阅读说明：本技术 空气动力学结构 (Aerodynamic structure ) 是由 S.厄尔莱迈纳斯 于 2019-06-27 设计创作，主要内容包括：本发明描述了一种用于安装到风力涡轮机转子叶片(2)的表面(20S、20P、30)的空气动力学结构(1),该空气动力学结构(1)包括多个梳元件(10T、10F),梳元件(10T、10F)包括布置在梳平面(10P)中的梳齿(100),其特征在于,被安装的梳元件(10T、10F)的梳平面(10P)大体上垂直于转子叶片(2)的后缘(TE)以及大体上垂直于转子叶片(2)的翼型件表面(20S、20P)。本发明还描述了一种包括至少一个这种空气动力学结构(1)的风力涡轮机转子叶片(2),以及为风力涡轮机转子叶片(2)配备这种空气动力学结构(1)的方法。(The invention describes an aerodynamic structure (1) for mounting to a surface (20S, 20P, 30) of a wind turbine rotor blade (2), the aerodynamic structure (1) comprising a plurality of comb elements (10T, 10F), the comb elements (10T, 10F) comprising comb teeth (100) arranged in a comb plane (10P), characterized in that the comb plane (10P) of the mounted comb elements (10T, 10F) is substantially perpendicular to a Trailing Edge (TE) of the rotor blade (2) and substantially perpendicular to an airfoil surface (20S, 20P) of the rotor blade (2). The invention also describes a wind turbine rotor blade (2) comprising at least one such aerodynamic structure (1) and a method of equipping a wind turbine rotor blade (2) with such an aerodynamic structure (1).)

1. An aerodynamic structure (1) for mounting to a surface (20S, 20P, 30) of a wind turbine rotor blade (2), said aerodynamic structure (1) comprising a plurality of comb elements (10T, 10F), a comb element (10T, 10F) comprising comb teeth (100) arranged in a comb plane (10P), characterized in that said comb plane (10P) of a mounted comb element (10T, 10F) is substantially perpendicular to a Trailing Edge (TE) of a rotor blade (2) and substantially perpendicular to an airfoil surface (20S, 20P) of said rotor blade (2).

2. The aerodynamic structure of claim 1, wherein the comb teeth (100) of a comb element (10T, 10F) terminate along a termination line (T) extending in a direction substantially perpendicular to the mounting surface (20S, 20P, 30).

3. The aerodynamic structure of claim 1 or claim 2, wherein a comb element (10T) is arranged on a mounting device (11T), said mounting device (11T) being realized for mounting said comb element (10T) to an airfoil surface (20S, 20P) of said rotor blade (2).

4. Aerodynamic structure according to claim 3, wherein the comb elements (10T, 10F) are arranged at a pitch of 0.5cm to 5 cm.

5. The aerodynamic structure of any one of the preceding claims, wherein a comb element (10T) is arranged on a mounting device (11T), the mounting device (11T) being realized for mounting the comb element (10T) onto serrations (30) of a serrated trailing edge assembly (3) of the rotor blade (2).

6. The aerodynamic structure of any one of the preceding claims, wherein the comb teeth (100) of a comb element (10T, 10F) start along a mounting line (10M), which mounting line (10M) extends in a direction substantially perpendicular to the Trailing Edge (TE) of the rotor blade (2).

7. The aerodynamic structure of any one of the preceding claims, wherein the comb teeth (100) of a comb element (10T, 10F) start along a mounting line (10M), the mounting line (10M) making an angle (Θ) of up to 45 ° with the Trailing Edge (TE) of the rotor blade (2).

8. The aerodynamic structure of any one of the preceding claims, wherein comb teeth (100) of a comb element (10T, 10F) are inclined with respect to the mounting surface (20S, 20P, 30) at an angle (a) in the range of 0 ° to 45 °.

9. The aerodynamic structure of any one of the preceding claims, wherein a comb element (10F) is arranged on a mounting means (11F), the mounting means (11F) being realized for mounting the comb element (10F) between the serrations (30) of the serrated trailing edge assembly (3) of the rotor blade (2).

10. A wind turbine rotor blade (2) comprising at least one aerodynamic structure (1) according to any of claims 1-9 mounted on a mounting surface (20S, 20P, 30) of the rotor blade (2).

11. A wind turbine rotor blade according to claim 10, wherein the mounting surface is a suction side (20S) of the rotor blade (2).

12. A wind turbine rotor blade according to claim 10 or claim 11, wherein the mounting surface is a pressure side (20P) of the rotor blade (2).

13. Wind turbine rotor blade according to any of claims 10 to 12, wherein the rotor blade (2) is equipped with a series of serrations (30) along its Trailing Edge (TE), and wherein the mounting line (10M) of the comb elements (10T, 10F) of the aerodynamic structure (1) extends along a centre line (30C) of the serrations (30).

14. Wind turbine rotor blade according to any of claims 10 to 13, wherein the rotor blade (2) is equipped with a series of serrations (30) along its Trailing Edge (TE) and further comprises a serration comb element (12) arranged between two adjacent serrations (30), wherein the teeth (100) of the serration comb element (12) start at an apex (30A) formed by adjacent serrations (30) and wherein the teeth (100) of a serration comb element (12) end along a termination line (T) substantially perpendicular to a plane containing the serrations (30).

15. A method of equipping a wind turbine rotor blade (2) with an aerodynamic structure (1), the method comprising the steps of:

-forming a comb element (10T, 10F), the comb element (10T, 10F) comprising comb teeth (100) arranged in a comb plane (10P);

-arranging the comb elements (10T, 10F) on an airfoil surface (20S, 20P, 30) of a rotor blade (2) such that the comb plane (10P) of a mounted comb element (10T, 10F) is substantially perpendicular to a Trailing Edge (TE) of the rotor blade (2) and substantially perpendicular to the airfoil surface (20S, 20P) of the rotor blade (2).

Technical Field

The invention describes an aerodynamic structure for a wind turbine rotor blade, a wind turbine rotor blade with such an aerodynamic structure, and a method of equipping a wind turbine rotor blade with an aerodynamic structure.

Background

The level of noise generated by wind turbines is a major factor in determining whether permission will be given to set up such wind turbines, particularly when the site is close to a residential area. In general, noise from aerodynamic rotors is considered the most troublesome. Accordingly, much effort is being devoted to finding ways to reduce the noise generated by wind turbine rotor blades as they move through the air. The simplest way to reduce the noise from the aerodynamic rotor is to reduce the rotational speed of the aerodynamic rotor, but this is directly related to the substantial loss of power output (substential penalty). Therefore, it would be more preferable to determine other methods of reducing the noise level.

For large wind turbines with rotor blade lengths exceeding 20-30 m, the main source of noise is the trailing edge noise. As the air flows over the suction side (suction side) or the pressure side, vortices develop, resulting in turbulence across the trailing edge of the blade. The noise that is mainly caused when this turbulence passes the trailing edge is called "trailing edge noise". The cause of the trailing edge noise can also be seen as scattering of the unsteady surface pressure at the trailing edge. The unsteady surface pressure is the "footprint" of the turbulent boundary layer, i.e., the unsteady surface pressure is caused by the pressure field of the turbulent eddies in the boundary layer. Due to the higher rotational speed towards the outer end of the rotor blade, trailing edge noise is mainly generated in the outer part of the rotor blade.

Various methods exist for modifying rotor blades in order to reduce trailing edge noise. For example, instead of a straight trailing edge, the trailing edge may have a serrated or "saw tooth" shape along the outer portion of the rotor blade. The serrations effectively reduce vortex scattering at the trailing edge. However, while such a jagged edge may reduce the trailing edge noise to some extent, it cannot completely eliminate the noise. Thus, while trailing edge serrations may reduce trailing edge noise, significant noise levels are still present.

The noise reduction of the trailing edge serrations may be improved by arranging comb elements between the serrations. The comb element starts along the edges of two adjacent teeth and ends at a termination line defined by the tips of these teeth. Such comb elements are located in the same plane as the teeth, i.e. the teeth of the comb are located close to the main air flow direction. The beneficial acoustic effects of such comb elements may be understood to be caused by the diffusion of horseshoe vortices (i.e. the combs between the serrations break up large vortices into smaller vortices) and/or the dissipation of some of the energy in the turbulent airflow.

While the serrations and in-plane comb elements can have a significant positive effect on trailing edge noise by spreading the turbulence just behind the trailing edge, they have no significant effect on the turbulence present upstream of the trailing edge. Therefore, known solutions have a limited ability to reduce the aerodynamic noise generated by the rotor blades.

Disclosure of Invention

It is therefore an object of the present invention to provide an improved method of reducing noise generated by a wind turbine rotor blade.

This object is achieved by: the wind turbine rotor blade aerodynamic structure of claim 1; the wind turbine rotor blade of claim 10; and a method of equipping a wind turbine rotor blade with an aerodynamic structure according to claim 15.

According to the invention, the aerodynamic structure is to be mounted to a surface of a wind turbine rotor blade and comprises a plurality of comb elements comprising comb teeth (also called comb fibers) arranged in a comb plane, characterized in that the comb plane of the mounted comb elements is substantially perpendicular to a trailing edge of the rotor blade and substantially perpendicular to an airfoil surface of the rotor blade. All of the teeth or fibers of the comb element lie in a common plane (i.e., the comb plane).

The mounting surface may be a surface of a rotor blade airfoil. Equivalently, the mounting surface may be a surface of a trailing edge assembly arranged along a trailing edge of the rotor blade. Comb elements that are substantially parallel to the mounting surface and/or substantially parallel to the trailing edge need not be exactly perpendicular to the mounting surface or the trailing edge, and the plane of the comb elements may in each case deviate from the normal by a few degrees. Comb elements may be mounted upstream and/or downstream of the trailing edge. The comb elements of the inventive aerodynamic structure extend in a direction outwards from the mounting surface and thus do not lie in the plane of the main airflow direction. In other words, the planes of the comb elements are not parallel to the airfoil surface or the trailing edge assembly surface, but are substantially perpendicular to the airfoil surface or the trailing edge assembly surface. Thus, the inventive comb elements act as spanwise separators in the boundary layer, and may be used to "smooth" any instabilities in the boundary layer as it passes over the trailing edge of the rotor blade. Unless otherwise stated, the terms "spanwise separator" and "comb element" may be considered as synonyms hereinafter. The inventive aerodynamic structure is implemented to counteract a specific source of aerodynamic noise, i.e. turbulence near the trailing edge. The function of the spanwise separator or comb element is to break up the vortices in this turbulence so that the airflow becomes more uniform as it passes over the trailing edge. Thus, the inventive aerodynamic structure may effectively reduce aerodynamic noise caused by turbulence near the trailing edge.

As used in its acceptable sense, "comb element" is understood to include a set of comb teeth or comb fibers that extend from an inner mounting line to an outer termination line. The inner ends of the comb teeth are positioned along the mounting line and the outer ends of the comb teeth are positioned along the termination line.

The comb elements are preferably mounted to the rotor blade such that the comb teeth of the comb elements are at an angle in the range of 0 ° to 45 ° to the mounting surface. Thus, the spanwise separator comb elements have a generally triangular shape, and the terms "spanwise separator" and "triangular comb elements" may be used synonymously hereinafter, unless otherwise indicated. Depending on the implementation of the aerodynamic structure, the triangular comb elements may be used to "cut" or "cut off" the incoming airflow, or may be used to push the incoming airflow further outward from the airfoil surface, as will be explained below. In order to counteract forces acting on the flexible teeth of the comb elements when the air flow passes the rotor blade, the spanwise separator comb elements may comprise one or more support ribs arranged to maintain a desired angle of inclination between the comb elements and the mounting surface of the rotor blade.

The wind turbine rotor blade comprises at least one example of an inventive aerodynamic structure mounted on a mounting surface of the rotor blade.

The noise emission of a wind turbine equipped with such rotor blades can be effectively reduced. During operation of the wind turbine, the rotor blade is moved through the air such that the air flow passes the rotor blade and the air flow will first pass the inventive aerodynamic structure before reaching the trailing edge of the rotor blade. Turbulence near the trailing edge of the rotor blade can be effectively spread by the spanwise separator so that the wind turbine can meet the requirements of applicable acoustic noise regulations when operating at its rated power output.

The dependent claims present particularly advantageous embodiments and features of the invention as disclosed in the following description. Features from different claim categories may be combined as appropriate to give further embodiments not described herein.

Preferably, the spanwise separator is arranged on a mounting device, which may be attached to a mounting surface, for example to an airfoil surface of a rotor blade. Alternatively or additionally, the mounting surface may be a surface of a trailing edge assembly of the rotor blade.

As mentioned above, the comb plane of the mounted comb elements may be substantially perpendicular to the trailing edge of the rotor blade and also substantially perpendicular to the airfoil surface of the rotor blade. Effectively, the mounting line of such spanwise separator comb elements extends in a direction substantially perpendicular to the trailing edge of the rotor blade. However, centrifugal effects may cause the airflow to exhibit a diagonal "sweep" toward the tip of the rotor blade. Thus, in a preferred embodiment of the invention, the mounting line of the separator comb element in the spanwise direction may be at an angle of up to 45 ° to the trailing edge, depending on its outboard position. Preferably, the mounting line of the more inner comb elements is substantially perpendicular to the trailing edge of the rotor blade, while the mounting line of the more outer comb elements is gradually at an even larger angle to the trailing edge, whereby the outermost comb elements are at an angle of up to 45 ° to the trailing edge.

It will be appreciated that the mounting means of the aerodynamic structure is attached to the airfoil surface of the blade in a spanwise direction (i.e. in a direction defined by a line extending between the blade root and the blade tip, or in a direction defined by the trailing edge of the rotor blade) such that the comb elements are arranged in the spanwise direction. In a preferred embodiment of the invention, the mounting means of the inventive aerodynamic structure is attached to the airfoil surface of the rotor blade at a distance inwards (i.e. upstream) from the trailing edge. The distance inward from the trailing edge may be determined by calculation using a suitable model and/or based on observations obtained from tests such as wind tunnel tests, in situ acoustic measurements, and the like. In such an embodiment, the mounting line is effectively arranged at a distance upwind of the trailing edge. Equally, the inventive aerodynamic structure may be realized such that the comb elements terminate along or beyond the trailing edge of the rotor blade. In any of these implementations, the aerodynamic structure preferably comprises a plurality of such spanwise separator comb elements arranged at a pitch of 0.5-5cm in the outer region of the rotor blade.

Alternatively or additionally, the mounting surface may be a surface of a trailing edge assembly of the rotor blade, e.g., the comb elements may be mounted to the serrations of a serrated trailing edge assembly. In such an implementation, the aerodynamic structure preferably comprises one or more spanwise separator comb elements on each serration.

The comb element may be made of any suitable material, such as plastic. The comb elements may be made using any suitable technique, such as injection molding, casting, and the like. Preferably, the comb fibers/teeth are parallel to each other and spaced apart a sufficiently large distance. For example, the comb fibers may have a diameter of about 1mm and may be spaced apart by about the same distance as the comb fiber diameter.

The aerodynamic structure may be constructed in any suitable manner. In a preferred embodiment of the invention, the aerodynamic structure is manufactured by forming the comb elements and embedding the teeth of the comb elements along the mounting line to a suitable depth in the mounting device. The series of points at which the teeth of the comb element extend outwardly from the mounting means can be considered collectively as the "mounting line" of the comb element. In an alternative embodiment, the aerodynamic structure is manufactured by forming the comb element and gluing the inner ends of the teeth of the comb element on the surface of the mounting means along the mounting line. In a further alternative embodiment, the aerodynamic structure is manufactured by the steps of: forming a comb element, forming a hole in the mounting device along the mounting line, and passing the teeth of the comb element through the hole from below the mounting device. The mounting means may be realized as a strip of material (e.g. plastic) glued or otherwise attached to the outer surface of the rotor blade, so that an already existing rotor blade may be retrofitted with one or more examples of the inventive aerodynamic structure.

Embodiments of the inventive aerodynamic structure may be mounted to the suction side of a rotor blade. Alternatively or additionally, embodiments of the inventive aerodynamic structure may be mounted to the pressure side of the rotor blade.

As mentioned above, the shape of the triangular comb elements or spanwise separators is defined by an inner mounting line and an outer termination line. The mounting line of the comb element is preferably straight; similarly, the termination line is preferably straight. The termination line of such comb elements also extends in a direction substantially perpendicular to the airfoil surface of the rotor blade. In such embodiments, when the comb element is mounted upstream of the trailing edge, the comb element has an overall triangular shape with the apex of the triangle furthest from the trailing edge. When the triangular comb elements are mounted on the serrations of the trailing edge assembly, the apex of the triangle may coincide with the trailing edge. In a preferred embodiment of the invention, the aerodynamic structure comprises a series of such upstanding comb elements which act as spanwise separators, i.e. the comb elements "cut through" or separate the air flow through the rotor blade, having the effect of diffusing or splitting the spanwise coherence of the boundary layer turbulence near the trailing edge. The aerodynamic structure may extend over the outer 50% of the rotor blade and may comprise such "upright" triangular comb elements arranged at a distance along the mounting means. The characteristics (spacing, height, etc.) of the comb planes may vary depending on their radial position along the rotor blade.

As mentioned in the introduction, for the purpose of reducing aerodynamic noise, a wind turbine rotor blade may be equipped with serrations along a portion of its trailing edge. In a preferred embodiment of the invention, the aerodynamic structure is realized such that the mounting line of the comb element coincides with the centre line of the serrations. In other words, the comb element is arranged in line with each sawtooth. The effect of this arrangement is to improve the spanwise separation of turbulence in the airflow upstream of the trailing edge serrations.

As explained above, it is also known to arrange comb elements in a plane between the serrations, i.e. in the same plane as the trailing edge serrations. By arranging the comb elements to "cut off" the sawtooth plane, further dissipation of turbulence around the trailing edge can be achieved. Thus, in a preferred embodiment of the invention, the teeth of the comb element start near a point between two adjacent teeth (e.g. just upstream of the trailing edge) and the end line of the comb element is substantially perpendicular to the plane containing the teeth. In this implementation, the comb element has an overall fan shape at right angles to its adjacent teeth. Comb elements of this type may have a beneficial effect in reducing turbulence near the trailing edge. Of course, such upstanding "sector comb elements" can be used in addition to any of the embodiments described above that include a plurality of triangular comb elements mounted to a mounting surface.

One of the noise reduction mechanisms associated with serrated trailing edges is that the suction side boundary layer may be pushed away from the airfoil surface, thereby increasing the distance between the suction side turbulence and the trailing edge and reducing the acoustic scattering efficiency, i.e., the efficiency of converting turbulence into acoustic pressure.

Another way to achieve this effect is to arrange additional aerodynamic elements on the suction side of the airfoil. The additional element may have the form of an elongated plane or rectangle aligned parallel to the trailing edge and inclined at an angle in the range of 0 ° to 45 ° with respect to the airfoil surface of the rotor blade, such that the planar element acts as a kind of "cover" for pushing the suction side boundary layer away from the airfoil surface. This has the attendant beneficial effect described above of moving the larger boundary layer vortices further outward from the airfoil surface in order to suppress acoustic scattering at the trailing edge. Preferably, such a planar element extends along the outer half or the outer third of the rotor blade.

Drawings

Other objects and features of the present invention will become apparent from the following detailed descriptions considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for the purposes of illustration and not as a definition of the limits of the invention.

FIG. 1 illustrates an embodiment of the inventive aerodynamic structure;

FIG. 2 illustrates an alternative embodiment of the aerodynamic structure of FIG. 1;

FIG. 3 shows a further embodiment of the inventive aerodynamic structure;

FIG. 4 illustrates an alternative embodiment of the aerodynamic structure of FIG. 3;

FIG. 5 shows a further embodiment of the inventive aerodynamic structure;

FIG. 6 shows a further embodiment of the inventive aerodynamic structure;

FIG. 7 illustrates an alternative implementation of a comb element;

FIG. 8 shows a rotor blade of a wind turbine;

fig. 9 shows the development of turbulence on the rotor blade.

In the drawings, like reference numerals refer to like elements throughout. Objects in the drawings are not necessarily drawn to scale.

Detailed Description

Fig. 1 shows an embodiment of the inventive aerodynamic structure 1, the aerodynamic structure 1 being attached to a suction side 20S of a wind turbine rotor blade 2. In this exemplary embodiment, the aerodynamic structure 1 comprises a plurality of triangular comb elements 10T, the triangular comb elements 10T being arranged on the mounting means 11T such that the comb elements 10 act as separators 10T in the spanwise direction. These separators 10T may be separated by a distance of 0.5-5 cm. The mounting means 11T has a depth or width 11W for accommodating the comb element 10T and is mounted at a distance 11D from the trailing edge TE of the rotor blade 2.

Each triangular comb element 10T has a shape defined by an inner mounting line M and an outer terminal line T. Here, the mounting line M of each comb element 10T extends in a direction substantially perpendicular to the trailing edge TE of the rotor blade 2, and the termination line T of each comb element 10T extends in a direction substantially perpendicular to the airfoil surface 20S of the rotor blade 2. In this exemplary embodiment, the mounting line M may extend over a length of, for example, 3-10cm, and the termination line T may extend to a height of up to 4 cm.

The rotor blade 2 also has a serrated trailing edge assembly, i.e., a series of serrations 30 are arranged along the trailing edge TE to reduce aerodynamic noise caused by the flow of vortices over the trailing edge of the rotor blade as it passes through the air. The figure also shows additional in-plane comb elements 31 between adjacent serrations 30, the purpose of which is to further reduce trailing edge noise.

The triangular comb elements 10T are evenly arranged along the mounting means 11T and are separated by a distance 10D. In this embodiment, each serration 30 has about two spanwise separators 10T arranged such that the mounting line M of each second comb element 10T extends along the centerline 30C of the serration 30. Alternatively, up to ten such triangular comb elements 10T may be arranged along the mounting device for each serration 30 at the trailing edge TE.

Instead of a single row of spanwise separators 10T as shown here, the mounting device may carry two or more rows of spanwise separators 10T. For example, one row of spanwise separators may be arranged upstream of a second row of spanwise separators. Alternatively, a staggered arrangement may be provided in which the spanwise separators of the second row start between the spanwise separators of the first row.

Another variation of this embodiment is shown in fig. 2, which (for clarity) shows only one such comb element 10T per serration 30. The figure also shows a parallel arrangement of comb teeth 100, wherein the comb teeth 100 extend from the mounting line M to a perpendicular termination line T. The comb teeth 100 or comb fibers 100 are substantially aligned with the main flow direction on the surface of the rotor blade 2. The figure also shows support ribs 101 for maintaining the upright shape of the comb element 10T.

In this embodiment, the mounting means 11T is attached to the airfoil surface 20S of the rotor blade such that the termination line T of the comb element 10T effectively intersects the trailing edge TE of the rotor blade 2. On the left hand side of the figure, three intersecting planes PX, PY, PZ are shown. The comb plane 10P of the triangular comb element or spanwise separator 10T coincides with a plane PZ that is effectively perpendicular or normal to the plane PX of the airfoil surface 10S, and also perpendicular or normal to a plane PY that includes the trailing edge TE and that is perpendicular to the plane PX.

Fig. 3 shows another embodiment, in which case two rows of comb elements 10T are mounted upstream of the trailing edge TE. For the sake of clarity, the figure only shows the outer part of the rotor blade 2. One row of comb elements 10T is offset from the other row of comb elements 10T. In the exemplary embodiment, the spacing between comb elements 10T decreases as the radial distance along rotor blade 2 increases outward. The comb element 10T may decrease in size towards the tip of the rotor blade. Of course, more than two rows of comb elements 10T may be used, and the rows need not include the same number of comb elements, and may include comb elements of different sizes.

Fig. 4 shows another possible embodiment of the inventive aerodynamic structure. Also, two rows of comb elements 10T are shown. In this case, two rows of comb elements 10T are mounted in line with each other. In the exemplary embodiment, the comb elements 10T decrease in size with increasing radial distance outward along the rotor blade 2. In this embodiment, the mounting line M of the comb element 10T is at right angles to the trailing edge at a more inboard position. While the more outboard comb elements 10T have mounting lines M at a greater angle theta to the trailing edge TE.

Of course, any combination of these embodiments may be used. For example, an arrangement of offset rows having relatively large comb elements and relatively large spacing pitches may be used in the more inboard portions of the outermost blade halves. Smaller comb elements at smaller spacing intervals may be used in the rest of the outer part of the rotor blade.

FIG. 5 illustrates another embodiment in which a row of spanwise separators 10T is disposed along the trailing edge TE of the rotor blade 2. In this embodiment, a planar "cover" 21 is also mounted to the suction side 20S of the blade 2 to help push the boundary layer away from the suction side of the blade 2. The cover 21 is preferably inclined at a small angle β of less than 45 ° relative to the airfoil surface 20S. The shroud 21 and the spanwise arrangement of separators 10T may be mounted on a common mounting device which is then attached to the airfoil surface 20S, or it may be mounted separately.

Another variation of this embodiment is shown in fig. 6. Here, the spanwise separator 10T is mounted on the serrations 30 of the trailing edge assembly. The mounting means 11T may in this case be a triangular adhesive sheet fitted on the outer surface of the saw tooth 30. The figure also shows an additional planar cover 21 that may be mounted to the airfoil surface 20S for the purpose of pushing turbulence away from the surface.

Fig. 7 shows an alternative embodiment. Here, the sector comb elements 10F are arranged between adjacent serrations 30 along the trailing edge TE of the rotor blade 2. The terminal line 12T of the sector comb element 10F is perpendicular to the plane of the serrations 30. The function of such fan-shaped comb elements 10F is to further diffuse turbulence between the serrations 30, and such fan-shaped comb elements 10F may be used in any of the embodiments described above, for example, in place of comb elements in any plane between the serrations 30 along the trailing edge TE. The sector comb elements 10F can be formed such that all of the comb teeth start at or just upstream of the apex between the serrations. The mounting means 11F may be any suitable means by which the comb element 10F may be attached between the serrations 30.

Fig. 8 shows a rotor blade 2 of a wind turbine. The figure shows the leading edge LE, the trailing edge TE and the suction side 20S. In the prior art it is known to attach a serration member 3 in the outboard part of the rotor blade along the mounting length L of the trailing edge TE. In the embodiment of the inventive aerodynamic structure 1 described above, it may be assumed that the mounting means are attached in a direction parallel to the trailing edge TE over a similar mounting length L.

FIG. 9 shows the rotationThe development of turbulence when the sub-blades 2 move in the direction of rotation. The figure shows an initial laminar airflow F in a boundary layer on the suction side 20S of the rotor blade 2_20SAnd an initial laminar air flow F in the boundary layer on the pressure side 20P of the rotor blade 2_20P. The boundary layer typically does not remain stable, and therefore trailing edge turbulence V develops as the airflow passes through the airfoil_TE. Due to vortices V in turbulent zones_TETo generate acoustic noise.

Although these figures primarily show aerodynamic structures in place on the suction side of the rotor blade, it will be understood that aerodynamic structures may alternatively or additionally be arranged on the pressure side. As explained above, the inventive aerodynamic structure serves to reduce the aerodynamic noise generated due to turbulence upstream of the trailing edge. Thus, while some of the figures show a serrated trailing edge, it will be appreciated that such a serrated trailing edge is not required for the inventive aerodynamic structure, but may be implemented due to its contribution in reducing trailing edge noise.

Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

For the sake of clarity, it will be understood that the use of "a" or "an" throughout this application does not exclude a plurality, and "comprising" does not exclude other steps or elements.