Multi-layer leading edge protection for wind turbine blades

Abstract

A wind turbine blade extending from a root to a tip is disclosed. A wind turbine blade includes a root region and an airfoil region including a tip, a pressure side, a suction side, and a chord line extending between a leading edge and a trailing edge. A wind turbine blade includes a leading edge protection element. The leading edge protection element is arranged at the leading edge of the wind turbine blade so as to form an exterior surface at the leading edge of the wind turbine blade. The leading edge protection element includes a first layer made of a first material having an added pigment material, where the added pigment material has a first weight content defined as a weight of the added pigment material divided by a weight of the first layer. The leading edge protection element includes at least one second layer made of a second material with or without an added pigment material, where the added pigment material has a second weight content defined as a weight of the added pigment material divided by a weight of the at least one second layer. The second weight content is less than the first weight content. The at least one second layer is disposed closer to the outer surface of the blade than the first layer.

Description

Field of the Invention

[0001] The present disclosure relates to wind turbine blades and the manufacture of wind turbine blades. More specifically, the present disclosure relates to the field of protection of wind turbine blades, such as the protection of the leading edge of a wind turbine blade. Background Art

[0002] As the size of wind turbines increases, the length of the wind turbine blades also increases, which means that the tip speed of the wind turbine blades increases. In addition, for wind turbines located offshore, noise may no longer be an issue, which means that higher tip speeds are allowable for the wind turbine blades. Therefore, large wind turbine blades (especially those for offshore use) typically have to withstand higher speeds and thus need to be more robust. During rotation at higher speeds, the airfoil (especially at the leading edge) is subject to increased wear caused by impact with particles or raindrops in the air. To reduce wear on the leading edge, robust materials are needed on the wind turbine blades and especially on the leading edge. Therefore, leading edge protection elements have been used in the field of wind turbine blade protection to protect the blade (especially at the leading edge). In addition to higher energy production due to the higher rotational speed of the wind turbine blades during operation, the improved robustness of the wind turbine blades can further extend the service life of an individual wind turbine blade.

[0003] In addition, during the manufacturing process, for example, during the manufacture of the leading edge protection element or during the manufacture of a wind turbine blade including the leading edge protection element, small defects or flaws may occur in the leading edge protection element, such as air bubbles or cracks. Colored materials used for the manufacture of the leading edge protection element are more prone to defects than non-colored or transparent materials. When using a co-extrusion process, defects may occur during manufacture. These defects can shorten the service life of the leading edge protection element and thus shorten the service life of the wind turbine blade or the time between required repairs. However, the leading edge protection element of the colored material can make the color of the wind turbine blade more uniform and protect the blade from damage by ultraviolet (UV) light. Therefore, it is desirable to use colored materials for protecting the leading edge of wind turbine blades.

[0004] Therefore, there is a need for a leading edge protection element that can protect a wind turbine blade during the service life of the blade and reduce the risk of downtime for repairing the leading edge protection element caused by defects in the leading edge protection element. Summary of the Invention

[0005] The object of the present disclosure is to provide a leading edge protection element for a wind turbine blade that overcomes at least some of the disadvantages of the prior art.

[0006] Accordingly, the present invention relates to a wind turbine blade extending from a root to a tip. The wind turbine blade includes a root region and an airfoil region, the airfoil region including a tip, a pressure side, a suction side, and a chord extending between a leading edge and a trailing edge. The wind turbine blade includes a leading edge protection element. The leading edge protection element is arranged at the leading edge of the wind turbine blade so as to form an outer surface at the leading edge of the wind turbine blade. The leading edge protection element includes a first layer made of a first material with added pigment material, wherein the added pigment material has a first weight content, which is defined as the weight of the added pigment material divided by the weight of the first layer. The leading edge protection element includes at least a second layer made of a second material, the second material having or not having added pigment material, wherein the added pigment material has a second weight content, which is defined as the weight of the added pigment material divided by the weight of the at least a second layer. The second weight content is less than the first weight content. The at least a second layer is arranged closer to the outer surface of the blade than the first layer.

[0007] An advantage of the present disclosure is that better protection of the wind turbine blade is provided due to the robust leading edge protection element. Another advantage of the present disclosure is that due to the materials used and the multi-layer structure, the leading edge protection element is less prone to defects. In particular, the material of the second layer is less prone to flaws during the manufacture of the leading edge protection element due to having less pigment material or even no pigment material, while the first layer including more pigment material is protected by one or more second layers. In addition, the multi-layers of the leading edge protection element reduce the size of potential flaws and thus reduce the risk of a through flaw occurring, which in turn increases the robustness and service life of the wind turbine blade.

[0008] The added coloring material may include one material or a combination of more than one material. The added coloring material may undergo chemical or physical changes during and / or after being added to the first layer and / or the second layer. Alternatively, the added coloring material may not undergo any chemical or physical changes during and / or after being added to the first layer and / or the second layer. The chemical or physical changes may occur naturally and / or as a reaction to the material treatment. The added coloring material may be organic, inorganic, or a combination of both. The added coloring material may include polymers. The added coloring material may be selected from the following combinations: acrylates, phthalocyanines, quinones, azo pigments, oxides, carbon black, titanium oxide, iron oxide.

[0009] The first layer can be the innermost layer of the leading edge protection element. Other layers, such as below or beneath the leading edge protection element, such as below or beneath the innermost layer of the leading edge protection element, such as below or beneath the first layer. The fiber-reinforced plastic layer can be part of the blade shell portion. The leading edge protection element can include an additional second layer made of a second material, which may or may not have an added pigment material, where the added pigment material has a second weight content defined as the weight of the added pigment material divided by the weight of at least one second layer, and the second layer can be arranged below or beneath the leading edge protection element. Alternatively, other layers or the additional second layer can be part of the leading edge protection element.

[0010] The leading edge protection element can include an inner surface (e.g., the surface facing at least one blade shell portion of the wind turbine blade) and an outer surface (e.g., the surface defining the outer surface of the wind turbine blade). The inner surface can be formed by the first layer. The outer surface can be formed by at least a second layer.

[0011] The first layer can be arranged between at least one second layer and at least one blade shell portion of the wind turbine blade. An attachment layer can be arranged between the first layer and at least one blade shell portion of the wind turbine blade. The attachment layer can include a pressure-sensitive adhesive.

[0012] The first layer and at least one second layer can be joined to each other, for example, using heat. Preferably, the first layer and / or at least one second layer is formed as a co-extruded element. The first layer and at least one second layer can be co-extruded. The first layer and the second layer can be joined to each other during co-extrusion while the layers are heated. Alternatively, the first layer and at least one second layer can be joined to each other while the first layer and / or the second layer is still formable (e.g., hot or warm).

[0013] The leading edge protection element can include a plurality of first layers.

[0014] The first layer and at least one second layer can be made of the same material. In other words, the first material and the second material can be the same base material, where the first material has an added pigment material, and the second material may or may not have an added pigment material. The first layer and the second layer can be the same material and have different properties. For example, the first layer and the second layer can have different elastic moduli.

[0015] The first layer and / or at least one second layer is made of a thermoplastic material. In a preferred embodiment, the first layer and at least one second layer are made of a thermoplastic material.

[0016] The first layer and / or at least one second layer may be made of an elastomeric material, such as a thermoplastic polymer material, for example a thermoplastic polyurethane material. In a preferred embodiment, the first layer and at least one second layer are made of a thermoplastic polyurethane material. Polyurethane is a versatile material that can be customized according to the required needs and has both thermosetting and thermoplastic properties. The polyurethane can be colored or uncolored, and the latter can provide at least a partially transparent material. By using a thermoplastic material, the layers of the leading edge protection element can be co-extruded, which provides a strong multi-layer structure with a low risk of impurities or defects causing defects throughout the entire thickness of the leading edge protection element.

[0017] The first layer may comprise a colored polyurethane material, and at least one second layer may comprise an uncolored material, such as a transparent or partially transparent polyurethane material, preferably thermoplastic.

[0018] The first weight content may be from 0.1 wt% to 10 wt%, such as from 0.5 wt% to 5 wt%, such as from 1 wt% to 2 wt%. When the leading edge protection element is arranged on a wind turbine blade, the pigment material in the first layer may have the same coloring color as the rest of the surface of the wind turbine blade. When the leading edge protection element is arranged on a wind turbine blade, the leading edge protection element may have the same coloring color as the rest of the wind turbine blade.

[0019] The second weight content may be less than 1 wt%, such as 0 wt%. The second layer may be uncolored, partially transparent or transparent. The second layer may be less colored or more transparent than the first layer. The coloring color of the second layer may be the same as or different from the coloring color of the first layer. The coloring color of the second layer may be the same as or different from the coloring color of the rest of the surface of the wind turbine blade.

[0020] The first layer may preferably have a first central thickness at the leading edge of the blade. The first central thickness may be between 100 μm and 800 μm, such as between 150 μm and 500 μm, such as 250 μm.

[0021] The leading edge protection element may comprise a plurality of second layers, such as 2 to 10 second layers, such as 2 to 8 second layers, such as 2 or 3 second layers. A plurality of second layers may be provided. The plurality of second layers and the first layer may be co-extruded. The plurality of second layers may be joined to each other, for example using heat or co-extrusion. The plurality of second layers may be provided as a co-extruded element. The plurality of second layers and the first layer may be provided as a co-extruded element.

[0022] Each of the plurality of second layers may preferably have a second central thickness at the leading edge of the blade. The second central thickness may be between 100 μm and 500 μm, such as between 150 μm and 300 μm, such as 250 μm.

[0023] Each of the first layer and / or the plurality of second layers may have a uniform thickness. The thicknesses of the plurality of second layers may be higher and lower in sequence or alternately. The thickness of each of the plurality of second layers may decrease in the chordwise direction from the inner surface of the leading edge protection element towards the outer surface of the leading edge protection element. The thickness of each of the plurality of second layers may increase in the chordwise direction from the inner surface towards the outer surface. Each of the plurality of second layers may have substantially the same thickness.

[0024] Each of the first layer and / or at least one second layer and / or the plurality of second layers may have a Shore A hardness between 75 and 120, such as between 80 and 100, such as between 85 and 98. The first layer and / or at least one second layer may have a Shore A hardness above 80. Each of the plurality of second layers may have a Shore A hardness different from each other. Each of the plurality of second layers may have a Shore A hardness relatively lower and higher than each other in sequence or alternately. Each of the plurality of second layers may have substantially the same Shore A hardness.

[0025] The Shore A hardness of each of the plurality of second layers may increase from the inner surface of the leading edge protection element towards the outer surface of the leading edge protection element. The inner layer with a lower Shore A hardness may be configured as a buffer layer. The outer layer with a higher Shore A hardness may provide improved impact resistance.

[0026] The Shore A hardness of each of the plurality of second layers may decrease from the inner surface of the leading edge protection element towards the outer surface of the leading edge protection element.

[0027] As can be seen from the above, the hardness or flexibility of the various layers can be customized according to the required needs. For example, the inner layer may have greater flexibility to provide damping or absorption, while the outer layer may have greater hardness to improve impact resistance.

[0028] At least one second layer and / or the first layer may be configured to act as a sacrificial layer.

[0029] The leading edge protection element may include a center thickness located at the leading edge of the blade. The center thickness may be between 250 μm and 5000 μm, such as between 500 μm and 4000 μm, such as 750 μm or 1500 μm.

[0030] The leading edge protection element may have a uniform thickness. In a preferred embodiment, the first layer and at least one second layer may have a uniform thickness such that the leading edge protection element provided after co - extrusion of the two layers has a uniform thickness.

[0031] In an alternative embodiment, the leading edge protection element may be tapered or chamfered in thickness in a first portion extending on the pressure side of the wind turbine blade, and / or may be tapered or chamfered in thickness in a second portion extending on the pressure side of the wind turbine blade.

[0032] The thickness of the leading edge protection element can be reduced, for example, by chamfering any or all of the edges, for example, to provide a smooth transition to the surface on which the leading edge protection element is disposed on the wind turbine blade. The thickness between the inner surface and the outer surface of the leading edge protection element can be reduced in a transverse direction towards the third edge and / or towards the fourth edge. For example, the leading edge protection element tapers towards the third edge and / or towards the fourth edge such that the transition from the leading edge protection element to the airfoil is minimized. The thickness between the inner surface and the outer surface of the leading edge protection element can be reduced in a longitudinal direction towards the first edge and / or towards the second edge. For example, the leading edge protection element tapers towards the first edge and / or towards the second edge.

[0033] The first part and / or the second part can be tapered or chamfered to a thickness of at most 0.5 mm, i.e., the thickness of the leading edge protection element at the third edge and / or the fourth edge is 0.5 mm or less.

[0034] A method for manufacturing a leading edge protection element for a wind turbine blade is also disclosed. The method includes providing a first layer made of a first material with an added pigment material, wherein the added pigment material has a first weight content, which is defined as the weight of the added pigment material divided by the weight of the first layer. The method includes providing at least one second layer made of a second material, which may or may not have an added pigment material, wherein the added pigment material has a second weight content, which is defined as the weight of the added pigment material divided by the weight of the at least one second layer. The second weight content is less than the first weight content. The first layer and / or the at least one second layer are manufactured using an extrusion process. The method further includes using heat to bond the first layer and the at least one second layer.

[0035] A method for protecting the leading edge of a wind turbine blade is also disclosed. The wind turbine blade extends from a root to a tip. The wind turbine blade includes a root region and an airfoil region, and the airfoil region includes a tip, a pressure side, a suction side, and a chord extending between a leading edge and a trailing edge. The method includes providing a wind turbine blade. The method includes providing a leading edge protection element having the features disclosed above. The method includes bonding the leading edge protection element to the leading edge of the wind turbine blade.

[0036] The leading edge protection element can be bonded to at least one blade shell part of the wind turbine blade using co-infusion. The leading edge protection element can be bonded to the wind turbine blade using co-infusion, for example, a blade shell part. After co-infusion of the leading edge protection element and the blade shell part, the leading edge protection element can form the outer surface of the wind turbine blade at the leading edge. Alternatively, the resin produced by the co-infusion process can form at least a part of the outer surface of the wind turbine blade at the leading edge.

[0037] The leading edge protection element and the shell material can be infused with resin and the resin is then cured. Vacuum assisted resin transfer molding (VARTM) can be applied. Alternatively, the shell material can be pre-impregnated, for example, the shell material can comprise a pre-impregnated glass fiber material. The leading edge protection element and the pre-impregnated material can be consolidated under pressure to form the leading edge. Optionally, heat can be applied during consolidation.

[0038] The leading edge protection element can be bonded to at least one blade shell portion of the wind turbine blade using heat. The leading edge protection element can be bonded to at least one blade shell portion of the wind turbine blade using a pressure sensitive adhesive.

[0039] There is also disclosed a leading edge protection element configured to be arranged at the leading edge of a wind turbine blade so as to form an outer surface of the leading edge of the wind turbine blade. The leading edge element comprises a first layer made of a first material with added pigment material, wherein the added pigment material has a first weight content defined as the weight of the added pigment material divided by the weight of the first layer. The leading edge element comprises at least one second layer made of a second material with or without added pigment material, wherein the added pigment material has a second weight content defined as the weight of the added pigment material divided by the weight of the at least one second layer. The second weight content is less than the first weight content. The at least one second layer is configured to be arranged closer to the outer surface of the blade than the first layer.

[0040] The leading edge protection element can be in the form of a tape or film. The leading edge protection element can be provided as a preformed element. The leading edge protection element can be provided as a film. The leading edge protection element can be provided wound on a reel. The leading edge protection element can be cut to a desired length, for example, between 10 m and 100 m, such as between 15 m and 70 m, such as between 20 m and 50 m, such as 30 m.

[0041] The leading edge protection element according to the present disclosure can be provided to be longer in length than the length of a single wind turbine blade and can be cut to a desired length. The length of the leading edge protection element in the longitudinal direction (e.g., the distance between a first edge and a second edge) can be longer than the length of the leading edge of the wind turbine blade. For example, the length of the leading edge protection element can be greater than 100 m, such as greater than 200 m, such as greater than 300 m.

[0042] The length of the leading edge protection element in the longitudinal direction (e.g., the distance between a first edge and a second edge) can be the same as the length of the leading edge of the wind turbine blade. Alternatively, the length can be less than the length of the leading edge of the wind turbine blade. The leading edge protection element can extend in the longitudinal direction starting from the tip or near the tip.

[0043] The width of a leading edge protection element (such as a first leading edge protection element and / or a second leading edge protection element) in the lateral direction may be between 40 mm and 500 mm, for example between 50 mm and 400 mm, for example between 50 mm and 100 mm or between 200 mm and 400 mm. The leading edge protection element may extend across the leading edge of the wind turbine blade in the lateral direction, for example at the intersection of the suction side and the pressure side of the wind turbine blade.

[0044] It is contemplated that any embodiment or element described in connection with any aspect, with necessary modifications, may be used with any other aspect or embodiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Embodiments of the present invention will be described in more detail below with reference to the drawings. Like reference numerals denote like elements throughout. Accordingly, for the description of each figure, like elements may not be described in detail. The drawings illustrate one way of implementing the present invention and should not be construed as limiting other possible embodiments falling within the scope of the appended claims. Additionally, the illustrated embodiments need not have all aspects or advantages shown. Aspects or advantages described in connection with a particular embodiment are not necessarily limited to that embodiment and may be practiced in any other embodiment, even if not so shown or even if not so explicitly described.

[0046] Figure 1 is a schematic view showing an exemplary wind turbine,

[0047] Figure 2 is a schematic view showing an exemplary wind turbine blade,

[0048] Figure 3 is a schematic view showing a cross-sectional view of an exemplary wind turbine blade,

[0049] Figure 4 is a schematic view showing an exemplary leading edge,

[0050] Figure 5 is a schematic view showing an exemplary leading edge protection element, and

[0051] Figure 6 is a schematic view showing an exemplary method of manufacturing a leading edge protection element. DETAILED DESCRIPTION

[0052] In the following description of the drawings, like reference numerals refer to like elements and thus may not be described for all figures.

[0053] Figure 1Shows a conventional modern upwind wind turbine 2 according to the so-called "Danish concept", which has a tower 4, a nacelle 6 and a rotor with a substantially horizontal rotor shaft. The rotor includes a hub 8 and three blades 10 extending radially from the hub 8, each blade having a blade root 16 closest to the hub and a blade tip 14 furthest from the hub 8.

[0054] Figure 2 Shows a schematic view of an exemplary wind turbine blade 10. The wind turbine blade 10 has the shape of a conventional wind turbine blade with a root end 17 and a tip end 15, and includes a root region 30 closest to the hub, a profile or airfoil region 34 furthest from the hub, and a transition region 32 between the root region 30 and the airfoil region 34. The blade 10 includes a leading edge 18 facing the rotational direction of the blade 10 when the blade is mounted on the hub, and a trailing edge 20 facing the opposite direction to the leading edge 18.

[0055] The airfoil region 34 (also referred to as the profile region) has a blade shape that is ideal or nearly ideal for generating lift, while the root region 30 has a substantially circular or elliptical cross-section due to structural considerations, for example, which makes it easier and safer to mount the blade 10 to the hub. The diameter (or chord length) of the root region 30 may be constant along the entire root region 30. The transition region 32 has a transition profile that gradually changes from the circular or elliptical shape of the root region 30 to the airfoil profile of the airfoil region 34. The chord length of the transition region 32 typically increases with the distance r from the hub. The airfoil region 34 has an airfoil profile with a chord that extends between the leading edge 18 and the trailing edge 20 of the blade 10. The width of the chord decreases with an increase in the distance r from the hub.

[0056] The shoulder 40 of the blade 10 is defined as the position where the blade 10 has its maximum chord length. The shoulder 40 is typically located at the boundary between the transition region 32 and the airfoil region 34.

[0057] It should be noted that the chords of the different sections of the blade generally do not lie in a common plane because the blade can twist and / or bend (i.e., pre-bend), and thus a corresponding twisted and / or bent path is provided to the chord plane, which is to compensate for the most common case depending on the local velocity of the blade at the radius from the hub.

[0058] The wind turbine blade 10 includes a blade shell, which includes two blade shell parts or half shells typically made of fiber-reinforced polymer: a first blade shell part 24 and a second blade shell part 26. The wind turbine blade 10 may include additional shell parts, such as a third shell part and / or a fourth shell part. The first blade shell part 24 is typically the pressure side or windward blade shell part. The second blade shell part 26 is typically the suction side or leeward blade shell part. The first blade shell part 24 and the second blade shell part 26 are fastened together along a joint line or glue joint 28 extending along the trailing edge 20 and the leading edge 18 of the blade 10 using an adhesive such as glue. Typically, the root ends of the blade shell parts 24, 26 have a semi-circular or semi-elliptical outer cross-sectional shape.

[0059] The wind turbine blade 10 includes a leading edge protection element 50 on the leading edge 18 of the wind turbine blade 10. The leading edge protection element 50 extends in the longitudinal direction between a first edge 52 and a second edge 54 and extends in the transverse direction between a third edge 56 and a fourth edge 58. The longitudinal direction of the leading edge protection element 50 may be parallel to the longitudinal direction of the wind turbine blade 10. The leading edge protection element 50 extends from a first blade position B1 located at or near the tip 15 to a second blade position B2 closer to the root end 17. The length L of the leading edge protection element 50 (e.g., the distance between the first edge 52 and the second edge 54) may be the same as the length of the leading edge 18 of the wind turbine blade 10, such that the leading edge protection element 50 extends along the length of the blade 10. However, as shown in the figure, the length L may be less than the length of the leading edge 18 of the wind turbine blade 10, such that the leading edge protection element 50 extends only along a part of the blade 10. The leading edge protection element 50 has an inner surface 60 and an outer surface 62. The inner surface 60 of the leading edge protection element faces the leading edge 18 of the wind turbine blade.

[0060] Figure 3 is a schematic cross-sectional view showing an exemplary wind turbine blade 10, for example, a cross-sectional view of the airfoil region of the wind turbine blade 10. The wind turbine blade 10 includes a leading edge 18, a trailing edge 20, a pressure side 24, and a suction side 26. The wind turbine blade 10 includes a chord line 38 between the leading edge 18 and the trailing edge 20. The wind turbine blade 10 includes shear webs 42, such as a leading edge shear web and a trailing edge shear web. Alternatively, the shear web 42 may be a spar box having spar sides such as a trailing edge spar side and a leading edge spar side. The shell parts 24, 26 may include glass fiber or carbon fiber.

[0061] can be achieved by providing a leading edge protection element 50 (such as Figures 2 to 3The leading edge protection element 50) is used to protect the wind turbine blade 10. For illustrative purposes, the leading edge protection element 50 is shown spaced apart from the leading edge 18 of the wind turbine blade 10. However, in the final product, the leading edge protection element 50 and the wind turbine blade 10 are attached to each other, or the leading edge protection element is embedded in the blade shell, for example, by co-infusion.

[0062] The leading edge protection element 50 can be attached to the leading edge 18 of the wind turbine blade 10 by orienting the leading edge protection element 50 such that the inner surface 60 faces the leading edge 18 of the wind turbine blade 10, so as to form the outer surface 44 of the wind turbine blade 10. The leading edge protection element 50 can be attached by applying an adhesive (such as a pressure-sensitive adhesive or a two-component adhesive and / or a heat-activated adhesive) and / or mechanical or chemical bonding. The adhesive can be applied on the inner surface 60 of the leading edge protection element 50 or on the leading edge 18 of the wind turbine blade 10. Alternatively, the shell materials 24, 26 of the wind turbine blade and the leading edge protection element 50 can be consolidated, for example, by infusing the shell materials 24, 26 and the leading edge protection element 50 with resin and curing the resin. Vacuum-assisted resin transfer molding (VARTM) can be applied. After co-infusion, the wind turbine blade 10 including the leading edge protection element 50 can have an outermost layer of resin.

[0063] When the leading edge protection element 50 is arranged and attached to the leading edge 18 of the wind turbine blade 10, the third edge 56 and the fourth edge 58 can extend substantially parallel to the longitudinal direction of the wind turbine blade. In this embodiment, the third edge 56 and the fourth edge 58 can be tapered or chamfered to minimize the height transition to the airfoil surface.

[0064] The leading edge protection element 50 includes a first layer 64 and at least one second layer 66, which will be described in more detail below.

[0065] Figures 4 to 5 is a schematic diagram showing the leading edge protection element 50. Figure 4 is a schematic cross-sectional view showing the leading edge of the wind turbine blade and the leading edge protection element (such as the leading edge 18 and the leading edge protection element 50 in the previous figure). Figure 5 is a schematic diagram showing the leading edge protection element 50 (such as Figures 2 to 4 the leading edge protection element 50).

[0066] The leading edge protection element 50 includes a first layer 64 and at least one second layer 66, such as one second layer 66 or two second layers 66 (see Figure 5 ) or three second layers (see Figure 4)。The first layer 64 is made of a first material having an added pigment material with a first weight content, as shown by the dashed pattern. The second layer 66 is made of a second material which may or may not have an added pigment material with a second weight content. The weight content is defined as the weight of the added pigment material divided by the weight of the first layer or the second layer. The second weight content is less than the first weight content, whereby the second layer 66 includes less pigment material than the first layer 64. The first layer 64 including more pigment material is arranged closer to the blade shells 24, 26 of the wind turbine blade. The second layer 66 including less pigment material is arranged closer to the outer surface 44 of the wind turbine blade 10 than the first layer 64. The second layer 66 may not include a coloring material. For example, the second layer 66 may be transparent. The first layer 64 provides color to the leading edge of the wind turbine blade 10. The color is preferably the same as the surface color of the remainder of the wind turbine blade 10. Due to the pigment material, the first layer 64 also protects the leading edge 18 from UV-induced damage.

[0067] The first layer 64 and the second layer 66 may be made of the same material, such as a thermoplastic material, such as a thermoplastic elastomer material, such as a thermoplastic polyurethane. The first layer 64 and the second layer(s) 66 are joined to each other, such as by thermoextrusion, such as by coextrusion, such as by using hot coextrusion.

[0068] Figure 4 A flaw 80 is further shown, such as a crack or a bubble that may occur during the manufacture of the leading edge protection element 50. Flaws are more likely to occur in a material having a higher weight content of the coloring material compared to a material having a lower or zero weight content of the coloring material. By providing a leading edge protection element 50 including a plurality of layers 64, 66, the risk of a larger flaw 80 extending substantially through the thickness of the leading edge protection element 50 (e.g., from the outer surface 44 to the blade shell portions 24, 26) is reduced because a possible flaw is likely to be present only in a single layer. In addition, providing at least one second layer 66 having a lower weight content or zero weight content of the coloring material generally reduces the occurrence of flaws 80 in the leading edge protection element 50. For example, the risk of a flaw 80 extending from the first layer 64 to at least the second layer 66 is reduced. By constructing the leading edge protection element 50 in several layers, possible flaws 80 are restricted to a single layer within the structure.

[0069] Figure 5 The leading edge protection element 50 is further shown, which extends in a longitudinal direction between a first edge 52 and a second edge 54 and in a transverse direction between a third edge 56 and a fourth edge 58.

[0070] Preferably, when the leading edge protection element 50 is arranged on the wind turbine blade, it has a thickness D between the inner surface 60 and the outer surface 62 at the leading edge. The central thickness D decreases in the lateral direction towards the edges 56, 58. Preferably, when the leading edge protection element 50 is provided on the wind turbine blade, the first layer 64 has a first central thickness D1 at the leading edge, and the (one or more) second layers 66 have a second central thickness D2. The central thickness D1 or D2 can decrease in the lateral direction towards the edges 56, 58.

[0071] The second central thickness D2 of each of the second layers 66 can be the same. The second central thickness D2 of each of the second layers 66 can be different from each other. For example, the second central thickness D2 of each of the second layers 66 can be alternately higher and lower, such that every other second layer 66 has a relatively large thickness and every other second layer 66 has a relatively small thickness. Alternatively, the thickness of consecutive second layers 66 can increase or decrease from the inner surface 60 towards the outer surface 62 (i.e., in the chordwise direction).

[0072] In addition, the Shore A hardness of each of the second layers 66 can be the same. The Shore A hardness of each of the second layers 66 can be different from each other. For example, the Shore A hardness of each of the second layers 66 can be alternately higher and lower, such that every other second layer 66 has a relatively large hardness and every other second layer 66 has a relatively small hardness. Alternatively, the Shore A hardness of consecutive second layers 66 can increase or decrease from the inner surface 60 towards the outer surface 62 (i.e., in the chordwise direction).

[0073] The leading edge protection element 50 can be provided in a wound configuration on a reel to facilitate handling and storage.

[0074] Although the layers and elements in the illustrated embodiments taper or chamfer towards the edges 56, 58, it should be recognized that the layers and elements can also have a uniform thickness. Thus, a leading edge protection element manufactured using coextrusion can subsequently undergo a tapering or chamfering process.

[0075] Figure 6 is a schematic view showing an exemplary method 200 of manufacturing a leading edge protection element, such as the leading edge protection element 50 in the previous figures. The method 200 includes providing raw materials for the first layer 164 and providing raw materials for at least one second layer 166, such as providing raw materials for two separate second layers 166. Each of the raw materials 164, 166 is provided in an extruder 100 and fed via a tube to a manifold extrusion die 102, where the raw materials 164, 166 are coextruded. The leading edge protection element 50 exits the die 102 in the form of a film or strip and is cooled on a cooling reel 106. It can be recognized that other coextrusion setups can also be used.

[0076] Item

[0077] Exemplary embodiments of the present disclosure are listed in the following items:

[0078] 1. A wind turbine blade extending from a root to a tip, the wind turbine blade including a root region and an airfoil region, the airfoil region including a tip, a pressure side, a suction side, and a chord extending between a leading edge and a trailing edge, the wind turbine blade including a leading edge protection element,

[0079] wherein the leading edge protection element is disposed at the leading edge of the wind turbine blade so as to form an outer surface at the leading edge of the wind turbine blade, and wherein the leading edge protection element includes:

[0080] - A first layer made of a first material with a pigment material added thereto, wherein the added pigment material has a first weight content, which is defined as the weight of the added pigment material divided by the weight of the first layer, and

[0081] - At least one second layer made of a second material, which may or may not have a pigment material added thereto, wherein the added pigment material has a second weight content, which is defined as the weight of the added pigment material divided by the weight of the at least one second layer,

[0082] wherein the second weight content is less than the first weight content, and

[0083] wherein the at least one second layer is disposed closer to the outer surface of the blade than the first layer.

[0084] 2. The wind turbine blade according to item 1, wherein the first layer is the innermost layer of the leading edge protection element.

[0085] 3. The wind turbine blade according to any one of the preceding items, wherein the first weight content is from 0.1 wt% to 10 wt%, such as from 0.5 wt% to 5 wt%, such as from 1 wt% to 2 wt%.

[0086] 4. The wind turbine blade according to any one of the preceding items, wherein the second weight content is less than 1 wt%, such as 0 wt%.

[0087] 5. The wind turbine blade according to any one of the preceding items, wherein the first layer is disposed between the at least one second layer and at least one blade shell portion of the wind turbine blade.

[0088] 6. The wind turbine blade according to any one of the preceding items, wherein an attachment layer is disposed between the first layer and at least one blade shell portion of the wind turbine blade.

[0089] 7. The wind turbine blade according to item 5, wherein the attachment layer includes a pressure-sensitive adhesive.

[0090] 8. A wind turbine blade according to any one of the preceding items, wherein the first layer and at least one second layer are thermally bonded to each other, for example.

[0091] 9. A wind turbine blade according to any one of the preceding items, wherein the leading edge protection element comprises a plurality of first layers.

[0092] 10. A wind turbine blade according to any one of the preceding items, wherein the first layer and at least one second layer are made of the same material.

[0093] 11. A wind turbine blade according to any one of the preceding items, wherein the first layer and / or at least one second layer are made of a thermoplastic material.

[0094] 12. A wind turbine blade according to any one of the preceding items, wherein the first layer and / or at least one second layer are formed as a co-extruded element.

[0095] 13. A wind turbine blade according to any one of the preceding items, wherein the first layer and / or at least one second layer are made of an elastomeric material, such as a thermoplastic polymer material, for example a thermoplastic polyurethane material.

[0096] 14. A wind turbine blade according to any one of the preceding items, wherein the first layer comprises a colored polyurethane material, and wherein at least one second layer comprises a non-colored material, such as a transparent polyurethane material, preferably thermoplastic.

[0097] 15. A wind turbine blade according to any one of the preceding items, wherein the leading edge protection element has the form of a strip or film.

[0098] 16. A wind turbine blade according to any one of the preceding items, wherein the first layer preferably has a first central thickness at the leading edge of the blade, and wherein the first central thickness is between 100 μm and 500 μm, such as between 150 μm and 300 μm, such as 250 μm.

[0099] 17. A wind turbine blade according to any one of the preceding items, wherein the leading edge protection element comprises a plurality of second layers, such as 2 to 10 second layers, such as 2 to 8 second layers, such as 2 or 3 second layers.

[0100] 18. A wind turbine blade according to any one of the preceding items, wherein each of the plurality of second layers preferably has a second central thickness at the leading edge of the blade, and wherein the second central thickness is between 100 μm and 500 μm, such as between 150 μm and 300 μm, such as 250 μm.

[0101] 19. A wind turbine blade according to any one of the preceding items, wherein each of the first layer and / or the plurality of second layers has a uniform thickness.

[0102] 20. A wind turbine blade according to item 19, wherein the plurality of second layers are bonded to each other, for example, using heat or co-extrusion.

[0103] 21. A wind turbine blade according to any one of items 19 to 20, wherein the thicknesses of the plurality of second layers are higher and lower in sequence or alternately.

[0104] 22. A wind turbine blade according to any one of items 19 to 21, wherein the thickness of each of the plurality of second layers decreases in the chordwise direction from the inner surface of the leading edge protection element towards the outer surface of the leading edge protection element.

[0105] 23. A wind turbine blade according to any one of items 19 to 22, wherein the thickness of each of the plurality of second layers increases in the chordwise direction from the inner surface of the leading edge protection element towards the outer surface of the leading edge protection element.

[0106] 24. A wind turbine blade according to any one of items 19 to 23, wherein each of the plurality of second layers has substantially the same thickness.

[0107] 25. A wind turbine blade according to any one of the preceding items, wherein the first layer and / or at least one of the second layers has a Shore A hardness between 75 and 120, such as between 80 and 100, such as between 85 and 98.

[0108] 26. A wind turbine blade according to any one of items 19 to 25, wherein each of the plurality of second layers has a different Shore A hardness from each other.

[0109] 27. A wind turbine blade according to any one of items 19 to 26, wherein each of the plurality of second layers has a Shore A hardness that is relatively lower and higher in sequence or alternately with respect to each other.

[0110] 28. A wind turbine blade according to any one of items 19 to 27, wherein each of the plurality of second layers has substantially the same Shore A hardness.

[0111] 29. A wind turbine blade according to any one of items 19 to 28, wherein the Shore A hardness of each of the plurality of second layers increases from the inner surface of the leading edge protection element towards the outer surface of the leading edge protection element.

[0112] 30. A wind turbine blade according to any one of items 19 to 29, wherein the Shore A hardness of each of the plurality of second layers decreases from the inner surface of the leading edge protection element towards the outer surface of the leading edge protection element.

[0113] 31. A wind turbine blade according to any one of the preceding items, wherein at least one of the second layer and / or the first layer is configured to act as an ablatable layer.

[0114] 32. A wind turbine blade according to any one of the preceding items, wherein the leading edge protection element includes a central thickness at the leading edge of the blade, wherein the central thickness is between 250 μm and 5000 μm, such as between 500 μm and 4000 μm, such as 750 μm to 1500 μm.

[0115] 33. A wind turbine blade according to any one of the preceding items, wherein the leading edge protection element has a uniform thickness.

[0116] 34. A wind turbine blade according to any one of the preceding items, wherein the leading edge protection element tapers or is chamfered in a first portion extending on the pressure side of the wind turbine blade, and / or tapers or is chamfered in a second portion extending on the pressure side of the wind turbine blade.

[0117] 35. A wind turbine blade according to item 34, wherein the first portion and / or the second portion taper or are chamfered to a thickness of at most 0.5 mm.

[0118] 36. A method for manufacturing a leading edge protection element for a wind turbine blade, the method comprising:

[0119] - providing a first layer made of a first material with an added pigment material, wherein the added pigment material has a first weight content, which is defined as the weight of the added pigment material divided by the weight of the first layer,

[0120] - providing at least one second layer made of a second material, the second material having or not having an added pigment material, wherein the added pigment material has a second weight content, which is defined as the weight of the added pigment material divided by the weight of the at least one second layer,

[0121] wherein the second weight content is less than the first weight content, and

[0122] wherein the first layer and / or the at least one second layer are manufactured using an extrusion process,

[0123] the method further comprising:

[0124] - using heat to bond the first layer and the at least one second layer.

[0125] 37. The method according to item 36, wherein the first layer and the at least one second layer are co-extruded.

[0126] 38. The method according to item 36, including providing a plurality of second layers and co-extruding the plurality of second layers and the first layer.

[0127] 39. A method for protecting the leading edge of a wind turbine blade,

[0128] wherein the wind turbine blade extends from a root to a tip and includes a root region and an airfoil region, the airfoil region including a tip, a pressure side, a suction side, and a chord extending between a leading edge and a trailing edge,

[0129] the method comprising:

[0130] - providing a wind turbine blade,

[0131] - providing a leading edge protection element having the features of any one of items 1 to 35,

[0132] - bonding the leading edge protection element to the leading edge of the wind turbine blade.

[0133] 40. The method according to item 39, wherein heat is used to bond the leading edge protection element to at least one blade shell portion of the wind turbine blade.

[0134] 41. The method according to item 39, wherein a pressure-sensitive adhesive is used to bond the leading edge protection element to at least one blade shell portion of the wind turbine blade.

[0135] 42. The method according to item 39, wherein the leading edge protection element is bonded to at least one blade shell portion of the wind turbine blade using co-infusion.

[0136] 43. A leading edge protection element configured to be arranged at the leading edge of a wind turbine blade so as to form an outer surface of the leading edge of the wind turbine blade, wherein the leading edge element includes:

[0137] - a first layer made of a first material with an added pigment material, wherein the added pigment material has a first weight content defined as the weight of the added pigment material divided by the weight of the first layer, and

[0138] - at least one second layer made of a second material with or without an added pigment material, wherein the added pigment material has a second weight content defined as the weight of the added pigment material divided by the weight of the at least one second layer,

[0139] wherein the second weight content is less than the first weight content, and

[0140] wherein the at least one second layer is configured to be closer to the outer surface of the blade than the first layer.

[0141] 44. The leading edge protection element according to item 43 is provided as a preformed element.

[0142] 45. The leading edge protection element according to item 43 is provided as a film.

[0143] List of reference signs

[0144] 2 Wind turbine

[0145] 4 Tower

[0146] 6 Nacelle

[0147] 8 Hub

[0148] 10 Blades

[0149] 12 Blade section

[0150] 14 Blade tip

[0151] 15 Tip end

[0152] 16 Blade root

[0153] 17 Root end

[0154] 18 Leading edge

[0155] 20 Trailing edge

[0156] 24 First blade shell part (pressure side)

[0157] 25 Front part of the pressure side

[0158] 26 Second blade shell part (suction side)

[0159] 28 Bonding line / gluing joint

[0160] 30 Root region

[0161] 32 Transition region

[0162] 34 Airfoil region

[0163] 38 Chord

[0164] 40 Shoulder

[0165] 42 Shear web or spar side

[0166] 44 Outer surface

[0167] 50 Leading edge protection element

[0168] 52 First edge

[0169] 54 Second edge

[0170] 56 Third edge

[0171] 58 Fourth edge

[0172] 60 Inner surface

[0173] 62 Outer surface

[0174] 64 First layer

[0175] 66 Second layer(s)

[0176] 80 Defect / flaw

[0177] 100 Extruder

[0178] 102 Multi - manifold extrusion die

[0179] 106 Cooling drum

[0180] 102 Extrusion process

[0181] 164 Raw material of the first layer

[0182] 166 Raw material of the second layer(s)

[0183] 200 Manufacturing method

[0184] L Length of the first leading - edge protection element

[0185] D Central thickness of the leading - edge protection element

[0186] D1 Central thickness of the first layer

[0187] D2 Central thickness of the second layer

[0188] B1 First blade position

[0189] B2 Second blade position

Claims

1. A wind turbine blade extending from a root to a tip, the wind turbine blade comprising a root region and an airfoil region, the airfoil region comprising a tip, a pressure side, a suction side, and a chord extending between a leading edge and a trailing edge, the wind turbine blade comprising a leading edge protection element, wherein the leading edge protection element is arranged at the leading edge of the wind turbine blade so as to form an outer surface at the leading edge of the wind turbine blade, wherein the leading edge protection element comprises: - a first layer made of a first material with added pigment material, wherein the added pigment material has a first weight content, the first weight content being defined as the weight of the added pigment material divided by the weight of the first layer, and - at least one second layer made of a second material, the second material having or not having added pigment material, wherein the added pigment material has a second weight content, the second weight content being defined as the weight of the added pigment material divided by the weight of the at least one second layer, wherein the second weight content is less than the first weight content, and wherein the at least one second layer is arranged closer to the outer surface of the blade than the first layer.

2. The wind turbine blade according to claim 1, wherein the first layer is the innermost layer of the leading edge protection element.

3. The wind turbine blade according to any one of the preceding claims, wherein the first weight content is from 0.1 wt% to 10 wt%, such as from 0.5 wt% to 5 wt%, such as from 1 wt% to 2 wt%.

4. The wind turbine blade according to any one of the preceding claims, wherein the second weight content is less than 1 wt%, such as 0 wt%.

5. The wind turbine blade according to any one of the preceding claims, wherein the first layer and / or the at least one second layer is made of a thermoplastic material.

6. The wind turbine blade according to any one of the preceding claims, wherein the first layer and / or the at least one second layer is formed as a co-extruded element.

7. The wind turbine blade according to any one of the preceding claims, wherein the first layer and / or the at least one second layer is made of an elastomeric material, such as a thermoplastic polymer material, for example a thermoplastic polyurethane material.

8. The wind turbine blade according to any one of the preceding claims, wherein the leading edge protection element comprises a plurality of second layers, such as from 2 to 10 second layers, such as from 2 to 8 second layers, such as 2 or 3 second layers.

9. The wind turbine blade according to any one of the preceding claims, wherein the first layer has a first central thickness preferably at the leading edge of the blade, and wherein the first central thickness is between 100 μm and 500 μm, such as between 150 μm and 300 μm, such as 250 μm, and wherein each of the plurality of second layers has a second central thickness preferably at the leading edge of the blade, and wherein the second central thickness is between 100 μm and 500 μm, such as between 150 μm and 300 μm, such as 250 μm.

10. A wind turbine blade according to any one of the preceding claims, wherein the first layer and / or the at least one second layer has a Shore A hardness between 75 and 120, such as between 80 and 100, such as between 85 and 98.

11. A method for manufacturing a leading edge protection element for a wind turbine blade, the method comprising: - providing a first layer made of a first material with an added pigment material, wherein the added pigment material has a first weight content defined as the weight of the added pigment material divided by the weight of the first layer, - providing at least one second layer made of a second material, the second material having or not having an added pigment material, wherein the added pigment material has a second weight content defined as the weight of the added pigment material divided by the weight of the at least one second layer, wherein the second weight content is less than the first weight content, and wherein the first layer and / or the at least one second layer is manufactured using an extrusion process, the method further comprising: - using heat to bond the first layer and the at least one second layer.

12. The method according to claim 11, wherein the first layer and the at least one second layer are co-extruded.

13. A method for protecting the leading edge of a wind turbine blade, wherein the wind turbine blade extends from a root to a tip and includes a root region and an airfoil region, the airfoil region including a tip, a pressure side, a suction side, and a chord extending between a leading edge and a trailing edge, the method comprising: - providing a wind turbine blade, - providing a leading edge protection element having the features of any one of claims 1 to 10, - bonding the leading edge protection element to the leading edge of the wind turbine blade.

14. The method according to claim 13, wherein the leading edge protection element is bonded to at least one blade shell portion of the wind turbine blade using co-infusion.

15. A leading edge protection element configured to be arranged at the leading edge of a wind turbine blade so as to form an outer surface of the leading edge of the wind turbine blade, wherein the leading edge element comprises: - a first layer made of a first material with an added pigment material, wherein the added pigment material has a first weight content defined as the weight of the added pigment material divided by the weight of the first layer, and - at least one second layer made of a second material, the second material having or not having an added pigment material, wherein the added pigment material has a second weight content defined as the weight of the added pigment material divided by the weight of the at least one second layer, wherein the second weight content is less than the first weight content, and wherein the at least one second layer is configured to be arranged closer to the outer surface of the blade than the first layer.

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