Method of manufacturing a wind turbine blade

Abstract

The present invention relates to a method of manufacturing a wind turbine blade. The method comprises adhesively joining a suction side shell half (69) and a pressure side shell half (68) along respective bond lines (80) at their leading and trailing edges, wherein, prior to joining, an impregnated carrier substrate (76) is arranged in between the shell halves along at least part of said bond lines (80). The carrier substrate (76) is impregnated with at least one compound having a functional moiety. The shell halves may be manufactured by placing a fibre lay-up including one or more fibre layers on a mould surface (66), arranging the impregnated carrier substrate (76) on the inside surface (72) at least along part of its peripheral edge (74) and injecting or infusing the fibre lay-up and the impregnated carrier substrate with a resin and subsequently curing the same.

Claims

1. A method of manufacturing 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), wherein the method comprises adhesively joining a suction side shell half (69) and a pressure side shell half (68) along respective bond lines (80) at said leading and trailing edges, wherein, prior to the step of adhesively joining, an impregnated carrier substrate (76) is arranged in between the suction side and the pressure side shell halves along at least part of said bond lines (80), wherein the carrier substrate (76) is impregnated with at least one compound having a functional moiety, wherein the impregnated carrier substrate (76) comprises a fabric formed from natural or synthetic textile material, and wherein the impregnated carrier substrate (76) comprises a patch or a strip, characterized in that the suction side and/or pressure side shell half is manufactured by a process comprising the steps of: a) placing a fibre lay-up, including one or more fibre layers, on a mould surface (66) to form a shell half structure comprising an aerodynamic outside surface (70) and an opposing inside surface (72) having a peripheral edge (74); b) arranging the impregnated carrier substrate (76) on said inside surface (72) at least along part of its peripheral edge (74); and c) injecting or infusing the fibre lay-up and the impregnated carrier substrate with a resin and subsequently curing the same.

2. The method of manufacturing a wind turbine blade according to claim 1, wherein the functional moiety is selected from a hydroxyl, an amino, a carbonyl, an isocyanate functional moiety and combinations thereof.

3. The method of manufacturing a wind turbine blade according to claim 1, wherein the functional moiety is a hydroxyl functional moiety.

4. The method of manufacturing a wind turbine blade according to claim 1, wherein the compound having a functional moiety is a polyol compound.

5. The method of manufacturing a wind turbine blade according to claim 1, wherein the blade further comprises one or more shear webs (82, 84) arranged within the blade, each shear web being adhesively joined to the suction side shell half (69) and to the pressure side shell half (68) at respective upper and lower adhesive joints, wherein the impregnated carrier substrate (76) is arranged at the upper and/or lower adhesive joints prior to joining the shear web to the shell halves.

6. The method of manufacturing a wind turbine blade according to claim 1, wherein the suction side and pressure side shell halves (69, 68) are joined with an adhesive comprising at least one vinyl ester compound, and/or wherein the suction side and pressure side shell halves (69, 68) are joined with an adhesive comprising an isocyanate compound, preferably free isocyanate.

7. The method of manufacturing a wind turbine blade according to claim 1, wherein the resin comprises a polyester compound, preferably an unsaturated polyester compound.

8. The method of manufacturing a wind turbine blade according claim 1, wherein step c) comprises the application of vacuum, and/or wherein the method further comprises a step of applying a peel ply on top of the impregnated carrier substrate (76) subsequent to step b), but prior to step c), wherein the peel ply is removed prior to adhesively joining the shell halves, and/or wherein the method further comprises a step of laying out a vacuum foil on top of the fibre lay-up and impregnated carrier substrate subsequent to step b), but prior to step c).

9. The method of manufacturing a wind turbine blade according claim 1, wherein the method further comprises a step of applying a gel coat or primer to the blade mould prior to step a).

10. The method of manufacturing a wind turbine blade according to claim 1, wherein the fibre lay-up comprises glass fibres.

11. The method of manufacturing a wind turbine blade according to claim 8, wherein the application of the vacuum comprises vacuum assisted transfer moulding.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The invention is explained in detail below with reference to embodiments shown in the drawings, in which

(2) FIG. 1 shows a wind turbine,

(3) FIG. 2 shows a schematic view of a wind turbine blade,

(4) FIG. 3 shows a schematic view of an airfoil profile through section I-I of FIG. 4,

(5) FIG. 4 shows a schematic view of the wind turbine blade, seen from above and from the side,

(6) FIG. 5 is a perspective drawing of a shell half structure of the present invention in a mould,

(7) FIG. 6 shows an enlarged cross section of the shell half structure of FIG. 5 taken along the line A-A′,

(8) FIG. 7 is a cross-sectional view of a wind turbine blade according to the present invention, and

(9) FIG. 8 is an enlarged view of section B in FIG. 7.

DETAILED DESCRIPTION

(10) 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 furthest from the hub 8. The rotor has a radius denoted R.

(11) FIG. 2 shows a schematic view of a first embodiment of a wind turbine blade 10 according to the invention. 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 furthest 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.

(12) 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.

(13) 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.

(14) 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.

(15) FIGS. 3 and 4 depict parameters which are used to explain the geometry of the wind turbine blade according to the invention.

(16) FIG. 3 shows a schematic view of an airfoil profile 50 of a typical blade of a wind turbine depicted with the various parameters, which are typically used to define the geometrical shape of an airfoil. The airfoil profile 50 has a pressure side 52 and a suction side 54, which during use—i.e. during rotation of the rotor—normally face towards the windward (or upwind) side and the leeward (or downwind) side, respectively. The airfoil 50 has a chord 60 with a chord length c extending between a leading edge 56 and a trailing edge 58 of the blade. The airfoil 50 has a thickness t, which is defined as the distance between the pressure side 52 and the suction side 54. The thickness t of the airfoil varies along the chord 60. The deviation from a symmetrical profile is given by a camber line 62, which is a median line through the airfoil profile 50. The median line can be found by drawing inscribed circles from the leading edge 56 to the trailing edge 58. The median line follows the centres of these inscribed circles and the deviation or distance from the chord 60 is called the camber f. The asymmetry can also be defined by use of parameters called the upper camber (or suction side camber) and lower camber (or pressure side camber), which are defined as the distances from the chord 60 and the suction side 54 and pressure side 52, respectively.

(17) Airfoil profiles are often characterised by the following parameters: the chord length c, the maximum camber f, the position d.sub.f of the maximum camber f, the maximum airfoil thickness t, which is the largest diameter of the inscribed circles along the median camber line 62, the position d.sub.t of the maximum thickness t, and a nose radius (not shown). These parameters are typically defined as ratios to the chord length c. Thus, a local relative blade thickness t/c is given as the ratio between the local maximum thickness t and the local chord length c. Further, the position d.sub.p of the maximum pressure side camber may be used as a design parameter, and of course also the position of the maximum suction side camber.

(18) FIG. 4 shows other geometric parameters of the blade. The blade has a total blade length L. As shown in FIG. 3, the root end is located at position r=0, and the tip end located at r=L. The shoulder 40 of the blade is located at a position r=L.sub.w, and has a shoulder width W, which equals the chord length at the shoulder 40. The diameter of the root is defined as D. The curvature of the trailing edge of the blade in the transition region may be defined by two parameters, viz. a minimum outer curvature radius r.sub.o and a minimum inner curvature radius r.sub.i, which are defined as the minimum curvature radius of the trailing edge, seen from the outside (or behind the trailing edge), and the minimum curvature radius, seen from the inside (or in front of the trailing edge), respectively. Further, the blade is provided with a prebend, which is defined as Δy, which corresponds to the out of plane deflection from a pitch axis 22 of the blade.

(19) FIG. 5 illustrates a blade mould 64 with a mould surface 66 for moulding a shell half 68 of a wind turbine blade. The moulding process involves placing a fibre lay-up including one or more fibre layers such as glass fibres on the mould surface 66. The shell half structure 68 comprises an aerodynamic outside surface 70 and an opposing inside surface 72 having a peripheral edge 74. As illustrated only on the left hand side of FIG. 5, an impregnated carrier substrate 76 in the form of a fabric strip is placed on the inside surface along its peripheral edge 74. Subsequently, the fibre lay-up and the impregnated carrier substrate are infused with a resin to create a fibre reinforced structure.

(20) This is further illustrated in the cross sectional view of FIG. 6, which is taken along the line A-A′ in FIG. 5. As contrasted to FIG. 5, the embodiment shown in FIG. 6 has impregnated carrier substrates 76 placed on both sides along the peripheral edge 74 of the inside surface 72 of the shell half structure 68. FIG. 7 is a cross-sectional view of a blade 10 of the present invention illustrating different bond lines B, C and adhesive joints D, E, F, G onto which the impregnated carrier substrate of the present invention can be applied prior to adhesive bonding. A pressure side shell half 68 is adhesively joined to a suction side shell half 69 along respective bond lines at the leading edge 18 and trailing edge 20 of the blade (see circles B and C). The impregnated carrier substrate 76 is placed between the shell halves 68, 69, which is best seen in the enlarged view of encircled are B in FIG. 8. In this embodiment, the pressure side shell half 68 comprises a bonding flange 78 for improved bonding with the suction side shell half 69. The impregnated carrier substrate is placed on the respective shell halves 68, 69 including the bonding flange 78, preferably prior to resin infusion in vacuum assisted resin transfer moulding. After curing, the shell halves 68, 69 including the impregnated carrier substrates 76 are adhesively bonded along a bond line 80 using a suitable adhesive or bonding paste.

(21) As also shown in FIG. 7, the blade 10 comprises a leading edge shear web 82 and a trailing edge shear web 84, both of which are substantially C-shaped. Both shear webs 82, 84 are adhesively bonded to the respective shell halves 68, 69, preferably to spar caps or main laminates integrated in the latter (not shown). The impregnated carrier substrate may be placed onto the upper and/or lower flanges of the shear webs and/or on the respective inside surfaces of the shell halves 68, 69, i.e. on the main laminates, prior to bonding.

(22) 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

(23) 2 wind turbine 4 tower 6 nacelle 8 hub 10 blade 14 blade tip 16 blade root 18 leading edge 20 trailing edge 22 pitch axis 30 root region 32 transition region 34 airfoil region 40 shoulder/position of maximum chord 50 airfoil profile 52 pressure side 54 suction side 56 leading edge 58 trailing edge 60 chord 62 camber line/median line 64 blade mould 66 mould surface 68 pressure side shell half 69 suction side shell half 70 outside surface of shell half 72 inside surface of shell half 74 peripheral edge of inside surface 76 carrier substrate 78 bonding flange 80 bond line 82 leading edge shear web 84 trailing edge shear web c chord length d.sub.t position of maximum thickness d.sub.r position of maximum camber d.sub.p position of maximum pressure side camber f camber L blade length r local radius, radial distance from blade root t thickness Δy prebend