Wind turbine blade

Abstract

A first aspect of the invention provides a wind turbine blade comprising an inboard wind turbine blade portion and an outboard wind turbine blade portion for joining together by a joint, each of the inboard wind turbine blade portion and the outboard wind turbine blade portion has an end portion having an airfoil profile wherein the airfoil profile has both a concave geometry and a convex geometry, the end of each of the respective wind turbine blade portions has a plurality of inserts embedded therein, each insert comprising: an end portion having a connection for coupling the insert to another of the inserts across the joint; and an extension portion extending away from the end portion to a tip wherein the plurality of inserts of one of the respective wind turbine blade portions comprises: at least one first insert; and at least one second insert wherein the geometry of the first insert is different from the geometry of the second insert.

Description

Technical Field

[0001] The present invention relates to wind turbine blades. Background Art

[0002] Wind turbine blades are subject to a variety of loads. These loads typically include aerodynamic forces generated by the wind (including air pressure on the blades, changing wind speed and direction), as well as loads from the blades' own weight.

[0003] Due to the increased energy production generated, there is a continuing drive to produce larger wind turbine blades. However, as the size of wind turbine blades continues to increase, the transportation of wind turbine blades can become more complicated, at least onshore. It has become desirable to manufacture and transport blades as separate parts, and to build the blades at a location closer to the wind turbine by connecting the blade parts. A pair of adjacent blade parts can have a plurality of inserts embedded in the ends of each of the respective blade parts, each insert being adapted to couple to another insert in the other of the pair of blade parts to form a connection between the blade parts. For large wind turbine blades, the loads across the connected blade parts can be significant, and therefore an aim has been to improve the joints between the blade parts. Summary of the Invention

[0004] A first aspect of the present invention provides a wind turbine blade comprising an inner wind turbine blade section and an outer wind turbine blade section for being joined together by a joint, each of the inner wind turbine blade section and the outer wind turbine blade section having an end section having an airfoil profile, wherein the airfoil profile has both a concave and a convex geometric portion, the end section of each respective wind turbine blade section having a plurality of inserts embedded therein, each insert comprising: an end section having a connection for coupling the insert to another of the inserts across the joint; and an extension section extending away from the end section to a tip, wherein the plurality of inserts of one of the respective wind turbine blade sections comprises:

[0005] at least one first insert; and

[0006] at least one second insert,

[0007] The geometric shape of the first insert is different from the geometric shape of the second insert.

[0008] Each insert may have an end portion having an outer peripheral surface defining a cross-section. The outer peripheral surface of the first insert may define a first cross-section. The outer peripheral surface of the second insert may define a second cross-section. The geometry of the first cross-section may differ from the geometry of the second cross-section.

[0009] The first cross-section and / or the second cross-section may be substantially quadrilateral.

[0010] The first cross-section and / or the second cross-section may be substantially trapezoidal, rectangular or square.

[0011] The first cross-section may be larger than the second cross-section.

[0012] The outer peripheral surface of each of the plurality of inserts may include: an end portion inner surface facing the interior of the wind turbine blade portion; an end portion outer surface facing the exterior of the wind turbine blade portion; and a pair of end portion side surfaces.

[0013] The outer face of the end portion may be wider or narrower than the inner face of the end portion or may have the same width as the inner face of the end portion.

[0014] Each end portion side may be a substantially planar facet.

[0015] The extension portion of each of the plurality of inserts may include: an extension portion inner surface facing the interior of the wind turbine blade portion; an extension portion outer surface facing the exterior of the wind turbine blade portion; and a pair of extension portion side surfaces. The extension portion inner surface may intersect with the end portion inner surface. The extension portion outer surface may intersect with the end portion outer surface. The extension portion side surfaces may intersect with the end portion side surfaces. The height between the extension portion inner surface and the extension portion outer surface may decrease as the extension portion extends away from the end portion.

[0016] The height may decrease uniformly as the extension portion extends away from the end portion.

[0017] The inner face of the extension and / or the outer face of the extension may be planar.

[0018] Adjacent outer peripheral surfaces of adjacent inserts may be oriented normal to the periphery of the airfoil profile at the end of the respective wind turbine blade portion.

[0019] The plurality of inserts may be arranged side by side around at least a portion of the periphery of the airfoil profile at the end of the respective wind turbine blade section. The plurality of inserts arranged side by side may have gaps therebetween, and the gaps may be filled with other blade materials such as fiberglass.

[0020] Each respective wind turbine blade section may have a leading edge, a trailing edge, a leeward side extending between the leading edge and the trailing edge, and a windward side extending between the leading edge and the trailing edge. The plurality of inserts may be arranged in groups, wherein a first group of inserts is proximate a thickest portion of the airfoil profile on the leeward side, a second group of inserts is proximate a thickest portion of the airfoil profile on the windward side, a third group of inserts is proximate the trailing edge on the windward side, and a fourth group of inserts is proximate the trailing edge on the leeward side.

[0021] The inserts of the first and / or second group of inserts may have a greater depth between the inner face of their end portion and the outer face of their end portion than the inserts of the third and / or fourth group of inserts.

[0022] The end of at least one of the inserts may have a bushing with a threaded bore for receiving a threaded fastener.

[0023] Threaded fasteners may form connections for joining wind turbine blade sections together.

[0024] The threaded hole diameter of at least one of the plurality of inserts may be different than the threaded hole diameter of another of the plurality of inserts.

[0025] At least one of the plurality of inserts may have a different size than another of the plurality of inserts.

[0026] A plurality of inserts may be sandwiched between layers of fiber reinforced composite material forming the shell of a wind turbine blade.

[0027] According to a second aspect, a wind turbine blade includes an inner wind turbine blade portion and an outer wind turbine blade portion for being joined together by a joint, each of the inner wind turbine blade portion and the outer wind turbine blade portion having an end, the end of each of the corresponding wind turbine blade portions having a plurality of inserts embedded therein, each insert including an end portion having a connection for coupling the insert to another of the inserts across the joint, and an extension portion extending away from the end portion to a tip. The joint may include a joint member between the inner wind turbine blade portion and the outer wind turbine blade portion. The end of at least one of the inserts may include a bushing having a threaded hole that receives a threaded fastener protruding from an end face of the insert opposite the tip. The joint member may include a flange having a first face and a second face opposite the first face, and a through hole between the first face and the second face. The first face may abut an end face of the insert. The first and second faces of the joint member may be non-parallel such that the second face is orthogonal to the longitudinal axis of the threaded fastener.The second aspect may be combined with the first aspect.

[0028] According to a third aspect, a wind turbine blade includes an inner wind turbine blade section and an outer wind turbine blade section for being joined together by a joint. The inner wind turbine blade section and the outer wind turbine blade section are each joined together by the joint, each of the inner wind turbine blade section and the outer wind turbine blade section having an end portion. The end portion of each corresponding wind turbine blade section has a plurality of inserts embedded therein, wherein the end portion of at least one of the inserts has a bushing having a threaded hole for receiving a threaded fastener. The threaded fastener may have a first threaded end received in the threaded hole of the insert; a second threaded end for receiving a nut; and a shank between the first and second threaded ends. The shank may have a solid non-circular cross-section having a major dimension substantially aligned with a perimeter of the end portion of the wind turbine blade section and a minor dimension substantially perpendicular to the major dimension. The third aspect may be combined with the first and / or second aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

[0030] Figure 1 A front view of a wind turbine is shown;

[0031] Figure 2 An isometric view of a wind turbine blade is shown;

[0032] Figure 3 A cross-sectional view of a blade portion is shown;

[0033] Figure 4 A detailed view of the joint connecting the two blade sections is shown;

[0034] Figure 5 Shown Figure 3 Magnified view of area A in FIG;

[0035] Figure 6 Shown Figure 3 Magnified view of area B in FIG;

[0036] Figure 7 An isometric view of the insert is shown;

[0037] Figure 8 A to Figure 8 D shows a cross-sectional view of four inserts with different geometries;

[0038] Figure 9 An isometric view of a blank body for forming an insert is shown;

[0039] Figure 10 a schematic diagram showing a portion of a joint; and

[0040] Figure 11 A to Figure 11 C shows an isometric view, a side view, and a plan view of a threaded fastener. DETAILED DESCRIPTION

[0041] In this specification, terms such as "leading edge," "trailing edge," "pressure side," "suction side," "thickness," and "chord length" are used. While these terms are well known and understood by those skilled in the art, for the avoidance of doubt, they are defined below.

[0042] The term "leading edge" is used to refer to the edge of a blade which is at the front of the blade when the blade rotates in the normal direction of rotation of the wind turbine rotor.

[0043] The term "trailing edge" is used to refer to the edge of a wind turbine blade which is located at the rear of the blade when the blade rotates in the normal direction of rotation of the wind turbine rotor.

[0044] The chord length of a blade is the straight-line distance from the leading edge to the trailing edge in a given cross section perpendicular to the spanwise direction of the blade. The term "chordwise" is used to refer to the direction from the leading edge to the trailing edge, or vice versa.

[0045] The pressure side (or windward side) of a wind turbine blade is the surface between the leading edge and the trailing edge which, when the blade is in use, has a higher pressure than the suction side of the blade.

[0046] The suction side (or lee side) of a wind turbine blade is the surface between the leading edge and the trailing edge which, when the blade is in use, has a lower pressure acting upon it than the pressure side.

[0047] The thickness of a wind turbine blade is measured perpendicular to the chord length of the blade and is the maximum distance between the pressure side and the suction side in a given cross section perpendicular to the spanwise direction of the blade.

[0048] The term "spanwise" is used to refer to the direction from the root end of a wind turbine blade to the tip end of the blade, or vice versa. When the wind turbine blade is mounted on a wind turbine hub, the spanwise direction and the radial direction are substantially the same.

[0049] In this context, the geometry of the insert is used to refer to the size, shape and / or orientation (relative to the perimeter of the airfoil profile of the blade).

[0050] Figure 1 A wind turbine 1 according to an example is shown. The wind turbine 1 comprises a tower 2 and a nacelle 3 mounted on the tower 2. A hub 4 is rotatably mounted on the nacelle 3 and carries three wind turbine blades 5 protruding outwardly from the nacelle 3. Figure 1The example shown has three blades 5 , but it will be appreciated that other numbers of blades 5 are possible.

[0051] When wind blows towards the wind turbine 1 , the wind turbine blades 5 generate lift, which causes a generator (not shown) in the nacelle 3 to generate electrical energy.

[0052] It will be appreciated that the depicted wind turbine 1 may be any suitable type of wind turbine 1. The wind turbine 1 shown is an upwind wind turbine, but it will be appreciated that the wind turbine 1 may be a downwind wind turbine. The wind turbine 1 may be an onshore wind turbine, with the foundation embedded in the ground, or the wind turbine 1 may be an offshore installation, in which case the foundation would be provided by a suitable offshore platform.

[0053] Figure 2 An isometric view of one of the wind turbine blades 5 is shown.

[0054] The wind turbine blade 5 comprises an inner wind turbine blade part 6 and an outer wind turbine blade part 7 for being joined together by a joint 8. Advantageously, providing the wind turbine blade 5 in two parts may help to simplify transportation of the wind turbine blade 5, in particular overland transportation.

[0055] Figure 3 A cross-sectional view of the end 9 of the outboard wind turbine blade part 7 is shown. A corresponding cross-sectional view of the end 9 of the inboard wind turbine blade part 6 may be Figure 3 The end 9 shown in FIG is a mirror image of the end 9 about a vertical plane. However, the end of the inboard wind turbine blade portion may have a different profile shape. Hereinafter, unless otherwise stated, anything discussed with respect to the end 9 of the outboard wind turbine blade portion 7 applies to the end 9 of the inboard wind turbine blade portion 6.

[0056] Each of the inboard wind turbine blade portion 6 and the outboard wind turbine blade portion 7 has an end portion 9 having an airfoil profile. The airfoil profile has both a convex geometric portion 10 and a concave geometric portion 11. The terms "concave" and "convex" are used in relation to the outer geometry of the end portion 9, i.e., as viewed from a point outside the airfoil profile, such that the convex portion curves outwardly and the concave portion curves inwardly.

[0057] like Figure 3As shown, the end portion 9 includes at least two convex geometric portions 10 and at least one concave geometric portion 11. Each respective wind turbine blade portion 6, 7 has a leading edge LE, a trailing edge TE, a leeward side L extending between the leading edge LE and the trailing edge TE, and a windward side W extending between the leading edge LE and the trailing edge TE. The windward side W of the end portion 9 includes a convex portion 10 between the leading edge LE and the trailing edge TE of the blade portion 7, adjacent to the concave portion 11. The leeward side L of the end portion 9 includes a convex portion 10 extending between the leading edge LE and the trailing edge TE. In an alternative example (not shown), the airfoil profile of the end portion 9 of the respective wind turbine blade portion 6, 7 may have any suitable airfoil shape.

[0058] The end 9 of each of the respective wind turbine blade parts 6, 7 has a plurality of inserts 12 embedded therein. Each insert 12 comprises an end portion 13 having a connection for coupling the insert 12 to another of the inserts 12 across a joint 8.

[0059] Figure 4 Shown through Figure 2 , a spanwise cross-sectional view of a wind turbine blade 5 is shown in FIG. Corresponding inserts 12 on the windward side W of the end 9 of the respective wind turbine blade part 6, 7 are coupled to one another across the joint 8. Similarly, corresponding inserts 12 on the leeward side L of the end 9 of the respective wind turbine blade part 6, 7 are coupled to one another across the joint 8. The end 9 of each respective wind turbine blade part 6, 7 has the same number of inserts 12. The inserts 12 each extend generally along the spanwise direction of the wind turbine blade 5.

[0060] The inboard wind turbine blade portion 6 and the outboard wind turbine blade portion 7 may be joined together by a joint 8. The joint 8 may include a joint member 30 between the inboard wind turbine blade portion 6 and the outboard wind turbine blade portion 7. The end portion 13 of at least one of the inserts 12 may have a bushing 32 having a threaded hole for receiving a threaded fastener 16. The threaded fastener 16 may form a connection for joining the wind turbine blade portions 6, 7 together.

[0061] exist Figure 41 , each fastener 16 is received by a hole 34 in the joint member 30 and a bushing 32 of one of the inserts 12 to secure the insert 12 to the joint member 30. The joint member 30 is made of a metal such as steel by a casting process. In alternative examples, the joint member 30 can be made of any suitable material, such as a fiber-reinforced composite material, by any suitable process. Advantageously, joining the inboard wind turbine blade portion 6 and the outboard wind turbine blade portion 7 together via the joint 8 allows the blade portions 6 and 7 to be transported separately and assembled at the site of the wind turbine 1.

[0062] The plurality of inserts 12 may be sandwiched between layers of fiber reinforced composite material (such as Figure 4 ). The insert may be bonded to adjacent fiber reinforced composite layers to transfer loads between the insert and the fiber reinforced composite layers.

[0063] The plurality of inserts 12 of a respective one of the wind turbine blade parts 6, 7 comprises at least one first insert 12a and at least one second insert 12b. The geometry of the first insert 12a differs from the geometry of the second insert 12b.

[0064] Each wind turbine blade section may have only two different insert geometries, eg one or more first inserts having the same geometry and one or more second inserts having the same geometry, wherein the first and second inserts have different geometries.

[0065] Alternatively, each wind turbine blade section may have three, four or more different insert geometries.

[0066] Figure 5 and Figure 6 Shown respectively Figure 3 1 and 2. An enlarged view of the regions A and B shown in FIG. Region A shows the convex portion 10 of the outer wind turbine blade portion 7. Region B shows the concave portion 11 of the outer wind turbine blade portion 7. Figure 5 and Figure 6 As shown, the plurality of inserts 12 include: a first insert 12a having the same geometric shape as one another; a second insert 12b having the same geometric shape as one another; a third insert 12c having the same geometric shape as one another; a fourth insert 12d having the same geometric shape as one another; and a fifth insert 12e having the same geometric shape as one another. The first insert 12a, the second insert 12b, the third insert 12c, the fourth insert 12d, and the fifth insert 12e all have different geometric shapes relative to one another.

[0067] Advantageously, providing inserts 12 with different geometries can enhance the filling of the inserts 12 within the convex portion 10 and concave portion 11 of each end portion 9, and can achieve a stronger bonded connection between the inserts and adjacent fiber reinforced composite layers. For example, if the inserts of a wind turbine blade section all have the same end cross-section, such as a trapezoidal shape, the filling of the inserts around the perimeter of the end portion of the blade section will be compromised because the concave and convex geometry of the airfoil profile varies around the perimeter. This poor filling can lead to undesirable gaps between adjacent inserts, which can lead to undesirable resin pooling when the blade is injected with resin, for example during manufacture using a vacuum-assisted resin transfer molding process. By providing at least two different insert geometries, the filling of the inserts can be improved, reducing these undesirable gaps between the inserts and avoiding resin pooling, which can lead to structural weaknesses and the possibility of pullout from the inserts under high tensile loads across the joint.

[0068] Advantageously, providing inserts 12 with different geometries can reduce the weight of the blade. For example, if the inserts of a wind turbine blade section all had the same geometry, they would need to be designed for the highest load transmitted across the joint. In practice, different inserts would encounter different loads across the joint, so some inserts would be overdesigned, increasing weight and cost. By providing at least two different insert geometries, the inserts around the perimeter of the end of the blade section can be tailored to the local loads, which can provide cost and weight savings.

[0069] Advantageously, providing inserts 12 having different geometries can enable the joint to be constructed without affecting the outer airfoil profile of the end of the blade section at the joint. For example, if the inserts of a wind turbine blade section all had the same geometry, their size might be constrained by the available space, particularly at the trailing edge of the blade section, or the outer airfoil profile of the end of the blade section might need to be altered to accommodate the inserts. This could undesirably affect the aerodynamic performance of the blade, and a fairing might be required to provide a smooth outer aerodynamic surface. By providing at least two different insert geometries, the inserts around the perimeter of the end of the blade section can be tailored to the local loads and the local space available within the blade airfoil profile, so that all of the inserts can fit within the blade airfoil profile, which can provide an aerodynamic performance enhancement.

[0070] Figure 7 An isometric view of one of the inserts 12 is shown.

[0071] Each insert 12 includes an extension portion 14 that extends away from the end portion 13 to a tip 15. The extension portion can provide a large surface area for transferring loads between the insert and the fiber reinforced composite layer. This helps prevent the insert from pulling out under high tensile loads across the joint.

[0072] exist Figure 7 In the embodiment, the extension portion 14 tapers in the width direction from the end portion 13 to the tip 15, which helps to smoothly transfer the load between the insert 12 and the fiber reinforced composite layer and avoid stress concentration. This helps to prevent the insert from pulling out under high tensile loads across the joint. The extension portion 14 can taper from the end portion 13 to the tip 15 so that the tip is closest to the periphery of the blade airfoil profile, that is, the taper of the extension portion 14 is towards the periphery of the blade airfoil profile. Alternatively, the tip 15 can be located near the mid-plane of the insert or can be located farthest from the periphery of the blade airfoil portion. The tip position can be the same for all inserts arranged around the periphery of the airfoil profile.

[0073] Each insert 12 may have an end portion 13 having an outer peripheral surface 17 defining a cross-section 18. The outer peripheral surface 17 of each of the plurality of inserts 12 may include an end portion inner face 20 oriented toward the interior of the wind turbine blade portion 6, 7, an end portion outer face 19 oriented toward the exterior of the wind turbine blade portion 6, 7, and a pair of end portion side faces 21. The end portion outer face may be wider, narrower, or the same width as the end portion inner face.

[0074] Each end portion side 21 may be a substantially planar facet. Advantageously, this helps to reduce gaps between adjacent inserts 12.

[0075] The extension portion 14 of each of the plurality of inserts 12 can include an extension portion inner face 22 oriented toward the interior of the wind turbine blade portion 6, 7, an extension portion outer face 23 oriented toward the exterior of the wind turbine blade portion 6, 7, and a pair of extension portion side faces 24. The extension portion inner face 22 can intersect with the end portion inner face 20. The extension portion outer face 23 can intersect with the end portion outer face 19. The extension portion side faces 21 can intersect with the end portion side faces 24. The height between the extension portion inner face 22 and the extension portion outer face 23 can decrease (e.g., uniformly) as it extends away from the end portion 13. The extension portion inner face 22 and / or the extension portion outer face 23 can be planar.

[0076] One of the extension side surfaces 24 and the extension inner surface 22 are Figure 7It is visible in the view shown, where the extension portion outer face 23 and the further extension portion side face 24 are indicated via arrows. The extension portion inner face 22 is arranged at a non-zero angle relative to the end portion inner face 20 (i.e. they are not parallel). The extension portion inner face 22 meets the end portion inner face 20 at an edge 25. Figure 4 As shown, the extension portion outer face 23 is coplanar with the end portion outer face 19. The extension portion inner face 22 is angled relative to the extension portion outer face 23 so that the height therebetween decreases uniformly as the extension portion 14 extends away from the end portion 13. The extension portion inner face 22 and the extension portion outer face 23 meet at the tip 15.

[0077] The outer peripheral surface 17 of the first insert 12a may define a first cross-section 18a ( Figure 5 The outer peripheral surface 17 of the second insert 12b may define a second cross-section 18b ( Figure 6 The geometric shape of the first cross-section 18a may be different from the geometric shape of the second cross-section 18b. The first cross-section 18a and / or the second cross-section 18b may be substantially quadrilateral. For example, the first cross-section 18a and / or the second cross-section 18b may be substantially trapezoidal, rectangular, or square.

[0078] Figure 8 A to Figure 8 D shows four examples of inserts 12 with end portion cross sections 18 of different geometries. Figure 8 A shows the trapezoidal shape of the first cross section 18a of each first insert 12a, which is the same as the shape of the fourth cross section 18d of each fourth insert 12d. The geometries of the first and fourth inserts 12a, 12d differ in their dimensions. Figure 8 B shows the trapezoidal shape of the second cross section 18b of each second insert 12b, which is the same as the shape of the fifth cross section 18e of each fifth insert 12e. The geometries of the second and fifth inserts 12b, 12e differ in their dimensions. Figure 8 C shows the trapezoidal shape of the third cross-section 18c of each third insert 12c. Figure 8 D shows the insert 12 (which may alternatively be present in Figures 2 to 6 An example rectangular cross-section 18f of a wind turbine blade 5 is shown.

[0079] The geometric shapes of the first cross section 18a and the fifth cross section 18e differ in their orientation. In particular, the geometric shape of the first cross section 18a corresponds to the geometric shape of the fifth cross section 18e rotated 180 degrees. The same is true for the second cross section 18b and the fourth cross section 18d. Advantageously, as Figure 5 and Figure 6As shown, inserts 12 are arranged side by side (the geometry of their cross-section 18 is in Figure 8 A and Figure 8 B) helps to minimize gaps between inserts 12 along both the convex portion 10 and the concave portion 11 of the airfoil profile present on the same side of the blade (windward or leeward). The first cross section 18a and the first cross section 18b may differ only in their orientation, measured relative to the perimeter of the blade's airfoil profile.

[0080] With respect to the first cross section 18a of the trapezoidal shape, Figure 8 The trapezoidal shape of the cross section 18c in C has a higher ratio between the widths of the outer face 19 and the inner face 20 and therefore has a different geometry than the first cross section 18a.

[0081] In alternative examples (not shown), the first cross-section 18a and / or the second cross-section 18b may have any suitable generally quadrilateral shape.

[0082] At least one of the plurality of inserts 12 may have a different size than another of the plurality of inserts 12. The first cross-section 18a may be larger than the second cross-section 18b.

[0083] like Figure 3 、 Figure 5 and Figure 6 As shown, the first cross-section 18a of the first insert 12a in region A may be larger than the cross-section 18b of the second insert 12b in region B. Furthermore, the cross-section 18 of all inserts 12 in region A may be larger than all inserts in region B. Providing inserts 12 with relatively smaller cross-sections 18 in region B enables these inserts 12 to be positioned closer to the trailing edge TE, which facilitates load transfer between the trailing edges TE of the respective wind turbine blade parts 6, 7.

[0084] Additionally or alternatively, at least one of the plurality of inserts 12 may be longer (in the spanwise direction), wider (in the chord-wise cross-sectional circumferential direction), and / or thicker than another of the plurality of inserts 12. As shown, the inserts 12 have a single bushing 32, but one or more of the inserts may include multiple bushings. For example, a wider and / or thicker insert may include two or three bushings.

[0085] A plurality of inserts 12 may be arranged side by side around at least a portion of the periphery of the airfoil profile at the end 9 of the respective wind turbine blade part 6, 7. Adjacent outer peripheral surfaces 17 of adjacent inserts 12 may be oriented orthogonal to the periphery of the airfoil profile at the end 9 of the respective wind turbine blade part 6, 7.

[0086] exist Figure 3 、 Figure 5 and Figure 6 , the end portion side surfaces 21 of adjacent inserts 12 are oriented orthogonal to the periphery of the airfoil profile. Advantageously, this helps minimize gaps between adjacent inserts 12 along the concave and convex portions 10, 11 of the airfoil profile, thereby enhancing the strength and stiffness of the coupling between the wind turbine blade sections 6, 7. In alternative examples (not shown), the adjacent outer peripheral surfaces 17 of adjacent inserts 12 may be oriented at any suitable angle relative to the periphery of the airfoil profile at the end portions 9.

[0087] exist Figure 3 、 Figure 5 and Figure 6 In the embodiment, the side surfaces 21 of the end portions of adjacent inserts 12 can be closely adjacent to each other but not in contact, and therefore a gap can exist between the side surfaces 21 of the end portions of at least two adjacent inserts 12. The gap is preferably narrow. This allows resin to be injected between the inserts during blade manufacturing, for example, by vacuum-assisted resin transfer molding, to bond the inserts together. Materials such as glass fabric can be placed in these gaps to facilitate resin injection. Spacer materials such as core material can also be placed between adjacent inserts.

[0088] The plurality of inserts 12 may be arranged in groups, wherein a first group G1 of inserts is located near the thickest portion of the airfoil profile on the leeward side L, a second group G2 of inserts is located near the thickest portion of the airfoil profile on the windward side W, a third group G3 of inserts is located near the trailing edge TE on the windward side W, and a fourth group G4 of inserts is located near the trailing edge TE on the leeward side L. The first and second groups of inserts may be connected to a main spar cap extending along the blade in the span direction near the thickest portion of the airfoil profile. The third and fourth groups of inserts may be connected to a trailing edge spar cap or stringer extending along the blade in the span direction near the trailing edge.

[0089] Figure 3 Four groups G1, G2, G3, G4 of inserts are shown. The inserts 12 within each group are arranged side by side along the periphery of the airfoil profile of the end portion 9. The groups G1, G2, G3, G4 are spaced apart from each other along the periphery of the airfoil profile of the end portion 9. The first group G1 and the second group G2 each include six inserts 12, but may include more or fewer. The third group G3 and the fourth group G4 each include four inserts 12, but may include more or fewer. Advantageously, providing the inserts 12 in such groups helps to minimize the number of inserts 12, because the inserts 12 can be located in the portion of the respective wind turbine blade part 6, 7 that is subjected to the greatest loads (e.g. bending and torsion) during operation.

[0090] The plurality of inserts 12 may be arranged in one, two, three or more than four groups of inserts having the same geometry.

[0091] Inserts 12 of the first and / or second groups G1 and G2 may have a greater depth between their end portion inner faces 20 and their end portion outer faces 19 than inserts 12 of the third and / or fourth groups G3 and G4.

[0092] like Figure 3 As shown, the inserts 12 of the first group G1 and the second group G2 have a greater depth between their end portion inner face 20 and their end portion outer face 19 than the inserts 12 of the third group G3 and the fourth group G4. Advantageously, providing the inserts 12 of the third and fourth groups G3 and G4 with a reduced depth enables these inserts 12 to be positioned closer to the trailing edge TE while maintaining the space between the third and fourth groups G3 and G4.

[0093] At least one of the plurality of inserts 12 may have a bushing having a threaded hole diameter that is different from the threaded hole diameter of another of the plurality of inserts 12 .

[0094] The inserts 12 in the third group G3 and the fourth group G4 may have bushings 32 with threaded holes, such as Figure 3 8 and have a smaller diameter relative to the inserts 12 in the first and second groups G1, G2. Advantageously, this enables the use of smaller, and therefore less massive, fasteners 16 to couple the inserts 12 in the third and fourth groups G3, G4 to the respective inserts 12 across the joint 8. Furthermore, this enables the use of larger fasteners 16 to couple the inserts in the first and second groups G1, G2, which are located in areas of the wind turbine blade parts 6, 7 that are likely to be subject to higher loads.

[0095] Figure 9 An exemplary blank body 50 for forming the first and second inserts 12a, 12b is shown.

[0096] The first insert 12a and the second insert 12b can be formed from a single blank body 50. The first insert 12a and the second insert 12b can be formed by cutting the blank body 50 along a plane P of the blank body 50. The blank body 50 may include an end portion 13a of the first insert 12a at a first end 50a of the blank body 50 and an end portion 13b of the second insert 12b at an opposite second end 50a of the blank body 50. The cutting plane P may extend diagonally across the blank body 50. The cutting plane P may extend from the end portion 13a of the first insert 12a at a first surface of the blank body 50 to the end portion 13b of the second insert 12b at an opposite second surface of the blank body 50. The cross-section of the first end 50a of the blank body 50 may be the same as the cross-section of the second end 50b of the blank body 50.

[0097] like Figure 9 As shown, the blank body 50 is cut along the plane P to form the extension 14 of the first insert 12a and the second insert 12b. Forming the first insert 12a and the second insert 12b from the blank body 50 provides two inserts 12 having end portions 13 with cross-sections 18 of different geometries. In particular, the geometry of the cross-section 18 of the first insert 12a corresponds to the geometry of the cross-section 18 of the second insert 12b rotated 180 degrees. For example, such as Figure 3 、 Figure 5 and Figure 6 Advantageously, forming the two inserts 12 via the blank body 50 simplifies the manufacture of the inserts 12 .

[0098] The blank body 50 may include two bushings 32 encapsulated in a composite material (eg, a glass reinforced composite material). The bushings 32 may be made of a metallic material such as steel.

[0099] like Figure 2 and Figure 3 As shown, the shell 42 of the wind turbine blade 50 has a span-wise taper in the blade chord length and blade thickness. The inserts 12 extending in the span direction of each wind turbine blade portion 6, 7 follow the tapered geometry of the shell 42 to transfer loads acting on the shell 42 to the joint 8. Due to the span-wise taper in the blade chord length and blade thickness, the inserts 12 and corresponding fasteners 16 on either side of the joint 8 will not be perpendicular to the joint 8. Figure 10 An example of a connection between one of the inserts 12 and the joint member 30 of the joint 8 is shown.

[0100] The end portion 13 of at least one of the inserts 12 can have a bushing 32 with a threaded hole that receives a threaded fastener 16 projecting from an end face 60 of the insert 12 opposite the tip 15. The joint member 30 can have a flange 62 having a first face 64 and a second face 66 opposite the first face 64. The flange 62 can have a through hole 34 between the first face 64 and the second face 66. The first face 64 can abut the end face 60 of the insert 12. The first face 64 and the second face 66 of the joint member 30 can be non-parallel, such that the second face 66 is orthogonal to the longitudinal axis X of the threaded fastener 16.

[0101] like Figure 10 As shown, the fastener 16 and the insert 12 are secured to the joint member 30 via a nut 68, which is tightened onto the free end of the fastener 16 that protrudes beyond the second face 66. Because the second face 66 is orthogonal to the longitudinal axis X of the fastener 16, the nut 68 can make uniform contact with the second face 66. Advantageously, this minimizes bending stresses in the fastener 16 when the fastener 16 is preloaded via the nut 68. The joint member 30 includes a number of flanges 62 corresponding to the number of inserts 12.

[0102] refer to Figure 4 It is advantageous to provide the threaded fastener 16 with as large a cross-sectional area as possible so that a high preload can be applied to the fastener 16 by the nut 68. However, during operation of the wind turbine 1, the threaded fastener 16 is subjected to bending stresses caused by the bending of the wind turbine blade 5. Therefore, in this respect, it is advantageous to reduce the cross-sectional area of ​​the fastener 16 (especially the middle portion of the fastener 16 away from its threaded end) in order to reduce the bending stresses.

[0103] Figure 11 A to Figure 11 C shows an example of one of the threaded fasteners 16 . Figure 11 A shows an isometric view of the threaded fastener 16 . Figure 11 B shows a cross-sectional view of the threaded fastener 16 . Figure 11 C shows a plan view of the threaded fastener 16 .

[0104] The threaded fastener 16 may have a first threaded end 70 received in the threaded hole of the insert 12, a second threaded end 72 for receiving the nut 68, and a shank 74 between the first threaded end 70 and the second threaded end 72. The shank 74 may have a solid non-circular cross-section having a major dimension Y generally aligned with the perimeter of the end 9 of the corresponding wind turbine blade portion 6, 7 and a minor dimension Z generally perpendicular to the major dimension Y.

[0105] like Figure 11 B and Figure 11As shown in FIG. 3C , the major dimension Y and the minor dimension Z are perpendicular to the longitudinal axis X of the fastener 16 .

[0106] Further references Figure 2 , the wind turbine blade 5 is primarily subjected to bending loads about the chord-wise axis C of the blade 5. Therefore, by aligning the major dimension Y with the periphery of the end 9 of the respective wind turbine blade portion 6, 7, the fastener 16 primarily bends about its axis aligned with the major dimension Y. Since the minor dimension is generally perpendicular to the major dimension Y, the bending stresses of the fastener 16 are reduced while maintaining a large cross-sectional area of ​​the fastener 16 for high preload.

[0107] Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims

1. A wind turbine blade comprising an inner wind turbine blade portion and an outer wind turbine blade portion for being joined together by a joint, each of the inner wind turbine blade portion and the outer wind turbine blade portion having an end portion, the end portion having an airfoil profile, wherein: The airfoil profile has both a concave and a convex geometric portion, the end of each of the respective wind turbine blade sections having a plurality of inserts embedded therein, each insert comprising: an end portion having a connection for coupling the insert to another of the inserts across the joint; and an extension portion extending away from the end portion to a tip, wherein the plurality of inserts of one of the respective wind turbine blade sections comprises: at least one first insert; and at least one second insert, The geometric shape of the first insert is different from the geometric shape of the second insert.

2. The wind turbine blade according to claim 1, wherein: Each insert has an end portion having an outer peripheral surface defining a cross-section, wherein the outer peripheral surface of the first insert defines a first cross-section and the outer peripheral surface of the second insert defines a second cross-section, and wherein the geometry of the first cross-section is different from the geometry of the second cross-section.

3. A wind turbine blade according to any one of the preceding claims, wherein The first cross-section and / or the second cross-section are / is substantially quadrilateral, and preferably, wherein the first cross-section and / or the second cross-section are / is substantially trapezoidal, rectangular or square.

4. A wind turbine blade according to any one of claims 2 to 3, wherein: The first cross-section is larger than the second cross-section.

5. A wind turbine blade according to any one of claims 2 to 4, wherein: The outer peripheral surface of each of the plurality of inserts comprises: an inner face of the end portion facing the interior of the wind turbine blade portion; outwardly of the end portion towards the exterior of the wind turbine blade portion; and A pair of end portion sides.

6. The wind turbine blade according to claim 5, wherein: Each end portion is flanked by a substantially planar facet.

7. A wind turbine blade according to any one of claims 5 to 6, wherein: The extension portion of each of the plurality of inserts comprises: an inner face of the extension portion facing an interior of the wind turbine blade portion; an outer portion of the extension portion toward the exterior of the wind turbine blade portion; and a pair of extension side surfaces; and wherein the inner surface of the extension portion meets the inner surface of the end portion, the outer surface of the extension portion meets the outer surface of the end portion, and the side surface of the extension portion meets the side surface of the end portion; and The height between the inner surface of the extension portion and the outer surface of the extension portion decreases as the extension portion extends away from the end portion.

8. A wind turbine blade according to any one of claims 2 to 7, wherein: Adjacent outer peripheral surfaces of adjacent inserts are oriented normal to the periphery of the airfoil profile at the end of the respective wind turbine blade portion.

9. A wind turbine blade according to any one of the preceding claims, wherein The plurality of inserts are arranged side-by-side around at least a portion of a perimeter of the airfoil profile at the end of the respective wind turbine blade section.

10. A wind turbine blade according to any one of the preceding claims, wherein Each respective wind turbine blade section has a leading edge, a trailing edge, a leeward side extending between the leading edge and the trailing edge, and a windward side extending between the leading edge and the trailing edge, wherein the plurality of inserts are arranged in groups, wherein a first group of inserts is proximate a thickest portion of the airfoil profile on the leeward side, a second group of inserts is proximate a thickest portion of the airfoil profile on the windward side, a third group of inserts is proximate the trailing edge on the windward side, and a fourth group of inserts is proximate the trailing edge on the leeward side.

11. A wind turbine blade according to claim 10 when dependent on claim 5, wherein The inserts of the first and / or second group of inserts may have a greater depth between the inner face of their end portion and the outer face of their end portion than the inserts of the third and / or fourth group of inserts.

12. A wind turbine blade according to any one of the preceding claims, wherein At least one of the inserts has a bushing at its end with a threaded hole for receiving a threaded fastener.

13. The wind turbine blade of claim 12, wherein: The threaded fastener forms the connection for joining the wind turbine blade sections together.

14. A wind turbine blade according to any one of claims 12 or 13, wherein: The threaded hole diameter of at least one of the plurality of inserts is different from the threaded hole diameter of another of the plurality of inserts.

15. A wind turbine blade according to any one of the preceding claims, wherein The plurality of inserts are sandwiched between layers of fiber reinforced composite material forming the shell of the wind turbine blade.

16. A wind turbine blade according to any one of the preceding claims, wherein The inner wind turbine blade portion and the outer wind turbine blade portion are joined together by a joint; wherein the joint comprises a joint member between the inboard wind turbine blade part and the outboard wind turbine blade part, wherein an end portion of at least one of the inserts has a bushing having a threaded hole for receiving a threaded fastener projecting from an end face of the insert opposite the tip, and wherein the joint member has a flange having a first face and a second face opposite the first face and a through hole between the first face and the second face, wherein the first face abuts an end face of the insert, and the first and second faces of the joint member are non-parallel such that the second face is orthogonal to a longitudinal axis of the threaded fastener.

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