Wind power blade tip extension structure

Abstract

The utility model relates to a blade tip extension structure of a wind power blade, which is characterized in that a stringer structure is arranged between a basic blade section and a blade tip extension section, and the stringer structure is in a structural form that a core material block is wrapped by double-shaft cloth, so that the shear resistance of the blade can be improved, and the bearing capacity of the blade extension structure is improved; meanwhile, the bonding mode that the core material block wraps the double-shaft cloth is used for replacing structural adhesive bonding, the weight of the blade tip extension structure can be reduced, and the defects that structural adhesive of a bonding section of a common blade extension structure lacks and the like are overcome. The safety and reliability of the blade tip extension structure can be improved, and the blade tip extension structure is simple in structure and convenient to use.

Description

Technical Field

[0001] The utility model belongs to the technical field of wind power generation, and relates to a blade of a wind turbine, in particular to a tip extension structure of a wind power blade. Background Art

[0002] With the rapid development of the domestic wind power market, the power generation efficiency of wind turbines is an important factor that each wind farm needs to consider. The blade is a key component of a wind turbine, and its swept area directly affects the power generation efficiency of the wind turbine. For the blades put into operation in the early stage, due to their short length, the power generation efficiency is not good. Therefore, in the prior art, the method of blade extension is often used to increase the swept area of the wind turbine unit and the power generation efficiency at low wind speeds, improve its power generation, and thus improve the economic benefits of the wind farm.

[0003] In order to fully improve the utilization rate of wind energy, installing a tip extension section on the original hanging blade is a commonly used and effective means. In the prior art, the production of the tip extension structure of a wind power blade is usually to bond the tip extension section and the basic blade section together with structural adhesive. The application of the structural adhesive depends on manual experience. Therefore, it is very difficult to ensure the bonding quality at the connection between the basic blade section and the tip extension section, and there are easily invisible bonding defects such as lack of glue, and the bonding strength of the structural adhesive may not be sufficient to withstand external forces such as wind vortices, resulting in the tip extension section being easily detached or damaged. In addition, the structural adhesive itself will also increase the weight of the blade and have a certain impact on the performance of the wind turbine.

[0004] The patent document "A Tip Extension Structure and Method for a Wind Power Blade" (CN106499578B) discloses a tip extension structure of a wind power blade. The tip extension section is composed of multiple sheets, each sheet is bonded to the basic blade, and each sheet uses a wedge-shaped ply to relieve the sharp change in the overall thickness, and a prefabricated bonding tongue is used to increase the bonding strength. By designing a toothed end and a spanwise groove structure, the stress concentration at the connection end is relieved, the fatigue crack propagation is inhibited, and the load-bearing capacity and reliability of the bonding are improved. However, its structure is complex, the process is cumbersome, and the construction efficiency is low.

[0005] Therefore, how to improve the safety and reliability of the tip extension structure and simplify the tip extension structure is a technical problem that needs to be solved urgently. Content of the Utility Model

[0006] (I) Purpose of the Utility Model

[0007] In view of the defects and deficiencies existing in the prior art of the tip extension structure of wind turbine blades, the present utility model proposes a tip extension structure for wind turbine blades. By arranging a spar structure between the basic blade section and the tip extension section, and setting the spar structure in the form of a biaxial cloth wrapped core material block, the shear resistance of the blade can be improved, and the bearing capacity of the blade extension structure can be enhanced. At the same time, using the bonding form of the core material block wrapped with the biaxial cloth to replace the structural adhesive bonding can reduce the weight of the tip extension structure and also avoid defects such as lack of structural adhesive in the bonding section of the general blade extension structure.

[0008] (II) Technical Solution

[0009] To achieve the purpose of the present utility model, the following technical solution is adopted:

[0010] A tip extension structure for a wind turbine blade, which includes a basic blade section and a tip extension section. The tip extension section is sleeved on the outer side of the front end of the basic blade section. The basic blade section includes two webs. It is characterized in that a cavity is formed at the connection between the basic blade section and the tip extension section. The tip extension structure for the wind turbine blade further includes a spar structure. The spar structure is arranged in the cavity. The spar structure includes a biaxial wrapping cloth and a trapezoidal core material block. The biaxial wrapping cloth wraps the core material block. The cross-section of the core material block is an isosceles trapezoid. Along the chord direction of the basic blade section, the core material block is arranged at the central position between the two webs of the basic blade section. The connection between the tip extension section and the basic blade section is formed by vacuum bag molding.

[0011] Preferably, the material of the core material block is PVC foam or PET foam.

[0012] Preferably, the bottom side length of the isosceles trapezoid is 100 mm, and the included angle between the hypotenuse and the bottom side of the isosceles trapezoid is 45 degrees.

[0013] Preferably, the material of the biaxial wrapping cloth is biaxial cloth material of BI600 or HBI600.

[0014] Preferably, the height of the core material block of the spar structure is determined by the height of the cavity at the connection.

[0015] Preferably, when the cavity height is less than 1 mm, no core material block is placed, and the bonding is directly achieved with the biaxial wrapping cloth.

[0016] Preferably, the biaxial wrapping cloth is set to 4 - 6 layers.

[0017] Preferably, the width of the biaxial wrapping cloth in the chord direction is 200 mm, and the dimensions by which the two ends of the biaxial wrapping cloth in the chord direction exceed the core material block are greater than 50 mm.

[0018] (III) Technical Effects

[0019] Compared with the prior art, the tip extension structure of the wind turbine blade of the present utility model has the following beneficial and remarkable technical effects:

[0020] (1) The structure of the spar structure of the present utility model, which wraps the core material block with biaxial fabric, can improve the shear resistance of the blade, enhance the bearing capacity of the blade extension structure, and has a simple structure and is convenient to use.

[0021] (2) The present utility model replaces the manual application of structural adhesive bonding with the bonding form of wrapping the biaxial fabric with the core material block, and uses the spar structure to fill the gap formed at the connection between the basic blade section and the tip extension section. Compared with filling the gap with structural adhesive, it can reduce the weight of the tip extension structure of the blade, and also avoid defects such as lack of structural adhesive in the bonding section of the general blade extension structure.

[0022] (3) The cross-section of the core material block is an isosceles trapezoid, and the two sides of the core material block and the biaxial wrapping fabric wrapping the core material block are transitioned with an obtuse angle, which can reduce the stress concentration phenomenon at the corner of the biaxial wrapping fabric wrapping the core material block and the core material block.

[0023] (4) In the chord direction, the core material block is placed at the chord position of the basic blade section, which is the central position between the two webs of the basic blade section. This setting method can increase the overall stiffness of the blade, making it more resistant to external forces such as wind force, thereby improving the stability and durability of the blade. It can also increase the bearing capacity of the blade, enabling it to better cope with challenges in complex environments such as wind vortices, and can make the blade distribute stress more evenly when subjected to external forces, reducing the stress concentration phenomenon, which is beneficial to extending the service life of the blade. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a sectional projection view of the tip extension structure of the wind turbine blade of the present utility model;

[0025] Figure 2 is a partial schematic view of the spar structure. DETAILED DESCRIPTION OF THE INVENTION

[0026] To better understand the present utility model, the content of the present utility model will be further clarified below in conjunction with embodiments. In the drawings, the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The described embodiments are some embodiments of the present utility model, rather than all embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present utility model, and should not be construed as a limitation to the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts fall within the scope of protection of the present utility model. The structure and technical solutions of the present utility model will be further specifically described below in conjunction with the drawings. Based on the common double-web structure type at the tip of the original blade of large megawatt-class blades at present, the specific implementation manner of the present utility model is described. An embodiment of the present utility model is given. Specific embodiment

[0028] As Figures 1 - 2 shown, the present utility model provides a tip extension structure for a wind turbine blade. The tip extension structure for the wind turbine blade includes a basic blade section 2 and a tip extension section 3. The tip extension section 3 is sleeved outside the front end of the basic blade section 2. The basic blade section 2 includes two webs 4. A cavity is formed between the basic blade section 2 and the tip extension section 3. The tip extension structure for the wind turbine blade further includes a spar structure 1. The spar structure is arranged in the cavity. The spar structure 1 includes a biaxial wrapping cloth 12 and a trapezoidal core material block 11. The trapezoidal core material block 11 is wrapped by the biaxial wrapping cloth 12. The core material of the core material block can be PVC foam or PET foam. The bonding form of wrapping the core material block with the biaxial cloth is used to replace the artificial application of structural adhesive bonding. The spar structure is used to fill the gap formed at the connection between the basic blade section and the tip extension section. Compared with filling the gap with structural adhesive, it can reduce the weight of the tip extension structure and avoid defects such as lack of structural adhesive in the bonding section of general blade extension structures.

[0029] A partial schematic diagram of the spar structure is as Figure 2 shown. The cross-section of the trapezoidal core material block 11 is an isosceles trapezoid. The bottom side length of the isosceles trapezoid is 100 mm wide, and the included angle between the hypotenuse and the bottom side of the isosceles trapezoid is 45 degrees. The core material block 11 is wrapped with a biaxial wrapping cloth 12 on the outside. The cross-section of the core material block adopts an isosceles trapezoid, and the two sides of the core material block and the biaxial wrapping cloth wrapping the core material block use an obtuse angle transition, which can reduce the stress concentration phenomenon at the corner of the biaxial wrapping cloth wrapping the core material block and the core material block.

[0030] The chordwise position of the core material block placed on the basic blade segment is the central position between the two webs 4 of the basic blade segment. The operator first needs to mark the chordwise position of the core material block at the corresponding positions on the outer surfaces of the pressure side and suction side of the basic blade segment 2. The spanwise cut-off position is determined by the cavity height of the two-blade connection segment. Where the cavity height is less than 1 mm, the core material block can be not placed and the bonding can be directly achieved with a biaxial wrapping cloth. In the chordwise direction, the chordwise position of the core material block placed on the basic blade segment is the central position between the two webs of the basic blade segment. This setting method can increase the overall stiffness of the blade, making it more resistant to external forces such as wind force, thereby improving the stability and durability of the blade. It can also increase the load-bearing capacity of the blade, enabling it to better cope with challenges in complex environments such as wind vortices. And it can make the stress more evenly distributed when the blade is subjected to external forces, reducing the stress concentration phenomenon, which is beneficial to extending the service life of the blade.

[0031] The height of the core material block can be pre-arranged with putty blocks at the connection position between the basic blade segment 2 and the tip extension segment 3, and the cavity height at each spanwise position can be obtained by trial fitting and profiling during the subsequent trial installation stage of the tip extension segment. A putty block can be placed every 200 mm in the spanwise position, and then a core material block with a certain height is processed according to the profiling height of the putty, and a linear transition is made at the thickness change.

[0032] The material of the biaxial wrapping cloth can be a biaxial cloth material of BI600 or HBI600. The height of the core material block of the spar structure is determined according to the cavity height at the connection. For example, the height here is generally about 3 - 5 mm. A core material block about 3 mm high can be wrapped with 4 - 6 layers of biaxial cloth with a small gram weight. Using biaxial cloth with a small gram weight is to reduce the weight of the extension segment connection structure.

[0033] When installing the tip extension segment for the first time, the tip extension segment can be pre-tried on. If the height of the core material block is not appropriate and there is interference at a local position and it cannot be put on, the core material block at that position can be polished according to the interference position, and then the formal installation work of the tip extension segment can be carried out.

[0034] When formally installing the extension segment, first place the core material block on the basic blade segment 2, then lay 4 - 6 layers of biaxial wrapping cloth and soak it with epoxy resin. The width of the biaxial wrapping cloth in the chordwise direction is 200 mm, and the dimensions of both ends of the biaxial wrapping cloth in the chordwise direction exceeding the core material block are greater than 50 mm. Since the number of cloth layers is small, there is no need to stagger the layers in the chordwise direction. Then install the tip extension segment 3. After installing the spar structure, a vacuum bag is set on the outside of the connection between the tip extension segment and the basic blade segment, and it is formed by the vacuum bag pressing method. The vacuum bag pressing time is about 2 hours at room temperature.

[0035] Through the above embodiments, the object of the present utility model is fully and effectively achieved. Those skilled in the art can understand that the present utility model includes but is not limited to the content described in the drawings and the above specific embodiments. Although the present utility model has been described with respect to the currently considered most practical and preferred embodiments, it should be understood that the present utility model is not limited to the disclosed embodiments, and any modifications that do not deviate from the functional and structural principles of the present utility model will be included within the scope of the claims.

Claims

1. A wind turbine blade tip extension structure, comprising a base blade segment and a blade tip extension segment, wherein the blade tip extension segment is sleeved on the front outer side of the base blade segment, and the base blade segment comprises two webs, characterized in that: A cavity is formed at the connection between the basic blade segment and the blade tip extension segment. The wind turbine blade tip extension structure also includes a truss structure, which is arranged in the cavity. The truss structure includes a biaxial wrapping cloth and a trapezoidal core material block. The biaxial wrapping cloth wraps the core material block, and the cross-section of the core material block is an isosceles trapezoid. Along the chord direction of the basic blade segment, the core material block is arranged at the center position between the two webs of the basic blade segment. The connection between the blade tip extension segment and the basic blade segment is formed by vacuum bag pressing.

2. The wind turbine blade tip extension structure according to claim 1, characterized in that: The core material block is made of PVC foam or PET foam.

3. The wind turbine blade tip extension structure according to claim 1, characterized in that: The length of the base of the isosceles trapezoid is 100 mm, and the angle between the hypotenuse and the base of the isosceles trapezoid is 45 degrees.

4. The wind turbine blade tip extension structure according to claim 1, characterized in that: The biaxial wrapping cloth is made of BI600 or HBI600 biaxial cloth material.

5. The wind turbine blade tip extension structure according to claim 1, characterized in that: The height of the core material block of the beam structure is determined by the height of the cavity at the connection.

6. The wind turbine blade tip extension structure according to claim 5, characterized in that: No core material block is placed where the cavity height is less than 1 mm, and the biaxial wrapping cloth is directly used to achieve bonding.

7. The wind turbine blade tip extension structure according to claim 5, characterized in that: The biaxial wrapping cloth is arranged in 4-6 layers.

8. The wind turbine blade tip extension structure according to claim 1, characterized in that: The width of the biaxial wrapping cloth along the chord direction is 200 mm, and the two ends of the biaxial wrapping cloth along the chord direction exceed the dimension of the core material block by more than 50 mm.

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