Large wind tunnel blade and forming process of skeleton structure of large wind tunnel blade

Abstract

The invention discloses a large wind tunnel blade and a forming process of a skeleton structure thereof. The invention relates to the technical field of wind tunnel blades, in particular to a large wind tunnel blade which is characterized in that a blade handle-frame beam-rib plate whole serves as a framework structure, a blade body and the blade handle are designed to be of a hollow structure, the framework structure bears the main load and centrifugal force of the blade, and the weight of the blade is greatly reduced on the premise that the strength and rigidity of the blade are guaranteed; the requirement on a fan hub is reduced, and the reliability and the operation efficiency of the fan are improved. The main beams, the web plates and the rib plates of the blade are designed into an integral framework structure, so that an integral support is formed in the blade. Meanwhile, the main beam and the web plate extend out of the blade body and are designed into the composite material blade handle, a blade handle-frame beam-rib plate integral framework structure is formed, the end of the blade handle is connected with the composite material blade handle through the embedded metal connecting piece, the weight of the blade can be effectively reduced, and the integral performance (rigidity and strength) of the blade can be guaranteed.

Description

Technical Field

[0001] The invention relates to a large wind tunnel blade and a molding process of a skeleton structure thereof, belonging to the technical field of wind tunnel blades. Background Art

[0002] Large wind tunnel blades have high rotation speed, large load and size. In order to ensure the aerodynamic performance and connection reliability of the blades, the blades must meet the requirements of low weight, high stiffness and high reliability connection. At present, most wind tunnel blades adopt the structural scheme of carbon fiber skin + main load-bearing beam + foam filling. The process of this structure is relatively mature and the performance is relatively stable. Since the entire blade body is filled with foam, the weight of the blade is also relatively large, which is particularly obvious when the blade body length exceeds 2m. The weight of the blade has a great impact on the reliability and economy of the wind turbine.

[0003] CN201410231078.4 discloses a composite material blade for wind tunnel and a carbon fiber composite material foam sandwich structure wind tunnel fan blade and molding method disclosed in CN201410408600.1, which relates to a composite material blade for wind tunnel, including skin, front / trailing edge reinforcement area, foam core material, main load-bearing beam and metal petiole; wherein the metal petiole includes a square-shaped blade part and a long rod-shaped shaft part; the blade part extends into the middle area of ​​the blade-shaped skin, and the front / trailing edge reinforcement area is set at the front / rear end of the skin, and the foam core material is filled in the skin and the blade part; a square main load-bearing beam is embedded between the skin and the blade part. The blade of this patent is a solid structure. Although it solves the problem of lightweight design of blades to a certain extent, it still does not solve the problem of low weight, high stiffness and high reliability connection for high-speed and high-load wind tunnel blades.

[0004] CN201410408600.1 discloses an anti-icing wind tunnel blade, in which the flat block of the petiole is inserted into the groove of the foam core, the boss of the foam core is inserted into the boss receiving groove of the flat block, and the flat block of the petiole is firmly attached to the foam core; the connecting waist receiving hole of the carbon beam is sleeved on the flat connecting waist of the petiole, and its vertical connecting wall is firmly attached to the end face where the connecting waist of the petiole flat block is located, and its upper and lower walls are firmly attached to the upper and lower receiving grooves of the foam core; the layers of the skin are tightly wrapped and bonded to the outside of the foam core and the carbon beam. This patented blade is a solid structure. Although the connection strength of the petiole, foam core and carbon beam and the blade strength are relatively high, the problem of low weight, high stiffness and high reliability connection has not been solved for high-speed and high-load wind tunnel blades.

[0005] CN202320642004.4 discloses a wind tunnel blade, including leading edge foam and trailing edge foam. The leading edge foam and the trailing edge foam are filled between the butted upper and lower halves. The upper and lower halves have the same structure, a core shaft is sandwiched between the centers of the upper and lower halves, and a conical sleeve is provided on the petiole of the upper and lower halves. This patent effectively solves the problem of insufficient strength and torsional resistance of existing blades. Blades with solid structures are far from solving the problem of low weight, high stiffness and high reliability connection.

[0006] In summary, it is very necessary to invent a large wind tunnel blade that solves the problem of low weight, high stiffness and high reliability connection. Summary of the invention

[0007] In order to solve the deficiencies of the above-mentioned prior art, the present invention aims at the characteristics of large wind tunnel blades with large blade and hub sizes and very high requirements for lightweight design of blades, focusing on the fact that lightweight blades can greatly reduce the weight of the whole machine (reduced load-bearing requirements), improve economic benefits, and fully consider the use requirements of blades with rigidity, high strength and high connection reliability. A large wind tunnel blade is provided, which adopts a large wind tunnel blade with an integral structure of blade handle-frame beam (main beam + web)-rib plate, achieving a breakthrough in the difficulty of balancing low weight and high rigidity; the main beam carbon fiber continuously bypasses the embedded blade root metal parts, and the metal connector is designed with an inverted cone and corrugated structure, which solves the problem of high reliability of blade root connection.

[0008] The technical means adopted by the present invention to solve the above problems are: Disclosed is a large wind tunnel blade, which adopts a petiole-frame beam-rib plate as a skeleton structure. The blade body and the petiole are designed as hollow structures. The skeleton structure bears the main load and centrifugal force of the blade. On the premise of ensuring the strength and rigidity of the blade, the weight of the blade is greatly reduced, the requirements for the fan hub are reduced, and the reliability and operation efficiency of the fan are improved.

[0009] The blade body in the present invention is designed as a hollow structure, and the main beam, web and rib of the blade are designed as an integral skeleton structure to form an integral support for the inside of the blade. At the same time, the main beam and web are extended out of the blade body and designed as a composite material petiole, thus forming a petiole-frame beam-rib integral skeleton structure, which is connected to the composite material petiole through a pre-embedded metal connector at the end of the petiole, which can effectively reduce the weight of the blade and ensure the overall performance (rigidity, strength) of the blade.

[0010] The large wind tunnel blade of the present invention is designed to be lightweight, and the blade body is designed to have a hollow structure, which can reduce the weight of the blade body while taking into account the mechanical properties and having good stability.

[0011] Furthermore, it includes a composite blade body and a skeleton structure extending into the composite blade body, the shell of the composite blade body adopts a hollow structure, and the skeleton structure forms an integral support for the inner wall of the blade; the frame beam includes a main beam and webs arranged on both sides of the main beam, and the main beam and the blade body extend in the same direction; a plurality of groups of ribs are arranged on both sides of the main beam; one end of the main beam extends out of the composite blade body and is connected to a petiole; the end of the petiole is connected to a pre-embedded metal connector, and then the petiole is connected to the hub through the metal connector; so as to ensure that the blade is light, rigid, strong and has high connection reliability.

[0012] Furthermore, the main beam is the main load-bearing member of the blade, including an upper beam plate and a lower beam plate, which are mainly laid in the 0° direction, and the thickness gradually decreases from the petiole / root to the tip.

[0013] Furthermore, the composite blade body comprises a suction surface shell and a pressure surface shell that are arranged opposite to each other, and a frame beam consisting of an upper beam plate, a lower beam plate and a web is supported between the suction surface shell and the pressure surface shell.

[0014] Furthermore, the ribs are arranged in groups, each group includes rib one and rib two of different lengths; some fibers on both sides of the main beam bypass the end faces of the metal connectors to maintain continuity and are integrally formed with the web and the ribs.

[0015] Furthermore, the petiole is a transition section that gradually converges from the main beam to the metal connector, and the thickness of the petiole gradually becomes thinner from one side of the main beam to the metal connector, and the thickness is less than or equal to the thickness of the main beam and greater than or equal to the thickness of the metal connector.

[0016] Furthermore, the metal connector structure is divided into a straight section and a conical section, and a corrugated or rectangular groove structure is designed in the straight section; the corrugated or rectangular groove structure and the inverted conical surface cooperate with the main beam or web to resist the centrifugal force of the blade under high-speed rotation and prevent the composite material petiole from detaching from the metal connector.

[0017] Furthermore, the metal connector is a conical flat structure, which is embedded in the end of the petiole and includes a protruding end and an embedded end. A corrugated portion is provided on the outer side of the embedded end to realize a threaded connection between the hub and the petiole; a connector inverted cone is provided on the end side of the corrugated portion close to the main beam for overlapping with the main beam; by extending the ply of the main beam to the corrugated part and then locking the winding through the winding layer, the radial deformation of the fiber when it is under tension is constrained by the winding layer.

[0018] Furthermore, the interior of the suction surface shell and the pressure surface shell is provided with an inner skin, an outer skin and a foam sandwich structure to enhance the shell stiffness; the surface layer of the outer skin is a fabric layer to ensure the integrity and appearance of the blade, and the surface layer of the outer skin is a unidirectional prepreg ±45° layer to improve the overall torsional resistance of the blade.

[0019] Another object of the present invention is to disclose a forming process of the above-mentioned skeleton structure, comprising the following steps: S1. Laying of frame beam structure: When laying the frame beam and the main beam, the prepreg is selected to extend beyond the end face of the metal connector: the prepreg of the upper beam plate bypasses the end face of the metal connector to be flush with the end of the lower beam plate, and the prepreg of the lower beam plate bypasses the end face of the metal connector to be flush with the end face of the upper beam plate, keeping the total thickness of the end face of the metal connector unchanged, forming a shoulder strap anti-swinging structure; S2. Web structure layer: The web is a carbon fiber foam sandwich structure with a foam thickness of 15-25mm and 0.5-1.5mm thick T700±45° prepreg on the upper and lower surfaces to improve the stability of the skeleton; S3. Rib structure layer: Foam thickness 3-5mm, surface 0.4-0.6mm composite material, using T700±45° prepreg; S4. The inner cavity of the mold is the molding surface. The fishbone structure is decomposed into frame beams and ribs to manufacture an erosion mold. An expansion bag is manufactured outside the erosion mold, and prepreg is laid outside the expansion bag. Through the design of the layers and the arrangement during laying, part of the layers are laid on the inner cavity surface of the female mold, and part of the layers are laid on the erosion mold. After the metal petiole and foam are bonded, they are laid on the mold as embedded parts through mold positioning, and a film is laid on the surface. The metal petiole and foam are wrapped inside by laying the prepreg of the upper and lower beam plates, and finally they are solidified and formed as a whole through internal expansion and hot pressing.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The large wind tunnel blade of the present invention adopts a petiole-frame beam-rib plate integral skeleton structure, a blade body and a hollow structure of the petiole. The integral skeleton structure bears the main load (centrifugal force) of the blade. Under the premise of ensuring the strength and rigidity of the blade, it can greatly reduce the weight of the blade, reduce the requirements for the fan hub, and improve the reliability and operating efficiency of the fan.

[0021] The metal connector structure of the large wind tunnel blade of the present invention is divided into a straight section and a tapered section. A corrugated or rectangular groove structure is designed in the straight section. The corrugated or rectangular groove structure and the inverted tapered surface cooperate with the main beam or the web to resist the centrifugal force of the blade under high-speed rotation and prevent the composite material petiole from detaching from the metal connector.

[0022] Part of the fibers on both sides of the main beam of the large wind tunnel blade of the present invention can bypass the end surface of the metal connector to maintain continuity, or the fibers of the suction side main beam and the pressure side main beam form an overlapping structure on the end surface of the metal connector, which significantly improves the bonding strength between the composite material petiole and the metal connector and prevents the composite material petiole from detaching from the metal connector. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings in the specification, which constitute a part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0024] Figure 1 It is a schematic diagram of the overall structure of the large wind tunnel blade described in the present invention.

[0025] Figure 2 It is a schematic structural diagram of the skeleton structure of the large wind tunnel blade described in the present invention.

[0026] Figure 3 It is a schematic diagram of the cross-sectional structure of the petiole of the large wind tunnel blade described in the present invention.

[0027] Figure 4 It is a schematic diagram of the cross-sectional structure of the blade body of the large wind tunnel blade described in the present invention.

[0028] Figure 5 It is a schematic diagram of the structure of the metal connector of the large wind tunnel blade according to the present invention.

[0029] 1. Metal connector, 2. Petiole, 3. Composite blade body, 4. Main beam, 5. Web, 6. Rib, 10. Suction surface shell, 11. Pressure surface shell, 12. Foam sandwich structure, 13. Corrugated part, 14. Connector inverted cone, 15-Mounting ring, 16-Transition platform, 17-Connecting shaft, 18-Mounting through hole, 41. Upper beam plate, 42. Lower beam plate, 61. Rib one, 62. Rib two, 101. Protruding end, 102. Embedded end. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with embodiments, but the protection scope of the present invention is not limited thereto. Example 1

[0031] like Figure 1-Figure 5 As shown, the large wind tunnel blade of this embodiment adopts the petiole-frame beam-rib plate as a skeleton structure, the blade body and petiole are designed as hollow structures, and the skeleton structure bears the main load and centrifugal force of the blade. Under the premise of ensuring the strength and rigidity of the blade, the weight of the blade is greatly reduced, the requirements for the fan hub are reduced, and the reliability and operation efficiency of the fan are improved.

[0032] Specifically, its overall structure includes a composite blade body 3 and a skeleton structure extending into the composite blade body 3. The composite blade body 3 adopts a hollow structure, and the skeleton structure forms an integral support for the inner wall of the blade; the frame beam includes a main beam 4 and webs 5 arranged on both sides of the main beam 4, and the main beam 4 is consistent with the extension direction of the blade body; a plurality of groups of ribs 6 are arranged on both sides of the main beam 4; one end of the main beam 4 extends out of the composite blade body 3 and is externally connected to a petiole 2; the end of the petiole 2 is connected to the embedded metal connector 1, and then the petiole 2 is connected to the hub through the metal connector 1; so as to ensure that the blade is light, rigid, strong and has high connection reliability.

[0033] The large wind tunnel blade body shell of this embodiment adopts a hollow structure, which can effectively reduce weight. The main beam 4, web 5, and rib 6 of the blade are designed as an integral skeleton structure, which is an asymmetric fishbone shape as a whole; forming an integral support for the blade skin. The blade body shell consists of an inner skin, a foam sandwich structure 12 and an outer skin. The foam sandwich structure is used to enhance the rigidity of the shell. The surface layer of the outer skin is a fabric layer to ensure the integrity and appearance of the blade. Other unidirectional prepreg ±45° plies improve the overall torsion resistance of the blade.

[0034] The main beam 4 is the main load-bearing member of the blade, including an upper beam plate 41 and a lower beam plate 42, which are mainly laid in the 0° direction, and the thickness gradually decreases from the petiole / root to the tip of the blade. The composite blade body 3 includes a suction surface shell 10 and a pressure surface shell 11 that are relatively arranged, and a frame beam is supported between the suction surface shell 10 and the pressure surface shell 11. The main beam 4 in this embodiment runs through the entire blade. Through the combination of the main beam 4 and the web 5, a support block that fits the inner wall of the blade is formed inside the entire blade, and this support block is hollow inside, which maximizes the lightweight while ensuring the strength of the entire blade.

[0035] The ribs 6 are arranged in groups on both sides of the main beam 4, each group including a rib 1 61 and a rib 2 62 of different lengths; the length of each group of ribs 6 is different in order to adapt to the internal space of the blade, and its length cannot be greater than the internal length reserved for the blade section. Figure 2 As shown, some fibers on both sides of the main beam 4 bypass the end surface of the metal connector 1 to maintain continuity and be integrally formed with the web 5 and rib 6. This design can effectively fix the skeleton structure, which has good integrity and can ensure the excellent strength and stiffness performance of the blade.

[0036] In this embodiment, the petiole 2 is a transition section that gradually converges from the main beam 4 to the metal connector 1, and the thickness of the petiole 2 gradually becomes thinner from one side of the main beam 4 to the metal connector 1, and the thickness is less than or equal to the thickness of the main beam 4, and greater than or equal to the thickness of the metal connector 1. This structural design can prevent the blade from being easily damaged when the blade is subjected to stress as a whole, thereby ensuring the service life of the entire blade.

[0037] Preferably, the structure of the metal connector 1 is divided into a straight section and a conical section, and a corrugated or rectangular groove structure is designed in the straight section; the corrugated / rectangular groove structure and the inverted conical surface cooperate with the main beam / web to resist the centrifugal force of the blade under high-speed rotation and prevent the composite material petiole from being separated from the metal connector. In this embodiment, the metal connector 1 is a conical flat structure, and the metal connector 1 is embedded in the end of the petiole 2, including an extended end 101 and an embedded end 102, and a corrugated portion 13 is arranged on the outer side of the embedded end 102 to realize the threaded connection between the hub and the petiole; a connector inverted cone 14 is arranged on one side of the end of the corrugated portion 13 close to the main beam 4 for overlapping with the main beam 4; more specifically, the extended end 101 includes a connecting shaft 17 coaxially arranged with the petiole, a mounting ring 15 is arranged on the outer periphery of the connecting shaft 17, and a mounting through hole 18 is arranged in the center of the connecting shaft 17 for connecting the hub. A transition platform 16 is provided between the connecting shaft 17 and the corrugated portion 13. The upper and lower ends of the transition platform 16 are flat and a connecting section is convex in the middle. The corrugated portion 13 is concave between the transition platform 16 and the connecting member inverted cone 14. By extending the ply of the main beam 4 to the corrugated part and then locking the winding with the winding layer, the radial deformation of the fiber when it is pulled is restrained by the winding layer.

[0038] As another technical solution, the metal connector embedded in the composite material petiole can be round instead of square in this embodiment.

[0039] As another technical solution, bolt connections may be added to the metal connector 1 or the entire composite material petiole may be circumferentially wound for reinforcement to ensure connection reliability.

[0040] The overall skeleton structure of petiole-frame beam-rib plate extends the main beam and web plate out of the blade body and is designed as a composite material petiole. The end of the petiole is connected to the composite material petiole by a pre-embedded metal connector, and then the petiole is connected to the hub by a metal connector. The main beam is the main load-bearing member of the blade, and is mainly laid in the 0° direction, and the thickness gradually decreases from the petiole / root to the tip of the blade. The internal expansion method is used for forming, and some fibers on both sides of the main beam 4 can bypass the end face of the metal connector to maintain continuity, or form a lap joint structure on the end face of the metal connector, and are integrally formed with the web plate and rib plate. The skeleton structure has good integrity and can ensure the excellent strength and stiffness performance of the blade.

[0041] As another alternative, the web and ribs can also adopt a sandwich structure to improve their rigidity and stability.

[0042] In order to facilitate the connection with the metal hub and improve the connection reliability, the metal connector 1 (high-strength alloy steel) is embedded at the end of the composite material petiole. A trapezoidal thread is provided on the connecting shaft 17 of the metal connector 1 to realize the threaded connection between the hub and the petiole. The metal connector 1 needs to bear the centrifugal load and aerodynamic load of the blade and prevent the composite material petiole from being thrown off and twisted. Therefore, it is designed as a flat structure, and a corrugated structure and a conical surface are designed on it. The main functions are: it is conducive to making the ply extended from the main beam into an overlap structure at the end to form the first anti-throw-off structure under the action of centrifugal force; by designing a corrugated structure and a taper on the metal joint, by extending the ply of the main beam to the corrugated part, and then winding and locking it through the winding layer, the radial deformation of the fiber when it is pulled is bound by the winding layer, forming the second and third anti-throw-off structures; under the action of aerodynamic load, the flat structure can effectively prevent the blade from torsional deformation and ensure its aerodynamic performance. Example 2

[0043] This embodiment is based on the structure of the large wind tunnel blade of Embodiment 1, and the molding process of the large wind tunnel blade includes the following steps: metal connector processing and surface treatment, integral molding of the skeleton structure (stalk + main beam + web + rib), shell autoclave molding, and bonding of the overall skeleton to the shell.

[0044] The steps of the forming process of the skeleton structure are as follows: S1. Laying of frame beam structure: frame beam is laid according to [+45 / 0 / 0 / 0 / 90 / 0 / 0 / 0 / -45] 3S, with thickness decreasing from 15mm at the blade root to 4mm at the blade tip. When laying the main beam, prepreg (3~6 layers, 12~16 layers, 21~24 layers, 30~34 layers, 39~42 layers, 48~52 layers) is regularly selected to exceed the metal end surface, and prepreg is selected to exceed the metal connector end surface: the upper beam plate prepreg bypasses the metal connector end surface to be flush with the lower beam plate end surface, and the lower beam plate prepreg bypasses the metal connector end surface to be flush with the upper beam plate end surface, keeping the total thickness of the metal connector end surface unchanged to form a shoulder strap anti-swing structure.

[0045] S2. Lamination of the web structure: The web is a carbon fiber foam sandwich structure with a foam thickness of 15-25 mm and 1 mm thick T700±45° prepreg on the upper and lower surfaces to improve the stability of the skeleton; in this embodiment, the foam thickness is 20 mm and 1 mm thick T700° prepreg on the upper and lower surfaces.

[0046] S3. Rib structure ply: foam thickness 3-5mm, surface 0.4-0.6mm composite material, using T700±45° prepreg; in this embodiment, the foam thickness is 5mm, the surface 0.54mm composite material, using T700° prepreg.

[0047] S4. The inner cavity of the mold is the molding surface. The fishbone structure is decomposed into frame beams and ribs to manufacture an erosion mold. An expansion bag is manufactured outside the erosion mold, and prepreg is laid outside the expansion bag. Through the design of the layers and the arrangement during laying, part of the layers are laid on the inner cavity surface of the female mold, and part of the layers are laid on the erosion mold. After the metal petiole and foam are bonded, they are laid on the mold as embedded parts through mold positioning, and a film is laid on the surface. The metal petiole and foam are wrapped inside by laying the prepreg of the upper and lower beam plates, and finally they are solidified and formed as a whole through internal expansion and hot pressing.

[0048] After demoulding, lay the petiole reinforcement layer: 2mm thick 90° prepreg is wound circumferentially. The prepreg needs to extend beyond the metal end surface for cross-crossing and alternating docking. After vacuuming to ensure no air leakage, hot autoclave molding is used.

[0049] The autoclave forming process of the blade body shell is as follows: the blade body shell is divided into a suction surface shell and a pressure surface shell, which is a foam sandwich structure. No foam is laid on the main beam and ribs. The front and rear ends are formed with flanges at one time. The flange positions of the suction surface shell and the pressure surface shell are relatively staggered, forming a bonding surface during compounding.

[0050] The bonding process of the skeleton structure and the shell is as follows: after the shell is hot-pressed, the surface is slightly trimmed and polished without demolding to meet the bonding profile requirements, and then the overall skeleton and the suction and pressure surface shells are pre-assembled and adjusted, and the amount of glue applied is strictly controlled. The upper and lower shell molds are molded together, heated and cured, and demolded after curing. Clean the structural glue of the front and rear edges and the upper and lower end faces, and polish them flat and smooth. Add 2 layers of double-axis around the mold seam for curing and reinforcement.

[0051] Those skilled in the art may make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should also fall within the protection scope of the present invention, and the protection scope of the present invention should be defined by the claims.

Claims

1. A large wind tunnel blade, characterized in that: The petiole-frame beam-rib plate is used as the overall skeleton structure. The blade body and petiole are designed as hollow structures. The skeleton structure bears the main load and centrifugal force of the blade. Under the premise of ensuring the strength and rigidity of the blade, it greatly reduces the weight of the blade, reduces the requirements for the fan hub, and improves the reliability and operation efficiency of the fan.

2. The large wind tunnel blade according to claim 1, characterized in that: The invention comprises a composite blade body (3) and a skeleton structure extending into the composite blade body (3); the shell of the composite blade body (3) adopts a hollow structure, and the skeleton structure forms an integral support for the inner wall of the blade; the frame beam comprises a main beam (4) and webs (5) arranged on both sides of the main beam (4); the main beam (4) and the blade body extend in the same direction; a plurality of groups of ribs (6) are arranged on both sides of the main beam (4); one end of the main beam (4) extends out of the composite blade body (3) and is externally connected to a petiole (2); the end of the petiole (2) is connected to a pre-embedded metal connector (1), and the petiole (2) is connected to the hub through the metal connector (1); so as to ensure the blade is lightweight, rigid, strong and has reliable connection.

3. The large wind tunnel blade according to claim 2, characterized in that: The main beam (4) is the main load-bearing member of the blade, and comprises an upper beam plate (41) and a lower beam plate (42), which are mainly laid in a 0° direction, and the thickness gradually decreases from the petiole / root to the tip.

4. The large wind tunnel blade according to claim 3, characterized in that: The shell of the composite blade (3) comprises a suction surface shell (10) and a pressure surface shell (11) arranged opposite to each other, and a frame beam consisting of an upper beam plate (41), a lower beam plate (42) and a web (5) is supported between the shells of the composite blade (3).

5. The large wind tunnel blade according to claim 4, characterized in that: The ribs (6) are arranged in groups, each group comprising a rib 1 (61) and a rib 2 (62) of different lengths; partial fibers on both sides of the main beam (4) bypass the end surface of the metal connecting piece (1) to maintain continuity and are integrally formed with the web (5) and the ribs (6).

6. The large wind tunnel blade according to claim 5, characterized in that: The petiole (2) is a composite material petiole, and is provided with a transition section which gradually converges from the main beam (4) to the metal connecting piece (1); the thickness of the petiole (2) gradually becomes thinner from one side of the main beam (4) to the direction of the metal connecting piece (1), and the thickness is less than or equal to the thickness of the main beam (4) and greater than or equal to the thickness of the metal connecting piece (1).

7. The large wind tunnel blade according to claim 4, characterized in that: The structure of the metal connector (1) is divided into a straight section and a tapered section, and a corrugated or rectangular groove structure is designed in the straight section; the corrugated or rectangular groove structure cooperates with the main beam or the web to resist the centrifugal force of the blade in a high-speed rotating state, and prevents the composite material petiole from being separated from the metal connector (1).

8. The large wind tunnel blade according to claim 7, characterized in that: The metal connector (1) is a conical flat structure, and is embedded in the end of the petiole (2), comprising a protruding end (101) and an embedded end (102). A corrugated portion (13) is provided on the outer side of the embedded end (102) to achieve a threaded connection between the hub and the petiole; a connector inverted cone (14) is provided on one side of the end of the corrugated portion (13) close to the main beam (4) to overlap the main beam (4); by extending the ply of the main beam (4) to the corrugated portion, and by locking the winding with the winding layer, when the fiber is under tension, the radial deformation is restrained by the winding layer.

9. The large wind tunnel blade according to any one of claims 4 to 8, characterized in that: The suction surface shell (10) and the pressure surface shell (11) are provided with an inner skin, an outer skin and a foam sandwich structure (12) inside to enhance the shell rigidity; the outer skin surface layer is a fabric layer to ensure the integrity and appearance of the blade; the outer skin surface layer is a unidirectional prepreg ±45° ply to enhance the overall anti-twisting performance of the blade.

10. A forming process of the skeleton structure according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Laying of frame beam structure: When laying the frame beam and the main beam, the prepreg is selected to extend beyond the end face of the metal connector: the prepreg of the upper beam plate (41) bypasses the end face of the metal connector to be flush with the end of the lower beam plate (42), and the prepreg of the lower beam plate (42) bypasses the end face of the metal connector to be flush with the end of the upper beam plate (41), keeping the total thickness of the end face of the metal connector (1) unchanged, forming a shoulder strap anti-swinging structure; S2. Web structure layer: The web (5) is a carbon fiber foam sandwich structure with a foam thickness of 15-25 mm and a T700 ± 45° prepreg of 0.5-1.5 mm thick on the upper and lower surfaces to improve the stability of the skeleton; S3. Rib structure layer: Foam thickness 3-5mm, surface 0.4-0.6mm composite material, using T700±45° prepreg; S4. The inner cavity of the mold is the molding surface. The fishbone structure is decomposed into frame beams and ribs to manufacture an erosion mold. An expansion bag is manufactured outside the erosion mold, and prepreg is laid outside the expansion bag. Through the design of the layers and the arrangement during laying, part of the layers are laid on the inner cavity surface of the female mold, and part of the layers are laid on the erosion mold. After the metal petiole and foam are bonded, they are laid on the mold as embedded parts through mold positioning, and a film is laid on the surface. The metal petiole and foam are wrapped inside by laying the prepreg of the upper and lower beam plates, and finally they are solidified and formed as a whole through internal expansion and hot pressing.

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