METHOD OF MANUFACTURING A WIND TURBINE BLADE AND SHEAR WEB ASSEMBLY FOR A WIND TURBINE BLADE

Abstract

The present invention relates to a method of manufacturing a wind turbine blade (10). The method comprises arranging one or more shear webs (50, 55) within a first shell half. At least one support frame (80) is fixe to one or more anchoring points (86) on the inside surface (36b) of the first shell half, the support frame comprising a free end (81) for engaging with a lateral surface of the shear web. One or more guide element (74) are fastened to at least one of the lateral surfaces of the shear web such that the guide element extends laterally from the shear web to form a receiving space (88) between the guide element (74) and the shear web (55). The shear webs are then lowered into the first shell half such that the free end (81) of the support frame (80) is received in the receiving space (88) between the guide element (74) and the shear web (55).

Claims

1. A method of manufacturing a wind turbine blade (10), the blade having a profiled contour including a pressure side (36) and a suction side (38), and a leading edge (18) and a trailing edge (20) with a chord having a chord length extending therebetween, the wind turbine blade (10) extending in a spanwise direction between a root end (16) and a tip end (14), the method comprising the steps of: forming a first shell half (36) and a second shell half (38), each shell half comprising an aerodynamic outside surface (36a, 38a) and an opposing inside surface (36b, 38b), arranging one or more shear webs (50, 55) within the first shell half, wherein each shear web comprises two opposing lateral surfaces (66, 68) extending in a spanwise direction, adhesively joining the one or more shear webs to the first shell half, and adhesively joining the second shell half to the first shell half and to the one or more shear webs, wherein the step of arranging the one or more shear webs within the first shell half comprises fixing at least one support frame (80) to one or more anchoring points (86) on the inside surface (36b) of the first shell half, the support frame comprising a free end (81) for engaging with a lateral surface of the shear web, fastening at least one guide element (74) to at least one of the lateral surfaces of the shear web such that the guide element extends laterally from the shear web to form a receiving space (88) between the guide element (74) and the shear web (55), and lowering the one or more shear webs into the first shell half such that the free end (81) of the support frame (80) is received in the receiving space (88) between the guide element (74) and the shear web (55).

2. A method of manufacturing a wind turbine blade according to claim 1, wherein the guide element (74) forms an acute angle (□) with the lateral surface (68) of the shear web.

3. A method of manufacturing a wind turbine blade according to claim 2, wherein the acute angle (□) is between 10 and 60°.

4. A method of manufacturing a wind turbine blade according to claim 1, wherein the anchoring points (86) on the inside surface of the first shell half are located within less than 20% chordal distance (c1) from either the leading edge or the trailing edge of the first shell half.

5. A method of manufacturing a wind turbine blade according to claim 1, wherein the guide element (72a) has a spanwise extent (90) of 25-250 mm, preferably 50-100 mm.

6. A method of manufacturing a wind turbine blade according to claim 1, wherein the step of fastening at least one guide element to at least one of the lateral surfaces of the shear web comprises fastening 2-10, preferably 4-6, guide elements to at least one of the lateral surfaces of the shear web, the guide elements being successively arranged in the spanwise direction.

7. A method of manufacturing a wind turbine blade according to claim 1, wherein the free end (81) of the support frame is a rounded end for being slidably received in the receiving space between the guide element and the shear web.

8. A method of manufacturing a wind turbine blade according to claim 1, wherein the free end (81) of the support frame comprises a guiding pin matching the shape of the receiving space between the guide element and the shear web.

9. A method of manufacturing a wind turbine blade according to claim 1, wherein a first shear web (50) and a second shear web (55) are arranged within the first shell half, the first and second shear web being releasably interconnected by a truss (70) placed in between the first and second shear web.

10. A method of manufacturing a wind turbine blade according to claim 1, wherein the at least one support frame (78, 80) and the truss (70) is removed after adhesively joining the second shell half to the first shell half and to the one or more shear webs.

11. A method of manufacturing a wind turbine blade according to claim 1, wherein the guide element extends laterally from the shear web within a chordal distance (c2) of 5-200 mm, preferably 5-100 mm.

12. A method of manufacturing a wind turbine blade according to claim 1, wherein the guide element has a total weight of less than 10% relative to the weight of the shear web.

13. A method of manufacturing a wind turbine blade according to claim 1, wherein the one or more anchoring points on the inside surface of the first shell half comprise a polymer anchor glued to the inside surface of the first shell half, the polymer anchor comprising a loop for receiving a mating pin of the support frame.

14. A shear web assembly (92) for a wind turbine blade, the blade (10) having a profiled contour including a pressure side and a suction side, and a leading edge (18) and a trailing edge (20) with a chord having a chord length extending therebetween, the wind turbine blade (10) extending in a spanwise direction between a root end (16) and a tip end (14), the shear web assembly comprising: one or more shear webs (50, 55), each shear web comprising two opposing lateral surfaces (66, 68) extending in a spanwise direction, at least one guide element (72, 74) fastened to at least one of the lateral surfaces of the shear web such that the guide element extends laterally from the shear web to form a receiving space (88) between the guide element and the shear web, wherein the guide element has a total weight of less than 10% relative to the weight of the shear web.

15. A shear web assembly for a wind turbine blade according to claim 14, comprising guide elements fastened to at least one of the lateral surfaces of the shear web, the guide elements being successively arranged in the spanwise direction.

Description

DESCRIPTION OF THE INVENTION

[0055] The invention is explained in detail below with reference to an embodiment shown in the drawings, in which

[0056] FIG. 1 shows a wind turbine,

[0057] FIG. 2 shows a schematic view of a wind turbine blade,

[0058] FIG. 3 shows a schematic view of a cross-section of a wind turbine blade,

[0059] FIG. 4 is a perspective cut-open view of a wind turbine blade with a shear web,

[0060] FIG. 5 is a schematic illustration of an arrangement of a shear web assembly in a blade half at a first stage,

[0061] FIG. 6 is a schematic illustration of an arrangement of a shear web assembly in a blade half at a second stage, and

[0062] FIG. 7 is an enlarged view of the encircled area in FIG. 6.

DETAILED DESCRIPTION

[0063] FIG. 1 illustrates a conventional modern upwind wind turbine according to the so-called “Danish concept” with a tower 4, a nacelle 6 and a rotor with a substantially horizontal rotor shaft. The rotor includes a hub 8 and three blades 10 extending radially from the hub 8, each having a blade root 16 nearest the hub and a blade tip 14 farthest from the hub 8. The rotor has a radius denoted R.

[0064] FIG. 2 shows a schematic view of a wind turbine blade 10. The wind turbine blade 10 has the shape of a conventional wind turbine blade and comprises a root region 30 closest to the hub, a profiled or an airfoil region 34 farthest away from the hub and a transition region 32 between the root region 30 and the airfoil region 34. The blade 10 comprises a leading edge 18 facing the direction of rotation of the blade 10, when the blade is mounted on the hub, and a trailing edge 20 facing the opposite direction of the leading edge 18.

[0065] The airfoil region 34 (also called the profiled region) has an ideal or almost ideal blade shape with respect to generating lift, whereas the root region 30 due to structural considerations has a substantially circular or elliptical cross-section, which for instance makes it easier and safer to mount the blade 10 to the hub. The diameter (or the chord) of the root region 30 may be constant along the entire root area 30. The transition region 32 has a transitional profile gradually changing from the circular or elliptical shape of the root region 30 to the airfoil profile of the airfoil region 34. The chord length of the transition region 32 typically increases with increasing distance r from the hub. The airfoil region 34 has an airfoil profile with a chord extending between the leading edge 18 and the trailing edge 20 of the blade 10. The width of the chord decreases with increasing distance r from the hub.

[0066] A shoulder 40 of the blade 10 is defined as the position, where the blade 10 has its largest chord length. The shoulder 40 is typically provided at the boundary between the transition region 32 and the airfoil region 34.

[0067] 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.

[0068] The blade is typically made from a pressure side shell part 36 and a suction side shell part 38 that are glued to each other along bond lines at the leading edge 18 and the trailing edge of the blade 20.

[0069] FIG. 3 shows a schematic view of a cross section of the blade along the line I-I shown in FIG. 2. As previously mentioned, the blade 10 comprises a pressure side shell part 36 and a suction side shell part 38. The pressure side shell part 36 comprises a spar cap 41, also called a main laminate, which constitutes a load bearing part of the pressure side shell part 36. The spar cap 41 comprises a plurality of fibre layers 42 mainly comprising unidirectional fibres aligned along the longitudinal direction of the blade in order to provide stiffness to the blade. The suction side shell part 38 also comprises a spar cap 45 comprising a plurality of fibre layers 46. The pressure side shell part 38 may also comprise a sandwich core material 43 typically made of balsawood or foamed polymer and sandwiched between a number of fibre-reinforced skin layers. The sandwich core material 43 is used to provide stiffness to the shell in order to ensure that the shell substantially maintains its aerodynamic profile during rotation of the blade. Similarly, the suction side shell part 38 may also comprise a sandwich core material 47.

[0070] The spar cap 41 of the pressure side shell part 36 and the spar cap 45 of the suction side shell part 38 are connected via a first shear web 50 and a second shear web 55. The shear webs 50, 55 are in the shown embodiment shaped as substantially I-shaped webs. The first shear web 50 comprises a shear web body and two web foot flanges. The shear web body comprises a sandwich core material 51, such as balsawood or foamed polymer, covered by a number of skin layers 52 made of a number of fibre layers. The second shear web 55 has a similar design with a shear web body and two web foot flanges, the shear web body comprising a sandwich core material 56 covered by a number of skin layers 57 made of a number of fibre layers. The sandwich core material 51, 56 of the two shear webs 50, 55 may be chamfered near the flanges in order to transfer loads from the webs 50, 55 to the main laminates 41, 45 without the risk of failure and fractures in the joints between the shear web body and web foot flange. However, such a design will normally lead to resin rich areas in the joint areas between the legs and the flanges. Further, such resin rich area may comprise burned resin due to high exothermic peeks during the curing process of the resin, which in turn may lead to mechanical weak points.

[0071] In order to compensate for this, a number of filler ropes 60 comprising glass fibres are normally arranged at these joint areas. Further, such ropes 60 will also facilitate transferring loads from the skin layers of the shear web body to the flanges. However, according to the invention, alternative constructional designs are possible.

[0072] The blade shells 36, 38 may comprise further fibre-reinforcement at the leading edge and the trailing edge. Typically, the shell parts 36, 38 are bonded to each other via glue flanges in which additional filler ropes may be used (not shown). Additionally, very long blades may comprise sectional parts with additional spar caps, which are connected via one or more additional shear webs.

[0073] FIG. 4 is a perspective cut-open view of a wind turbine blade with a shear web 50. The blade has a first shell half 36 and a second shell half 38, each shell half comprising an aerodynamic outside surface 36a, 38a and an opposing inside surface 36b, 38b. The shear web 50 comprises lateral surface 62 extending in a spanwise direction. The blade is manufactured by adhesively joining the shear web 50 to the first shell half 36, and adhesively joining the second shell half 38 to the first shell half 36 and to the shear web 50. The shear web 50 comprises two guide elements 72a and 72b on its lateral surface 62, each having a relatively modest spanwise extent 90 of 25-250 mm. It is seen that each guide element 72a, 72b is located within a mid-portion of the vertical extent, i.e. in the flapwise extent, of the shear web at the given spanwise location along the shear web. In the illustrated embodiment each guide element is installed at the approximate same flapwise height.

[0074] According to the method of manufacturing a wind turbine blade of the present invention, two shear webs 50, 55 can be arranged within the first shell half 36, as illustrated in FIGS. 5-7. The shear web 50 comprises two opposing lateral surfaces 62, 64, and the shear web 55 comprises two opposing lateral surfaces 66, 68 extending in a spanwise direction. The step of arranging the shear webs 50, 55 within the first shell half 36 comprises fixing at least support frames 87, 80 to one or more anchoring points 86 on the inside surface 36b of the first shell half 36, as shown in the detailed view of FIG. 7. The anchoring points 86 on the inside surface 36b of the first shell half are located within less than 20% chordal distance c1 from either the leading edge or the trailing edge of the first shell half. This allows easy access by operators 84 standing on scaffold 82 next to the blade mould 76.

[0075] Each support frame comprises a free end 81 for engaging with a lateral surface 68 of the shear web 55. Guide elements 72, 74 are fastened to the lateral surfaces 62, 68 of the respective shear webs 50, 55 such that the guide elements 72, 74 extend laterally from the shear webs 50, 55. This forms a receiving space 88 between the guide element 74 and the shear web 55, as shown in the detailed view of FIG. 7. The same applies to the other shear web 50. As best seen in FIG. 7, guide element 74 forms an acute angle α with the lateral surface 68 of the shear web 55. Also, the guide element 74 extends laterally from the shear web 55 within a chordal distance c2 of 5-200 mm.

[0076] As seen in FIGS. 5 and 6, the first and second shear webs 50, 55 are releasably interconnected by a truss 70 placed in between the first and second shear webs 50, 55. The shear web assembly 92 is lowered into the first shell half 36 such that the free end 81 of the support frame 80 is received in the receiving space 88 between the guide element 74 and the shear web 55. The same applies to shear web 50. FIG. 6 illustrates a stage wherein the shear web assembly has almost been lowered to its final position, wherein the flanges of the shear webs contact the inside surface 36b of the shell half.

[0077] As seen in FIG. 7, the free end 81 of support frame 80 is a rounded end for being slidably received in the receiving space 88 between the guide element 74 and the shear web 55. The support frames 78, 80 and the truss 70 are removed after adhesively joining the second shell half to the first shell half and to the one or more shear webs.

[0078] The invention is not limited to the embodiments described herein, and may be modified or adapted without departing from the scope of the present invention.

LIST OF REFERENCE NUMERALS

[0079] 4 tower [0080] 6 nacelle [0081] 8 hub [0082] 10 blades [0083] 14 blade tip [0084] 16 blade root [0085] 18 leading edge [0086] 20 trailing edge [0087] 30 root region [0088] 32 transition region [0089] 34 airfoil region [0090] 36 pressure side shell part [0091] 36a aerodynamic outside surface [0092] 36b inside surface [0093] 38 suction side shell part [0094] 38a aerodynamic outside surface [0095] 38b inside surface [0096] 40 shoulder [0097] 41 spar cap [0098] 42 fibre layers [0099] 43 sandwich core material [0100] 45 spar cap [0101] 46 fibre layers [0102] 47 sandwich core material [0103] 50 first shear web [0104] 51 core member [0105] 52 skin layers [0106] 55 second shear web [0107] 56 sandwich core material of second shear web [0108] 57 skin layers of second shear web [0109] 60 filler ropes [0110] 62 right lateral surface of first shear web [0111] 64 left lateral surface of first shear web [0112] 66 right lateral surface of second shear web [0113] 68 left lateral surface of second shear web [0114] 70 truss [0115] 71 lifting rail [0116] 72 guide element [0117] 74 guide element [0118] 76 blade mould [0119] 78 first support frame [0120] 79 free end of first support frame [0121] 80 second support frame [0122] 81 free end of second support frame [0123] 82 scaffold [0124] 84 operators [0125] 86 anchoring points [0126] 88 receiving space [0127] 90 spanwise extent of guide element [0128] 92 shear web assembly [0129] α angle [0130] H height [0131] L length [0132] r distance from hub [0133] R rotor radius