Wind turbine blades

Abstract

To reduce a thickness of a rear edge of a windmill blade.SOLUTION: In a windmill blade 10, a positive pressure side blade element 12p and a negative pressure side blade element 12n are joined to form an outer wall. In at least a part of a rear edge 26 of the windmill blade 10, one (12n) of the two blade elements 12p, 12n extends rearward farther than the other (12p) to allow the part to be formed only by the one (12n) of the blade elements.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a wind turbine blade, and more particularly to a wind turbine blade having an outer wall formed by joining pressure side and suction side blade elements. [Background technology]

[0002] The installation of wind power generation equipment equipped with propeller-type wind turbines has been progressing for some time. A propeller-type wind turbine is composed of multiple blades and a hub to which the blade roots are connected. When each blade catches the wind, the hub rotates, and the rotational energy is converted into electrical energy.

[0003] In many cases, blades are manufactured by separately manufacturing the pressure side blade outer wall and the suction side blade outer wall (hereinafter referred to as the blade elements) and integrating them by bonding. Patent Document 1 discloses a wind turbine blade in which a pressure side shell and a suction side shell are bonded at the leading edge and the trailing edge of the blade. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-129091 A Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional wind turbine blades, in which the outer wall is formed by joining the blade elements on the pressure and suction sides, have a problem in that the trailing edge of the blade becomes thick because the two blade elements overlap at the trailing edge of the blade. When the trailing edge of the blade becomes thicker, the wind flowing from the front to the rear of the blade on the pressure and suction sides is prevented from smoothly joining behind the trailing edge of the blade. This reduces the lift generated by the blade, and there is a risk of power generation efficiency deteriorating.

[0006] An object of the present invention is to thin the trailing edge of a wind turbine blade having an outer wall formed by joining pressure side and suction side blade elements. [Means for solving the problem]

[0007] The wind turbine blade according to the present invention is a wind turbine blade in which an outer wall is formed by joining a pressure side blade element and a suction side blade element, The wind turbine blade is formed so as to gradually change from a cylindrical shape to a blade shape from the blade root to the blade tip, and the rear end of one of the two blade elements is folded back inwardly forward at the blade-shaped portion, the folded back portion gradually opens toward the cylindrical portion, and the plate thickness of the folded back portion gradually increases toward the cylindrical portion, and the outer surface of the rear end of one of the blade elements is continuously joined to the inner surface of the rear portion of the other of the two blade elements from the blade-shaped portion to the cylindrical portion, The wind turbine blade In the wing-shaped portion At least a portion of the trailing edge The above on the other hand The folded portion of the blade element Compared to The other blade element By extending backwards, The other It is characterized in that it is formed by blade elements.

[0008] In the wind turbine blade according to the present invention, the negative pressure side blade element extends rearward compared to the positive pressure side blade element, In the wing-shaped portion At least a portion of the trailing edge may be defined by the suction side blade element.

[0009] In the wind turbine blade according to the present invention, The above The rear end of the pressure side blade element may be folded back forward and inward at the vane-shaped portion, and the outer surface of the rear end of the pressure side blade element may be continuously joined to the inner surface of the rear part of the suction side blade element from the vane-shaped portion to the cylindrical portion.

[0010] In the wind turbine blade according to the present invention, the blade element on the positive pressure side extends rearward compared to the blade element on the negative pressure side, In the wing-shaped portion At least a portion of the trailing edge may be defined by the pressure side blade element.

[0011] In the wind turbine blade according to the present invention, The aboveThe rear end of the suction side blade element may be folded back forward and inward at the vane-shaped portion, and the outer surface of the rear end of the suction side blade element may be continuously joined to the inner surface of the rear portion of the pressure side blade element from the vane-shaped portion to the cylindrical portion.

[0013] In the wind turbine blade according to the present invention, a front end of the pressure side blade element may be folded back inward and rearward at the vane-shaped portion, and an outer surface of the front end of the pressure side blade element may be continuously joined to an inner surface of the front end of the suction side blade element from the vane-shaped portion to the cylindrical portion.

[0014] In the wind turbine blade of the present invention, the front end of the negative pressure side blade element may be folded back inward and rearward at the vane-shaped portion, and the outer surface of the front end of the negative pressure side blade element may be continuously joined to the inner surface of the front end of the positive pressure side blade element from the vane-shaped portion to the cylindrical portion. Effect of the Invention

[0015] According to the present invention, at least a part of the trailing edge of the wind turbine blade is formed by a single blade element, so that the thickness of that part can be made thin. Behind the thin trailing edge formed by a single blade element, the winds flowing on the pressure side and suction side of the blade smoothly join together, so that the lift generated by the blade can be improved. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a perspective view of a wind turbine blade according to an embodiment. [Diagram 2] FIG. 2 is a perspective view showing the back side of the wind turbine blade according to the embodiment. [Diagram 3] FIG. 2 is an end view taken along line AA in FIG. [Figure 4] FIG. 2 is an end view taken along line BB in FIG. [Diagram 5]FIG. 2 is an end view taken along line CC in FIG. [Figure 6] FIG. 2 is an end view taken along line DD in FIG. [Figure 7] 1. FIG. 4 is an end view of a wind turbine blade according to another embodiment, showing the end face at a position corresponding to line AA in FIG. [Figure 8] 1. FIG. 4 is an end view of a wind turbine blade according to another embodiment, showing the end face at a position corresponding to line BB in FIG. [Figure 9] 1. FIG. 4 is an end view of a wind turbine blade according to another embodiment, showing the end face at a position corresponding to line CC in FIG. [Figure 10] 1. FIG. 4 is an end view of a wind turbine blade according to another embodiment, showing the end face at a position corresponding to line DD in FIG. [Figure 11] FIG. 1 is a perspective view of a wind turbine blade according to a comparative technique. [Figure 12] FIG. 12 is an end view taken along line aa in FIG. [Figure 13] FIG. 12 is an end view taken along line bb in FIG. [Figure 14] FIG. 12 is an end view taken along line cc in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiment described here. The shape, material, manufacturing method, etc. of each member can be changed as appropriate. The same elements in all drawings are given the same reference numerals, and duplicated explanations will be omitted.

[0018] Fig. 1 is a perspective view of a wind turbine blade 10 according to an embodiment, and Fig. 2 is a perspective view showing the back side of the wind turbine blade 10. In each of the drawings including Figs. 1 and 2, only the outer wall of the wind turbine blade 10 is shown, and other structures are omitted. The wind turbine blade 10 (hereinafter also simply referred to as the blade 10) is used in a wind power generating device for a propeller-type wind turbine. For example, three blades 10 are attached to a hub to form a wind turbine propeller.

[0019] The blade 10 includes a pressure side blade element 12p and a suction side blade element 12n. The two blade elements 12p, 12n are manufactured separately, and are joined together to form the outer wall of the blade 10. The material of the blade elements 12p, 12n is FRP (Fiber Reinforced Plastics). Although the blade elements 12p, 12n are hatched differently in each drawing, they are made of the same material. In another embodiment, the blade elements 12p, 12n may be made of different materials.

[0020] The blade 10 has a blade root 20 (wing root) that is connected to the hub, a leading edge 24 that receives (cuts) the wind, a blade tip 22, and a trailing edge 26 that the wind moves away from. The two blade elements 12p, 12n are continuously bonded together and integrated at the outer periphery of the blade 10 (the leading edge 24 side, the blade tip 22, and the trailing edge 26 side) except for the blade root 20. The blade root 20 has a cylindrical shape and is open.

[0021] Figures 3, 4, 5, and 6 are end views (showing only the end shape, not the rear shape) taken along lines AA, BB, CC, and DD in Figure 1, respectively. Figure 3 shows an enlarged view of the inside of the dashed dotted line of the blade 10. Note that in Figure 2, the positions corresponding to lines AA, BB, CC, and DD in Figure 1 are indicated by arrows A, B, C, and D, respectively.

[0022] As shown in Figures 3 to 6, the blade 10 has a shape that gradually changes from a cylindrical shape to a wing shape (flattened tube shape) from the blade root (Figure 6) to the blade tip side (Figure 3). The wing shape is a shape that generates lift in the blade 10, and the wing-shaped portion is from near line BB in Figure 1 to just before the blade tip 22. From line AA in Figure 1 to just before the blade tip 22, the width of the blade 10 (the distance from the leading edge 24 to the trailing edge 26) gradually narrows, but the end face shape has the same wing shape as in Figure 3.

[0023] Here, the blade elements 12p and 12n will be further described. The blade elements 12p and 12n are each manufactured by VaRTM (Vacuum assisted Resin Transfer Molding). VaRTM is a method in which a reinforcing fiber substrate (glass fiber, carbon fiber fabric, etc.) is laminated in a desired manner on a molding die, the upper side is covered with a flexible film to form a closed space, and then liquid resin is pumped into the closed space while vacuum-suctioning the air, so that the liquid resin is impregnated into the reinforcing fiber substrate and hardened. As shown in Figures 3 and 4, the blade elements 12p and 12n are partially thicker and thinner. Such a difference in thickness is realized in the VaRTM method by laminating reinforcing fiber substrates (hereinafter referred to as substrates) having different shapes in a plan view and partially changing the number of laminated substrates.

[0024] 3 and 4, the blade element 12p has a shape in which the front end 31p and the rear end 33p are folded back, and in another embodiment described with reference to Figs. 7 and 8, the blade element 12n has a shape in which the front end 31n (see the lower left diagrams in Figs. 7 and 8) and the rear end 33n are folded back. In the VaRTM method, such a folded shape is realized by folding back the laminated base material and holding it in a mold, covering the upper side and the inside of the fold (only when a space is formed inside the fold) with a flexible film, vacuum-suctioning the air in the closed space formed by the flexible film and the mold, sending resin into the closed space, and impregnating the base material with the resin and curing it.

[0025] 3 and 4, at the positions of lines AA and BB, the rear end 33p of the blade element 12p is folded back toward the inside and forward, and an outer surface 38p of the rear end 33p of the blade element 12p is joined to an inner surface 36n of the rear portion 32n of the blade element 12n. The two blade elements 12p and 12n are joined by applying an adhesive (not shown) to their surfaces where they come into contact with each other.

[0026] In the position of Fig. 3, there is no space inside the folded back of the rear end 33p of the blade element 12p, but in the position of Fig. 4, a space is provided inside the folded back of the rear end 33p, and as shown in Figs. 5 and 6, the folded back of the rear end 33p gradually opens toward the blade root (Fig. 6). Also, the rear end 33p of the blade element 12p is formed thin in the position of Fig. 3 (the wing-shaped part of the blade 10), thereby suppressing the thickness of the folded back part. The rear end 33p of the blade element 12p has a shape that gradually becomes thicker toward the blade root (Fig. 6).

[0027] An outer surface 38p of the rear end 33p of the blade element 12p is continuously joined to an inner surface 36n of the rear portion 32n of the blade element 12n from the vane-shaped portion (FIG. 3) to the cylindrical portion (FIG. 6). In this manner, at the rear portion of the blade 10, a substantially constant bonding width is ensured from the vane-shaped portion to the cylindrical portion, and the two blade elements 12p, 12n are bonded (joined).

[0028] As shown in Fig. 3, at the position of line AA, the suction side blade element 12n extends rearward compared to the pressure side blade element 12p, so that the trailing edge 26 of the blade 10 is formed only by the suction side blade element 12n. The section where the trailing edge 26 of the blade 10 is formed only by the suction side blade element 12n is the portion from near the arrow A to just before the blade tip 22, as shown in Fig. 2.

[0029] In this way, a portion of the trailing edge 26 of the blade 10 is formed by one blade element 12n, so that portion can be made thin. Behind the thin trailing edge 26 formed by one blade element 12n, the winds flowing on the pressure side (outer surface 38p of the blade element 12p) and the suction side (outer surface 38n of the blade element 12n) of the blade 10 smoothly join together, so that the lift generated by the blade 10 can be improved.

[0030] 3 and 4, at the positions of lines AA and BB, front end 31p of blade element 12p is folded back inward and rearward, and outer surface 38p of front end 31p of blade element 12p is joined to inner surface 36n of front end 31n of blade element 12n. As shown in Figures 3 to 6, front end 31p is folded back in a shape that gradually opens from the vane-shaped portion (Figure 3) toward the cylindrical portion (Figure 6).

[0031] An outer surface 38p of the front end 31p of the blade element 12p is continuously joined to an inner surface 36n of the front end 31n of the blade element 12n from the vane-shaped portion (FIG. 3) to the cylindrical portion (FIG. 6). In this manner, even at the front end of the blade 10, a substantially constant bonding width is ensured from the vane-shaped portion to the cylindrical portion, and the two blade elements 12p, 12n are bonded (joined).

[0032] Here, the comparative technology will be described. Fig. 11 is a perspective view of a wind turbine blade 100 of the comparative technology. Figs. 12, 13, and 14 are end views taken along lines aa, bb, and cc in Fig. 11, respectively. The outer wall of the blade 100 is formed by joining a pressure side blade element 112p and a suction side blade element 112n.

[0033] 12 (the vane-shaped portion), an inner surface 136p of a rear end 133p of blade element 112p is joined to an inner surface 136n of a rear end 133n of blade element 112n. Meanwhile, since blade 100 changes from a vane shape (FIG. 12) to a cylindrical shape (FIG. 14), an end surface 142p of a rear end 133p of blade element 112p is joined to an end surface 142n of a rear end 133n of blade element 112n at the position in FIG. 14 (the cylindrical portion).

[0034] The same is true for the front ends 131p, 131n of the two blade elements 112p, 112n, and in the position of Figure 12 (the blade-shaped part), the inner surfaces 136p, 136n are joined to each other, while in the position of Figure 14 (the cylindrical part), the end faces 140p, 140n are joined to each other.

[0035] In this configuration, between the vane-shaped portion (FIG. 12) and the cylindrical portion (FIG. 14), there is provided a region where the bonding surfaces switch from the inner surfaces 136p, 136n to the end surfaces 142p, 142n, as shown in FIG. 13. In this transition region, the bonding width of the blade elements 112p, 112n becomes narrower at the leading edge 124 and the trailing edge 126 of the blade 100, respectively, resulting in a problem that the strength is lower than in other portions.

[0036] On the other hand, according to the blade 10 of the embodiment of the present invention described above, the rear end 33p and the front end 31p of the blade element 12p are folded back and joined to the inner surface 36n of the blade element 12n in the wing-shaped portion (FIGS. 3 and 4), and the fold is gradually opened toward the cylindrical portion (FIG. 6), so there is no need to provide a switching region for the adhesive surface as in the comparative technique (FIG. 13). Therefore, a substantially constant adhesive width is secured from the wing-shaped portion (FIG. 3) to the cylindrical portion (FIG. 6) of the blade 10, and the strength of the blade 10 can be increased.

[0037] Next, another embodiment will be described. The embodiment described above is the first embodiment, and from here, second to fourth embodiments will be described. As shown in Figures 7 to 10, the blade 10A of the second embodiment has a rear structure that is different from that of the blade 10 of the first embodiment.

[0038] Figures 7, 8, 9, and 10 are views showing the end face of blade 10A of the second embodiment at a position corresponding to line AA in Figure 1, a position corresponding to line BB in Figure 1, a position corresponding to line CC in Figure 1, and a position corresponding to line DD in Figure 1, respectively. Note that the front end of the blade shown at the lower left of each of Figures 7 to 10 relates to the third and fourth embodiments, which will be described later.

[0039] As shown in Figures 7 and 8, at the position corresponding to lines AA and BB in Figure 1, the rear end 33n of the blade element 12n is folded back forward and inward, and the outer surface 38n of the rear end 33n of the blade element 12n is joined to the inner surface 36p of the rear portion 32p of the blade element 12p.

[0040] In the position shown in Fig. 7, there is no space inside the folded back portion of the rear end 33n of the blade element 12n, but in the position shown in Fig. 8, a space is provided inside the folded back portion of the rear end 33n, and as shown in Figs. 9 and 10, the folded back portion of the rear end 33n gradually opens toward the blade root (Fig. 10). Also, the rear end 33n of the blade element 12n is formed thin in the position shown in Fig. 7 (the wing-shaped portion of the blade 10), thereby suppressing the thickness of the folded back portion. The rear end 33n of the blade element 12n has a shape that gradually becomes thicker toward the blade root (Fig. 10).

[0041] An outer surface 38n of the rear end 33n of the blade element 12n is continuously joined to an inner surface 36p of the rear portion 32p of the blade element 12p from the vane-shaped portion (FIG. 7) to the cylindrical portion (FIG. 10). In this manner, at the rear portion of the blade 10, a substantially constant bonding width is ensured from the vane-shaped portion to the cylindrical portion, and the two blade elements 12p, 12n are joined together.

[0042] As shown in Fig. 7, at the position corresponding to line AA in Fig. 1, the pressure side blade element 12p extends rearward compared to the suction side blade element 12n, so that the trailing edge 26 of the blade 10 is formed only by the pressure side blade element 12p. The section where the trailing edge 26 of the blade 10 is formed only by the pressure side blade element 12p is the portion from near the arrow A in Fig. 2 to just before the blade tip 22, as in the first embodiment.

[0043] The blade 10A of the second embodiment described above can also provide the same effects as those of the blade 10 of the first embodiment.

[0044] Next, a blade according to a third embodiment will be described. In the blade according to the third embodiment, the front end portion of the blade 10 (FIGS. 3 to 6) according to the first embodiment is replaced with the front end portion of the blade shown in the lower left of each of FIGS. 7 to 10.

[0045] In the third embodiment (see the lower left diagrams of Figs. 7 and 8), the front end 31n of the blade element 12n is folded back toward the rear, and the outer surface 38n of the front end 31n of the blade element 12n is joined to the inner surface 36p of the front end 31p of the blade element 12p. As shown in the lower left diagrams of Figs. 7 to 10, the front end 31n is folded back in a shape that gradually opens from the wing-shaped portion (Fig. 7) toward the cylindrical portion (Fig. 10). The outer surface 38n of the front end 31n of the blade element 12n is continuously joined to the inner surface 36p of the front end 31p of the blade element 12p from the wing-shaped portion (Fig. 7) to the cylindrical portion (Fig. 10). With such a blade of the third embodiment, the same effects as those of the blades of the above-mentioned embodiments can be obtained.

[0046] Next, a blade according to a fourth embodiment will be described. The blade according to the fourth embodiment has a configuration in which the front end portion of the blade 10A (FIGS. 7 to 10) according to the second embodiment is replaced with the front end portion of the blade shown in the lower left of each of FIGS. 7 to 10 (see the lower left drawings of FIGS. 7 to 10). Even with this configuration, it is possible to obtain the same effects as the blades according to the above-mentioned embodiments. [Explanation of symbols]

[0047] 10,10A wind turbine blade, 12p pressure side blade element (blade element), 12n suction side blade element (blade element), 20 blade root, 22 blade tip, 24 leading edge, 26 trailing edge, 31p,31n front end, 32p,32n rear end, 33p,33n rear end, 36p,36n inner surface, 38p,38n outer surface, 100 wind turbine blade, 112p pressure side blade element (blade element), 112n suction side blade element (blade element), 120 blade root, 122 blade tip, 124 leading edge, 126 trailing edge, 131p,131n front end, 133p,133n rear end, 136p,136n inner surface, 140p,140n end surface, 142p,142n end surface.

Claims

1. A wind turbine blade having an outer wall formed by joining a pressure side blade element and a suction side blade element, The wind turbine blade is formed so that the shape gradually changes from a cylindrical shape to a wing shape from the blade root to the blade tip, a rear end portion of one of the two blade elements is folded back inwardly forward at the wing-shaped portion, the fold back gradually opens toward the cylindrical portion, and the plate thickness of the fold back portion gradually increases toward the cylindrical portion, and an outer surface of the rear end portion of the one of the blade elements is continuously joined to an inner surface of a rear portion of the other of the two blade elements from the wing-shaped portion to the cylindrical portion, At least a part of a trailing edge of the wing-shaped portion of the wind turbine blade is formed by the other blade element by extending the other blade element rearward compared to the folded-back portion of the one blade element. A wind turbine blade comprising:

2. A wind turbine blade according to claim 1, The negative pressure side blade element extends rearward compared to the positive pressure side blade element, so that at least a part of a trailing edge of the wing-shaped portion of the wind turbine blade is formed by the negative pressure side blade element. A wind turbine blade comprising:

3. A wind turbine blade according to claim 2, a rear end of the pressure side blade element is folded back forward and inward at the vane-shaped portion, and an outer surface of the rear end of the pressure side blade element is continuously joined to an inner surface of the rear part of the suction side blade element from the vane-shaped portion to the cylindrical portion. A wind turbine blade comprising:

4. A wind turbine blade according to claim 1, The pressure side blade element extends rearward compared to the suction side blade element, so that at least a part of a trailing edge of the wing-shaped portion of the wind turbine blade is formed by the pressure side blade element. A wind turbine blade comprising:

5. A wind turbine blade according to claim 4, a rear end portion of the suction side blade element is folded back forward and inward at the vane-shaped portion, and an outer surface of the rear end portion of the suction side blade element is continuously joined to an inner surface of a rear portion of the pressure side blade element from the vane-shaped portion to the cylindrical portion. A wind turbine blade comprising:

6. A wind turbine blade according to any one of claims 1 to 5, a front end portion of the pressure side blade element is folded back inwardly at the vane-shaped portion, and an outer surface of the front end portion of the pressure side blade element is continuously joined to an inner surface of the front end portion of the suction side blade element from the vane-shaped portion to the cylindrical portion; A wind turbine blade comprising:

7. A wind turbine blade according to any one of claims 1 to 5, a front end portion of the suction side blade element is folded back inwardly at the vane-shaped portion, and an outer surface of the front end portion of the suction side blade element is continuously joined to an inner surface of the front end portion of the pressure side blade element from the vane-shaped portion to the cylindrical portion; A wind turbine blade comprising:

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