A Wind Turbine Blade Comprising Two Blade Parts and an Aerodynamic Sleeve

Abstract

This invention relates to a sleeve and a modular wind turbine blade comprising such a sleeve. The modular wind turbine blade comprises a first blade and a second blade section, wherein the two blade sections are joined together to form a joint interface having a number of adjoining end lines located in the outer surfaces. A sleeve is positioned over the joint interface and connected to both the first and second blade sections. The body of the sleeve extends over the adjoining end lines and protects them from environmental and external impacts. The sleeve further comprises a number of airflow modifying elements projecting from the outer surface of the sleeve. The airflow modifying elements may be stall fences.

Claims

1. A sleeve (20) for installation on a modular wind turbine blade, the modular wind turbine blade comprising a first blade section (17) and at least a second blade section (18) each extending in a chordwise direction and a longitudinal direction, the first blade section (17) comprises a first joint end and the at least second blade section (18) comprises at least a second joint end, wherein the first and second joint ends, when joined together, define a joint interface (19) extending in the chordwise direction, wherein said joint interface (19) comprises a number of adjoining end lines (36) located in at least one first outer surface of the first and second blade sections (17, 18), the sleeve (20) has a body (21) with an aerodynamic profile, the body (21) has an inner surface (23) and a second outer surface (24) extending from a first end (25) to a second end (26), the body (21) further extends from a local leading edge (28) to a local trailing edge (29), wherein the inner surface (23) of said body (21) is configured to extend over the joint interface (19), when installed, so that the body (21) covers said number of adjoining end lines (36), characterised in that a first airflow modifying element (22) and a second airflow modifying element (22) projects outwards from the second outer surface (24), wherein the first airflow modifying element (22) extends along the first end (25) and the second airflow modifying element (22) extends along the second end (26).

2. A sleeve according to claim 1, characterised in that at least the first or second airflow modifying element (22) has a local length, wherein said local length is between 50% to 100% of a chord length of said body (21) or of said modular wind turbine blade.

3. A sleeve according to claim 1, characterised in that at least the first or second airflow modifying element (22) further extends around at least one of the local leading and trailing edges (28, 29).

4. A sleeve according to claim 3, characterised in that at least the first or second airflow modifying element (22) extends along the circumference of said body (21).

5. A sleeve according to claim 1, characterised in that a number of intermediate airflow modifying elements (22a) and/or a number of vortex generators (30) is arranged between the first and second airflow modifying elements (22).

6. A sleeve according to claim 1, characterised in that the first and second airflow modifying elements (22), the intermediate airflow modifying elements (22a) and/or the vortex generators (30) have a substantially uniform height in the chordwise direction or a height that tapers from a local second edge to a local first edge.

7. A sleeve according to claim 1, characterised in that the sleeve further comprises a number of noise reducing elements (31) or a trailing edge extender (32) extending along the local trailing edge (29).

8. A sleeve according to claim 1, characterised in that at least the first and second airflow modifying elements (22) are flexible elements configured to bend in the chordwise direction and/or the longitudinal direction when installed.

9. A sleeve according to claim 1, characterised in that the body (21) is formed by a single continuous element or comprise at least two body parts (21, 21) which combined define the body (21).

10. A sleeve according to claim 1, characterised in that the body (21) is a flexible body configured to substantially adapt to outer contours of said first and second blade sections (17, 18) and/or said joint interface (19).

11. A sleeve according to claim 1, characterised in that at least one recess (38) is formed in the inner surface (23) of the sleeve (20), wherein said at least one recess (38) is configured to receive and hold at least one adhesive tape or film and/or a fluid adhesive.

12. A sleeve according to claim 11, characterised in that the sleeve further comprises a number of through holes (40) arranged in the body (21) which extend from the second outer surface (24) to the inner surface (23), e.g. the at least one recesses (38), wherein the through holes (40) are configured to be partly or fully filled with a fluid adhesive when installed.

13. A sleeve according to claim 1, characterised in that said first and second airflow modifying elements (22) and/or said intermediate airflow modifying elements (22a) are shaped as stall fences.

14. A modular wind turbine blade, the modular wind turbine blade comprising a first blade section (17) and at least a second blade section (18) each extending in a chordwise direction and a longitudinal direction, the first blade section (17) comprises a first joint end and the at least second blade section (18) comprises at least a second joint end, wherein the first and second joint ends, when joined together, define a joint interface (19) extending at least in the chordwise direction, wherein said joint interface (19) comprises a number of adjoining end lines (36) located in at least one first outer surface of the first and second blade sections (17, 18), characterised in that a sleeve (20) according to claim 1 is positioned at the joint interface (19) so that said number of adjoining end lines (36) in the first outer surface are covered by the body (21) of said sleeve (20).

Description

DESCRIPTION OF DRAWINGS

[0086] The invention is explained in detail below with reference to embodiments shown in the drawings, in which

[0087] FIG. 1 shows a wind turbine,

[0088] FIG. 2 shows an exemplary embodiment of the wind turbine blade,

[0089] FIG. 3 shows a first embodiment of the sleeve according to the invention with two stall fences,

[0090] FIG. 4 shows a perspective view of the sleeve of FIG. 3,

[0091] FIG. 5 shows a cross-section of a second embodiment of the sleeve with two body parts,

[0092] FIG. 6 shows a third embodiment of the sleeve with array of stall fences,

[0093] FIG. 7 shows a four embodiment of the sleeve with vortex generators,

[0094] FIG. 8 shows a fifth embodiment of the sleeve with noise reducing elements,

[0095] FIG. 9 shows a sixth embodiment of the sleeve with a trailing edge extender,

[0096] FIGS. 10-12 show three alternative embodiments of the sleeve,

[0097] FIGS. 13a-d show various cross-sectional profiles of the airflow modifying elements,

[0098] FIG. 14 shows an exemplary embodiment of the joint interface, and

[0099] FIG. 15 shows a seventh embodiment of the sleeve with a recess for receiving adhesive and through holes for applying said adhesive.

LIST OF REFERENCES

[0100] 1. Wind turbine [0101] 2. Wind turbine tower [0102] 3. Nacelle [0103] 4. Hub [0104] 5. Wind turbine blades [0105] 6. Pitch bearing [0106] 7. Blade root [0107] 8. Tip end [0108] 9. Leading edge [0109] 10. Trailing edge [0110] 11. Blade shell [0111] 12. Pressure side [0112] 13. Suction side [0113] 14. Blade root portion [0114] 15. Aerodynamic blade portion [0115] 16. Transition portion [0116] 17. First blade section [0117] 18. Second blade section [0118] 19. Joint interface [0119] 20. Sleeve [0120] 21. Body [0121] 22. Stall fences [0122] 22a. Intermediate stall fences [0123] 23. Inner surface [0124] 24. Second outer surface [0125] 25. First end [0126] 26. Second end [0127] 27. Sleeve [0128] 28. Leading edge of sleeve body [0129] 29. Trailing edge of sleeve body [0130] 30. Vortex generators [0131] 31. Noise reducing elements [0132] 32. Trailing edge extender [0133] 33. Main laminate [0134] 34. Shear web [0135] 35. Overlapping laminate [0136] 36. Adjoining end lines [0137] 37. Sleeve [0138] 38. Recess [0139] 39. Peripheral walls [0140] 40. Through holes

[0141] The listed reference numbers are shown in abovementioned drawings where no all reference numbers are shown on the same figure for illustrative purposes. The same part or position seen in the drawings will be numbered with the same reference number in different figures.

DETAILED DESCRIPTION OF THE DRAWINGS

[0142] FIG. 1 shows a modern wind turbine 1 comprising a wind turbine tower 2, a nacelle 3 arranged on top of the wind turbine tower 2, and a rotor defining a rotor plane. The nacelle 3 is connected to the wind turbine tower 2 via a yaw bearing unit. The rotor comprises a hub 4 and a number of wind turbine blades 5, here three wind turbine blades are shown. The rotor may comprise a smaller or greater number of wind turbine blades 5. The hub 4 is connected to a drive train located in the nacelle 3 via a rotation shaft.

[0143] The hub 4 comprises a mounting interface for each wind turbine blade 5. A pitch bearing unit 6 is optionally connected to this mounting interface and further to a blade root of the wind turbine blade 5.

[0144] FIG. 2 shows a schematic view of the wind turbine blade 5 which extends in a longitudinal direction from a blade root 7 to a tip end 8. The wind turbine blade 5 further extends in a chordwise direction from a leading edge 9 to a trailing edge 10. The wind turbine blade 5 comprises a blade shell 11 having two opposite facing first outer surfaces defining a pressure side 12 and a suction side 13 respectively. The blade shell 11 further defines a blade root portion 14, an aerodynamic blade portion 15, and a transition portion 16 between the blade root portion 14 and the aerodynamic blade portion 15.

[0145] The blade root portion 14 has a substantially circular or elliptical cross-section (indicated by dashed lines). The blade root portion 14 together with a load carrying structure, e.g. a main laminate combined with a shear web or a box beam, are configured to add structural strength to the wind turbine blade 5 and transfer the dynamic loads to the hub 4. The load carrying structure extends between the pressure side 12 and the suction side 13 and further in the longitudinal direction.

[0146] The blade aerodynamic blade portion 15 has an aerodynamically shaped cross-section (indicated by dashed lines) designed to generate lift. The cross-sectional profile of the blade shell 11 gradually transforms from the circular or elliptical profile into the aerodynamic profile in the transition area 16.

[0147] The wind turbine blade 5 is a modular wind turbine blade comprising a first blade section 17 and a second blade section 18. Here the first blade section 17 is shown as a main blade section and the second blade section 18 is shown as a tip end section. The wind turbine blade 5 may comprise a greater number of blade sections. The first and second blade sections 17, 18 are joined together at a joint interface 19. The joint interface 19 is covered by a sleeve 20. This increases the adaptability of the wind turbine blade 5 and reduces the complexity and costs of transporting and handling of the wind turbine blade 5.

[0148] FIGS. 3 and 4 show a first embodiment of the sleeve 20 installed on the wind turbine blade 5 at the joint interface 19. The sleeve 20 comprises a body 21 and a number of airflow modifying elements. The body 21 is a flexible element extending along the entire circumference of the first and second blade sections 17, 18. The body 21 has a second outer surface defining a local pressure side, a local suction side 13, a local leading edge (shown in FIG. 6) and a local trailing edge (shown in FIG. 6).

[0149] As indicated in FIGS. 3 and 4, the airflow modifying elements are here illustrated as stall fences 22 extending in the chordwise direction. The stall fences 22 extend along the local pressure (shown in FIG. 5) and suction sides 13 and further over both the local leading and trailing edges. In this first embodiment, a stall fence 22 is arranged at either ends of the body 21. This reduces the tip losses and tip vortices.

[0150] In an alternative embodiment, the sleeve 20 may comprise only the body 21 and thus no airflow modifying elements, as shown in FIG. 10.

[0151] FIG. 5 shows a cross-section of a second embodiment of the sleeve, wherein the sleeve 20 comprises a number of body parts 21, 21 which together defines the body of the sleeve 20. Here two body parts are shown. But the sleeve 20 may comprise a smaller or greater number of body parts.

[0152] The body, e.g. the body parts 21, 21, has a first end 25 facing the blade root 7 and a second end 26 facing the tip end 8. The width of the body is measured between the first and second ends 25, 26.

[0153] The body, e.g. the body parts 21, 21, further has an inner surface 23 facing the pressure and suction sides 12, 13 of the wind turbine blade 5, respectively. The body, e.g. the body parts 21 21, has a second outer surface 24 forming a local pressure side 12 and a local suction side 13, respectively. The length of the body is measured between a local leading edge (shown in FIG. 6) and a local leading edge (shown in FIG. 6) parallel to the chord line of the wind turbine blade 5. The thickness of the body is measured between the inner surface 23 and the second outer surface 24 perpendicularly to the chord line.

[0154] As indicated in FIG. 5, the airflow modifying elements, e.g. the stall fences 22, are separate elements which are installed on the body of the sleeve 20. The airflow modifying elements, e.g. the stall fences 22, can also be integrally formed together with the body of the sleeve 20, as indicated in FIG. 15.

[0155] FIG. 6 shows a third embodiment of the sleeve, wherein the sleeve 27 comprises a number of intermediate stall fences 22a arranged between the first and second stall fences 22. Here three stall fences are illustrated, but the sleeve may comprise a greater number of stall fences.

[0156] The stall fences 22, 22a extend along a part of the local pressure side 12, over the local leading edge 28 and further along a part of the local suction side 13. The free ends of the stall fences 22, 22a are placed at a distance from the local trailing edge 29.

[0157] FIG. 7 shows a four embodiment of the sleeve, wherein the sleeve 27 comprises an array of airflow modifying elements shaped as vortex generators 30. The vortex generators 30 are arranged in pairs as illustrated in FIG. 7. Here two vortex generators are illustrated, but the sleeve may comprise a greater number of vortex generators.

[0158] FIG. 8 shows a fifth embodiment of the sleeve, wherein the sleeve 27 comprises an array of airflow modifying elements shaped as noise reducing elements 31. The noise reducing elements 31 are formed as serrations arranged at the local trailing edge 29. Here six serrations are illustrated, but the sleeve may comprise a smaller or greater number of serrations.

[0159] FIG. 9 shows a sixth embodiment of the sleeve, wherein the sleeve 27 comprises an airflow modifying element shaped as a trailing edge extender 32. The trailing edge extender 32 is arranged at the local trailing edge 29 has a length substantially corresponding to the width of the sleeve 27.

[0160] The trailing edge extender 32 may simple be a flexible or rigid plate shaped element installed on or integrated into the body 21 of the sleeve 27.

[0161] The first and second airflow modifying elements, e.g. stall fences 22, can be combined with any one of the embodiments of FIGS. 6-9 (indicated by dashed lines) for further enhancing the aerodynamic effect and/or reducing trailing edge noise.

[0162] FIGS. 10-12 show three alternative embodiments of the sleeve 20 wherein the stall fences 22 extend partly along the circumference of the body 21.

[0163] In FIG. 10, the stall fence 22 extends along the local suction side 13 and the free ends thereof are terminated at the local leading and trailing edges 28, 29. The stall fence 22 thus has a length substantially equal to the length of the body 21.

[0164] In FIG. 11, the stall fence 22 extends partly along the local suction side 13 and has a length of about 50% of the chord length of the body 21. Here, the stall fence 22 is arranged at the local leading or trailing edge 28, 29 and extends towards the opposite edge.

[0165] In FIG. 12, the stall fence 22 extends partly along the local suction side 13 and has a length of about 75% of the chord length of the body 21. Here, the stall fence 22 is arranged a chordwise position between the local leading and trailing edges 28, 29.

[0166] FIGS. 13a-d show various cross-sectional profiles of the airflow modifying elements, e.g. the stall fences 22. The stall fences 22 can have a substantially rectangular cross-sectional profile as indicated in FIGS. 13a and 13d. The stall fence 22 can be relative wide, as indicated in FIG. 13a, or relative narrow, as indicated in FIG. 13d.

[0167] The stall fence 22 can also have a substantially triangular cross-sectional profile, e.g. a scalene or equilateral triangular profile as indicated in FIG. 13b. Further, the stall fence 22 can also have a semi-circular or semi-elliptical cross-sectional profile as indicated in FIG. 13c.

[0168] FIG. 14 shows an exemplary embodiment of the joint interface 19 of the wind turbine blade 5. The blade shell 11 of the first and second blade sections 17, 18 comprises a main laminate arranged between the trailing edge 10 and the leading edge 9 and extending in the longitudinal direction. For illustrative purposes, only a cross-section of the load carrying structure is shown.

[0169] The load carrying structure comprises a main laminate 33 arranged at the two opposite facing first outer surfaces 26 of the first and second blade sections 17, 18. One or more shear webs 34 are extending between the two main laminates 33. The load carrying structure adds stiffness to the first and second blade sections 17, 18.

[0170] Each joint ends of the first and second blade sections 17, 18 comprises a recess formed in at least the main laminate 33, wherein the recess is arranged in the first outer surface 26. When the joint ends are brought into contact with each other, the recesses form a combined recess in which an overlapping laminate 35 is arranged. A resin is applied to the gaps between the overlapping laminate 35 and the main laminate 33 and cured to form a scarf joint as illustrated in FIG. 10.

[0171] The scarf joint forms two adjoining end lines 36 in the form of two glue lines extending in at least the chordwise direction. These adjoining end lines 36 are covered by the sleeve 20 when it is installed on the wind turbine blade 5. Here, the sleeve 20 comprises just the body 21 and no airflow modifying elements. Alternatively, the sleeve 20 may comprise only one airflow modifying element as illustrated. For illustrative purposes, the sleeves 20, 20 are only shown on one side of the wind turbine blade.

[0172] FIG. 15 shows a seventh embodiment of the sleeve, wherein the body 21 of the sleeve 37 comprises a recess 38 for receiving and holding an adhesive (marked by grey colour) used to adhere the sleeve 37 to the wind turbine blade 5. The recess 38 is arranged in the inner surface 23 and enclosed by peripheral walls 39 of the body 21.

[0173] The body 21 further comprises a number of through holes 40 extending between the inner surface 23 and the second outer surface 24. Here, three through holes are shown, but the sleeve 37 may comprise a smaller or greater number of through holes.

[0174] The adhesive may be a fluid adhesive applied through the trough holes 40. Any excess adhesive can be pushed back through the holes 40 and then removed. The adhesive may also be an adhesive tape or film arranged in the recess 38, wherein the free surface of the adhesive tape or film projecting outwards from the inner surface 23.

[0175] The abovementioned embodiments may be combined in any combinations without deviating from the present invention.