WO2022112647A1

WO2022112647A1 - Wind turbine blade erosion shield

Info

Publication number: WO2022112647A1
Application number: PCT/FI2021/050738
Authority: WO
Inventors: Petri SUURNÄKKI; Raul PRIETO
Original assignee: Teknologian Tutkimuskeskus Vtt Oy
Priority date: 2020-11-30
Filing date: 2021-10-29
Publication date: 2022-06-02
Also published as: FI20206218A1

Abstract

According to an example aspect of the present invention, there is provided a wind turbine blade erosion shield (1) comprising a curved metallic layer (2), wherein the curved metallic layer (2) is configured to extend from a suction side (3) to a pressure side (4) of a wind turbine blade (5), a flexible intermediate layer (6), wherein the intermediate layer (6) is configured to be arranged between the curved metallic layer (2) and a part of the wind turbine blade (5), wherein the shield (1) further comprises at least one mechanical interconnection (7) from a suction side (8) to a pressure side (9) of the shield (1) through at least a part of the intermediate layer (6), and wherein the at least one mechanical interconnection (7) is configured to engage with at least one structure (10) protruding from the wind turbine blade (5).

Description

WIND TURBINE BLADE EROSION SHIELD

FIELD [0001] The present invention relates to a wind turbine blade erosion shield.

[0002] Further, the present invention relates to an arrangement comprising a wind turbine blade and a wind turbine blade erosion shield.

[0003] Furthermore, the present invention relates to a use of a wind turbine blade erosion shield in connection with protection of a leading edge of a wind turbine blade. [0004] Even further, the present invention relates to a method of manufacturing a wind turbine blade.

[0005] Additionally, the present invention relates to a gluing lip for a wind turbine blade. BACKGROUND

[0006] Wind turbine blades are often made of a composite material reinforced with fibres such as glass fibres, carbon fibres or a combination of glass and carbon fibres. The fibres are embedded in a polymer matrix, typically polyester, vinylester or epoxy. A common manufacturing process uses Vacuum Assisted Resin Transfer Moulding. Several blade components are manufactured and then bonded with adhesive. Commonly, a pressure side shell and a suction side shell are manufactured separately and then bonded together. A so-called “gluing lip” in the form of a composite piece is sometimes used to provide a strong connection at the leading edge of the blade, and sometimes also at the trailing edge of the blade. [0007] Due to their operation in various locations and across a wide variety of environmental conditions, wind turbine blades can experience cracking or failure of the blade surface due to continued impact of particles including rain, hail, dust, etc., on the blades, in particular on the leading edge of the blades. Erosion can also have a negative impact on the aerodynamic performance of a wind turbine blade, resulting in an associated loss in wind turbine power production. Such continued erosion, cracking or failure requires relatively complicated service operations such as repair operations or blade replacement. These service operations can increase the operating costs of the wind turbines considerably. Typically, the blades have to be refurbished every 2-3 years if no protection is used.

[0008] Different solutions are known by means of which protection of a wind turbine blade in the area of the leading edge of the blade is possible. This may be e.g. in the form of a leading edge protective coating or tape provided on the blade surface. The coating or tape is formed from a material adapted to present improved resistance to environmental erosion compared to the material normally used in the construction of the wind turbine components, e.g. fibre-based composite material used in the manufacture of a wind turbine blade body, and/or an epoxy or polyester-based gelcoat used to coat such a wind turbine blade body. [0009] Document EP 2927482 A1 further discloses a wind turbine blade having a blade shell body made of a composite material comprising reinforcement fibres of a first fibre type embedded in a matrix material of a first matrix type. The blade comprises a tip end and a root end as well as a leading edge and a trailing edge. The blade comprises an erosion shield extending along an exterior surface of at least a portion of the blade shell body. The erosion shield comprises at least one inner layer of aramid reinforcement fibres embedded in a matrix material of a second matrix type, and at least one outer layer made of an UV resistant coating layer.

[0010] Additionally, WO 2018/060298 A1 describes a protective cover system for protecting a leading edge of a wind turbine rotor blade from erosion. The system comprises a first protective cover and a second protective cover. Both covers comprise a polymer and are pre-formed into a curved shape so as to accommodate at least a part of a wind turbine blade to be protected.

[0011] Wind turbine blade leading edge erosion has become an increasing problem particularly with larger turbines, higher tip speeds and construction of offshore plants. [0012] In view of the foregoing, it would be beneficial to provide a system for protection of a wind turbine blade, in particular in the area of the leading edge of the blade. The system should be capable of being manufactured in industrial scale.

SUMMARY OF THE INVENTION

[0013] The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

[0014] According to a first aspect of the present invention, there is provided a wind turbine blade erosion shield comprising a curved metallic layer, wherein the curved metallic layer is configured to extend from a suction side to a pressure side of a wind turbine blade, a flexible intermediate layer, wherein the intermediate layer is configured to be arranged between the curved metallic layer and a part of the wind turbine blade, wherein the shield further comprises at least one mechanical interconnection from a suction side to a pressure side of the shield through at least a part of the intermediate layer, and wherein the at least one mechanical interconnection is configured to engage with or to be coupled to at least one structure protruding from the wind turbine blade.

[0015] Various embodiments of the first aspect may comprise at least one feature from the following bulleted list: the intermediate layer is made of rubber, for example EPDM rubber · the intermediate layer comprises one or more layers

• the curved metallic layer is made of Nickel, Nickel-Cobalt alloy, Steel, Titanium or Titanium alloy

• the shield comprises at least one first recess on the suction side of the shield and at least one second recess on the pressure side of the shield

• the at least one mechanical interconnection is formed by a bolt, a rod, a screw, a tensioned cable, or a tensioned strap

• at least one metallic plate or at least one metallic tile is arranged in each recess

• at least one fixation element is arranged in each recess for fixation of the at least one mechanical interconnection • an adhesive layer is provided between the curved metallic layer and the intermediate layer

• an adhesive layer is provided between the intermediate layer and said part of the wind turbine blade

• the curved metallic layer is clamped with the intermediate layer on the suction side and on the pressure side of the shield

• the curved metallic layer comprises one or more layers

• the curved metallic layer is coated

[0016] According to a second aspect of the present invention, there is provided an arrangement comprising a wind turbine blade and a wind turbine blade erosion shield as described above.

[0017] Various embodiments of the second aspect may comprise at least one feature from the following bulleted list:

• the structure protruding from the wind turbine blade is comprised by or attached to a gluing lip attached to a suction side shell and a pressure side shell of the wind turbine blade

• the structure protruding from the wind turbine blade is comprised by or attached to at least one of a suction side shell and a pressure side shell of the wind turbine blade

[0018] According to a third aspect of the present invention, there is provided a use of a wind turbine blade erosion shield as described above in connection with protection of a leading edge of a wind turbine blade.

[0019] According to a fourth aspect of the present invention, there is provided a method of manufacturing a wind turbine blade, the method comprising bonding a suction side shell and a pressure side shell, wherein a wind turbine blade having a structure protruding from the wind turbine blade is provided, providing a curved metallic layer such that the curved metallic layer extends from a suction side to a pressure side of the wind turbine blade, providing a flexible intermediate layer such that the intermediate layer is arranged between the curved metallic layer and a part of the wind turbine blade, arranging at least one mechanical interconnection through at least a part of the intermediate layer, and coupling the at least one mechanical interconnection to the at least one structure.

[0020] Various embodiments of the fourth aspect may comprise at least one feature from the following bulleted list: · providing a rubber layer as the intermediate layer, for example EPDM rubber

• providing a layer made of Nickel, Nickel-Cobalt alloy, Steel, Titanium or Titanium alloy as the curved metallic layer

• providing at least one first recess on the suction side of the intermediate layer and at least one second recess on the pressure side of the intermediate layer

• arranging at least one metallic plate or at least one metallic tile in each recess

• arranging at least one fixation element in each recess for fixation of the at least one mechanical interconnection

• providing an adhesive layer between the curved metallic layer and the intermediate layer

• providing an adhesive layer between the intermediate layer and the wind turbine blade

• clamping the curved metallic layer with the intermediate layer

• coating the curved metallic layer [0021] According to a fifth aspect of the present invention, there is provided a gluing lip for a wind turbine blade, the gluing lip comprising a structure configured to protrude from a base of the gluing lip to the outside of a wind turbine blade, wherein the base is configured to be attached to a suction side shell and a pressure side shell of the wind turbine blade, and wherein the structure is configured to engage with or be coupled to a mechanical interconnection comprised by a wind turbine blade erosion shield. According to certain embodiments of the present invention, the structure of the gluing lip is configured to engage with or be coupled to a mechanical interconnection comprised by a wind turbine blade erosion shield as described above.

[0022] Considerable advantages are obtained by means of certain embodiments of the present invention. A wind turbine blade erosion shield is provided. The shield removes or at least reduces continued erosion, cracking or failure requiring relatively complicated service operations such as repair operations or blade replacement. The shield decreases service operations, and thus the operating cost of the wind turbines considerably.

[0023] The shield incorporates a curved metallic layer and a flexible intermediate layer and is configured to be mechanically coupled to a wind turbine blade. The intermediate layer mitigates the larger deformations by deforming itself. Thus, the stresses in the metallic shield can be reduced and also the shear stresses the adhesive needs to endure. The modular structure of the shield itself also mitigates the formations of high stresses during large deformations and the extension parts protect the forming gap between elements. The mechanical interconnection of the shield through the intermediate layer decreases the need for adhesives between said two layers to create a better and longer lasting connection. The mechanical interconnection also keeps the shield in place during deformations. Further, the mechanical interconnection allows to adjust the curved metallic layer in order to achieve a smooth aerodynamic surface without steps in the direction of the flow. Even further, the mechanical attachment solution is compatible with bonded attachment, where the intermediate layer is bonded to both the metallic layer and the blade composite laminate, providing a connection which is redundant to the adhesive connection, therefore increasing the reliability of the connection.

[0024] The present invention makes it possible to incorporate a metallic shield into a wind turbine leading edge in a way that can take place in the manufacturing process. The solution isolates the metallic shield from the strain experienced by the underlying blade material, so that the fatigue damage experienced by the metallic shield is sufficiently low. modular structure of the shield makes it further possible to offer a lifetime solution against erosion as the structure endures structural loads better. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIGURE 1 illustrates a schematic view of a part of a known wind turbine blade,

[0026] FIGURE 2 illustrates a schematic cross sectional view of a wind turbine blade erosion shield in accordance with at least some embodiments of the present invention, [0027] FIGURE 3 illustrates a schematic cross sectional view of another wind turbine blade erosion shield in accordance with at least some embodiments of the present invention, and

[0028] FIGURE 4 illustrates a schematic view of details of a wind turbine blade erosion shield in accordance with at least some embodiments of the present invention.

EMBODIMENTS

[0029] In FIGURE 1 a schematic view of a part of a known wind turbine blade 5 is illustrated. The wind turbine blade 5 is formed by a suction side shell 12 and a pressure side shell 13 bonded together. The two shells 12, 13 are fixedly attached to each other via a gluing lip 11 in the region of the leading edge 18 of the wind turbine blade 5. The gluing lip 11 is a prefabricated composite piece which overlaps with both the suction side shell 12 and the pressure side shell 13, thus increasing the contact area for bonding the shells 12, 13. Adhesive 19 is used to couple the gluing lip 11 to the shells 12, 13 of the wind turbine blade 5.

[0030] Erosion, mainly rain and hail, deteriorates the leading edge 18 of the wind turbine blade 5, thus decreasing aerodynamic performance and the structural integrity of the blade.

[0031] In FIGURE 2 and FIGURE 3 a schematic cross sectional view of a wind turbine blade erosion shield 1 in accordance with at least some embodiments of the present invention is illustrated. The wind turbine blade erosion shield 1 comprises a curved metallic layer 2. The curved metallic layer 2 is configured to extend from a suction side 3 to a pressure side 4 of a wind turbine blade 5, i.e. in a region forming the aerodynamic surface of a leading edge of the blade 5. The curved metallic layer is made of Nickel, Nickel-Cobalt alloy, Steel, Titanium or Titanium alloy, for instance. The curved metallic layer 2 may be made from a sheet or plate like substrate. The curved metallic layer 2 may be formed of one substrate or by attachment of several substrates. In other words, an object with aerodynamic properties is arranged to cover at least a part of a leading edge 18 of the wind turbine blade 5. A flexible intermediate layer 6 is configured to be arranged between the curved metallic layer 2 and a part of the wind turbine blade 5. The flexible intermediate layer 6 may be, for example, made of rubber, for example EPDM rubber. The flexible intermediate layer 6 may comprise one layer or several layers. In other words, the intermediate layer 6 serves as a buffer or damper between the curved metallic layer 2 and the wind turbine blade 5.

[0032] The shield 1 further comprises at least one mechanical interconnection 7 from a suction side 8 to a pressure side 9 of the shield 1 through at least a part of the intermediate layer 6. The at least one mechanical interconnection 7 is configured to engage with or be coupled to a structure 10 protruding from the wind turbine blade 5. The at least one mechanical interconnection 7 may be, for example, formed by a bolt, a rod, a screw, a tensioned cable, or a tensioned strap.

[0033] The shield 1 comprises at least one first recess 14 on the suction side 8 of the shield 1 and at least one second recess 15 on the pressure side 9 of the shield 1. Typically, the shield 1 comprises a plurality of opposite recesses on both the suction side 8 and the pressure side 9 of the shield 1 along the blade 5. Typically, at least one fixation element 17 is arranged in each recess 14, 15 for fixation of the at least one mechanical interconnection 7. The fixation element 17 may be, for example, a screw nut, a pin, a ring or any other fixation element.

[0034] Typically, an adhesive layer is provided between the curved metallic layer 2 and the intermediate layer 6. Instead or in addition, the curved metallic layer 2 may also be clamped with the intermediate layer 6 on the suction side 8 and on the pressure side 9 of the shield 1.

[0035] The shown shield 1 is used in connection with protecting at least a part of a leading edge 18 of a wind turbine blade 5. Consequently, an arrangement is formed, wherein the wind turbine blade erosion shield 1 is coupled to a wind turbine blade 5. The at least one mechanical interconnection 7 is coupled to a structure 10 protruding from the wind turbine blade 5. The shield is typically arranged between a tip of the blade 5 and 25- 40 % of the total length of the blade 5, i.e. in a region where local velocity relative to air is substantial during operation of the wind turbine. However, the shield 1 may also be arranged between the tip of the blade 5 and the root of the blade 5 according to certain embodiments.

[0036] The structure 10 protruding from the wind turbine blade 5 may be, for example, comprised by or attached to a gluing lip 11. The structure 10 protrudes from a base 21 of the gluing lip 11. The base 21 of the gluing lip 11 is attached to a suction side shell 12 and a pressure side shell 13 of the wind turbine blade 5 as shown in FIGURE 2. In other words, the gluing lip 11 may comprise a flange or lug protruding from the external part of the leading edge 18 so as to create a portion through which the mechanical interconnection 7 is secured to the blade composite structure. The gluing lip 11 provides two different functions, i.e. its traditional function providing a connection between the suction side shell 12 and the pressure side shell 13 as well as forming one or more flanges or lugs to connect with the shield 1 via the mechanical interconnection 7.

[0037] According to another example, the structure 10 protruding from the wind turbine blade 5 may be comprised by or attached to at least one of a suction side shell 12 and a pressure side shell 13 of the wind turbine blade 5. The shells 12, 13 may, for example, form a flange as shown in FIGURE 3. As shown, the pressure side shell laminate and the suction side shell laminate extend in a substantially 90 degree angle to form a bonding flange or lug so as to create a portion through which the mechanical interconnection 7 is secured to the blade composite structure. The flange or lug may be discontinuous to prevent buckling under load.

[0038] The intermediate layer 6 may be further attached to the wind turbine blade 5 by means of adhesive. A filler material may be used to fill gaps or holes between the metallic layer 2 and the shells 12, 13 of the wind turbine blade 5.

[0039] In FIGURE 4 a schematic view of details of a wind turbine blade erosion shield in accordance with at least some embodiments of the present invention is illustrated. Several structures 10 protruding from a wind turbine blade 5 are shown. The structures 10 are arranged along the blade 5 in a discontinuous form, i.e. the structures 10 are separated from each other. Each structure 10 comprises two openings or borings 20, for instance.

[0040] Additionally, a plurality of plates or tiles 16 are shown. The tiles 16 are arranged along the blade 5 in a discontinuous form, i.e. the tiles 16 are separated from each other. Each tile 16 overlaps with two adjacent structures 10. Each tile 16 further comprises openings or borings aligned with the borings 20 of the structures 10. The tiles 16 are typically arranged in the at least one first recess on the suction side of the shield and/or in the at least one second recess on the pressure side of the shield. The tiles 16 are typically made of metal. Normally, at least one metallic plate or at least one metallic tile 16 is arranged in each recess. One mechanical interconnection is provided for each opening 20. [0041] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0042] Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed.

[0043] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

[0044] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0045] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below. [0046] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", that is, a singular form, throughout this document does not exclude a plurality.

INDUSTRIAL APPLICABILITY

[0047] At least some embodiments of the present invention find industrial application in protection of wind turbine blades. At least some embodiments of the present invention find industrial application in equipping wind turbine blades having high wind turbine blade tip speeds.

REFERENCE SIGNS LIST

1 wind turbine shield

2 curved metallic layer 3 suction side of wind turbine blade

4 pressure side of wind turbine blade

5 wind turbine blade

6 intermediate layer 7 mechanical interconnection 8 suction side of the shield

9 pressure side of the shield 10 structure

11 gluing lip

12 suction side shell

13 pressure side shell 14 first recess

15 second recess

16 metallic plate or tile

17 fixation element

18 leading edge of wind turbine blade 19 adhesive

20 opening

21 base

CITATION LIST Patent Literature EP 2927482 A1 WO 2018/060298 A1

Non Patent Literature

Claims

CLAIMS:

1. A wind turbine blade erosion shield (1) comprising:

- a curved metallic layer (2), wherein the curved metallic layer (2) is configured to extend from a suction side (3) to a pressure side (4) of a wind turbine blade (5),

- a flexible intermediate layer (6), wherein the intermediate layer (6) is configured to be arranged between the curved metallic layer (2) and a part of the wind turbine blade (5),

- wherein the shield (1) further comprises at least one mechanical interconnection (7) from a suction side (8) to a pressure side (9) of the shield (1) through at least a part of the intermediate layer (6), and wherein the at least one mechanical interconnection (7) is configured to engage with at least one structure (10) protruding from the wind turbine blade (5).

2. The wind turbine blade erosion shield (1) according to claim 1, wherein the intermediate layer (6) is made of rubber.

3. The wind turbine blade erosion shield (1) according to claim 1 or 2, wherein the curved metallic layer is made of Nickel, Nickel-Cobalt alloy, Steel, Titanium or Titanium alloy

4. The wind turbine blade erosion shield (1) according to any one of claims 1 - 3, wherein the shield (1) comprises at least one first recess (14) on the suction side (8) of the shield (1) and at least one second recess (15) on the pressure side (9) of the shield (1).

5. The wind turbine blade erosion shield (1) according to claim 4, wherein the at least one mechanical interconnection (7) is formed by a bolt, a rod, a screw, a tensioned cable, or a tensioned strap.

6. The wind turbine blade erosion shield (1) according to claim 4 or 5, wherein at least one metallic plate (16) or at least one metallic tile is arranged in each recess (14, 15).

7. The wind turbine blade erosion shield (1) according to any one of claims 4 - 6, wherein at least one fixation element (17) is arranged in each recess (14, 15) for fixation of the at least one mechanical interconnection (7).

8. The wind turbine blade erosion shield (1) according to any one of claims 1 - 7, wherein an adhesive layer is provided between the curved metallic layer (2) and the intermediate layer (6).

9. The wind turbine blade erosion shield (1) according to any one of claims 1 - 8, wherein the curved metallic layer (2) is clamped with the intermediate layer (6) on the suction side (8) and on the pressure side (9) of the shield (1).

10. An arrangement comprising a wind turbine blade (5) and a wind turbine blade erosion shield (1) according to any one of claims 1 - 9.

11. The arrangement according to claim 10, wherein the structure (10) protruding from the wind turbine blade (5) is comprised by or attached to a gluing lip (11) attached to a suction side shell (12) and a pressure side shell (13) of the wind turbine blade (5).

12. The arrangement according to claim 10, wherein the structure (10) protruding from the wind turbine blade (5) is comprised by or attached to at least one of a suction side shell (12) and a pressure side shell (13) of the wind turbine blade (5).

13. Use of a wind turbine blade erosion shield (1) according to any one of claims 1 - 9 in connection with protection of a leading edge (18) of a wind turbine blade (5).

14. A method of manufacturing a wind turbine blade (5), the method comprising:

- bonding a suction side shell (12) and a pressure side shell (13), wherein a wind turbine blade (5) having a structure (10) protruding from the wind turbine blade (5) is provided,

- providing a curved metallic layer (2) such that the curved metallic layer (2) extends from a suction side (3) to a pressure side (4) of the wind turbine blade (5), - providing a flexible intermediate layer (6) such that the intermediate layer (6) is arranged between the curved metallic layer (2) and a part of the wind turbine blade

(5),

- arranging at least one mechanical interconnection (7) through at least a part of the intermediate layer (6), and

- coupling the at least one mechanical interconnection (7) to the at least one structure

(10).

15. A gluing lip (11) for a wind turbine blade (5), the gluing lip (11) comprising: - a structure (10) configured to protrude from a base (21) of the gluing lip (11) to the outside of a wind turbine blade (5), wherein the base (21) is configured to be attached to a suction side shell (12) and a pressure side shell (13) of the wind turbine blade (5),

- and wherein the structure (10) is configured to engage with or be coupled to a mechanical interconnection (7) comprised by a wind turbine blade erosion shield

(I)·