, or an S-shape.

[0056] It should be noted that the so-called accumulation line of the blade trailing edge 34 refers to the line connecting the points of the trailing edge 34 of each section of the blade 3 along the blade height direction (from the blade root to the blade tip). It determines the spatial orientation of the blade exit edge and has an important influence on the flow direction, pressure distribution and wake shape of the airflow when it leaves the blade 3.

[0057] When the 34-degree stacking line at the blade trailing edge is straight, it exhibits the simplest geometric features. This design makes the blade's exit edge structure from the root to the tip neat and uniform, facilitating mold manufacturing and demolding. The straight stacking line is suitable for applications with relatively conventional aerodynamic performance requirements, enabling stable and reliable mass production while ensuring basic flow characteristics. It is a basic design choice that balances performance and economy.

[0058] When the blade trailing edge overlap line adopts an arc shape, the exit flow field can be effectively controlled. The arc-shaped overlap line gives the blade's exit edge a smooth, curved shape. This layout allows for a more uniform exit pressure distribution along the blade height as the airflow exits the blade. In traditional designs, due to the influence of the boundary layer on the blade root and tip walls, the exit pressure often exhibits a distribution characteristic of being high in the middle and low at both ends, easily inducing flow separation in the corner regions near the rotor disk and rotor cover. The arc-shaped overlap line compensates for the flow in the two end regions by adjusting the spatial position of the blade exit edge, effectively suppressing corner separation, reducing flow losses, and thus improving the aerodynamic efficiency of the wind turbine.

[0059] When the blade trailing edge overlap line adopts an S-shaped design, it enables precise control of the exit flow field. The S-shaped curve is composed of reverse-curving arc segments, giving the blade exit edge a more complex spatial orientation. This design allows for targeted optimization based on the different flow characteristics of the blade root and tip regions: for example, the blade root region 31 near the rotor 2 is significantly affected by the boundary layer, and the S-shaped overlap line can allow the exit edge of this region to be appropriately swept forward or backward to match the local flow state; while the blade tip region near the rotor cover 1 can be adjusted in the opposite direction as needed. Through this differentiated design, the S-shaped overlap line can maximize the balance of the exit pressure distribution across the entire blade height range, further weakening the intensity of the vortex system in the corner region, allowing the airflow to enter the downstream flow channel in a more uniform and stable state. At the same time, the S-shaped overlap line also helps improve the load distribution of the blade, avoiding flow deterioration caused by excessive local loads.

[0060] Furthermore, the overlapping lines of different shapes can work in synergy with the airfoil design of blade 3 to jointly optimize the acoustic quality of the wind turbine. By adjusting the spatial orientation of the exit edge, the shedding frequency and scale of the wake vortex can be changed, dispersing the originally concentrated noise energy into a wider frequency band, thereby reducing the peak value of discrete noise and making the sound of the wind turbine running more mellow.

[0061] Furthermore, the leaf trailing edge 34 is serrated.

[0062] Firstly, regarding the noise reduction mechanism, the serrated blade trailing edge 34 effectively alters the vortex structure in the blade exit region, reducing aerodynamic noise at its source. When airflow passes over the blade surface and exits the trailing edge 34, vortices are formed at the trailing edge. The scale and shedding frequency of these vortices directly determine the characteristics of the aerodynamic noise. In traditional smooth trailing edge designs, vortices often exhibit regular, large-scale characteristics, with their energy concentrated within a specific frequency range, easily forming sharp, discrete noise peaks that are perceived as harsh rotating noise by the human ear. However, by designing the blade trailing edge 34 as serrated, the originally single, continuous trailing edge is divided into a series of tiny structural units by several grooves and protrusions. When airflow passes through these serrated units, the large-scale, regular vortices are cut into several small-scale, irregularly distributed vortices. These small-scale vortices have dispersed energy and a wide frequency distribution, allowing the noise energy originally concentrated at a specific frequency to be diffused over a wider frequency band, thereby effectively reducing the noise peak amplitude and making the sound of the wind turbine operation softer and smoother, significantly improving the acoustic quality of the product.

[0063] Secondly, the serrated blade trailing edge has a rectifying effect on the wake flow at the blade exit. The presence of the serrated structure is equivalent to introducing a small disturbance source at the blade trailing edge 34. These disturbances can promote the mixing of fluids in the wake region, accelerate the recovery of velocity deficit, and make the downstream flow field more uniform. Uniform wake flow not only helps to reduce broadband noise caused by airflow pulsation, but also further improves the operational stability of the entire ventilation system.

[0064] Secondly, in terms of aerodynamic performance, the noise reduction effect of a serrated trailing edge usually does not come at the expense of efficiency. By rationally designing the depth, width, and distribution density of the serrations, it is possible to maintain or even optimize the aerodynamic performance of the blades while effectively reducing noise. The serrated structure increases the surface area of ​​the trailing edge to a certain extent, which helps to improve the pressure distribution on the blade surface and suppresses localized minor flow separation, thereby maintaining high aerodynamic efficiency of the wind turbine while reducing noise.

[0065] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A backward centrifugal impeller, characterized in that: It includes a wheel cover (1), a wheel disk (2) and several blades (3), wherein the blades (3) are installed between the wheel cover (1) and the wheel disk (2), and the several blades (3) are equidistantly arranged around the wind turbine rotation axis L; The wheel cover (1) has an air inlet (01) at its center and an air outlet (02) is formed between adjacent blades (3). The blade (3) is wing-shaped and includes a leaf root (31), a leaf tip (32), a leading edge (33) and a trailing edge (34). The roulette wheel (2) includes a central part (21) and several wing parts (22). The wing parts (22) are evenly arranged around the outer edge of the central part (21), and a hollow part (23) is formed between adjacent wing parts (22). The number of blades (3) is the same as the number of disc wings (22); The blade tip (32) is connected to the wheel cover (1), the blade leading edge (33) is close to the air inlet (01), the blade trailing edge (34) is close to the air outlet (02), and the blade roots (31) of several blades (3) are respectively connected to several wheel disc wings (22) one by one; Under the axial projection of the wind turbine, the projection area of ​​the hollow part (23) at least partially overlaps with the projection area of ​​the air inlet (01).

2. A backward centrifugal impeller according to claim 1, characterized in that: The number of blades (3) is z, where 5≤z≤11.

3. A backward centrifugal impeller according to claim 2, characterized in that: The maximum outer diameter of the wheel (2) is smaller than the maximum outer diameter of the wheel cover (1).

4. A backward centrifugal impeller according to claim 2, characterized in that: The wheel wing (22) includes a first curve (221), a second curve (222), and a connecting section; The connecting section is connected to the center part (21) of the wheel; One end of the first curve (221) is connected to one end of the connecting segment, and the other end of the first curve (221) extends in a direction away from the wind turbine rotation axis L; One end of the second curve (222) is connected to the other end of the connecting segment, and the other end of the second curve (222) is connected to the other end of the first curve (221); The first curve (221) is connected to the leaf root (31); The ends of two adjacent connecting segments are connected by a transition arc segment (223), which is formed on the outer edge of the center part (21) of the disk and is recessed in the direction of the wind turbine rotation axis L.

5. A backward centrifugal impeller according to claim 4, characterized in that: The wrap angle of the transition arc segment (223) is α, where, .

6. A backward centrifugal impeller according to claim 5, characterized in that: The wheel (2) also includes a raised edge (25) located on one side of the second curve (222) of the wheel wing (22).

7. A backward centrifugal impeller according to claim 5, characterized in that: The wheel (2) also includes a reinforcing rib (24), which is disposed on the surface of the wheel (2) away from the blade (3); The reinforcing rib (24) includes a radial extension (241) and a flange extension (242). The radial extension (241) is located at the center of the wheel (21), and the radial extension (241) extends radially along the center of the wheel (21); The flange extension (242) is located on the wheel disc wing (22) and extends along the extension directions of the first curve (221) and the second curve (222).

8. A backward centrifugal impeller according to claim 4, characterized in that: The shape of the second curve (222) can be any one of straight line, arc, S-shape or wave shape.

9. A backward centrifugal impeller according to claim 1, characterized in that: The overlapping line of the leaf trailing edge (34) can be any one of a straight line, an arc, or an S-shape.

10. A backward centrifugal impeller according to claim 1, characterized in that: The leaf tail edge (34) is serrated.

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