阅读说明：本技术 一种风力发电机叶片及该风力发电机叶片的制造方法 (Wind driven generator blade and manufacturing method thereof ) 是由 詹斯·格鲁德 吉安卡洛·吉罗洛米尼 拉尔斯·欧佛高 于 2020-04-22 设计创作，主要内容包括：一种风力发电机叶片(5)及制造该风力发电机叶片(5)的方法,其中,风力发电机叶片(5)包括复合结构(15,15’,15",15"’)及环绕层。复合结构(15,15’,15",15"’)包括拉挤成型元件(19)堆叠,其中相邻的拉挤成型元件(19)对之间设置有促进灌注层(23,23’,23",23"’,24)。促进灌注层(23,23’,23",23"’,24)比环绕层具有更高的渗透率,使得树脂在堆叠结构内的流动速度高于在环绕层中的流动速度。(A wind turbine blade (5) and a method of manufacturing the wind turbine blade (5), wherein the wind turbine blade (5) comprises a composite structure (15,15',15",15"') and a surrounding layer. The composite structure (15,15',15",15"') comprises a stack of pultruded elements (19), wherein between adjacent pairs of pultruded elements (19) a perfusion-promoting layer (23,23',23",23"',24) is arranged. The perfusion-promoting layer (23,23',23",23"',24) has a higher permeability than the surrounding layer, so that the flow velocity of the resin within the stacked structure is higher than the flow velocity in the surrounding layer.)

1. A wind turbine blade for a wind turbine, comprising:

-at least one composite structure having a length, a width and a thickness, the at least one composite structure comprising a plurality of pultruded elements arranged in at least one stack, wherein at least one perfusion-promoting layer having a first permeability parameter K in the width direction is provided between at least two adjacent pultruded elements in the at least one stack₁And has another permeability parameter K in the length direction₂In which K is₂Less than K₁，

-at least one surrounding layer arranged in relation to the at least one composite structure, the at least one surrounding layer having a second permeability parameter K in width direction_1aThe method is characterized in that:

-K₁greater than K_1aAnd an

-wherein a first infusion speed V of the resin through said at least one infusion-promoting layer₁Greater than a second infusion speed V of the resin through the at least one surrounding layer_1a。

2. The wind turbine blade according to claim 1, wherein the at least one infusion promoting layer is a fabric with unidirectional fibers.

3. The wind turbine blade of claim 2, wherein the fibers are angled at an angle of 85-95 degrees with respect to the length direction.

4. A wind turbine blade according to claim 2 or 3, wherein the fabric comprises untwisted threads.

5. Wind turbine blade according to any of claims 1 to 4, wherein said at least one pro-acceleration layer has an areal weight of 50-300 grams per square meter.

6. Wind turbine blade according to any of claims 1 to 5, wherein said at least one perfusion-promoting layer has a third permeability parameter K in the thickness direction₃In which K is₁Greater than K₃。

7. Wind turbine blade according to any of claims 1 to 6, wherein the local width of said at least one perfusion-promoting layer corresponds to the local width of said at least one stacking structure or one pultruded element.

8. Aerogenerator blade as claimed in any of the claims 1 to 7, characterized in that said at least one surrounding layer constitutes a part of said composite structure or an aerodynamic shell of the aerogenerator blade.

9. Wind turbine blade according to any of claims 1 to 8, wherein said composite structure constitutes a spar cap of said wind turbine blade.

10. A method of manufacturing a wind turbine blade, comprising:

-providing a plurality of pultruded elements

-further providing at least one surrounding layer having a second permeability parameter K in the width direction_1a，

-arranging the plurality of pultruded elements in at least one stack, wherein at least one perfusion-promoting layer having a first permeability parameter K in the width direction is arranged between adjacent pultruded elements within the at least one stack₁Another permeability parameter K in the length direction₂Wherein, K is₂Less than K₁,

-introducing a resin into the at least one stacked structure and the at least one surrounding layer using a potting process,

-curing the at least one stack with a resin to form a composite structure having a length, a width and a thickness,

characterized in that K is₁Greater than K_1aSo that the resin is poured at a first pouring speed V₁Flows through the at least one perfusion-promoting layer and is further perfused at a second perfusion velocity V_1aFlows through the at least one surrounding layer, wherein V₁Greater than V_1a。

11. The method of claim 10, wherein the resin is introduced chordally.

12. The method of claim 10 or 11, wherein the plurality of pultruded elements and the perfusion-promoting layer are laid in a blade mould or a separate mould and cured while being placed in the blade mould or the separate mould.

13. Fabrics with unidirectional glass fibers and untwisted threads are used as a resin promoting layer in a composite structure in a wind turbine blade.

Technical Field

The invention relates to a wind turbine blade comprising a spar cap formed from a stack of pultruded elements, wherein a perfusion promoting layer is provided between adjacent pultruded elements in the stack. The stack is filled with resin in the width direction through a series of filling channels and excess resin is removed from the stack through a series of outlet channels.

Background

It is well known that the manufacture of wind turbine blades requires the formation of preforms which are manufactured using a pultrusion process or an extrusion process. The preforms are then arranged to form a stack structure, and resin is then injected to form a blade component, such as a spar cap. This stacked structure makes it difficult to detect any internal defects using non-destructive testing (NDT).

Thus, a perfusion-promoting layer may be arranged relative to the stack to control the flow of resin around the stack. Furthermore, a facilitated infusion layer may be arranged between adjacent preforms to control resin flow through the stack. Thereby reducing the risk of backfill and dry spots in the stacked structure.

WO 2015/096840 a1 discloses a permeable fibre layer arranged at the chordwise edges of the stack and the core element. The resin is introduced through a set of inlet channels and further enters the stack through the chordal edge. The permeable fiber layer has an areal weight of 100-700 grams per square meter (gsm) that limits resin flow in the spanwise direction and provides for controlled resin flow in the chordwise direction.

WO 2016/015736 a1 discloses a perfusion-promoting layer arranged between adjacent pultruded elements and a further perfusion-promoting layer arranged between stacks of adjacent pultruded elements. The perfusion-promoting layer is a woven biaxial fiber layer with interwoven twists. The fiber layer had an areal weight of 100-300gsm and the fibers were arranged at 0/90 degrees or +/-45 degrees. It is claimed that the rate of infusion through the infusion-promoting layer may be selected to match the rate of infusion of the other blade members, or to be within 5-15% of the rate of infusion of the other blade members.

WO 2018/029240 a1 likewise discloses a perfusion-promoting layer arranged between adjacent pultruded elements. In this patent, the perfusion-promoting layer is a Unidirectional (UD) fiber layer, and the fibers are aligned with the axial direction of the stacked structure. The areal weight of the fibrous layer was 800 gsm.

WO 20147/108685 a1 discloses a plurality of flow-promoting strips arranged between adjacent layers of GFRP or CFRP material. The flow-promoting strips are spaced to form internal channels for resin flow. The flow-promoting strips are angled at 90 degrees or 40-45 degrees from the longitudinal direction of the stack.

Disclosure of Invention

It is an object of the present invention to provide an alternative composite structure and method of controlling resin flow through the composite structure.

It is another object of the present invention to provide a composite structure and method that enables the quality of the perfusion to be checked using non-destructive testing methods.

It is a further object of the present invention to provide a composite structure and method having improved resin promoting properties.

One object of the invention is achieved by a wind turbine blade for a wind turbine, comprising:

-at least one composite structure having a length, a width and a thickness, the at least one composite structure comprising a plurality of pultruded elements arranged in at least one stack, wherein at least one perfusion-promoting layer having a first permeability parameter K in the width direction is provided between at least two adjacent pultruded elements of the at least one stack₁And has another permeability parameter K in the length direction₂In which K is₂Less than K₁，

-at least one surrounding layer arranged with respect to the at least one composite structure, the at least one surrounding layer having a second permeability parameter K in width direction_1aThe method is characterized in that:

-K₁greater than K_1aAnd an

-wherein a first infusion speed V of the resin through said at least one infusion-promoting layer₁Greater than a second infusion speed V of the resin through the at least one surrounding layer_1a。

This provides a composite structure that has high resin permeability in the chordwise direction and therefore can have a high infusion rate in the chordwise direction. The local infusion rate of the present composite structure within the stack is greater than the local infusion rate of the blade component adjacent to the composite structure. This ensures correct pouring of the stack and prevents backfilling of the intermediate layer. Furthermore, it may also prevent the formation of potential dry spots inside the stack, thereby allowing the composite structure to be inspected using non-destructive testing.

Herein, the term "intermediate layer" is defined as any layer arranged within the stack. Furthermore, the term "surrounding layer" is defined as any layer adjacent or proximate to one or both edges or sides of the stack. Furthermore, the term "blade component" is defined as an aerodynamic shell or other structural component of a wind turbine blade. The hoop layer may form part of the composite structure or blade component.

The composite structure includes stacked pultruded elements arranged in one or more rows and/or columns. Preferably, all or part of the rows and/or columns comprise two or more pultruded elements arranged in the width direction and/or the length direction. The stack includes a first side and a second side arranged between a first edge and a second edge, wherein each edge and side extends in a length direction. Thus, the number of pultruded elements may be adapted to the geometry of the wind turbine blade and/or the thickness of the blade shell and spar cap of the wind turbine blade.

Preferably, the pultruded elements comprise rounded corners extending in the longitudinal direction. This reduces the risk of pinching the surrounding and/or intermediate layer, thereby providing a more robust perfusion process. Thus, wrinkles can be prevented from being formed in the surrounding layer and/or the intermediate layer.

According to one embodiment, the at least one perfusion-promoting layer is a fabric with unidirectional fibers.

The inventors have found that a perfusion-promoting layer formed from a fabric with unidirectional fibres has a surprising effect on the mechanical properties of the composite structure. The unidirectional fiber fabric increases the fracture toughness at the interface between individual pultruded elements in the stacked configuration. For example, the interface may have a thickness of about 1100J/m²The rate of energy release. Fracture toughness testing indicates that twisted fabrics fail at lower forces.

The fibers may be made of glass, carbon, aramid, metal, polyester or nylonAnd (4) preparing. Thus, the permeability (K) of the fabric in the direction of the dimension₁) Can be higher than the permeability (K) in the cross-fiber direction₂). Thus, the fabric may be used to direct the flow of resin along the fibers during infusion, thereby providing a controlled flow of resin. This results in a permeability ratio (K) of the fabric₁/K₂) And (4) maximizing.

Mention is made of WO 2016/015736A 1The woven fabric of TF970 is a biaxial fabric with a fiber orientation of 0/90 °. Unlike this, the fibers are symmetrically arranged so that they have equal permeability in the longitudinal and width directions. Such fabrics are commonly used in the production of wind turbine blades.

Preferably, the fabric may be a non-crimp fabric in which unidirectional fibers are disposed in a plurality of multiple layers. The plurality of layers of unidirectional fibers may be stitched together in the thickness direction using a stitching thread. Due to the high fiber straightness, the fabric has good mechanical properties. Such fabrics may also have higher permeability than crimped fabrics. Furthermore, due to its excellent drapability, the fabric is better able to conform to the shape of the stacked structure.

Alternatively, the fabric may be a crimped fabric in which unidirectional fibers are interwoven with weft yarns in one or more layers. The weave pattern may be selected according to the best compromise between mechanical properties and fabric integrity. This gives the fabric good shear strength and may have a competitive price advantage over non-crimped fabrics.

According to one embodiment, the fibers are angled from 85 to 95 degrees from the length direction.

Preferably, the fibres are orientable with respect to the length direction of the fabric. The fibers may be angled at an angle of 85 to 95 degrees, such as between 88 and 92 degrees, relative to the length direction. The fiber direction can be selected according to the desired flow rate. The high permeability in the width direction causes the resin to flow mainly in that direction.

According to one embodiment, the fabric comprises untwisted threads.

The fabric may advantageously comprise untwisted threads which have a surprising effect on improving resin flow compared to twisted threads. This in turn promotes fibre bridging and results in improved mechanical properties of the interface between two adjacent pultruded elements. This reduces the spacing between adjacent pultruded elements compared to the twisted threads of WO 2016/015736 a 1.

The inventors have found that the use of untwisted yarns can further enhance the effect of using unidirectional fibers. Thus, the use of unidirectional fibers and twisted threads has an enhanced combination of effects.

According to one embodiment, the areal weight of the at least one promoter layer is from 50 to 300 grams per square meter.

The areal weight of the perfusion-promoting layer may be between 50 and 300 grams per square meter (gsm), preferably 100-200gsm, for example 150-180 gsm. This provides for optimal resin infusion through the intermediate layer. The area weight of commercially available unidirectional glass fabrics is much higher than 300gsm, which is not suitable for use as a resin promoting layer due to the high area weight.

According to one embodiment, the at least one perfusion-promoting layer further has a third layer in the thickness directionPermeability parameter K₃And K is₁Greater than K₃。

The stack structure may comprise one or more perfusion-promoting layers extending in the thickness direction between adjacent pultruded elements or stacks of adjacent pultruded elements. Alternatively, the one or more perfusion-promoting layers may extend partially in the thickness direction and partially in the width direction. The perfusion-promoting layer may also have a permeability parameter K in the thickness direction₃In which K is₃Less than K₁. This reduces the local perfusion rate in the thickness direction and reduces the risk of backfill.

Further, the stack structure may also include one or more perfusion-promoting layers extending lengthwise between adjacent pultruded elements in one or more stacks. Alternatively, the one or more perfusion-promoting layers may extend partially in the length direction and/or partially in the width direction. The perfusion-promoting layer may also have a permeability parameter K in the length direction₂In which K is₂Less than K₁. This achieves a controlled resin flow in the length direction.

Further, one or more hoop layers may extend partially or completely in the width direction and/or the length direction. For example, the surrounding layer may be arranged on the first side and/or the second side of the stack. Alternatively, one or more of the surrounding layers may extend partially or fully in the width direction and/or the thickness direction. For example, the surrounding layer may be arranged on a first and/or second edge of the stack. For example, the surrounding layers may be arranged on first and second edges of the second side of the stack. For example, the hoop layer may surround or enclose the stack in the width plane and extend partially or completely along the length of the stack. During infusion, the surrounding layer may act as a resin distribution layer.

Further, the surrounding layer may have a permeability parameter K in a length direction_2aIn the thickness direction, there may also be a permeability parameter K_3a. Preferably, the permeability parameter K of the surrounding layer_2aLess than permeability parameter K of the perfusion-promoting layer₁. Furthermore, the permeability parameter K of the surrounding layer_3aLess than permeability parameter K of the perfusion-promoting layer₃. This may ensure that the stack is correctly primed, thereby avoiding internal dry spots or air pockets.

According to one embodiment, the local width of the at least one perfusion-promoting layer corresponds to the local width of the at least one stack structure or one pultruded element.

The width and/or length of each perfusion-promoting layer may be adapted to the geometry and shape of the composite structure and/or the wind turbine blade.

For example, the local width of the perfusion-promoting layer may correspond to the width of one or a row of pultruded elements. This enables the priming layer to extend the full width of the stack. Similarly, the local length of the perfusion-promoting layer may correspond to the length of one or an array of pultruded elements. This enables the perfusion-promoting layer to extend the entire length of the stack.

For example, the perfusion-promoting layer may extend along one or more pultruded elements in the width direction and further along a column of pultruded elements in the thickness direction. Thereby enabling the local width of the perfusion-promoting layer to be adapted to the width and thickness of the stacked structure.

The pultruded elements may be arranged in rows and columns within the stack. Alternatively, the pultruded elements may be arranged in a zigzag pattern within the stack. Alternatively, the pultruded elements may be offset relative to each other to form a composite structure having a parallelogram or trapezoidal cross-sectional profile.

According to one embodiment, the at least one surrounding layer constitutes a part of the composite structure or an aerodynamic shell of the wind turbine blade.

A hoop layer may be disposed on the first side and/or the second side of the composite structure. For example, the first resin distribution layer may be arranged on the first side after lamination or placement of the composite structure. Further, the second resin distribution layer may be arranged in the recess of the pneumatic housing such that it faces the second side of the composite structure. This enables the resin to be distributed over the composite structure during infusion.

Alternatively, an additional perfusion-promoting layer may extend partially or completely around the stacked structure. The additional priming-promoting layer may form a protruding flange on the inner surface of the pneumatic housing. This enables a controlled resin flow around the stack.

Alternatively, the stack may comprise a plurality of surrounding layers arranged at a first side of the stack. The stack may also include a plurality of surrounding layers disposed on a second side of the stack. These surrounding layers may act as the inner and/or outer skin of the composite structure. A perfusion promoting layer may be arranged between the outer skin and the outermost row of pultruded elements. A further infusion promoting layer may be arranged between the inner skin and the innermost row of pultruded elements.

According to one embodiment, the composite structure constitutes a spar cap for a wind turbine blade.

The present composite structure is advantageous as a spar cap, but may also form part of another structural component of a wind turbine blade, such as a shear web.

One object of the invention is also achieved by a method of manufacturing a wind turbine blade, comprising:

-providing a plurality of pultruded elements

-further providing at least one surrounding layer having a second permeability parameter K in the width direction_1a，

-arranging the plurality of pultruded elements in at least one stack, wherein at least one perfusion-promoting layer having a first permeability parameter K in the width direction is arranged between adjacent pultruded elements within the at least one stack₁Permeability parameter K in the length direction₂In which K is₂Less than K₁,

-introducing a resin into the at least one stacked structure and the at least one surrounding layer using a potting process,

-curing the at least one stack with a resin to form a composite structure having a length, a width and a thickness,

characterized in that K is₁Greater than K_1aThis enables the resin to be poured at a first pouring speed V₁Flows through the at least one perfusion-promoting layer and is further perfused at a second perfusion velocity V_1aFlows through the at least one surrounding layer, wherein V₁Greater than V_1a。

The method allows resin to flow faster in the intermediate layers of the stack than in the surrounding layers, thereby reducing the risk of backfill and dry spots forming inside the stack. This enables the composite structure to be non-destructively tested.

The resin is introduced into the inlet channel at a predetermined infusion rate and then distributed over the composite structure. Then, the resin flows through the inside of the stacked structure via the intermediate layer, and further flows around the stacked structure. The permeability of the composite structure means that the resin flows faster through the stack than around the stack. This ensures correct priming of the stacked structure.

According to one embodiment, the resin is introduced in a chord direction.

After the stacking is completed, the injection channels may be provided on the stacking and/or the pneumatic housing. The injection passage may extend in a length direction and enable introduction of resin into the stacked structure in a width direction. This enables a simpler and faster perfusion process.

The invention can suitably be used to incorporate different types of resins, such as epoxy, polyester, vinyl ester or polyurethane.

According to one embodiment, the plurality of pultruded elements and the perfusion-promoting layer are laid in a blade mould or a separate mould and cured when placed in the blade mould or the separate mould.

The present composite structure may be manufactured directly in a blade mould, wherein the pultrusion elements and the perfusion-promoting layer are laid in the grooves of the pneumatic housing. The stack is then poured in one step together with the rest of the pneumatic housing and cured. This enables the composite structure to be integrated into a pneumatic housing.

Alternatively, the pultruded elements and the infusion-promoting layer may be laid down in separate moulds, wherein resin may be introduced into the stack. The stacked structure with resin may then be cured to form a composite structure. The cured composite structure may then be lifted into place and bonded to the pneumatic housing using an adhesive or resin infusion. This enables the composite structure to be manufactured separately from the blade mould.

Alternatively, the dried stack may be lifted into position on the pneumatic housing and then the resin injected. The stacked structure with the resin may be cured. This allows the composite structure to be poured while placed in the blade mould.

One object of the invention is also achieved by using a fabric with unidirectional glass fibers, preferably with untwisted threads, as a resin promoting layer in a composite structure of a wind turbine blade.

The inventors have found that the internal infusion rate within the composite structure can be significantly increased compared to conventional resin promoting layers such as those mentioned in WO 2016/015736 a 1. This achieves the advantageous effect that the composite structure can be poured faster than the surrounding layers, thereby ensuring that the composite structure is correctly poured.

The inventors have also found that the resin flow in unidirectional glass fabric can be further improved by using untwisted threads. Compared with the traditional twisted glass fiber fabric (such asTF970), the use of untwisted yarn also provides the composite structure with a higher fracture toughness.

Drawings

The invention is described by way of example only and with reference to the accompanying drawings in which:

figure 1 shows an exemplary embodiment of a wind power generator,

figure 2 shows a first embodiment of a wind turbine blade,

figure 3 shows a second embodiment of a wind turbine blade,

figure 4 shows a first embodiment of the composite structure,

figure 5 shows a second embodiment of the composite structure,

figure 6 shows the composite structure and the pneumatic housing during resin infusion,

figure 7 shows a first embodiment of a composite structure,

figure 8 shows a second embodiment of the composite structure,

figure 9 shows a third embodiment of a composite structure,

figure 10 shows a fourth embodiment of the composite structure,

FIGS. 11a-e illustrate the flow of resin through a composite structure during infusion, an

Fig. 12 shows a test apparatus for determining permeability parameters of a perfusion-promoting layer.

In the following, the drawings will be described one by one, and different parts and positions seen in the drawings will be numbered with the same numerals in different drawings. Not all of the components and locations indicated in the drawings need be discussed with this drawing.

Wherein the content of the first and second substances,

1 wind power generator

2 wind power generator tower

3 cabin

4 yawing mechanism

5 wind driven generator blade

6 rotor hub

7 variable pitch mechanism

8 tip, second end

9 blade root, first end

10 leading edge

11 trailing edge

12 main beam cap

13 second end

14 first end

15 composite structure

16 grooves

17 pneumatic housing

18 shear web

19 pultrusion element

20 pneumatic outer cover inner skin

21 pneumatic housing skin

22 core element

23 perfusion-promoting layer

24 perfusion-promoting layer

25 injection channel

25a outlet channel

26 width direction

27 length direction of

28 thickness direction

29 composite structural endothelium

30 composite structural skin

31 substrate and tray

32 cover and lid

33 seal

34 vacuum channel

35 outlet port

36 sprue

V₀Resin injection rate

V₁Promoting the perfusion rate of the perfusion layer

V_1aPerfusion rate of surrounding layer

K₁Permeability parameter for promoting width direction of perfusion layer

K_1aPermeability parameter across the width of the surrounding layer

K₂Permeability parameter for promoting length direction of perfusion layer

K_2aPermeability parameter in the length direction of the surrounding layer

K₃Permeability parameter for promoting thickness direction of perfusion layer

K_3aPermeability parameter around the thickness direction of the layer

Detailed Description

Fig. 1 shows a wind turbine 1 comprising a wind turbine tower 2 and a nacelle 3 arranged on top of the wind turbine tower 2 by a yaw mechanism 4. The yaw mechanism 4 is configured to yaw the nacelle 3 into a yaw angle. The rotor comprises at least two wind turbine blades 5 mounted to a rotor hub 6 by a pitch mechanism 7. The pitch mechanism 7 is configured to pitch the wind generator blades 5 to a pitch angle. The rotor hub 6 is rotatably connected to a generator arranged in the wind turbine 1 by means of a rotor shaft.

Each aerogenerator blade 5 comprises a tip 8 and a root 9, wherein the aerogenerator blade 5 comprises an aerodynamic profile defining a leading edge 10 and a trailing edge 11.

Fig. 2 shows a first embodiment of a wind turbine blade 5, in which the wind turbine blade 5 is a full-span blade. The aerogenerator blade 5 comprises a spar cap 12, which spar cap 12 extends from a local first end towards the blade root 9 to a local second end towards the tip 8.

Fig. 3 shows a second embodiment of a wind turbine blade 5, in which the wind turbine blade 5 is a modular blade. The wind turbine blade 5 comprises an inner blade section extending from a first end, which may for example be the blade root 9, to a second end 13 and further from the leading edge 10 'to the trailing edge 11'. The aerogenerator blade 5 also comprises an outer blade section extending from a first end 14 to a second end, which may be for example the tip 8, and further from a leading edge 10 'to a trailing edge 11'.

Similarly, the spar cap 12' is divided into an inner portion disposed in the inner blade section and an outer portion disposed in the outer blade section. The two blade segments, including the spar cap 12' portions, are joined at the interface of the first and second ends 13, 14.

The wind turbine blade 5 may also be a partial pitch blade, wherein the pitch mechanism 7 is arranged at the second end 13. In this configuration, the pitch mechanism 7 is configured to pitch the outer blade section relative to the inner blade section.

Fig. 4 illustrates a first embodiment of a spar cap 12, 12' formed from a composite structure 15. Here, the composite structure 15 is manufactured in a separate mould (not shown) and then placed in a recess 16 of an aerodynamic shell 17 of the aerogenerator blade 5. The composite structure 15 will subsequently be bonded to the pneumatic housing 17 by adhesive or resin infusion.

Here, the composite structure 15 and the pneumatic housing 17 have no curvature in the width direction. However, both the composite structure 15 and the aerodynamic shell 17 may be curved in the width direction.

Fig. 5 shows a second embodiment of a composite structure 15', which composite structure 15' is manufactured directly in the recess 16 of the pneumatic housing 17. Here, a stack structure is laid in the groove 16, and resin is injected. The stacked structure with resin is then cured to bond the composite structure 15' to the pneumatic housing 17.

Structural components are then arranged on the spar caps 12, for example on the composite structure 15', in the form of shear webs 18.

Fig. 6 shows the composite structure 15 and the pneumatic housing 17 during resin infusion. A stack comprising six pultruded elements 19 is shown.

The plurality of fibre layers forms an inner skin 20 of the aerogenerator blade 5. Furthermore, a plurality of fiber layers form the outer skin 21 of the wind turbine blade 5. A plurality of core elements 22 are arranged between the inner and outer skins 20, 21 forming a sandwich structure.

The stack is arranged between core elements 22 as shown in figure 6 to form a unified composite structure. A plurality of perfusion-promoting layers 23, 24 are arranged between adjacent pultruded elements 19. Here, the partial perfusion-promoting layer 23 extends in the width direction 26 and has a partial width corresponding to the width of the pultruded element 19. The further perfusion-promoting layer 24 extends in the thickness direction 28 and locally has a width equal to the thickness of the stack.

As shown in fig. 6, the pultruded elements 19 and the perfusion-promoting layer, for example, in the composite structure 15 further extend in the length direction 27.

The perfusion-promoting layers 23, 24 have a permeability parameter K in the width direction₁Having a permeability parameter K in the length direction₂And a permeable member having a permeability in the thickness directionNumber K₃。

The resin is injected into a series of injection channels 25 provided on the pneumatic housing 17, optionally the injection channels 25 being provided on the composite structure 15. Resin injection velocity V₀Is injected into the injection channel 25. Then, resin is introduced into the pneumatic housing 17 and enters the composite structure 15 in the width direction.

Resin is poured at a speed V₁Flows through the perfusion-promoting layer 23 and thus through the stack. Furthermore, the resin is poured at a speed V_1aFlows through the surrounding layer, which may be, for example, the inner skin 20. In this configuration, the perfusion velocity V₁Greater than the filling speed V_1aThis ensures that the stack is correctly primed.

Fig. 7 shows a first embodiment of a composite structure 15, in which the pultruded elements 19 are arranged in rows and columns. An infusion promoting layer 23 is arranged between adjacent pultruded elements 19 in each column. Furthermore, a perfusion-promoting layer 24 is arranged between adjacent columns of pultruded elements 19.

Fig. 8 shows a second embodiment of a composite structure 15", in which the first side of the stack of pultruded elements 19 is provided with an inner skin 29. Furthermore, a skin 30 is provided on a second side of the stack of pultruded elements 19. The inner skin 29 and the outer skin 30 each include a plurality of fiber layers extending in the width direction and the length direction.

A further perfusion-promoting layer 23 is also arranged between the inner skin 29 and the stack. Similarly, a further perfusion-promoting layer 23 may also be provided between the skin 30 and the stack. Here, a facilitated infusion layer 23 is arranged between one column of the stack and the skin 30, while another facilitated infusion layer 23' is arranged between another column of the stack and the skin 30. The infusion-promoting layer 23' further extends in the thickness direction between the two rows of pultruded elements 19.

Fig. 9 shows a third embodiment of a composite structure 15"', in which the pultruded elements 19 are arranged in a zigzag pattern. As shown in fig. 9, the second row of pultruded elements 19 is offset with respect to the first and third rows of pultruded elements. The infusion-promoting layer 23 "extends along the entire width of a row of pultruded elements 19 to ensure that the composite structure is correctly infused with resin.

Fig. 10 shows a third embodiment of a composite structure 15', in which the pultruded elements 19 are arranged in an offset pattern. The second row of pultruded elements 19 is offset with respect to the first row of pultruded elements. The third row of pultruded elements 19 is further offset with respect to the second row of pultruded elements and so on, as shown in fig. 9. The facilitated infusion layer 23"' extends along the entire width of the row of pultruded elements 19 to ensure that the composite structure is correctly infused with resin.

Fig. 11a-e show a schematic view of the resin flow through the composite structure 15 and the pneumatic housing 17 during infusion. Fig. 11a shows a cross-section of the composite structure 15 arranged between the upper and lower fibre layers of the wind turbine blade 5 after the laying process has been completed.

Here, the lower fibre layer forms at least the outer skin 21 of said pneumatic housing 17. The upper fibrous layer is formed by an inner skin 20 extending over the composite structure 15. Alternatively, the upper fibrous layer may be formed from an additional fibrous layer that extends on top of the composite structure 15 and also extends along a portion of the inner skin 20 on both sides of the composite structure 15.

The infusion and outlet channels are then placed on the inner surface and the entire structure is enclosed in a vacuum bag by sealing the respective edges. The resin infusion system is then connected to the respective injection ports and outlets so that air can be expelled from the enclosed space.

For ease of illustration, only one outlet channel 25a is shown in FIGS. 11 b-d. Alternatively, more than one outlet channel 25a may be placed above the composite structure, as shown in dashed lines.

As shown in fig. 11b, the resin is introduced chordally from the side. As shown in fig. 11b-d, during infusion, the front end of the resin flows faster within the composite structure 15 than in the upper and lower fiber layers. As shown in fig. 11b, the permeability of the perfusion-promoting layer 23Number K₁Higher than permeability parameter K of upper and lower fiber layers_1aThus the internal filling velocity V₁Greater than the external perfusion velocity V_1a。

When the resin front reaches the resin promoting layer 24 disposed between the stacks or rows of pultruded elements 19, the resin will flow in the thickness direction along the resin promoting layer 24 while continuing to flow in the chord direction. As shown in fig. 11d, the resin will then enter the upper and lower fiber layers disposed at the stack or column interface and begin to flow in the opposite chordal direction. Excess resin will enter the outlet channel 25a from the opposite side.

Similarly, when the resin front reaches the opposite side edge of the composite structure 15, the resin will flow in the thickness direction. Subsequently, the resin will enter the upper and lower fibre layers at the side edges and start to flow in the opposite direction chordally towards the outlet channel 25 a. The resin may also continue to flow along the inner and outer skins 20, 21 to an outlet passage (not shown) on the pneumatic housing 17.

This prevents the formation of dry spots in the fibre laminate and ensures that the composite structure 15 is correctly resin-impregnated. Figure 11e shows the composite structure 15 and the upper and lower fibre layers after infusion. For ease of illustration, the infusion channels, the outlet channels, and the vacuum bag are omitted. Subsequently, the poured structure is cured.

Fig. 12 shows a test arrangement for determining permeability parameters of the perfusion-promoting layers 23, 24. Here, the testing device is configured to determine in-plane a first and a second permeability parameter k of said perfusion-promoting layer 23, 24₁And k₂。

The test samples 23', 24' of the perfusion-promoting layers 23, 24 are arranged on a substrate 31, which substrate 31 may be, for example, a glass tray or tray. A cap or cover 32 is placed on top of the test samples 23', 24', and the substrate 31 and cover 32 are sealed by a seal 33. A vacuum channel 34 is provided in the sealed space and is connected to an outlet 35 for evacuation of the sealed space.

Subsequently, resin is introduced into the test specimens 23', 24' from an injection port 36, which may be located, for example, in the center of the test specimens 23', 24'. Next, the permeability of the test samples 23', 24' is measured in-plane by using standardized measurement techniques. As shown in fig. 12, the first and second permeability parameters k1 and k2 for each direction are determined based on the measurements.

As can be seen from the test results, the glass fiber fabric having no twisted threads in the present invention has improved resin flowability as compared to the conventional glass fiber fabric having twisted threads. Furthermore, it can be seen from the test results that the unidirectional fabric of the present invention also has improved resin flow compared to the conventional biaxial fabric. From the test results, it is known that the optimum results are achieved by the combination of unidirectional glass fiber fabric and non-twisted threads.