Patent Description:
The rotor blades of wind turbines may be exposed to extreme loads and weather conditions. In particular at high speeds, raindrops, hail or bird strikes can cause damage and erosion of the leading edge of the rotor blade. Erosion of the leading edge may reduce the aerodynamic efficiency of the blade and thus the power output of the wind turbine significantly. Repairing wind turbine blades, for example after only a few years of operation, is very costly, especially in the case of offshore installations.

Known systems to protect the leading edges of wind turbine blades include adhering a protective layer to the outer surface of a blade body, as disclosed in <CIT>. However, tip speeds of modern large wind turbines, in particular at offshore sites, may reach <NUM>-<NUM>/s or more. The impact energy caused by, for example, raindrops hitting the leading edge of the blade is increasing with increasing tip speed. Hence, leading edge protection is becoming even more important in the case of large tip speeds.

Further documents representing the prior art are e.g. <CIT> and <CIT>.

It is one object of the present invention to provide a wind turbine blade with an improved leading edge protection system and an improved method for manufacturing a leading edge protection system for a wind turbine blade.

Accordingly, a wind turbine blade with a leading edge protection system is provided. The leading edge protection system comprises a shell portion. Further, a surface of the shell portion forms part of an outer surface of the blade. Furthermore, the shell portion includes at least one cavity integrally formed inside a material of the shell portion, and the at least one cavity is a closed cavity filled with a shock absorbing medium and/or the at least one cavity is filled with a shock absorbing material.

Having the leading edge protection system comprising the shell portion with the at least one cavity filled with the shock absorbing material and/or medium provides an improved shock absorption at the leading edge of the wind turbine blade. Thus, erosion of the leading edge of the blade during operation of the wind turbine can be better prevented. Therefore, degradation of the aerodynamic profile of the blade can be better avoided. This can improve the annual energy production of the wind turbine. Further, repairing the wind turbine blade at the leading edge is not or less often necessary.

The shell portion is, in particular, attached to a blade body of the blade. The shell portion is, in particular, attached to the blade body at a leading edge region of the blade body. The leading edge region includes, in particular, the leading edge, a portion of the suction side adjacent to the leading edge and a portion of the pressure side adjacent to the leading edge.

The blade body is, for example, manufactured from fiber-reinforced resin. However, the blade body may also be manufactured by a different method. The blade body comprises, for example a blade shell having an outer surface and an inner surface, the inner surface defining an inner cavity of the blade.

The shell portion of the leading edge protection system is, in particular, a premanufactured element. The shell portion is, in particular, a one-piece element. The shell portion is, in particular, attached to the completed blade body as a single integral premanufactured element. In case that the shell portion comprises the shock absorbing material, the shell portion together with the shock absorbing material is, in particular, a premanufactured element and/or a one-piece element, and/or the shell portion together with the shock absorbing material is attached to the completed blade body as a single integral premanufactured element.

The surface of the shell portion forming part of the outer surface of the blade is, in particular, a convex surface of the shell portion. The surface of the shell portion forming part of an outer surface of the blade forms, in particular, part of the outermost surface of the whole blade (i.e. the blade including the leading edge protection system installed). In other words, said surface of the shell portion forms, in particular, part of the aerodynamic profile of the blade in operation.

The shell portion comprises in addition to said surface forming part of the outer surface of the blade, in particular, a further surface facing the blade body. The further surface facing the blade body is, in particular, a concave surface of the shell portion.

In embodiments, the shell portion consists of the surface (concave surface) and the further surface (convex surface).

The material of the shell portion is, for example, an elastic material. The material of the shell portion includes, for example, polymer, thermoplastic polymer, polyurethane or the like.

The at least one cavity filled with the shock absorbing material is, for example, a closed cavity. Alternatively, the at least one cavity filled with the shock absorbing material is, for example, an open cavity and/or forms, for example, a recess from the further surface of the shell portion (e.g., from the surface of the shell portion facing the blade body).

The at least one closed cavity (filled with the shock absorbing medium and/or material) is, for example, surrounded completely by the material of the shell portion. In case of the closed cavity filled with the shock absorbing medium, the at least one cavity may also be surrounded by the material of the shell portion apart from an opening with a closing mechanism such as a valve.

The wind turbine blade is part of a rotor of a wind turbine. The wind turbine is an apparatus to convert the wind's kinetic energy into electrical energy. The wind turbine comprises, for example, the rotor having one or more of the blades connected each to a hub, a nacelle including a generator, and a tower holding, at its top end, the nacelle. The tower of the wind turbine may be connected to a foundation of the wind turbine such as a monopile in the seabed.

The wind turbine blade, e.g., a root portion of the blade body, is, for example fixedly connected to the hub. The wind turbine blade is, for example, directly bolted to the hub.

Alternatively, the wind turbine blade, e.g., the root portion of the blade body, is rotatably connected to the hub. For example, the wind turbine blade is connected to a pitch bearing of the wind turbine, and the pitch bearing is connected to the hub. The pitch bearing is configured to adjust the angle of attack of the blade according to the wind speed to control the rotational speed of the blade.

Apart from the essentially cylindrical root portion connected with the hub, the outer surface of the wind turbine blade has an aerodynamically shaped cross-section (airfoil). The aerodynamically shaped cross-section of the wind turbine blade comprises, for example, a pressure side (upwind side) and a suction side (downwind side). The pressure side and the suction side are connected with each other at a leading edge and a trailing edge.

As the wind turbine blade comprises the blade body and the leading edge protection system with the shell portion attached to the blade body, the overall outer surface of the blade body and the shell portion together define, as seen in cross-section, the airfoil of the blade with the leading edge, the trailing edge, the pressure side and the suction side.

According to an embodiment, the shock absorbing medium and/or material assumes a shape of the at least one cavity.

In particular, there is no gap between inner walls of the cavity and the shock absorbing medium and/or material.

The at least one cavity is, for example, filled completely with the shock absorbing material and/or medium.

According to a further embodiment, the shock absorbing medium includes a flowable medium, a gaseous medium, a liquid medium, a viscous medium, a fluid, gel and/or foam.

Having a flowable shock absorbing medium allows to easily fill the at least one cavity of the leading edge protection system. Further, a very good shock absorption can be achieved.

In particular, the shock absorbing medium includes a flowable medium, a gaseous medium, a liquid medium, a viscous medium, a fluid, gel and/or foam in the manufactured state of the leading edge protection system and/or during operation of the wind turbine.

The gaseous medium is, for example, air. However, the gaseous medium may also include another gas.

According to a further embodiment, the shock absorbing material includes an elastic material, a deformable material, a non-flowable material and/or a material being softer than the material of the shell portion.

The shock absorbing material is, for example, a non-flowable material in the manufactured state of the leading edge protection system and/or during operation of the wind turbine.

The shock absorbing material includes, for example, a polymeric material, a thermoplastic polymer and/or polyurethane.

The material of the shell portion is, for example, a first elastic material of the leading edge protection system, and the shock absorbing material is, for example, a second elastic material of the leading edge protection system.

According to a further embodiment, the shell portion or the shell portion together with the shock absorbing material filled into the cavity comprise(s) a further surface, and at least a major part of the further surface lies against an outer surface of a blade body.

Thus, an impact energy of, for example, raindrops hitting the leading edge of the blade can be better absorbed and distributed over a larger area of the blade body.

For example, the shell portion or the shell portion together with the shock absorbing material filled into the cavity are configured to lie against or abut to the outer surface of the blade body at the leading edge region.

According to a further embodiment, the shell portion or the shell portion together with the shock absorbing material filled into the cavity comprise(s) a further surface, and at least a major part of the further surface is bonded to an outer surface of a blade body.

Thus, the shell portion (with or without the shock absorbing material) can be reliably and durably fixed to the blade body.

For example, at least a major part of the further surface is bonded to the outer surface of the blade body using an adhesive. By using an adhesive a strong and stable joint between the shell portion and the blade body can be provided.

In embodiments, the further surface is bonded in its entirety to the outer surface of the blade body.

According to a further embodiment, the shell portion or the shell portion together with the shock absorbing material filled into the cavity comprise(s) a further surface, and the further surface comprises one or more indentations filled with an adhesive for bonding the shell portion to the blade body.

An adhesive bond is provided in addition to adsorption by mechanical interlocking when the adhesive flows into pores and irregularities of the adhering surface. Having the indentations in the adherend surface, the adhesive can flow into the indentations, thereby increasing the adhesive bond by mechanical interlocking. Thus, an even stronger bond between the shell portion and the blade body is achieved.

A shape of the indentations may, for example, be tapered towards the further surface.

According to a further embodiment, the shell portion or the shell portion together with the shock absorbing material filled into the cavity is/are formed by extrusion or pultrusion.

Thus, the shell portion or the shell portion together with the shock absorbing material can be easily manufactured. Further, also large (e.g., long) shell portions (with or without shock absorbing material) can be easily manufactured. Hence, a leading edge protection system covering a large fraction of the leading edge region of the blade can be provided.

According to a further embodiment, the shell portion includes several cavities being filled with different shock absorbing media and/or materials.

The different shock absorbing media and/or materials have, for example, different shock absorbing abilities. Thus, the degree of shock absorption can be appropriately varied over the leading edge region of the blade.

According to a further embodiment, the shell portion includes, as seen in cross section of the blade, several cavities and/or the shell portion includes several cavities distributed in a lengthwise direction of the blade.

Having several cavities arranged besides each other as seen in cross section of the blade allows to adapt the shock absorption strength along the airfoil of the blade. Having several cavities distributed in the lengthwise (spanwise) direction of the blade allows to adapt the shock absorption strength along the length of the blade.

According to the invention the at least one closed cavity is filled with a gaseous medium and the leading edge protection system includes means to inflate the at least one cavity.

Having the one or more inflatable cavities allows to control the leading edge geometry during operation of the wind turbine. Hence, annual energy production of the wind turbine can be improved and loads on the turbine reduced.

Further, the one or more inflatable cavities may be used for de-icing and noise reduction purposes.

The at least one closed cavity filled with the gaseous shock absorbing medium is, for example, surrounded by the material of the shell portion apart from an opening with a closing mechanism such as a valve. Hence, the at least one cavity can be filled with gas through the valve. Alternatively or in addition to one or more valves, the leading edge protection system may include a permeable membrane.

According to a further embodiment, the shell portion includes several closed cavities filled with a gaseous medium, and the inflating means are configured to inflate each cavity separately.

Thus, a fine adjustment of the leading edge geometry during operation of the wind turbine can be performed. Further, also de-icing and noise reduction measures can be better and more precisely applied.

According to a further aspect, a method for manufacturing a leading edge protection system for a wind turbine blade as described above is proposed. The method comprises the step of forming a body with at least one cavity from a raw material by extrusion or pultrusion.

The raw material is, for example, a granulate, in particular a polymeric granulate. The raw material is, for example, an elastic granulate. The production process involves, for example, deforming the raw material and/or applying pressure and/or heat to the raw material.

The method comprises, for example, a step of cutting the body to appropriate length. The body cut to length is, in particular, any of the shell portions described above.

According to an embodiment of the further aspect, the body is formed from a first raw material and the at least one cavity is filled during the extrusion or pultrusion process with at least one second raw material, the at least one second raw material being softer than the first raw material.

For example, the body and the at least one filled cavity are formed in a single process step by multi-component extrusion.

According to a further embodiment of the further aspect, the body and the at least one filled cavity are formed from the first and at least one second raw material by means of a multi-component extrusion die head or multi-component pultrusion die head.

The embodiments and features described with reference to the wind turbine blade of the present invention apply mutatis mutandis to the method of the present invention.

In the figures, like reference numerals designate like or functionally equivalent elements, unless otherwise indicated.

<FIG> shows a wind turbine <NUM> according to an embodiment. The wind turbine <NUM> comprises a rotor <NUM> having one or more blades <NUM> connected to a hub <NUM>. The hub <NUM> is connected to a generator (not shown) arranged inside a nacelle <NUM>. During operation of the wind turbine <NUM>, the blades <NUM> are driven by wind to rotate and the wind's kinetic energy is converted into electrical energy by the generator in the nacelle <NUM>. The nacelle <NUM> is arranged at the upper end of a tower <NUM> of the wind turbine <NUM>. The tower <NUM> is erected on a foundation <NUM> such as a concrete foundation or a monopile driven into the ground or seabed.

<FIG> shows a portion of a blade <NUM> of the wind turbine <NUM> of <FIG> in a cross-section view. The blade <NUM> comprises a blade body <NUM>. The blade body <NUM> is, for example, made from fiber-reinforced laminate. The blade <NUM> further comprises a leading edge protection system <NUM> according to an embodiment. The leading edge protection system <NUM> comprises a shell portion <NUM>. The shell portion <NUM> is made from an elastic material <NUM>. The shell portion <NUM> includes a cavity <NUM> integrally formed inside the material <NUM> of the shell portion <NUM>. The cavity <NUM> in the example of <FIG> is a closed cavity surrounded completely by the material <NUM> of the shell portion <NUM>. The cavity <NUM> is filled with a shock absorbing medium <NUM>. The shock absorbing medium <NUM> is, for example, a gaseous medium such as air. The shock absorbing medium <NUM> assumes, in particular, a shape <NUM> of the closed cavity <NUM>. In particular, the cavity <NUM> in <FIG> is filled completely with the shock absorbing medium <NUM>.

The shell portion <NUM> further comprises a surface <NUM> facing away from blade body <NUM>. The surface <NUM> is a convex surface. The surface <NUM> of the shell portion <NUM> forms part of an outer surface <NUM> of the blade <NUM>.

In addition, the shell portion <NUM> comprises a further surface <NUM> facing towards the blade body <NUM>. The further surface <NUM> is a concave surface. At least a major part of the further surface <NUM> lies against an outer surface <NUM> of the blade body <NUM>. In the example shown in <FIG>, the further surface <NUM> lies entirely against the outer surface <NUM> of the blade body <NUM>. Furthermore, at least a major part of the further surface <NUM> is bonded to the outer surface <NUM> of the blade body <NUM>, for example by means of an adhesive (not shown).

Having the leading edge protection system <NUM> allows to reduce erosion of the blade <NUM> in the leading edge region R. Hence, degradation of an aerodynamic profile of the blade <NUM>, i.e. of an aerodynamic profile defined by the outer surface <NUM> of the blade <NUM>, can be better prevented.

<FIG> shows, in cross-section view, a further embodiment of a shell portion <NUM> of a leading edge protection system <NUM> of a blade <NUM> of the wind turbine <NUM> of <FIG>. The shell portion <NUM> in the embodiment of <FIG> is also made from an elastic material <NUM> and comprises a closed cavity <NUM> integrally formed inside the material <NUM> of the shell portion <NUM>. The cavity <NUM> in the example of <FIG> is filled with a shock absorbing elastic material <NUM>, in particular a non-floating deformable material <NUM>. The shock absorbing material <NUM> assumes a shape <NUM> of the closed cavity <NUM>. In particular, the cavity <NUM> in <FIG> is filled completely with the shock absorbing material <NUM>.

The shell portion <NUM> comprises a surface <NUM> (<FIG>) facing away from blade body <NUM> (<FIG>) and a further surface <NUM> (<FIG>) facing towards the blade body <NUM> (<FIG>). The surface <NUM> of the shell portion <NUM> shown in <FIG> forms part of an outer surface <NUM> (<FIG>) of the blade <NUM>.

<FIG> shows, in cross-section view, a further embodiment of a shell portion <NUM> of a leading edge protection system <NUM> of a blade <NUM> of the wind turbine <NUM> of <FIG>. The shell portion <NUM> in the embodiment of <FIG> is also made from an elastic material <NUM>. Further, the shell portion <NUM> comprises a cavity <NUM> integrally formed inside the material <NUM> of the shell portion <NUM>. The cavity <NUM> in the example of <FIG> is an open cavity in form a of recess.

The cavity <NUM> in the example of <FIG> is filled with a shock absorbing elastic material <NUM>, in particular a non-floating deformable material <NUM>. The shock absorbing material <NUM> assumes a shape <NUM> of the open cavity <NUM>. In particular, the cavity <NUM> in <FIG> is filled completely with the shock absorbing material <NUM>.

The shell portion <NUM> comprises a surface <NUM> (<FIG>) facing away from the blade body <NUM> (<FIG>) and a further surface <NUM> (<FIG>) facing towards the blade body <NUM> (<FIG>). The surface <NUM> of the shell portion <NUM> shown in <FIG> forms part of an outer surface <NUM> (<FIG>) of the blade <NUM>.

<FIG> shows, in cross-section view, a further embodiment of a shell portion <NUM> of a leading edge protection system <NUM> of a blade <NUM> of the wind turbine of <FIG>. The embodiment of the shell portion <NUM> shown in <FIG> deviates from the embodiment of the shell portion <NUM> shown in <FIG> by that a further surface <NUM> of the shell portion <NUM> comprises indentations <NUM>. The further surface <NUM> is (as the further surface <NUM> in <FIG>) facing towards the blade body <NUM> (<FIG>).

The indentations <NUM> are configured to be filled with an adhesive <NUM> for bonding the shell portion <NUM> to the blade body <NUM> (<FIG>). <FIG> illustrates exemplarily four indentations <NUM> having different shapes. Further, the indentations <NUM> are shown in an exaggerated size for illustrative purposes. It is noted that the shell portion <NUM> may include many more indentations <NUM> as those shown in <FIG>. Further, the indentations <NUM> may have all the same shape or may show a variety of different shapes. Further, a shape of one, some or all of the indentations <NUM> may, for example, be tapered towards the further surface <NUM>. In this case a size A at the further surface <NUM> of a respective indentation <NUM> is smaller than a size B of the same indentation <NUM> at a bottom <NUM> of the respective indentation <NUM>.

By having the indentations <NUM> (<FIG>), a strength of an adhesive bond (adhesive <NUM> in <FIG>) between the shell portion <NUM> and the blade body <NUM> (<FIG>) can be increased due to an enhanced mechanical interlocking.

Although not shown in the figures, the embodiments of other shell portions described herein, such as the shell portion <NUM> (<FIG>) and the shell portion <NUM> (<FIG>) or other described shell portions, may also be configured to have indentations at the respective further surface (e.g., further surface <NUM> in <FIG> and further surface <NUM> in <FIG>).

<FIG> shows, in cross-section view, a further embodiment of a shell portion <NUM> of a leading edge protection system <NUM> of a blade of the wind turbine of <FIG>. The shell portion <NUM> deviates from the shell portions shown in <FIG> in that the shell portion <NUM> comprises two closed cavities <NUM>, <NUM>. In the shown example in <FIG>, the two closed cavities <NUM>, <NUM> are filled with different shock absorbing materials/media <NUM>, <NUM>. For example, the cavity <NUM> is filled with a shock absorbing medium <NUM> such as air. Further, the cavity <NUM> is, for example, filled with a non-flowable shock absorbing material <NUM>.

In other examples, the shell portion <NUM> may also comprise more than two closed cavities. Further, the two or more cavities may be filled with the same shock absorbing material/medium or with different shock absorbing materials/media.

<FIG> shows, in cross-section view, a further embodiment of a shell portion <NUM> of a leading edge protection system <NUM> of a blade of the wind turbine of <FIG>. The shell portion <NUM> deviates from the shell portion <NUM> shown in <FIG> in that a single closed cavity <NUM> of the shell portion <NUM> comprises two different shock absorbing materials <NUM>, <NUM>. Both shock absorbing materials <NUM>, <NUM> are, in particular, non-flowable materials. The shock absorbing materials <NUM>, <NUM> may differ from each other, for example, in their softness. In other examples, the closed cavity <NUM> may also comprise more than two different shock absorbing materials <NUM>, <NUM>.

It is noted that also the cavity <NUM> of the shell portion <NUM> shown in <FIG> or the one or more cavities <NUM>, <NUM> shown in <FIG> may be filled with two or more different shock absorbing materials in a similar manner as in <FIG>.

<FIG> shows, in cross-section view, a further embodiment of a shell portion <NUM> of a leading edge protection system <NUM> of a blade of the wind turbine of <FIG>. The shell portion <NUM> deviates from the shell portion <NUM> shown in <FIG> in that a closed cavity <NUM> of the shell portion <NUM> has, as seen in cross-section, a different geometric shape <NUM>. In particular, the shape <NUM> of the cavity <NUM> in <FIG> is an irregular shape.

It is noted that the cavities <NUM> (<FIG>), <NUM> (<FIG>), <NUM> (<FIG>), <NUM> and <NUM> (<FIG>), <NUM> (<FIG>) and <NUM> (<FIG>) can have any suitable cross-section shape.

<FIG> shows a plan view of a shell portion <NUM> of a leading edge protection system <NUM> of a blade of the wind turbine <NUM> of <FIG> according to a further embodiment. As illustrated in <FIG>, the shell portion <NUM> may include several cavities <NUM>, <NUM>, <NUM>, <NUM> distributed in a lengthwise direction L (<FIG>) of the blade <NUM> (<FIG> and <FIG>). One, some or all of the cavities <NUM>, <NUM>, <NUM>, <NUM> may be closed cavities (as in <FIG> and <FIG>) and/or one, some or all of the cavities <NUM>, <NUM>, <NUM>, <NUM> may be open cavities (as in <FIG>). One, some or all of the cavities <NUM>, <NUM>, <NUM>, <NUM> may be filled with a shock absorbing medium and/or one, some or all of the cavities <NUM>, <NUM>, <NUM>, <NUM> may be filled with a shock absorbing material. In the case that some or all of the cavities <NUM>, <NUM>, <NUM>, <NUM> are filled with a gaseous shock absorbing medium, the respective cavities <NUM>, <NUM>, <NUM>, <NUM> may be interconnected with valves <NUM> (<FIG>).

<FIG> shows a view similar as <FIG> but with a leading edge protection system <NUM> according to the invention, the leading edge protection system <NUM> comprising an inflatable cavity <NUM> and inflating means <NUM>. In the embodiment of <FIG>, a shell portion <NUM> of the leading edge protection system <NUM> is also made of an elastic material <NUM>. Further, the shell portion <NUM> also comprises a closed cavity <NUM> filled with a shock absorbing medium <NUM>, namely a gaseous medium <NUM>. However, in contrast to the embodiment of <FIG>, the cavity <NUM> comprises an opening <NUM> closed with a valve <NUM>. Furthermore, the inflating means <NUM> comprise, for example, a pump <NUM> and a motor <NUM>. By pumping a gas such as air by means of the pump <NUM> into the cavity <NUM>, the outer surface <NUM> of the shell portion <NUM> can be moved outwards (i.e. away from the blade body <NUM>). Further, by pumping a gas such as air by means of the pump <NUM> out of the cavity <NUM>, the outer surface <NUM> of the shell portion <NUM> can be moved inwards (i.e. towards the blade body <NUM>). This allows to adjust the leading edge geometry of the blade <NUM>' during operation of the wind turbine <NUM> for improving an aerodynamic performance, for de-icing and/or noise reduction. Although not shown, the opening <NUM> may also be closed by means of a permeable membrane such that the cavity <NUM> can be filled and drained through the membrane.

<FIG> shows a variant of the embodiment of <FIG>. A leading edge protection system <NUM> of a blade <NUM>" in the embodiment of <FIG> comprises two inflatable cavities <NUM>, <NUM> filled each with a gaseous shock absorbing medium <NUM>, <NUM>. Further, inflating means <NUM> comprise, for example, a pump <NUM> and a motor <NUM> for pumping gas through openings <NUM> closed by valves <NUM> for adjusting the aerodynamic shape of the blade <NUM>". The inflating means <NUM> are, in particular, configured to inflate each cavity <NUM>, <NUM> separately. Although not shown, the shell portion <NUM> of the leading edge protection system <NUM> may also comprise more than two (e.g., separately) inflatable cavities <NUM>, <NUM>. For example, the cavities <NUM>, <NUM>, <NUM> and <NUM> shown in <FIG> may also be (e.g., separately) inflatable cavities.

In the following, a method for manufacturing a leading edge protection system, such as the leading edge protection system <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> shown in the previous figures, is described with respect to <FIG>.

In a first step S1, a body <NUM> (<FIG>) is extruded from a raw material <NUM>, in particular from elastic polymeric granules. At least one extruder <NUM> is provided for this purpose. The extruder <NUM> presses the raw material <NUM>, applying pressure and heat, through an extrusion head <NUM>. The extrusion head <NUM> has a suitable profile to form a body <NUM> with a cavity serving as a shell portion for a leading edge protection system such as the shell portion <NUM> with the cavity <NUM> shown in <FIG> or any other shell portion described herein. Accordingly, after the extrusion head (die head) <NUM>, a smooth body <NUM> with a cavity is produced such as the shell portion <NUM> with the cavity <NUM> shown in <FIG> or any other shell portion described herein.

In a second step S2, the correspondingly manufactured shell portion <NUM> is suitably cut to length by a cutting device (not shown) to form a shell portion (e.g., <NUM> in <FIG>).

Furthermore, an additional extruder <NUM> (<FIG>) can be provided, which presses another raw material <NUM>, for example another elastic polymeric granulate, through the die head <NUM> (also referred to as co-extrusion), which in this case is designed as a multi-component extrusion die head. This allows to manufacture, for example, the shell portion <NUM> filled with one or more shock absorbing materials <NUM> (<FIG>). In particular, the shell portion <NUM> filled with one or more shock absorbing materials <NUM> can be manufactured in a single process step. In particular, the body <NUM> is formed from the first raw material <NUM> and the at least one cavity (e.g., cavity <NUM> in <FIG>) is filled during the extrusion process with at least one second raw material <NUM>. Further, the at least one second raw material <NUM> is softer than the first raw material <NUM>. In this way, a shell portion filled with one or more shock absorbing materials can be easily manufactured.

Claim 1:
A wind turbine blade (<NUM>) with a leading edge protection system (<NUM>, <NUM>, <NUM>,<NUM>), wherein: the leading edge protection system (<NUM>, <NUM>, <NUM>, <NUM>) comprises a shell portion (<NUM>, <NUM>, <NUM>, <NUM>), a surface (<NUM>, <NUM>, <NUM>) of the shell portion (<NUM>, <NUM>, <NUM>, <NUM>) forms part of an outer surface (<NUM>) of the blade, the shell portion (<NUM>, <NUM>, <NUM>, <NUM>) includes at least one cavity (<NUM>, <NUM>, <NUM>) integrally formed inside a material (<NUM>, <NUM>, <NUM>) of the shell portion (<NUM>, <NUM>, <NUM>, <NUM>), and the at least one cavity (<NUM>) is a closed cavity filled with a shock absorbing medium (<NUM>) and/or the at least one cavity (<NUM>, <NUM>) is filled with a shock absorbing material (<NUM>, <NUM>); wherein the at least one closed cavity (<NUM>) is filled with a gaseous medium (<NUM>) characterised in that the leading edge protection system (<NUM>) includes means (<NUM>) to inflate the at least one cavity (<NUM>).