Large wind tunnel blade and preparation method thereof

Abstract

The invention discloses a large wind tunnel blade which is characterized in that a pressure surface shell and a pressure surface main beam are co-cured into a whole, a plurality of first rib plates are adhered to one side of the pressure surface main beam of the pressure surface shell, a suction surface shell and a suction surface main beam are co-cured into a whole, and a plurality of second rib plates are adhered to one side of the suction surface main beam of the suction surface shell. The pressure surface main beam and the suction surface main beam are bonded to form an integral main beam, one end of the metal blade root is tightly held at one end of the pressure surface main beam and one end of the suction surface main beam and is bonded with the pressure surface main beam and the suction surface main beam in a matched mode, and the suction surface shell and the pressure surface shell are bonded to form a blade body. The first rib plate and the second rib plate are distributed on the two sides of the integral main beam and bonded between the pressure surface shell and the suction surface shell. The invention further discloses a preparation method of the large wind tunnel blade. The large wind tunnel blade and the manufacturing method thereof have the advantages that connection is convenient, the connection strength is guaranteed, the requirement for a mold is low, and the manufacturing cost is low.

Description

Technical Field

[0001] This invention relates to the field of wind tunnel equipment technology, specifically to a large wind tunnel blade and its manufacturing method. Background Technology

[0002] Chinese patent document with application number 202411803561.5 discloses a full-size wind tunnel high-load blade, relating to the field of wind tunnel equipment technology. It includes a metal blade root, a hollow main beam, and a blade body. One end of the metal blade root is provided with a main beam connecting section, the sidewall of which is a first conical sidewall. The larger end of the first conical sidewall is closer to the end of the metal blade root with the main beam connecting section than the smaller end. The hollow main beam is made of carbon fiber cloth. One end of the hollow main beam is provided with a blade root connecting section, which is fixedly fitted onto the main beam connecting section. The inner sidewall of the blade root connecting section is a second conical sidewall, which fits against the first conical sidewall. The blade body is made of carbon fiber. The blade body is fixedly mounted on the hollow main beam. The hollow main beam of the high-load blade of the full-size wind tunnel is generally manufactured as a single piece. On the one hand, the hollow main beam is connected by wrapping the metal blade root with carbon fiber cloth, which is inconvenient to connect and difficult to guarantee the connection strength. On the other hand, the hollow main beam is a hollow irregular column, and the integral molding requires high mold requirements and has high manufacturing cost. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a large wind tunnel blade and its preparation method that is convenient to connect, conducive to ensuring connection strength, and has low requirements for molds and low manufacturing costs.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A large wind tunnel blade includes a pressure surface main beam, a suction surface main beam, a pressure surface shell, a suction surface shell, and a metal blade root. The pressure surface shell and the pressure surface main beam are co-cured into one piece. Multiple first ribs, spaced apart along the extension direction of the pressure surface main beam, are bonded to one side of the pressure surface shell. The suction surface shell and the suction surface main beam are co-cured into one piece. Multiple second ribs, spaced apart along the extension direction of the suction surface main beam, are bonded to one side of the suction surface main beam. The pressure surface main beam and the suction surface main beam are bonded together to form an integral main beam. One end of the metal blade root is tightly fitted to one end of the pressure surface main beam and the suction surface main beam, and is adapted and bonded to them. The suction surface shell and the pressure surface shell are bonded together to form the blade body. The first and second ribs are distributed on both sides of the integral main beam and bonded between the pressure surface shell and the suction surface shell.

[0005] As a further improvement to the above technical solution: The left sidewall of the pressure surface main beam is lower than the right sidewall, and the left sidewall of the suction surface main beam is higher than the right sidewall.

[0006] The first rib is bonded to the outer side of the right sidewall of the pressure surface main beam, and the second rib is bonded to the outer side of the left sidewall of the suction surface main beam.

[0007] The upper edge of the left sidewall of the suction surface main beam is provided with an upper convex plate, which is bonded to the outer surface of the left sidewall of the pressure surface main beam. The lower edge of the right sidewall of the pressure surface main beam is provided with a lower convex plate, which is bonded to the outer surface of the right sidewall of the suction surface main beam.

[0008] One end of the metal blade root is provided with a tapered connector with a larger outer end and a smaller inner end. One end of the pressure surface main beam and the suction surface main beam are respectively provided with a first fitting surface and a second fitting surface that are adapted to the tapered connector. The first fitting surface and the second fitting surface are tightly wrapped around the outer circumferential surface of the tapered connector and are bonded to the tapered connector.

[0009] The end of the metal blade root facing the tapered connector has an alignment ring surface, and the end faces of the pressure surface main beam and the suction surface main beam both abut against the alignment ring surface.

[0010] Both the pressure surface main beam and the suction surface main beam are bonded to the alignment ring surface.

[0011] The pressure surface shell and pressure surface main beam, as well as the suction surface shell and suction surface main beam, are first laid with fiber prepreg layers through a mold and then heated to a temperature of T1 for pre-curing. After being spliced ​​together, they are heated together to a temperature of T2 for co-curing into one piece, where T1 < T2.

[0012] The pressure surface main beam and suction surface main beam, pressure surface shell and suction surface shell, pressure surface main beam and first rib, and suction surface main beam and second rib are all bonded together with structural adhesive. The pressure surface main beam and suction surface main beam are bonded to the metal blade root with structural adhesive. The first rib and second rib are bonded between the pressure surface shell and the suction surface shell with structural adhesive.

[0013] A method for manufacturing the above-mentioned large wind tunnel blade includes the following steps: S1. First, the fiber prepreg layer is laid through the mold and then heated to T1 temperature to pre-cur it to form the pressure surface main beam, the suction surface main beam, the pressure surface shell and the suction surface shell respectively. Then, the pressure surface shell and the pressure surface main beam are spliced ​​together and heated to T2 temperature to be cured into one piece. The suction surface shell and the suction surface main beam are spliced ​​together and heated to T2 temperature to be cured into one piece. T1 < T2. S2. Remove the molds of the pressure surface main beam and the suction surface main beam, and bond multiple first ribs arranged at intervals along the extension direction of the pressure surface main beam to one side of the pressure surface shell and multiple second ribs arranged at intervals along the extension direction of the suction surface main beam to one side of the suction surface shell. S3. Bond the pressure surface main beam and the suction surface main beam to form an integral main beam, and make one end of the metal blade root hug and bond it to one end of the pressure surface main beam and the suction surface main beam. At the same time, bond the suction surface shell and the pressure surface shell to form the blade body, and make the first rib and the second rib distributed on both sides of the integral main beam and bonded between the pressure surface shell and the suction surface shell. S4. Demold the pressure surface shell and the suction surface shell separately.

[0014] Compared with the prior art, the advantages of the present invention are as follows: The large wind tunnel blade of this invention uses a modular main beam (pressure surface main beam and suction surface main beam) bonded together, which is relatively integrally molded. Firstly, one end of the metal blade root can be tightly bonded to one end of the pressure surface main beam and the suction surface main beam to achieve connection, which is convenient and helps to ensure connection strength. Secondly, the pressure surface main beam and the suction surface main beam (generally, the mating surfaces of the pressure surface main beam and the suction surface main beam coincide with the central axis of the overall main beam) are formed by lay-up using their respective molds, which reduces the requirements for molds and reduces manufacturing costs. Thirdly, the connection method of co-curing and bonding ensures overall strength and improves overall manufacturing efficiency.

[0015] The method for manufacturing large wind tunnel blades of the present invention has the following aspects: First, one end of the metal blade root is tightly bonded to one end of the pressure surface main beam and one end of the suction surface main beam to achieve connection, which is both convenient and conducive to ensuring connection strength; Second, the pressure surface main beam and the suction surface main beam are formed by lay-up using their respective molds, which has low requirements for molds and low manufacturing cost; Third, the separate pressure surface main beam and suction surface main beam will face the problem of splicing and alignment. This is addressed by first laying up the pressure surface main beam, suction surface main beam, pressure surface shell, and suction surface shell using molds (laying fiber prepreg layers), heating and pre-curing to form the blades, and then attaching the pressure surface main beam to the suction surface shell. The method of separately splicing the shell and pressure surface main beam, as well as the suction surface shell and suction surface main beam, and then heating and curing them into a whole improves the bonding strength; fourthly, the method of separately curing the pressure surface main beam and suction surface main beam with the pressure surface shell and suction surface shell before demolding, and the method of demolding the pressure surface shell and suction surface shell after the overall assembly is completed, helps to ensure the alignment accuracy and bonding strength, and solves the splicing alignment problem; fifthly, the sequence of each step is cleverly set, and the combination of curing molding and bonding is adopted, which is conducive to improving the preparation efficiency and the overall bonding strength. Attached Figure Description

[0016] Figure 1This is a three-dimensional structural schematic diagram of the large wind tunnel blade of the present invention.

[0017] Figure 2 This is a three-dimensional structural diagram of the main beam of the large wind tunnel blade of the present invention.

[0018] Figure 3 This is an exploded structural diagram of the overall main beam of the large wind tunnel blade of the present invention.

[0019] Figure 4 This is a schematic diagram of the cross-sectional structure of the integral main beam of the large wind tunnel blade of the present invention.

[0020] Figure 5 This is a schematic diagram of the structure of the first rib for mounting the large wind tunnel blades of the present invention.

[0021] Figure 6 This is a schematic diagram of the structure of the first rib for mounting the large wind tunnel blades of the present invention.

[0022] The labels in the diagram represent: 1. Pressure surface main beam; 11. Lower convex plate; 12. First mating surface; 2. Suction surface main beam; 21. Upper convex plate; 22. Second mating surface; 3. Pressure surface shell; 4. Suction surface shell; 5. Metal blade root; 51. Conical connector; 52. Alignment ring surface; 6. First rib; 7. Second rib. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "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.

[0025] Furthermore, the terms "first" and "second" 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" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] In this invention, unless otherwise explicitly specified and limited, the terms "assembly," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] Example 1: Figures 1 to 6 This invention illustrates an embodiment of a large wind tunnel blade. The large wind tunnel blade of this embodiment includes a pressure surface main beam 1, a suction surface main beam 2, a pressure surface shell 3, a suction surface shell 4, and a metal blade root 5. The pressure surface shell 3 and the pressure surface main beam 1 are co-cured as one unit. Multiple first ribs 6, spaced apart along the extension direction of the pressure surface main beam 1, are bonded to one side of the pressure surface shell 3. The suction surface shell 4 and the suction surface main beam 2 are co-cured as one unit. The suction surface shell 4 is attached to the suction surface main beam... Multiple second ribs 7 are bonded to one side of the main beam 2 along the extension direction of the suction surface beam 2. The pressure surface beam 1 and the suction surface beam 2 are bonded together to form an integral main beam. One end of the metal blade root 5 is tightly attached to one end of the pressure surface beam 1 and the suction surface beam 2 and is adapted to be bonded to the pressure surface beam 1 and the suction surface beam 2. The suction surface shell 4 and the pressure surface shell 3 are bonded together to form the blade body. The first rib 6 and the second rib 7 are distributed on both sides of the integral main beam and are bonded between the pressure surface shell 3 and the suction surface shell 4.

[0028] The manufacturing process of this large wind tunnel blade is as follows: First, a fiber prepreg layer is laid using a mold and then heated to temperature T1 for pre-curing to form the pressure surface main beam 1, suction surface main beam 2, pressure surface shell 3, and suction surface shell 4. Then, pressure surface shell 3 and pressure surface main beam 1 are spliced ​​together and heated to temperature T2 to cure them as a single unit. Similarly, suction surface shell 4 and suction surface main beam 2 are spliced ​​together and heated to temperature T2 to cure them as a single unit, where T1 < T2. Second, the molds for pressure surface main beam 1 and suction surface main beam 2 are removed. Multiple spaced components extending along the direction of pressure surface main beam 1 are then bonded to one side of pressure surface shell 3 on the pressure surface main beam 1. The first rib 6 is arranged, and multiple second ribs 7 are bonded to one side of the suction surface shell 4 on the suction surface main beam 2, which are spaced apart along the extension direction of the suction surface main beam 2; the third step is to bond the pressure surface main beam 1 and the suction surface main beam 2 to form an integral main beam, and to hold and bond one end of the metal blade root 5 to one end of the pressure surface main beam 1 and the suction surface main beam 2. At the same time, the suction surface shell 4 and the pressure surface shell 3 are bonded to form the blade body, so that the first rib 6 and the second rib 7 are distributed on both sides of the integral main beam and bonded between the pressure surface shell 3 and the suction surface shell 4; the fourth step is to demold the pressure surface shell 3 and the suction surface shell 4 respectively.

[0029] The main beam of this large wind tunnel blade is manufactured by bonding two separate parts (pressure surface main beam 1 and suction surface main beam 2) together, which is relatively integrally formed. Firstly, one end of the metal blade root 5 can be tightly bonded to one end of the pressure surface main beam 1 and the suction surface main beam 2 to achieve connection, which is convenient and helps to ensure the connection strength. Secondly, the pressure surface main beam 1 and the suction surface main beam 2 (generally, the mating surfaces of the pressure surface main beam 1 and the suction surface main beam 2 coincide with the central axis of the overall main beam) are formed by lay-up using their respective molds, which has low requirements for molds and low manufacturing cost. Thirdly, the integral bonding and bonding method ensures the overall strength and helps to improve the overall manufacturing efficiency.

[0030] Furthermore, such as Figures 2 to 4 As shown, in this embodiment, the left sidewall of the pressure surface main beam 1 is lower than the right sidewall, and the left sidewall of the suction surface main beam 2 is higher than the right sidewall. That is, the two mating surfaces of the pressure surface main beam 1 and the suction surface main beam 2 are not coplanar. This design, with one side higher and the other lower, facilitates the placement of the first rib 6 or the second rib 7 on the higher side during the manufacturing process.

[0031] Further, in this embodiment, the first rib 6 is bonded to the outer side of the right sidewall of the pressure surface main beam 1, and the second rib 7 is bonded to the outer side of the left sidewall of the suction surface main beam 2. Preferably, the first rib 6 is adapted to be bonded to the right sidewall of the pressure surface main beam 1, and the side of the first rib 6 facing the suction surface housing 4 is adapted to be bonded to the suction surface housing 4; the second rib 7 is adapted to be bonded to the left sidewall of the suction surface main beam 2, and the side of the second rib 7 facing the pressure surface housing 3 is adapted to be bonded to the pressure surface housing 3. Furthermore, in this embodiment, an upper protruding plate 21 is provided on the upper edge of the left sidewall of the suction surface main beam 2. The upper protruding plate 21 is bonded to the outer surface of the left sidewall of the pressure surface main beam 1, increasing the bonding area and thus improving the connection strength. A lower protruding plate 11 is provided on the lower edge of the right sidewall of the pressure surface main beam 1. The lower protruding plate 11 is bonded to the outer surface of the right sidewall of the suction surface main beam 2, increasing the bonding area and thus improving the connection strength.

[0032] Furthermore, such as Figure 3As shown, in this embodiment, one end of the metal blade root 5 is provided with a tapered connector 51, which is larger at the outer end and smaller at the inner end. One end of the pressure surface main beam 1 and the suction surface main beam 2 are respectively provided with a first fitting surface 12 and a second fitting surface 22 that are adapted to the tapered connector 51. The first fitting surface 12 and the second fitting surface 22 are tightly fitted onto the outer circumferential surface of the tapered connector 51 and bonded to it. The inner end of the tapered connector 51 is the end connected to the metal blade root 5, and the outer end is the end away from the metal blade root 5. The tapered connector 51 is tapered, which facilitates coaxiality with the overall main beam after being tightly bonded to the pressure surface main beam 1 and the suction surface main beam 2, improving assembly accuracy. Furthermore, during the process of tightly bonding the tapered connector 51 to the pressure surface main beam 1 and the suction surface main beam 2, a tight bond can be achieved by pulling the metal blade root 5 outwards, while ensuring the thickness of the adhesive layer.

[0033] Furthermore, in this embodiment, the end of the metal blade root 5 facing the conical connector 51 has an alignment ring surface 52, and the end faces of the pressure surface main beam 1 and the suction surface main beam 2 both abut against the alignment ring surface 52. Under the limiting effect of the alignment ring surface 52, the assembly accuracy of the conical connector 51 with the pressure surface main beam 1 and the suction surface main beam 2 can be further improved.

[0034] Furthermore, in this embodiment, both the pressure surface main beam 1 and the suction surface main beam 2 are bonded to the alignment ring surface 52, further improving the overall connection strength.

[0035] Furthermore, in this embodiment, the pressure surface shell 3 and the pressure surface main beam 1, as well as the suction surface shell 4 and the suction surface main beam 2, are all first pre-cured by laying fiber prepreg layers through a mold and then heated to temperature T1. After being spliced ​​together, they are heated together to temperature T2 to cure into a whole, where T1 < T2. The pressure surface main beam 1, the suction surface main beam 2, the pressure surface shell 3, and the suction surface shell 4 are each pre-cured by laying fiber prepreg layers through a mold, then heated to temperature T1 (e.g., 80°C) and held at that temperature for an appropriate time (e.g., 30 min) to achieve pre-curing (the overall structure is now formed). The pressure surface shell 3 and the pressure surface main beam 1, as well as the suction surface shell 4 and the suction surface main beam 2, are spliced ​​together in the pre-cured state. After splicing, they are then heated together to temperature T2 (e.g., 125°C) and held at that temperature for an appropriate time (e.g., 90 min) to cure into a whole. Finally, they are cooled to room temperature to achieve good bonding strength.

[0036] Furthermore, in this embodiment, the pressure surface main beam 1 and the suction surface main beam 2, the pressure surface shell 3 and the suction surface shell 4, the pressure surface main beam 1 and the first rib 6, and the suction surface main beam 2 and the second rib 7 are all bonded together with structural adhesive. The pressure surface main beam 1 and the suction surface main beam 2 are both bonded to the metal blade root 5 with structural adhesive. The first rib 6 and the second rib 7 are bonded between the pressure surface shell 3 and the suction surface shell 4 with structural adhesive. The use of existing high-strength structural adhesives ensures the connection strength.

[0037] Example 2: A method for preparing a large wind tunnel blade according to Embodiment 1 includes the following steps: S1. First, the fiber prepreg layer is laid through the mold and then heated to T1 temperature to pre-cur it to form the pressure surface main beam 1, the suction surface main beam 2, the pressure surface shell 3 and the suction surface shell 4 respectively. Then, the pressure surface shell 3 and the pressure surface main beam 1 are spliced ​​together and heated to T2 temperature to cure them into one piece. The suction surface shell 4 and the suction surface main beam 2 are spliced ​​together and heated to T2 temperature to cure them into one piece. T1 < T2. S2. Remove the molds of the pressure surface main beam 1 and the suction surface main beam 2, and attach multiple first ribs 6 arranged at intervals along the extension direction of the pressure surface main beam 1 to one side of the pressure surface shell 3 on the pressure surface main beam 1, and attach multiple second ribs 7 arranged at intervals along the extension direction of the suction surface main beam 2 to one side of the suction surface shell 4 on the suction surface main beam 2. S3. The pressure surface main beam 1 and the suction surface main beam 2 are bonded together to form an integral main beam, and one end of the metal blade root 5 is tightly held and bonded to one end of the pressure surface main beam 1 and the suction surface main beam 2. At the same time, the suction surface shell 4 and the pressure surface shell 3 are bonded together to form the blade body, and the first rib plate 6 and the second rib plate 7 are distributed on both sides of the integral main beam and bonded between the pressure surface shell 3 and the suction surface shell 4. S4. Demold the pressure surface shell 3 and the suction surface shell 4 separately.

[0038] The manufacturing method of this large wind tunnel blade has the following aspects: First, one end of the metal blade root 5 is tightly bonded to one end of the pressure surface main beam 1 and the suction surface main beam 2, which facilitates connection and ensures connection strength. Second, the pressure surface main beam 1 and the suction surface main beam 2 are formed by layering using their respective molds, which reduces mold requirements and manufacturing costs. Third, the separate pressure surface main beam 1 and suction surface main beam 2 will face the problem of splicing and alignment. This is addressed by first layering the pressure surface main beam 1, suction surface main beam 2, pressure surface shell 3, and suction surface shell 4 using molds (laying fiber prepreg layers), pre-curing them by heating, and then splicing the pressure surface shell 3 and pressure surface main beam 1, as well as the suction surface shell 4 and suction surface main beam 2, together by heating and co-curing them into a single unit, thereby improving the bonding strength. Fourth, the pressure surface main beam 1 and suction surface main beam 2 are used in a manner that allows for layering and pre-curing of the pressure surface main beam 1 and suction surface main beam 2 using molds. The method of demolding the main beam 2, pressure shell 3, and suction shell 4 separately after curing them into one piece, and demolding the pressure shell 3 and suction shell 4 after the overall assembly is completed, helps to ensure alignment accuracy and bonding strength, and solves the splicing alignment problem (the molds of pressure main beam 1, suction main beam 2, pressure shell 3, and suction shell 4 can be respectively equipped with docking mechanisms and locking mechanisms. The docking mechanism achieves precise alignment between pressure shell 3 and pressure main beam 1, suction shell 4 and suction main beam 2, pressure main beam 1 and suction main beam 2, and pressure shell 3 and suction shell 4. The locking mechanism ensures bonding strength). Fifthly, the sequence of each step is cleverly set, and the combination of curing and bonding is adopted, which is conducive to improving preparation efficiency and overall bonding strength.

[0039] It should be noted that the pressure surface main beam 1, the suction surface main beam 2, the pressure surface shell 3, and the suction surface shell 4 can all be formed by laying fiber prepreg on the mold and embedding other materials (such as foam) and then heating and curing.

[0040] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A large wind tunnel blade, characterized in that: The system includes a pressure surface main beam (1), a suction surface main beam (2), a pressure surface shell (3), a suction surface shell (4), and a metal blade root (5). The pressure surface shell (3) and the pressure surface main beam (1) are co-cured into one piece. The pressure surface shell (3) has multiple first ribs (6) bonded to one side of the pressure surface main beam (1) at intervals along the extension direction of the pressure surface main beam (1). The suction surface shell (4) and the suction surface main beam (2) are co-cured into one piece. The suction surface shell (4) has multiple first ribs (6) bonded to one side of the suction surface main beam (2) at intervals along the extension direction of the suction surface main beam (2). The second rib (7) is arranged at intervals in the extension direction. The pressure surface main beam (1) and the suction surface main beam (2) are bonded together to form an integral main beam. One end of the metal blade root (5) is tightly wrapped around one end of the pressure surface main beam (1) and the suction surface main beam (2) and is adapted to be bonded to the pressure surface main beam (1) and the suction surface main beam (2). The suction surface shell (4) and the pressure surface shell (3) are bonded together to form the blade body. The first rib (6) and the second rib (7) are distributed on both sides of the integral main beam and are bonded between the pressure surface shell (3) and the suction surface shell (4).

2. The large wind tunnel blade according to claim 1, characterized in that: The left sidewall of the pressure surface main beam (1) is lower than the right sidewall, and the left sidewall of the suction surface main beam (2) is higher than the right sidewall.

3. The large wind tunnel blade according to claim 2, characterized in that: The first rib (6) is bonded to the outside of the right side wall of the pressure surface main beam (1), and the second rib (7) is bonded to the outside of the left side wall of the suction surface main beam (2).

4. The large wind tunnel blade according to claim 2, characterized in that: The upper edge of the left side wall of the suction surface main beam (2) is provided with an upper convex plate (21), which is bonded to the outer surface of the left side wall of the pressure surface main beam (1). The lower edge of the right side wall of the pressure surface main beam (1) is provided with a lower convex plate (11), which is bonded to the outer surface of the right side wall of the suction surface main beam (2).

5. The large wind tunnel blade according to claim 1, characterized in that: One end of the metal leaf root (5) is provided with a tapered connector (51) with a larger outer end and a smaller inner end. One end of the pressure surface main beam (1) and the suction surface main beam (2) are respectively provided with a first fitting surface (12) and a second fitting surface (22) that are adapted to the tapered connector (51). The first fitting surface (12) and the second fitting surface (22) are tightly wrapped around the outer circumferential surface of the tapered connector (51) and bonded to the tapered connector (51).

6. The large wind tunnel blade according to claim 5, characterized in that: The metal blade root (5) has an alignment ring surface (52) at one end facing the tapered connector (51), and the end faces of the pressure surface main beam (1) and the suction surface main beam (2) abut against the alignment ring surface (52).

7. The large wind tunnel blade according to claim 6, characterized in that: Both the pressure surface main beam (1) and the suction surface main beam (2) are bonded to the alignment ring surface (52).

8. The large wind tunnel blade according to any one of claims 1 to 7, characterized in that: The pressure surface shell (3) and pressure surface main beam (1), as well as the suction surface shell (4) and suction surface main beam (2), are first laid with fiber prepreg layer through mold and then heated to T1 temperature for pre-curing. After splicing, they are heated together to T2 temperature for co-curing into one piece, where T1 < T2.

9. The large wind tunnel blade according to any one of claims 1 to 7, characterized in that: The pressure surface main beam (1) and suction surface main beam (2), pressure surface shell (3) and suction surface shell (4), pressure surface main beam (1) and first rib (6), and suction surface main beam (2) and second rib (7) are all bonded together with structural adhesive. The pressure surface main beam (1) and suction surface main beam (2) are bonded together with metal blade root (5) with structural adhesive. The first rib (6) and second rib (7) are bonded together with structural adhesive between pressure surface shell (3) and suction surface shell (4).

10. A method for preparing a large wind tunnel blade according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. First, the fiber prepreg layer is laid through the mold and then heated to T1 temperature to pre-cur it to form the pressure surface main beam (1), the suction surface main beam (2), the pressure surface shell (3) and the suction surface shell (4). Then, the pressure surface shell (3) and the pressure surface main beam (1) are spliced ​​together and heated to T2 temperature to be cured into one piece. The suction surface shell (4) and the suction surface main beam (2) are spliced ​​together and heated to T2 temperature to be cured into one piece. T1 < T2. S2. Remove the mold of the pressure surface main beam (1) and the suction surface main beam (2), and attach multiple first ribs (6) arranged at intervals along the extension direction of the pressure surface main beam (1) to the pressure surface shell (3) on one side of the pressure surface main beam (1), and attach multiple second ribs (7) arranged at intervals along the extension direction of the suction surface main beam (2) to the suction surface shell (4) on one side of the suction surface main beam (2). S3. The pressure surface main beam (1) and the suction surface main beam (2) are bonded together to form an integral main beam, and one end of the metal blade root (5) is tightly held and bonded to one end of the pressure surface main beam (1) and the suction surface main beam (2). At the same time, the suction surface shell (4) and the pressure surface shell (3) are bonded together to form the blade body, and the first rib (6) and the second rib (7) are distributed on both sides of the integral main beam and bonded between the pressure surface shell (3) and the suction surface shell (4). S4. Demold the pressure surface shell (3) and the suction surface shell (4) respectively.

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