AN IMPROVED INTERLAYER, SPAR CAP AND WIND TURBINE BLADE

Abstract

A flow-enhancing fabric extends in a longitudinal direction and in a transverse direction. The fabric includes a plurality of fibre layers including a first fibre layer and a second fibre layer arranged upon each other, the first fibre layer has a first plurality of fibre bundles oriented in parallel in a first fibre direction and has a plurality of first glass fibre bundles and a number of first carbon fibre bundles. The second fibre layer has a second plurality of fibre bundles oriented in parallel in a second fibre direction different from the first direction and has a plurality of second glass fibre bundles and a number of second carbon fibre bundles. At least a number of first carbon fibre bundles intersect and contact a number of second carbon fibre bundles. The fabric has a plurality of monofilaments arranged between the first and second fibre layer along the transverse direction.

Claims

1-25. (canceled)

26. A flow-enhancing fabric (1) extending in a longitudinal direction (6) and in a transverse direction (8), the fabric comprising a plurality of fibre layers including a first fibre layer (10) and a second fibre layer (20) arranged upon each other, the first fibre layer (10) comprising a first plurality of fibre bundles oriented in parallel in a first fibre direction (16) and comprising a plurality of first glass fibre bundles (14) and a number of first carbon fibre bundles (13), and the second fibre layer (20) comprising a second plurality of fibre bundles oriented in parallel in a second fibre direction (26) different from the first direction and comprising a plurality of second glass fibre bundles (24) and a number of second carbon fibre bundles (23), so that at least a number of first carbon fibre bundles (13) intersect and contact a number of second carbon fibre bundles (23), and the fabric further comprises a plurality of monofilaments (30) arranged between the first and second fibre layer (10, 20) along the transverse direction (8) of the fabric, the plurality of monofilaments (30) each having a mutual spacing (31) between them.

27. A fabric (1) according to claim 26, wherein an angle between each of the first and second fibre directions (16, 26) relative to the longitudinal direction (6) of the fabric is in the range of 20-70 degrees or wherein an angle between the first and second fibre directions (16, 26) are between 70-110 degrees.

28. A fabric (1) according to claim 26, wherein the first and/or second fibre layer (10, comprises alternating glass fibre bundles (14, 24) and carbon fibre bundles (13, 23).

29. A fabric (1) according to claim 26, wherein the first and/or second fibre layer (10, comprises a carbon fibre bundle (13, 23) for every Xth glass fibre bundle (14, 24), wherein X is in the range of 2-50.

30. A fabric (1) according to claim 26, wherein at least some of the fibres in the fabric are stitched together with one or more threads, such that the fibre bundles, including the first and second glass fibre bundles (14, 24) as well as the first and second carbon fibre bundles (13, 23), and the monofilaments (30) are maintained relative to each other by a stitching pattern and/or wherein at least some of the fibres in the fabric, including the first and second glass fibre bundles (14, 24) as well as the first and second carbon fibre bundles (13, 23), and the monofilaments (30) are maintained relative to each other by a binder, such as neoxil.

31. A fabric (1) according to claim 26, wherein the monofilaments (30) are polymeric filaments, preferably thermoplastic monofilaments, such as polyester filaments, polypropylene filaments, polyethylene filaments, PET filaments, glass or other synthetic material or conductive fibres such as carbon fibres, cooper fibre or steel fibres or any combination thereof.

32. A fabric (1) according to claim 26, wherein the first fibre layer (10) has a first upper fibre surface (11) and a first lower fibre surface (12) and wherein the second fibre layer (20) has a second lower fibre surface (22) and a second upper fibre surface (21) and wherein the first fibre layer (10) and the second fibre layer (20) are arranged upon each other such that at least part of the first lower fibre surface (12) is in contact with the second upper fibre surface (21).

33. A fabric (1) according to claim 26, wherein the fabric (1) has an upper fabric surface (2) and a lower fabric surface (4) and wherein the first upper fibre surface (11) is the upper fabric surface (2) and the second lower fibre surface (22) is the lower fabric surface (4).

34. A fabric (1) according to claim 26, wherein the area weight of the flow-enhancing fabric is in the range of 50-500 g/m{circumflex over ( )}2.

35. A spar cap (100, 7400, 7600) for a wind turbine blade (1000) comprising a plurality of electrically conductive precured fibre-reinforced elements including a first precured fibre-reinforced element (50) and a second precured fibre-reinforced element (60), wherein a flow-enhancing fabric (1) according to claim 1 are arranged between the first precured fibre-reinforced element (50) and the second precured fibre-reinforced element (60).

36. A spar cap (100, 7400, 7600) according to claim 35, wherein each of the plurality of precured fibre-reinforced elements has a length in the longitudinal direction, a width in the transverse direction, and a height in a thickness direction, wherein the length is longer than the width and the width is longer than the height, wherein the first precured fibre-reinforced element (50) has a lower surface (52) and an upper surface (51) extending in the longitudinal direction and the width direction and the second precured fibre-reinforced element (60) has a lower surface (62) and an upper surface (61) extending in the longitudinal direction and the width direction, and wherein the first precured fibre-reinforced element (50) and the second precured fibre-reinforced element (60) are arranged such that the lower surface (52) of the first precured fibre-reinforced element (50) is facing the upper surface (61) of the second precured element (60), and wherein the flow-enhancing fabric (1) is being arranged between the lower surface (52) of the first precured fibre-reinforced element (50) and the upper surface (61) of the second precured element (60).

37. A spar cap (100, 7400, 7600) according to claim 35, wherein the flow-enhancing fabric (1) is arranged such that the longitudinal direction (6) of the flow-enhancing fabric (1) is substantially parallel with the length of the spar cap and the transverse direction (8) of the flow-enhancing fabric (1) is substantially parallel with the width of the spar cap.

38. A spar cap (100, 7400, 7600) according to claim 35, wherein the precured fibre-reinforced elements (50, 60) are pultruded carbon elements.

39. A spar cap (100, 7400, 7600) according to claim 35, wherein the spar cap is resin infused and wherein the thickness of the flow-enhancing fabric, when resin infused, is in the range of 0.2 mm-0.5 mm, such as 0.3 mm.

40. A wind turbine blade (1000) comprising a spar cap (100, 7400, 7600) according to claim 35.

41. Method of manufacturing a spar cap for a wind turbine blade according to claim 40, comprising the steps of: providing a plurality of precured fibre-reinforced elements and a plurality of flow-enhancing fabrics; arranging the plurality of precured fibre-reinforced elements to provide a desired spar cap structure, wherein the plurality of flow-enhancing fabrics are arranged between the plurality of precured fibre-reinforced elements to enhance resin flow between the plurality of precured fibre-reinforced elements; infusing the spar cap structure with resin; and curing the resin to form the spar cap.

42. The method according to claim 39, wherein the spar cap is made in a spar cap mould and the method further comprises the steps of: providing a spar cap mould, the spar cap mould comprising a moulding surface; and arranging the plurality of precured fibre-reinforced elements in the spar cap mould, and stacking them to provide a desired spar cap structure, wherein the plurality of flow-enhancing fabrics are arranged between the plurality of precured fibre-reinforced elements to enhance resin flow between the plurality of precured fibre-reinforced elements or wherein the spar cap structure is made directly in a blade shell member mould.

43. Method of manufacturing a wind turbine shell member comprising a spar cap according to claim 35, comprising the steps of: providing a blade shell member mould comprising a moulding surface and a moulding cavity; arranging a number of fibre-reinforced elements, such as fibre layers, within the blade shell member mould; arranging a spar cap according to claim 1 on a spar cap area of the fibre-reinforced elements; infusing the blade moulding cavity with resin; and curing the resin to form the blade shell member.

44. Method according to claim 43, wherein the spar cap is a pre-manufactured spar cap manufactured.

45. Method according to claim 43, wherein the spar cap is not pre-manufactured but is laid up directly in the blade mould.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0058] Embodiments of the disclosure will be described in more detail in the following with regard to the accompanying figures. The figures show one way of implementing the present disclosure and are not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

[0059] FIG. 1 is a schematic diagram illustrating a wind turbine,

[0060] FIG. 2 is a schematic diagram illustrating a wind turbine blade and a spar cap structure arranged within the wind turbine blade,

[0061] FIG. 3 is a schematic diagram illustrating a first or second fibre layer according to an embodiment of the present invention,

[0062] FIG. 4 is a schematic diagram illustrating a flow-enhancing fabric according to an embodiment of the present invention,

[0063] FIG. 5 is a schematic diagram illustrating a preferred embodiment of a flow-enhancing fabric according to the present invention, and

[0064] FIG. 6 is a schematic diagram illustrating a cross-sectional view of a flow-enhancing fabric arranged between precured fibre-reinforced elements.

DETAILED DESCRIPTION

[0065] Various exemplary embodiments and details are described hereinafter, with reference to the figures when relevant. It should be noted that the figures may or may not be drawn to scale and that elements of similar structures or functions are represented by like reference numerals throughout the figures. It should also be noted that the figures are only intended to facilitate the description of the embodiments. They are not intended as an exhaustive description of the invention or as a limitation on the scope of the invention. In addition, an illustrated embodiment needs not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced in any other embodiments even if not so illustrated, or if not so explicitly described.

[0066] FIG. 1 illustrates a conventional modern upwind wind turbine according to the so-called “Danish concept” with a tower 400, a nacelle 600 and a rotor with a substantially horizontal rotor shaft. The rotor includes a hub 800 and three blades 1000 extending radially from the hub 800, each having a blade root 1600 nearest the hub and a blade tip 1400 furthest from the hub 800.

[0067] FIG. 2A shows a schematic view of a first embodiment of a wind turbine blade 1000. The wind turbine blade 1000 has the shape of a conventional wind turbine blade and comprises a root region 3000 closest to the hub, a profiled or an airfoil region 3400 furthest away from the hub and a transition region 3200 between the root region 3000 and the airfoil region 3400. The blade 1000 comprises a leading edge 1800 facing the direction of rotation of the blade 1000, when the blade is mounted on the hub, and a trailing edge 2000 facing the opposite direction of the leading edge 1800.

[0068] The airfoil region 3400 (also called the profiled region) has an ideal or almost ideal blade shape with respect to generating lift, whereas the root region 3000 due to structural considerations has a substantially circular or elliptical cross-section, which for instance makes it easier and safer to mount the blade 1000 to the hub. The diameter (or the chord) of the root region 3000 may be constant along the entire root region 3000. The transition region 3200 has a transitional profile gradually changing from the circular or elliptical shape of the root region 3000 to the airfoil profile of the airfoil region 3400. The chord length of the transition region 3200 typically increases with increasing distance r from the hub. The airfoil region 3400 has an airfoil profile with a chord extending between the leading edge 1800 and the trailing edge 2000 of the blade 1000. The width of the chord decreases with increasing distance r from the hub.

[0069] A shoulder 4000 of the blade 1000 is defined as the position, where the blade 1000 has its largest chord length. The shoulder 4000 is typically provided at the boundary between the transition region 3200 and the airfoil region 3400.

[0070] It should be noted that the chords of different sections of the blade normally do not lie in a common plane, since the blade may be twisted and/or curved (i.e. pre-bent), thus providing the chord plane with a correspondingly twisted and/or curved course, this being most often the case in order to compensate for the local velocity of the blade being dependent on the radius from the hub.

[0071] FIG. 2B is a schematic diagram illustrating a cross-sectional view of an exemplary wind turbine blade 1000, e.g. a cross-sectional view of the airfoil region of the wind turbine blade 1000. The wind turbine blade 1000 comprises a leading edge 1800, a trailing edge 2000, a pressure side 2400, a suction side 2600, a first spar cap 7400, and a second spar cap 7600. The wind turbine blade 1000 comprises a chord line 3800 between the leading edge 1800 and the trailing edge 2000. The wind turbine blade 1000 comprises shear webs 4200, such as a leading edge shear web and a trailing edge shear web. The shear webs 4200 could alternatively be a spar box with spar sides, such as a trailing edge spar side and a leading edge spar side. The spar caps 7400, 7600 may comprise carbon fibres while the rest of the shell parts 2400, 2600 may comprise glass fibres.

[0072] FIG. 3 is a schematic diagram illustrating an embodiment of a first or second fibre layer 10, 20 configured to form part of a flow-enhancing fabric 1 according to the present invention. FIG. 3A illustrates a three-dimensional view, FIG. 3B illustrates a top view and FIG. 3C illustrates a cross-sectional view along the dotted line illustrated in FIG. 3B.

[0073] The fibre layer 10, 20 extends in a longitudinal direction 6 and in a transverse direction 8. The fibre layer 10, 20 comprises a plurality of fibre bundles 13, 14, 23, 24 oriented in parallel in a fibre direction 16, 26. The white fibre bundles are glass fibre bundles 14, 24 and the black fibre bundles are carbon fibre bundles 13, 23. In FIGS. 3A and 3B, the fibre layer 10, 20 comprises a carbon fibre bundle 13, 23 for every fifth glass fibre bundle 14, 24. However, the number of glass fibre bundles 14, 24 relative to carbon fibre bundles 13, 23 may be different in other embodiments. The angle between the fibre direction 16, 26 relative to the longitudinal direction 6 of the fabric is preferably around 45 degrees. However, it may be between 10-80 degrees. In FIG. 3B the angle is 60 degrees.

[0074] Even though not visible in FIG. 3, the different fibres in the fabric may be maintained relative to each other by stitching and/or use of a binder and/or weaving.

[0075] FIG. 4A is a schematic illustration of an exploded cross-sectional view along the longitudinal direction 6 of a flow-enhancing fabric 1 according to an embodiment of the present invention. The flow-enhancing fabric 1 comprises a first fibre layer 10 and a second fibre layer 20 configured to be arranged upon each other. The first fibre layer 10 has a first upper fibre surface 11 and a first lower fibre surface 12. In the same way, the second fibre layer 20 has a second lower fibre surface 21 and a second upper fibre surface 22. Furthermore, the flow-enhancing fabric 1 comprises a plurality of monofilaments 30 arranged between the first and second fibre layers 10, 20 along the transverse direction 8. The monofilaments 30 are arranged with a mutual spacing 31 between them.

[0076] FIG. 4B is a schematic illustration of a cross-sectional view along the longitudinal direction of the flow-enhancing fabric in FIG. 4A. The first fibre layer 10 and the second fibre layer 20 are arranged upon each other such that part of the first lower fibre surface 12 is in contact with part of the second upper fibre surface 21 and such that an upper fabric surface 2 of the flow-enhancing fabric 1 is also the first upper fibre surface 11 of the first fibre layer 10 and a lower fabric surface 4 of the flow-enhancing fabric 1 is the second lower fibre surface 22 of the second fibre layer 20.

[0077] The plurality of monofilaments 30 is arranged between the first and second fibre layers 10, 20 with a mutual spacing 31 between them. By arranging the monofilaments along a transverse direction 8 of the flow-enhancing fabric, between the first and second fibre layers 10, 20, a void 32 wherein fluid can flow is formed adjacent to the monofilaments 30, as illustrated in FIG. 3C (in an exaggerated way), which is a close-up of part of the flow-enhancing fabric 1 of FIG. 4B.

[0078] FIG. 5 is a schematic illustration of a preferred embodiment of a flow-enhancing fabric 1 according to the present invention.

[0079] As can be seen in FIG. 5, the flow-enhancing fabric 1 extends in a longitudinal direction 6 and in a transverse direction 8. The fabric comprises a first fibre layer 10 and a second fibre layer 20 arranged upon each other. The first fibre layer 10 comprises a first plurality of fibre bundles oriented in parallel in a first fibre direction 16 and the second fibre layer 20 comprising a second plurality of fibre bundles oriented in parallel in a second fibre direction 26 different from the first direction. The white fibre bundles in the first fibre layer 10 are first glass fibre bundles 14 and the grey fibre bundles are first carbon fibre bundles 13. In the same way, the white fibre bundles in the second fibre layer 20 are second glass fibre bundles 24 and the grey fibre bundles are second carbon fibre bundles 23.

[0080] In FIG. 5, the first and second fibre layers 10, 20 each comprise a carbon fibre bundle for every ninth glass fibre bundle. However, the number of glass fibre bundles relative to carbon fibre bundles may be different in the first and/or the second fibre layer 10, 20.

[0081] In the preferred embodiment in FIG. 5, the angle between the first fibre direction 16 relative to the longitudinal direction 6 of the fabric is −45 degrees. Similarly, the angle between the second fibre direction 26 relative to the longitudinal direction 6 of the fabric is 45 degrees. Furthermore, the angle between the first and second fibre directions 16, 26 is 90 degrees. In this way, the first carbon fibre bundles 13 intersect and contact the second carbon fibre bundles 23 in a plurality of intersection points 9, allowing electrical conductivity through the flow-enhancing fabric 1 in the thickness direction. The fibre bundles 13, 14, 23, 24 may also be arranged at a different angle, as long as at least a number of first carbon fibre bundles 13 intersect and contact a number of second carbon fibre bundles 23.

[0082] The fabric further comprises a plurality of monofilaments 30 arranged between the first and second fibre layers 10, 20 along the transverse direction 8 of the fabric. As can be seen in FIG. 5, the plurality of monofilaments 30 each have a mutual spacing 31 between them. By having this spacing between the monofilaments 30, a void 32 on each side of the monofilaments 30 will be present, as shown in FIG. 4C, when the first and second fibre layers 10, 20 are compressed, allowing fluid to flow into the void 32 and through the flow-enhancing fabric 1 along the monofilaments 30 in the transverse direction 8.

[0083] Even though not visible in FIG. 5, the different fibres in the fabric may be maintained relative to each other by stitching and/or use of a binder and/or weaving.

[0084] The flow-enhancing fabric in FIG. 5 is configured to be used as an interlayer in a spar cap for a wind turbine blade. The flow-enhancing fabric 1 is configured to be arranged such that the longitudinal direction 6 of the flow-enhancing fabric 1 is substantially parallel with a length direction of a spar cap and such that the transverse direction 8 of the flow-enhancing fabric 1 is substantially parallel with a width direction of the spar cap.

[0085] FIGS. 6A and 6B are schematic illustrations of a cross-sectional view of a flow-enhancing fabric 1, such as that of FIG. 5, arranged between a first and a second precured fibre-reinforced element 50, 60. FIG. 6A is an exploded view, whereas FIG. 6B is an assembled view.

[0086] The first precured fibre-reinforced element 50 and the second precured fibre-reinforced element 60 are arranged such that a lower surface 52 of the first precured fibre-reinforced element 50 is facing a second upper surface 61 of the second precured element 60. A flow-enhancing fabric 1, such as the flow-enhancing fabric of FIG. 5, is arranged between the lower surface 52 of the first precured fibre-reinforced element 50 and the upper surface 61 of the second precured element 60, e.g. such that the upper fabric surface 2 is in contact with the first lower surface 52 of the first fibre-reinforced element 50 and the lower fabric surface 4 is in contact with the second upper surface 61 of the second fibre-reinforced element 60. The precured fibre-reinforced elements 50, 60 and the flow-enhancing fabric may form part of a spar cap 100 arranged in a wind turbine blade, such as the first and second spar caps 7400, 7600 of the wind turbine blade 1000 as illustrated in FIG. 2.

[0087] FIG. 6C is a schematic diagram illustrating a cross-sectional view of a fibre-reinforced composite material 100, e.g. spar cap or part of a spar cap 100, comprising a plurality of precured fibre-reinforced elements, including a first precured fibre-reinforced element 50 and a second precured fibre-reinforced element 60. The plurality of precured fibre-reinforced elements are arranged in an array with three rows of precured fibre-reinforced elements arranged adjacent to each other. Each row of precured fibre-reinforced elements are separated by a flow-enhancing fabric 1 according to the present invention. The fibre-reinforced composite material 100 may form part of a spar cap 100 arranged in a wind turbine blade, such as the first and second spar caps 7400, 7600 of the wind turbine blade 1000 as illustrated in FIG. 2. Although not specifically illustrated, flow-enhancing fabrics 1 may also be provided between adjacent precured fibre-reinforced elements in the width direction.

REFERENCE SIGNS

[0088] 1 flow-enhancing fabric [0089] 2 upper fabric surface [0090] 4 lower fabric surface [0091] 6 longitudinal direction [0092] 8 transverse direction [0093] 9 intersection point [0094] 10 first fibre layer [0095] 11 first upper fibre surface [0096] 12 first lower fibre surface [0097] 13 first carbon fibre bundle [0098] 14 first glass fibre bundle [0099] 16 first fibre direction [0100] 20 second fibre layer [0101] 21 second upper fibre surface [0102] 22 second lower fibre surface [0103] 23 second carbon fibre bundle [0104] 24 second glass fibre bundle [0105] 26 second fibre direction [0106] 30 monofilament [0107] 31 spacing between monofilaments [0108] 32 void [0109] 50 first precured fibre-reinforced element [0110] 51 first upper surface [0111] 52 first lower surface [0112] 60 second precured fibre-reinforced element [0113] 61 second upper surface [0114] 62 second lower surface [0115] 100 spar cap [0116] 200 wind turbine [0117] 400 tower [0118] 600 nacelle [0119] 800 hub [0120] 1000 blade [0121] 1400 blade tip [0122] 1600 blade root [0123] 1800 leading edge [0124] 2000 trailing edge [0125] 2200 pitch axis [0126] 2400 pressure side [0127] 2600 suction side [0128] 3000 root region [0129] 3200 transition region [0130] 3400 airfoil region [0131] 3800 chord line [0132] 4000 shoulder/position of maximum chord [0133] 4200 shear webs [0134] 7400 first spar cap [0135] 7600 second spar cap