Wind turbine blade

Abstract

A wind turbine blade has a generally hollow blade body (11) comprising upper and lower half-shells (12, 13) and first and second elongated webs (16, 17), each extending along the longitudinal direction of the blade (5) and disposed between and connected to the upper and lower half-shells (12, 13), wherein each web (16, 17) includes upper and lower flanges (22) connecting the respective web (16, 17) to the respective half-shell (12, 13), and wherein the first and second webs (16, 17) are supported by respective first and second reinforcing structures (23). Supported by corresponding half-shells (12, 13), the reinforcing structure (23) extends along the longitudinal direction of the blade (5), wherein each of the first and second reinforcing structures (23) supporting the first and second webs (16) includes at least one stack (24) consisting of a plurality of pultruded composite strips (25) comprising carbon fibers, wherein the strips (25) are fixed in a resin matrix (35), wherein each of the at least one stack (25) consisting of the pultruded composite strips is an integral part of the corresponding first and second webs (17) and forms a corresponding flange (22) which is attached to the inner layer (29) of the corresponding upper and lower shells (12, 13).

Description

Technical Field

[0001] The present invention relates to a wind turbine blade having a generally hollow blade body comprising an upper half-shell and a lower half-shell, and first and second elongated webs, each extending along the longitudinal direction of the blade and disposed between and connected to the upper and lower half-shells, wherein a second web is arranged closer to the trailing edge of the blade and extends only a portion of the trailing edge, wherein each web includes an upper flange and a lower flange connecting the respective web to the respective half-shell, and wherein the first and second webs are supported relative to the respective half-shells by respective first and second reinforcing structures extending along the longitudinal direction of the blade, wherein each first and second reinforcing structure supporting the first and second webs includes at least one stacked member consisting of a plurality of pultruded composite strips comprising carbon fibers, wherein the strips are fixed in a resin matrix. Background Technology

[0002] As is well known, wind turbine blades are part of a wind turbine used to generate electrical power. A wind turbine typically consists of three blades attached to a hub, which is connected to a generator housed in a nacelle. These blades interact with the passing wind, causing the hub to rotate, ultimately driving the generator.

[0003] Turbine blades typically comprise a hollow blade body with an upper half-shell and a lower half-shell, which are usually manufactured separately and attached to each other. Within this hollow blade body are first and second elongated webs that connect and support the two half-shells, while also transmitting loads acting on the respective shells due to aerodynamics and the circumferential motion of the blade during rotation. These loads include pressure and suction loads on the upper and lower half-shells, as well as compressive and tensile loads. For example, a wind turbine blade with this common configuration is disclosed in EP 2 791 500 B1.

[0004] To support the half-shell and to transfer the corresponding load, each elongated web extends longitudinally and is connected to the corresponding half-shell via flanges disposed on the respective web sides, the flanges being attached to the inner layers of the upper and lower half-shells by adhesive. To transfer the load or, consequently, to support the corresponding shell, each web is supported relative to the corresponding half-shell via corresponding first and second reinforcing structures. Such reinforcing structures are commonly referred to as spar caps. Like the corresponding webs and their flanges, these reinforcing structures or spar caps also extend longitudinally along the blade. As disclosed, for example, in EP 2 791 500 B1, these reinforcing structures are made from a stack comprising separate carbon fiber pultrusion strips arranged on top of each other and fixed in a resin matrix. During the manufacture of such pultrusion strips, carbon fibers are drawn through a supply of liquid resin, which is then heated and cured, ultimately forming the respective pultrusion strip. These pultruded carbon fiber strips exhibit excellent mechanical properties in bearing and distributing loads, and also absorb the high bending moments generated during blade rotation.

[0005] In known wind turbine blade designs, such as those disclosed in EP 2 791 500 B1, the blade includes two first webs that extend almost entirely along the length of the blade and are arranged in the central body region, i.e., in an area where the upper and lower half-shells are significantly apart when viewed in a teardrop cross-section. A second web is also provided, arranged near the trailing edge of the blade. This second web extends only along a portion of the trailing edge, which typically has a specific edge design and is subjected to specific loads, which are borne or distributed accordingly by the second web.

[0006] All webs comprise elongated web bodies with flanges disposed at the ends of the web bodies. Each web is supported by two reinforcing structures, namely spar caps, such that a total of six spar caps are arranged in two shells to support the three webs. Although the mass of the spar caps themselves is reduced in some way due to the use of carbon fiber pultruded stacks, the total mass of such known turbine blades is high due to the need to integrate three webs and six spar caps, and the carbon fiber pultruded stacks are expensive.

[0007] Therefore, an improved wind turbine blade design is needed to allow for adequate load support and a less complex and heavy design. Summary of the Invention

[0008] To address this issue, the wind turbine blades mentioned above are characterized in that each of at least one stacked member made of pultruded composite strips is an integral part of the corresponding first and second webs and forms a corresponding flange which is attached to the inner layer of the corresponding upper and lower shells.

[0009] The wind turbine blade of the present invention is characterized by a specific arrangement of the first and second reinforcing structures, and has an improved design superior to known blade designs. The at least one stack forming the respective first and second reinforcing structures is composed of several pultruded composite strips comprising carbon fibers, wherein these strips are fixed in a resin matrix. In this embodiment, the respective first and second spar caps are made of carbon fiber pultruded strips. The respective first and second reinforcing structures are integral parts of the respective first and second webs and form the respective flanges, which are attached to the inner layer of the respective shell by means of an adhesive. The second web according to this embodiment has an H-shape, having a central web body and an integral reinforcing flange attached to the web body. Since the web body comprises a resin matrix, the matrix also integrally extends into the respective flange or the respective carbon strip stack, thereby making the respective flange of the H-shaped web very rigid and a mechanically adaptable component. The web body may comprise a core, for example made of balsa wood, PET, or PVC, arranged in a resin-infused glass fiber sheath or shell. When producing the web, all the corresponding parts, namely the web body and the carbon pultruded strip, can be easily arranged in a common web mold by simply inserting the corresponding core and fiber layers or the corresponding fabric and pultruded strip, and by finally pouring the entire web assembly.

[0010] A particular advantage of this embodiment is that the H-shaped web can be manufactured outside the corresponding shell, thus already including the corresponding spar cap. This allows for simplified spar cap manufacturing and, in particular, allows for proper inspection of the connection between the web or the corresponding reinforcement structure, i.e., the connection between the spar cap and the web body. Furthermore, the adhesive connection between the web flange, i.e., the spar cap, and the inner layers of the upper and lower shells needs to withstand relatively small loads, and the corresponding reinforcement structure or the corresponding spar cap is an integral part of the web. Because no adhesive joint is provided between the web and the carbon strip reinforcement structure, since they are integral parts of each web, the overall robustness of the blade is improved.

[0011] The reinforcing structural arrangement of the present invention can be implemented in different blade configurations. The two webs may extend over approximately the same length of the blade. Here, both webs are arranged at locations where the half-shells within the hollow blade are relatively far apart from each other. Alternatively, the second web may be arranged closer to the trailing edge of the blade and extend only along a portion of that trailing edge. Here, the second web is adjacent to the trailing edge to stiffen that region.

[0012] Furthermore, the integral first and second reinforcing structures of the flange or the corresponding carbon stack may also include a biaxial glass and / or carbon fiber layer between each pair of strips, said layer being infused with resin. To bond these strips together, fiber layers or fiber fabrics are inserted between the respective strips of the stack. Thus, the entire stack has a sandwich arrangement in which pultruded strips are followed by fiber layers or fabrics, which in turn are followed by another strip, and so on. Inventively, the biaxial fiber layers are infused with resin, which forms the resin matrix into which the entire stack is embedded. The biaxial fiber layers comprise fibers arranged at an angle of 0° and other fibers arranged at angles of, for example, ±45°. Such biaxial layers are advantageous because they allow for the bearing of loads in different directions or correspondingly different types, such as loads caused by blade flapping or oscillating bending.

[0013] Since the flanged webs are produced outside the corresponding half-shell, the flange design can be easily adjusted to suit the specific needs by using a corresponding web mold that is also designed for arranging and pouring pultruded strip stacks together with biaxial layers. The pre-fabricated webs are then attached to the separately molded shell by means of adhesive.

[0014] In another embodiment of the invention, each of the integral reinforcement structures of the first and second flanges includes more than one stacked member arranged in parallel, preferably three stacked members arranged adjacent to each other. This allows the integral shape of the respective flange, i.e., the spar cap, to be formed along the slightly curved shape of the respective upper and lower inner layers, such that the respective spar cap closely follows the shape of the inner layers.

[0015] Because the reinforcing structure, i.e., the spar cap, is an integral part of the web and forms its flange, the design of the corresponding shell in the area where the web flange is attached can be adjusted. Preferably, the inner layer is arranged closer to the outer layer in the area where the corresponding flange of the corresponding web is attached. The cross-section or corresponding thickness of the shell in the attachment area is reduced because it is not necessary to integrate the spar cap into the corresponding half-shell, which results in lighter weight but still mechanical rigidity.

[0016] It is possible that the inner layer is directly attached to the outer layer. Here, because the inner layer, which is spaced a distance from the outer layer in a region adjacent to the flange attachment area, is typically integrated with the core element, it is guided towards the outer layer and directly attached to it, resulting in a very small thickness in this region. Alternatively, an additional reinforcing device is arranged between the inner and outer layers of the respective half-shell. This reinforcing element is preferably very thin, so that the total thickness of this region remains small compared to adjacent regions. Such a reinforcing device may comprise several layers of glass fiber embedded in the entire resin matrix of the shell. The fiber fabric is very thin, so that even when several layers are stacked, the overall thickness is not significantly greater. Alternatively, a core element embedded in the entire resin matrix of the shell can be provided. This high-density core element further strengthens or reinforces this region, but its small thickness keeps the overall thickness of this region small as well. Regardless of which reinforcing device is integrated, it provides better support and load transfer via the first and second webs.

[0017] To adjust the mechanical properties of the blades in the region near the respective flange attachment area, several additional core elements can be provided between the outer and inner layers of the respective upper and lower half-shells. These core elements, like those that can be sandwiched in the thinned flange attachment area of ​​the respective shell, can be made of materials with sufficiently high density, such as foam, wood, polymers, or composite materials, including, for example, resin-infused fiber layers or fabrics, but this list is not exhaustive.

[0018] Regardless of the material used, the core element is an integral part of the corresponding housing and is sandwiched between the outer and inner layers. If a wood or polymer core element is used, it is manufactured as a preform and subsequently inserted into the corresponding housing mold, where the corresponding layers or elements for setting the corresponding half-shell are also inserted. It is then fixed to the housing with resin. When using a core element made of a composite material such as fiberglass layers, the corresponding laminate can be directly set in the housing mold and subsequently co-injected with resin during integral housing infusion.

[0019] The present invention also relates to a wind turbine comprising a plurality of wind turbine blades as described above, preferably three turbine blades. Attached Figure Description

[0020] Other objects and features of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings. However, the drawings are merely schematic diagrams designed for illustrative purposes only and do not limit the invention. The drawings show:

[0021] Figure 1 A simplified schematic diagram of a wind turbine.

[0022] Figure 2 A view of a wind turbine blade of the present invention, including a first web and a second web, according to a first embodiment.

[0023] Figure 3 A view of a wind turbine blade of the present invention, including a first web and a second web, according to a second embodiment.

[0024] Figure 4 : Along line IV-IV Figure 2 A cross-sectional view of the blade.

[0025] Figure 5 The first embodiment Figure 3 An enlarged view of section V, and

[0026] Figure 6 Second embodiment Figure 3 An enlarged view of section V. Detailed Implementation

[0027] Figure 1 A schematic diagram of a wind turbine 1 is shown, which includes a tower 2, a nacelle 3 mounted on top of the tower 2, and a rotor 4. The rotor 4 includes three wind turbine blades 5 attached to a hub 6, which is operatively coupled to a generator arranged in the nacelle 3. The generator is driven by the rotational energy of the rotor 4 to generate electrical power as is generally known.

[0028] This invention relates to the arrangement of wind turbine blades 5.

[0029] Figure 2 A schematic diagram of a turbine blade 5 according to a first embodiment is shown. The turbine blade 5 has a root 7 for attaching the blade 5 to a hub and a tip 8 at the end of another blade. It also includes a leading edge 9 and a trailing edge 10.

[0030] Figure 3 A schematic diagram of a turbine blade 5 according to a second embodiment is shown. The turbine blade 5 has a root 7 for attaching the blade 5 to a hub and a tip 8 located at the end of another blade. It also includes a leading edge 9 and a trailing edge 10.

[0031] See Figure 4 The blade 5 includes a hollow blade body 11, which is made of an upper half-shell 12 and a lower half-shell 13, which are fixed to each other by an adhesive 14 and enclose a hollow space 15. A first web 16 and a second web 17 are arranged in this space 15. The first web 16 is arranged in a position where the upper half 12 and the lower half 13 have approximately their maximum distance, or correspondingly, the blade has approximately its maximum profile thickness. Figure 2As shown, the ventral plate 16 extends almost the entire length of the leaf 5, starting from the adjacent root 7 and ending near the terminal 8.

[0032] The second web plate 17 is arranged closer to the trailing edge 10. It can be arranged in different ways. For example... Figure 2 As shown, like the first web 16, the second web 17 can extend almost the entire length of the leaf 5, beginning near the root 7 and terminating near the tip 8. The two webs can preferably extend in parallel, but this is not mandatory. Figure 3 As shown, the web 17 may also extend only on a portion of the blade length near the trailing edge 10.

[0033] Both the first and second webs 16 and 17 are used to support the blade shells 12 and 13, and to bear and distribute the corresponding loads placed on the blades, which are caused by aerodynamic reasons due to the rotation of the rotor 4 and mechanical reasons due to the weight of the blades 5 themselves.

[0034] Although referenced below Figure 5 and Figure 6 The configuration of the first web 16 has been described in detail, but it should be noted that the same description also applies to the configuration of the second web 17.

[0035] The first web 16 includes a web body 18, for example, see the illustration. Figure 4 The enlarged cross-section V Figure 5 The web body 18 includes a core 19, which is made of, for example, balsa wood, stabilized foam, or composite materials, thereby exhibiting the mechanical properties required to harden the entire web 16. The core 19 is surrounded by one or more glass fiber layers 20, which are infused with resin, i.e., embedded in cured resin 21.

[0036] The web 16 also includes two flanges 22, which are integral parts of the web 16 and are integrally attached to the end of the web body 18. Figure 5 Only one flange is shown; the other flange has the same configuration. Each flange 22 also includes an integrated reinforcing structure 23 comprising a stack 24 made of multiple pultruded strips 25, each pultruded strip comprising carbon fibers embedded in resin. Although Figure 5Only three strips 25 are shown, but two or more strips may also be provided. One or more layers of biaxial fiberglass fabric 26 are placed between each pair of adjacent strips 25. This biaxial fiberglass fabric is infused with resin to secure the strips 25. The biaxial fiber layers or fabric comprise fibers arranged at 0° angles, while other fibers are arranged at, for example, ±45° angles. The overall arrangement of the strips 25 and fiber layers 26 is fully embedded in a monolithic resin 21, which is embedded in all components of the web 16. Thus, the reinforcing structure 23, i.e., the carbon pultruded strips 25 with interlaced fiber layers 26, is an integral part of the web 16, so that the web 16 can be produced as a single, complete piece outside the respective half-shells 12, 13, and can be attached to them when the blades 5 are finally completed.

[0037] Because the two webs 16, 17 are manufactured separately, as mentioned, they are identical in their arrangement, and the half-shells 12, 13 are also manufactured separately in their respective molds. Since the reinforcing structure 23 is integral part of the respective webs 16, 17 or correspondingly constructs the respective flanges of each web 16, 17, it is not necessary to integrate specific reinforcing structures into the respective half-shells 12, 13. Therefore, see [link to relevant documentation]. Figure 5 and Figure 6 The webs 16 and 17 of the housings 12 and 13 may have a specific design in the areas to which they are attached by their respective flanges 22.

[0038] Figure 5 A first embodiment of such a housing design is shown, while Figure 5 The design of the corresponding attachment area of ​​the flange 22 of the web 16 of the housing 12 is shown only, but the same description applies to the design of the corresponding attachment area of ​​the flange 22 of the web 17 and the attachment area of ​​the housing 13.

[0039] Each housing 12, 13 includes an outer layer 27 and an inner layer 29. The outer layer 27 includes one or more fiberglass layers 28, and the inner layer 29 also includes one or more fiberglass layers 30. A corresponding core element 31 is sandwiched between the outer layer 28 and the inner layer 29. These core elements 31 may be made of balsa wood, high-density foam, or any other particularly lightweight reinforcing material.

[0040] like Figure 5 As clearly shown, in the attachment region of the web flange, the inner layer 29 is directed to be closer to the outer layer 27, or see accordingly. Figure 5As shown, they are in direct contact through the corresponding fiberglass layers 28 and 30. Therefore, the shell area is very thin. As shown, additional reinforcing devices 32 can be arranged in this area, here in the form of additional fiberglass layers 33, which are either adjacent to the fiberglass layer 30 of the inner layer 29 or sandwiched between the fiberglass layers 28 and 30. Although in Figure 5 Only one glass fiber layer 28, 30 and 33 is shown, but it is possible that more of each of these layers could be provided.

[0041] Preferably, a plurality of glass fiber layers 33 are provided. These can be uniaxial or biaxial layers, and the two types can be integrated in a random order, such as a uniaxial layer followed by a biaxial layer, which in turn is a uniaxial layer, or in any other order. The biaxial fiber layer or fabric comprises fibers arranged at an angle of 0°, while other fibers are arranged at angles of, for example, ±45°. Such a biaxial layer is advantageous because it allows for the resistance to loads in different directions or correspondingly different types, such as flapwise or edgewise bending loads from the blades. The uniaxial layer is preferably adapted to reinforce resistance to flapwise bending.

[0042] As a whole, the corresponding attachment area is thinner than the blade section adjacent to the attachment section.

[0043] In order to attach the corresponding flange 22 of each web 16, 17 to the half shell 12, 13, an adhesive 34 is used, through which the flange 22 is firmly attached to the corresponding shell 12, 13.

[0044] As already mentioned, in order to manufacture the blade 5 of the present invention, both the webs 16 and 17 and the housings 12 and 13 are manufactured separately in corresponding molds. The corresponding components of the webs 16 and 17 and the housings 12 and 13 are arranged in a specific mold, which is then filled with resin to securely embed all components. The web components are embedded in resin 21, while the housing components are embedded in resin 35.

[0045] Subsequently, the two half-shells 12 and 13 are arranged on top of each other, and the webs 16 and 17 are arranged between them and fixed to the respective shells 12 and 13 by adhesive 34. Adhesive 14 is also provided so that the entire blade 5 is firmly fixed.

[0046] Figure 6Another embodiment of the blade design for the attachment region of the corresponding web flange 22 is shown. Similarly, the inner layer 29, or its corresponding fiberglass layer 30, is directed closer to the outer shell surface of the outer layer 27, or the corresponding outer fiberglass layer 30, but not in direct contact. As shown, at least one core element 36 is sandwiched or interposted between the outer layer 27 and the inner layer 29, or between the corresponding outer fiberglass layer 28 and the inner fiberglass layer 30. This core element 36 may also be made of a lightweight reinforcing material suitable as a reinforcing device 32, such as balsa wood, high-density foam, etc.

[0047] Even with such a core element 31 integrated, the total thickness of the housings 12 and 13 in the attachment region is still significantly less than the thickness of the housings 12 and 13 in the adjacent portions where the core element 31 is sandwiched. Therefore, as Figure 5 and Figure 6 As shown, the respective flanges 22 of the web 16 and the flanges of the web 17 can be integrated into corresponding recesses in the surfaces of the inner layers 29 of the respective housings 12, 13 by means of adhesive 34. This allows the respective flanges 22 to be recessed into the inner layers 29 or surfaces, which can be almost flush with the surface. A very compact design and arrangement can be achieved, which reduces the overall mass of the blade and advantageously provides only one adhesive joint between the integral web reinforcement structure 23 and the housings 12, 13. Since no adhesive joint is provided between the respective reinforcement structures 23, i.e., the respective spar caps of the stacks 24 including pultruded carbon strips 25, and the web body 18, the robustness of the blade design can be increased.

[0048] Another advantage is that the joint itself, achieved by the adhesive 34, can be repaired if needed, because the joint area can be drilled from the outside of the blade 5, since only the glass fiber layer in the matrix resin 35, or possibly the core element 36, is arranged in the area, which can be easily drilled.

[0049] Another advantage of the separate manufacturing of the H-shaped webs 16 and 17 is that the quality of the webs can be thoroughly inspected, ensuring perfect web quality, and any repairs can be made directly on the web manufacturing side if necessary, without affecting the lead time of the shell mold.

[0050] Similarly, the basic configuration of all webs arranged in the blade is the same. Each web includes: a corresponding web body having a core and resin within an outer glass fiber layer; and an integrated flange comprising an integrated reinforcing structure consisting of at least one stack of pultruded strips comprising carbon fibers, regardless of whether the corresponding web extends almost the entire blade length or only a portion thereof. If desired, each of these web flange integrated reinforcing structures may also include two or more parallel carbon pultruded stacks, thereby allowing the geometry of the corresponding flange to be shaped according to the geometry of the attachment region. Independent of the final web configuration, they all share the common feature that the corresponding reinforcing structure or corresponding sparsor cap is fully integrated into the web.

[0051] Although the invention has been described in detail with reference to preferred embodiments, the invention is not limited to the disclosed examples, and other variations can be derived by those skilled in the art from the disclosed examples without departing from the scope of the invention.

Claims

1. A wind turbine blade having a generally hollow blade body (11), the blade body (11) comprising upper and lower half-shells (12, 13) and first and second elongated webs (16, 17), each of the first and second elongated webs (16, 17) extending along the longitudinal direction of the blade (5) and disposed between and connected to the upper and lower half-shells (12, 13), wherein each web (16, 17) includes upper and lower flanges (22) connecting the respective web (16, 17) to the respective half-shell (12, 13), and wherein the first and second webs (16, 17) are supported relative to the respective half-shells (12, 13) by respective first and second reinforcing structures (23), the reinforcing structures (23) extending along the longitudinal direction of the blade (5), wherein, Each of the first and second reinforcing structures (23) supporting the first and second webs (16) includes at least one stack (24) consisting of a plurality of pultruded composite strips (25) comprising carbon fibers, wherein the strips (25) are fixed in a resin matrix. The stack (24) is characterized in that each of the at least one stack consisting of the pultruded composite strips is an integral part of the corresponding first and second webs (17) and forms a corresponding flange (22) attached to the inner layer (29) of the corresponding upper and lower shells (12, 13). The inner layer (29) is arranged closer to the outer layer (27) in the region where the corresponding flange (22) of the corresponding web (16, 17) is attached to the inner layer (29). Additional reinforcing devices (32) are arranged between the inner layer (29) and the outer layer (27) of the corresponding half-shells (12, 13).

2. The wind turbine blade according to claim 1, characterized in that, Two webs (16, 17) extend over approximately the same length of the blade (5), or a second web (16) arranged closer to the trailing edge (10) of the blade (5) extends only along a portion of the trailing edge (10).

3. The wind turbine blade according to claim 1 or 2, characterized in that, Each of at least one stack of the corresponding reinforcing structure (23) includes a biaxial glass and / or carbon fiber layer (26) between each pair of strips (25), the carbon fiber layer (26) being resin-infused.

4. The wind turbine blade according to claim 1 or 2, characterized in that, Each reinforcement structure (23) includes more than one stacked member arranged in parallel.

5. The wind turbine blade according to claim 1, characterized in that, The inner layer (29) is attached to the outer layer (27), or the additional reinforcing device (32) is arranged between the corresponding fiber layers (29, 30) of the inner layer (29) and the outer layer (27), or between the inner layer (29) or their corresponding fiber layers (30) and the flange (22).

6. The wind turbine blade according to claim 5, characterized in that, The reinforcing device (32) includes multiple glass fiber layers (33) or a core element (36) embedded in a resin matrix.

7. The wind turbine blade according to claim 6, characterized in that, Multiple additional core elements (31) are disposed between the outer and inner layers (27, 29) of the respective upper and lower half-shells (12, 13).

8. The wind turbine blade according to claim 7, characterized in that, The core element (36) or the other core element (31) is made of foam, wood, polymer or composite material.

9. A wind turbine comprising a plurality of wind turbine blades (5) according to any one of the preceding claims.

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