Rotor blade for a wind turbine and wind turbine

Abstract

A rotor blade (10) for a wind turbine has a rotor blade root (12) that defines a reference plane (BE) for fastening to a hub. A profile region (16) continues from the rotor blade root (12) to a rotor blade tip (26). Within the profile region (16), the rotor blade (10) has a wing profile (28) that defines a chord (34). A chord angle (α) between the reference plane (BE) and the chord (34) increases throughout the profile region (16) from the rotor blade root (12) toward the rotor blade tip (26).

Description

[Technical field]

[0001] The invention relates to a rotor blade for a wind turbine according to claim 1 and to a wind turbine according to claim 13. [Background technology]

[0002] Rotor blades of wind turbines and wind turbines with rotor blades are generally known and are disclosed, for example, in EP 3 330 530 A1, EP 3 147 499 A1, EP 2 840 255 A2, EP 1 019 631 B1, WO 2019 / 030205 A1, WO 2018 / 046067 A1, WO 2010 / 046000 A2 and Dutch Patent No. 1 030 111.

[0003] The invention relates in particular to rotor blades for wind turbines and to wind turbines comprising rotor blades of this kind, the rotor blades having a rotor diameter of 1.5 m to 8 m or a rotor blade length of approximately 0.75 m to approximately 4 m. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] European Patent Application Publication No. 3330530(A1) [Patent Document 2] European Patent Application Publication No. 3147499(A1) [Patent Document 3] European Patent Application Publication No. 2840255(A2) [Patent Document 4] European Patent No. 1019631(B1) [Patent Document 5] International Publication No. 2019 / 030205(A1) [Patent Document 6] International Publication No. 2018 / 046067(A1) [Patent Document 7] International Publication No. 2010 / 046000(A2) [Patent Document 8] Dutch Patent No. 1030111 Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the invention is to provide a rotor blade for a wind turbine and a wind turbine comprising such a rotor blade, which has low noise emissions and good starting behavior. [Means for solving the problem]

[0006] This problem is solved by a rotor blade according to claim 1 and a wind turbine according to claim 13.

[0007] The rotor blades of a wind turbine have, in a known manner, a rotor blade root for fastening the rotor blades to a rotor shaft or a hub, the rotor blade root defining a reference plane, the hub being fixed, as is customary, to the rotor shaft, and during operation the rotor shaft or its axis of rotation is oriented at least approximately in the direction of the incoming wind.

[0008] The profile area of ​​the rotor blade is continuous with the rotor blade root and extends to a rotor blade tip area opposite to the rotor blade root. Preferably, the profile area extends to the rotor blade tip, i.e. to the free end of the rotor blade; however, it is also conceivable that the profile area ends in the rotor blade tip area at a distance from the rotor blade tip, and the rotor blade continues to the profile area and has rotor blade parts of different shapes up to the rotor blade tip.

[0009] The rotor blade nose and the rotor blade rear edge extend over the entire length of the profile area. The wing profile of the rotor blade, which extends over the entire length of the profile area from the rotor blade nose to the rotor blade rear edge, has an upper side forming a suction side and a lower side forming a pressure side.

[0010] The top is on the leeward side and the bottom is on the windward side.

[0011] The chord of the wing profile extends through the rotor blade nose and the rotor blade rear edge. The chord and the reference plane form a chord angle, where the lower side of the wing profile points towards the reference plane and the upper side of the wing profile points away from the reference plane.

[0012] The spacing between the reference plane and the chord increases in the direction of the rotor blade nose.

[0013] The reference plane BE, with the rotor blades 10 mounted thereon, forms with the rotor shaft 18 and its axis of rotation 20 an angle of attack β of preferably maximum 70° and minimum 50°, which angle of attack β is the smallest measurable angle between the axis of rotation 20 and the reference plane BE.

[0014] The underside of the wing profile is oriented to allow the wind to flow over it.

[0015] In accordance with the present invention, the chord angle increases over the profile region in a direction from the rotor blade root to the rotor blade tip region.

[0016] Experiments and computer simulations have shown that rotor blades of this type and wind turbines with rotor blades of this type already exhibit good cp values ​​with low noise emissions, and therefore have good starting characteristics, at low wind speeds of, for example, 4.5 to 5 meters per second.

[0017] In a preferred manner, the chord angle increases continuously, preferably at least approximately linearly, which results in a rotor blade having high efficiency and simple construction.

[0018] This increase in chord angle is preferably done up to the rotor blade tip, but the chord angle can also increase linearly from the rotor blade root to the rotor blade tip region and more strongly in the rotor blade tip region, which helps good response behavior when wind speeds are low.

[0019] Preferably the chord angle is between 0° and 4° in the start section directly adjacent to the rotor blade root, and between 20° and 26° in the rotor blade tip region, which gives good results for rotor blade lengths of about 0.75 m to about 4 m, and therefore rotor diameters of about 1.5 m to about 8 m.

[0020] Preferably the chord angle is 0° at the rotor blade root end of the profile region.

[0021] Preferably, the rotor blade rear edge extends at least approximately straight, which results in a particularly simple construction of the rotor blade.

[0022] A particularly simple construction and good efficiency is supported if the rotor blade rear edges extend, as is preferred, at least approximately in the reference plane.

[0023] Preferably, the profile depth decreases over the entire profile area in the direction from the rotor root to the rotor blade tip area, which allows low mechanical stresses in the rotor blade.

[0024] Preferably, the profile depth decreases continuously, preferably linearly, which also results in a particularly simple and efficient rotor blade.

[0025] Preferably the profile depth is reduced by a factor of two to four, preferably at least approximately a factor of three, following the rotor blade root in the rotor blade tip region, which results in a rotor blade that is simple in construction, stable and efficient.

[0026] In a preferred manner, the profile thickness also decreases over the entire profile area in the direction from the rotor blade root to the rotor blade tip area, preferably continuously, in particular at least approximately linearly, so that the wing profile can have an at least approximately equal (similar) shape over the entire profile area, which results in a particularly simple construction.

[0027] In a preferred manner, it has been found that an at least approximately constant ratio of profile thickness to profile depth over the entire profile area results in an efficient and simple construction of the rotor blade, preferably this ratio being at least approximately 0.07.

[0028] Preferably, the ratio of the profile depth, measured at the rotor blade root end of the profile area, to the length of the profile area (measured in the longitudinal direction of the rotor blade) is at least approximately 0.2.

[0029] The rotor blades are arranged to rotate about a rotation axis of the wind turbine, whereby the rotation axis is oriented at least approximately in the direction of the wind during operation, and the rotor blades are preferentially on the windward side, so that the wind can flow unhindered onto the rotor blades.

[0030] The wing profile is preferably a normal profile with a convexly curved upper side and an S-shaped curved lower side, where at the lower side the transition from the convex to the concave shape is located near the profile nose, preferably within the first 15% of the profile depth, whereby an elongated wing profile is obtained.

[0031] An energy unit equipped with rotor blades of this kind has a rotor shaft defining a rotation axis and a hub fixedly mounted thereon, to which the rotor blades are fixed, the rotation axis being oriented at least approximately in the direction of the incoming wind during operation of the wind turbine, and the rotor blades being located on the windward side so that the wind can flow over them unhindered.

[0032] The wind turbine preferably has two to five, particularly preferably three, rotor blades, which on the one hand ensures a symmetrical construction and, on the other hand, a quiet operation.

[0033] Preferably, the wind turbine is formed in the form of a ducted wind turbine, in order to obtain a particularly good efficiency.

[0034] Preferably, the rotor blades are arranged such that their longitudinal direction extends at least approximately radially relative to the axis of rotation, the same applies to wind turbines having two or more rotor blades, which are then arranged in a uniform distribution in the circumferential direction.

[0035] The rotor blade nose extends at least approximately in a plane that extends perpendicular to the reference plane.

[0036] It is also possible for the rotor blade root to be arranged on the hub or rotor shaft so that it can be swung about a swing axis extending in the longitudinal direction of the rotor blade, in particular in order to swing the rotor blade into a neutral position or to optimize the flow when no driving force is to be generated.

[0037] As a reminder, during actuation the rotor blade nose rotates in a leading manner and the rotor blade rear edge rotates in a trailing manner in the direction of rotation of the rotor blade.

[0038] Preferably, the rotor blade root has two fastening holes for fastening to a hub or rotor shaft, the through holes extending at least approximately perpendicular to a reference plane.

[0039] The invention will now be explained in more detail with the aid of figures, which are purely schematic. [Brief description of the drawings]

[0040] [Figure 1] 1 shows a rotor blade according to the present invention. [Diagram 2] 2 is a cross-sectional view of the rotor blade of FIG. 1 taken along the section line BB. [Diagram 3] 2 is a cross-sectional view of the rotor blade of FIG. 1 taken along section line CC. [Figure 4] FIG. 2 is a cross-sectional view of the rotor blade of FIG. 1 taken along the section line DD. [Diagram 5] 2 is a cross-sectional view of the rotor blade of FIG. 1 taken along section line EE. [Figure 6] FIG. 2 is a cross-sectional view of the rotor blade of FIG. 1 taken along the section line FF. [Figure 7] FIG. 7 is a side view of the rotor blade shown in FIGS. 1 to 6, as viewed in the direction of arrow VII in FIG. [Figure 8] FIG. 8 is a side view of the rotor blade shown in FIGS. 1 to 7, as viewed in the direction of arrow VIII in FIG. [Figure 9] 2 is a cross-sectional view of a rotor blade taken along the section line AA in FIG. 1. [Figure 10] The rotor blade shown in Figures 1 to 9 is shown from below. [Figure 11] The rotor blade shown in Figures 1 to 10 is shown from above. [Figure 12] 2 is a longitudinal section of a rotor blade taken along section line GG in FIG. 1, which extends perpendicular to the axis of rotation. [Figure 13] FIG. 13 is a perspective view of a wind turbine having three rotor blades as shown in FIGS. 1 to 12. [Figure 14] FIG. 13 is a perspective view of a wind turbine, made in the form of a ducted wind turbine, having three rotor blades as shown in FIGS. 1 to 12. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] The rotor blade 10 shown in Figures 1 to 12 has a rotor blade root 12 and a profile region 16 which is directly contiguous with the rotor blade root 12 and extends to a rotor blade tip region 13 opposite the rotor blade root 12. The rotor blade 10 is fixed to a hub by the rotor blade root 12 or is designed so that it can be fixed to a hub. The hub is non-rotatably mounted, in a known manner, on a rotor shaft 18, which defines a rotation axis 20 for the rotor blade 10. Reference is now made in this connection to Figures 13 and 14 and their description further below.

[0042] A leading rotor blade nose 22 and a trailing rotor blade rear edge 24 extend across the profile area 16 in the direction of rotation D of the rotor blade 10 .

[0043] In the illustrated embodiment, the profile region 16 extends to the rotor blade tip 26, i.e., to the free end of the rotor blade 10. However, it is conceivable that the profile region 16 simply extends into the rotor blade tip region 14, in which case the rotor blade 10 has a rotor blade end member of another shape following the profile region 16 to the rotor blade tip 26.

[0044] The rotor blade 18 has a wing profile 28 in the profile region 16 which, in a known manner, defines a suction side by its upper side 30 and a pressure side by its lower side 32. The wing profile 28 extends from the rotor blade nose 22 to the rotor blade rear edge 24.

[0045] 2, the arrow W indicates the direction of the wind blowing when the rotor blades are in motion, so that the lower side 32 is on the windward side and the upper side 30 is on the leeward side.

[0046] The wing profile 28 has a chord 34 that extends through the rotor blade nose 22 and the rotor blade rear edge 24 and defines a chord angle α that is defined by the (minimum) angle between the chord 34 and the reference plane BE.

[0047] In the embodiment, the reference plane BE is defined by a flat surface of the rotor blade root 12. The reference plane E further extends in a longitudinal direction L of the rotor blade 10, which extends radially relative to the axis of rotation 20.

[0048] As can be seen from FIG. 2, the reference plane BE forms with the axis of rotation 20 an angle of attack β of minimum 50° and maximum 70°.

[0049] Furthermore, as can be seen particularly from FIGS. 2 through 6, the chord angle α increases continuously throughout the profile region 16 in the direction from the rotor blade root 20 to the rotor blade tip 26 .

[0050] As is conventional, the rotor blade 10 fixed to the rotor shaft 18 or a hub attached thereto is covered by a shaft cover 68 up to the beginning of the rotor blade side of the profile area 16, i.e. up to the rotor blade root 12, which is shown in relation to Figures 13 and 14.

[0051] In the illustrated embodiment, directly adjacent to the rotor blade root 12, the chord angle α is 0°. However, it is also possible for the chord angle to have a small angle, for example up to 4°.

[0052] In the illustrated embodiment, the chord angle at the rotor blade tip is approximately 26°, but may be selected to be less or greater. In the rotor blade tip region 14, the chord angle α is preferably between 20° and 28°.

[0053] As can be seen from FIGS. 2 through 6, particularly with reference to FIG. 1, the chord angle α increases linearly in the direction from the rotor blade root 12 to the rotor blade tip 26.

[0054] In the representation of Figure 1, the rotor blade nose 22 and the rotor blade trailing edge 24 are straight. As the chord angle α changes, as is particularly evident from Figures 7 to 12, the rotor blade nose 22 extends slightly curved, and the rotor blade trailing edge 24 (see Figure 10) lies substantially in the reference plane BE over its entire length.

[0055] The profile depth 38, i.e., the spacing between the rotor blade nose 22 and the rotor blade rear edge 24, decreases continuously, and in the illustrated embodiment linearly, throughout the profile region 16 in the direction from the rotor blade root 12 to the rotor blade tip 26.

[0056] In the illustrated embodiment, at the rotor blade tip 26 , the profile depth 38 is one-third the profile depth 38 at the end of the profile region 16 toward the rotor blade root 12 .

[0057] The ratio of the profile depth 36 at the rotor blade root end of the profile area 16 to the length of the profile area 36 (ie, the distance between the rotor blade root 12 and the rotor blade tip 26) is 0.2.

[0058] The profile thickness 40 also decreases continuously, and in the illustrated embodiment, linearly, throughout the profile region 16 from the rotor blade root 12 to the rotor blade tip 26 .

[0059] The ratio of profile thickness 40 to profile depth 38 is approximately 0.07 throughout the profile area 16. This results in a very elongated wing profile 28.

[0060] As can be seen in particular from Figures 2 to 6, the illustrated wing profile 28 is a normal profile having a convex upper side 30 and an S-shaped lower side 32, where at the lower side 32 the transition from the convex area to the concave area is located in the vicinity of the rotor blade nose 22; the distance from the rotor blade nose 22 is approximately 10% of the profile depth 38.

[0061] As can be seen in particular from Figures 13 and 14, the rotor blade 10 is arranged to rotate about a rotation axis 20 of the wind turbine, whereby the rotation axis extends at least approximately in the direction of the incoming wind W and the rotor blade 10 is on the upwind side of the wind turbine.

[0062] Two wind turbines are shown in Figures 13 and 14, each equipped with three rotor blades 10 as shown in Figures 1 to 12 and described above.

[0063] These rotor blades 10 are fixed to a hub 42 by means of two bolts, not shown, which pass through respective fastening holes 44 in the rotor blade roots 12, as shown in particular in Figure 9. The longitudinal direction of these fastening holes 44 and therefore of the bolts extends perpendicular to the reference plane BE.

[0064] In the embodiment of the wind turbine shown in Fig. 13, a streamlined generator housing 48 is mounted on a vertical support 46, in which a generator 50 is arranged for generating electrical energy. Three rotor blades 10 are fixed to a hub 46, which is mounted on a rotor shaft 18 that drives the generator 50, and are uniformly distributed around the circumference. At the leeward end of the generator housing 48, a tail unit 52 is provided for orienting the generator housing 48 about the vertical axis of the vertical support 46, so that the rotation axis 20 is oriented against the oncoming wind 36. The rotor blade root 12 is covered by a shaft cover 68.

[0065] The wind turbine embodiment shown in FIG. 14 is configured as a ducted wind turbine, as disclosed in WO 2019 / 076514 A1, in which the three rotor blades 10 are configured as shown in FIGS. 1 to 12.

[0066] A duct 54 is mounted on the vertical support 36 so as to be rotatable about a vertical axis, which duct is rotationally symmetrical with respect to the axis of rotation 22 and has a wing-shaped cross section. An inner duct upper side 56 defines a flow passage 58 for the wind. A guide element 60 is ring-shaped and rotationally symmetrical with respect to the axis of rotation 20. The outside diameter of the guide element 60 is smaller than the smallest inside dimension of the flow passage 58.

[0067] The guide member profile nose 62 is disposed upstream with respect to the duct profile nose 64 and the guide member profile rear edge 66 is disposed downstream with respect to the duct profile nose 64 but upstream with respect to the minimum inside dimension of the flow passage 58 .

[0068] A propeller having three rotor blades 10 for driving an electric generator 50 is arranged at least near the guide member profile rear edge 66 .

[0069] The duct 54 is powerably rotatable about the axis of the vertical support 46 in order to orient the duct 54 and thus the axis of rotation 20 relative to the oncoming wind 36 .

[0070] The subject matter of the invention may also be defined as follows:

[0071] A rotor blade for a wind turbine, comprising a rotor blade root 12 for fixing the rotor blade 10 to a hub, a profile region 16 continuous with the rotor blade root 12 and extending to a rotor blade tip region 14 opposite the rotor blade root, a rotor blade nose 22 and a rotor blade rear edge 24 extending over the entire profile region 16, an upper side 30 forming a suction side and a lower side 32 forming a pressure side of a wing profile 28 extending from the rotor blade nose 22 to the rotor blade rear edge 24 over the entire profile region 16, and a chord 34 of the wing profile 28 extending through the rotor blade nose 22 and the rotor blade rear edge 24, wherein a chord angle α between the reference plane BE and the chord 34 increases over the profile region 16 in the direction from the rotor blade root 12 to the rotor blade tip region 14.

[0072] The reference plane BE extends in the longitudinal direction L of the rotor blade 10 and in which at least approximately a chord 34 extends at the rotor blade root-side end of the profile region 16 .

[0073] The upper side 30 of the wing profile 28 faces away from the reference plane BE and lies to the leeward side, whereas the lower side 32 therefore lies to the windward side.

[0074] The reference plane E forms with the axis of rotation 20 and therefore with the wind blowing therewith an angle of attack β preferably between 50° and 70°.

Claims

1. A rotor blade for a wind turbine, comprising: a rotor blade root (12) defining a reference plane (BE) for fixing the rotor blade (10) to a hub, the reference plane (BE) extending radially with respect to a rotation axis (20) and in a longitudinal direction L of the rotor blade (10); a profile region (16) continuing from the rotor blade root (12) and extending into a rotor blade tip region (14) opposite the rotor blade root (12); a rotor blade nose (22) and a rotor blade rear edge (24) extending over the entire profile region (16); an upper side (30) forming a suction side and a lower side (32) forming a pressure side of a wing profile (28) extending over the entire profile region (16) from the rotor blade nose (22) to the rotor blade rear edge (24); and a chord (34) of the wing profile (28) extending through the rotor blade nose (22) and the rotor blade rear edge (24), 1. A rotor blade comprising: a rotor blade having a profile region (16) and a chord angle (α) between the reference plane (BE) and the chord (34) increasing in a direction from the rotor blade root (12) to the rotor blade tip region (14).

2. 2. A rotor blade according to claim 1, characterized in that the chord angle (α) increases continuously.

3. 3. A rotor blade according to claim 1 or 2, characterized in that the chord angle (α) is between 0° and 4° in a starting section continuing from the rotor blade root (12) and between 20° and 28° in the rotor blade tip region (14).

4. A rotor blade according to any one of claims 1 to 3, characterized in that the rotor blade rear edge (24) extends at least approximately linearly.

5. 5. A rotor blade according to claim 1, wherein the profile depth (38) decreases over the entire profile region (16) in a direction from the rotor blade root (12) to the rotor tip region (14).

6. A rotor blade according to claim 5, characterized in that the profile depth (38) decreases continuously.

7. 7. A rotor blade according to claim 5 or 6, characterized in that the profile depth (38) is reduced by a factor of between half and a quarter, preferably at least approximately a factor of a third.

8. 8. A rotor blade according to claim 1, wherein the profile thickness (40) decreases over the profile region (16) in a direction from the rotor blade root (12) to the rotor blade tip region (14).

9. A rotor blade according to claim 8, characterized in that the profile thickness (40) decreases continuously.

10. 10. A rotor blade according to claim 8 or 9, characterized in that the ratio of profile thickness (40) to profile depth (38) is at least approximately constant within the entire profile area (16), preferably at least approximately 0.

07.

11. 11. A rotor blade according to any one of claims 1 to 10, characterized in that the rotor blade (10) is arranged to rotate about a rotation axis (20) of the wind turbine, whereby the rotation axis (20) extends at least approximately in the direction of the incoming wind (36) and whereby a reference plane (BE) forms with the rotation axis (20) an angle of attack (β) of at least 50°.

12. 12. A rotor blade according to any one of claims 1 to 11, characterized in that the wing profile (28) is a normal profile having a convexly curved upper side (30) and an S-shaped curved lower side (32).

13. 13. A wind turbine having a rotor shaft (18) defining a rotation axis (20) with a hub (42), to which rotor blades (10) according to any one of claims 1 to 12 are fixed by their rotor blade roots (12), wherein the rotation axis (20) is oriented at least approximately in the direction of an incoming wind (36) during operation.

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