WIND TURBINE BLADE BRUSH
A wind turbine blade for use in a wind energy system comprises a blade body having a trailing edge and a leading edge, and a plurality of bristles disposed on an outer surface of said blade body. The bristles are typically attached to said blade body in the vicinity of said trailing edge and serve to reduce noise caused by the airflow around the blade during operation.
The present invention relates to a wind turbine blade with bristles or a brush disposed on an outer surface thereof. The present invention further relates to a wind energy system including the same.
Wind energy systems have gained more and more importance as a source of energy in recent years. As areas suitable for their economical operation are relatively scarce in a number of countries, a growing number of wind energy systems are located close to populated areas. As the running of wind turbines in wind energy systems causes noise, this leads to various problems, such as resistance from neighbourhoods and the like. Though a variety of sources contribute to the overall noise emission of such systems, air flow around the blades is known to be one of the main sources. This causes, for example, typical “hissing” or “swishing” sounds in the 1 kHz frequency range. Sound levels are greatly influenced by the design of the turbine blades, especially the choice of the airfoil profile. As this choice is also influenced by other criteria such as high efficiency operation, the goal of low noise operation is often contradicted by aspects regarded to be more important by the designer. Moreover, even a design optimized for low noise operation still causes emissions, which may be intolerable under certain conditions. Thus, what is needed are measures to reduce the noise emission of a given wind turbine blade.
It is known from the field of airplane technology to apply physical measures to an aircraft wing in order to reduce noise caused by the airflow. For example, zig-zag shaped bands have been attached to the airfoil in the vicinity of the leading edge. Another technique is proposed for commercial airliners. So-called slats, which are the equivalent of a landing flap, but located on the front side of the wing, are known to be a major source of noise during take-off and landing. Research has shown that this might be due to the gap between the main body of the wing and the slat together with the concave shape of the lower portion of the slat. In order to reduce noise caused by the turbulences between the slat and the wing, it was proposed to locate bristles on the lower part of the slat.
BRIEF DESCRIPTION OF THE INVENTIONIn view of the above, a wind turbine blade for use in a wind energy system is provided, which includes a blade body having a trailing edge and a leading edge, and a plurality of bristles disposed on an outer surface of the blade body.
In a first aspect of the present invention, there is provided a rotor blade for use in a wind energy system. It includes a plurality of fibres, which are located on the shell of the rotor blade that includes a leading edge and a trailing edge.
Conventional methods to reduce noise produced by the rotor blade of a wind turbine include mainly the modification of the airfoil's profile during design. In the present invention, it is proposed to dispose a number of bristles or fibres on part of a wind turbine blade in order to reduce noise emissions. The present invention bears significant advantages over the known art. First of all, the invention can be applied to an arbitrary airfoil, not depending on the aerodynamic design thereof. Hence, an airfoil for use with the present invention can be designed with the goal of best performance in terms of efficiency and the like, while still achieving improved noise emissions behaviour of the system. The measures used are made from commercially available goods, typically man made fibres, and are both easy to produce and relatively cheap. Furthermore, the invention can both be applied during the production process of a blade or to an existing wind energy system with relatively little effort and costs. The bristles can be applied to the blade by a variety of methods such as gluing, fusing, heat-sealing etc. or by mechanical insertion into small pinholes provided on the blade body or an intermediate carrier element. Rotor blades according to the present invention may be used in wind turbines with one, two, three or more rotor blades.
In an embodiment of the invention, the bristles are attached to the blade body in the vicinity of the trailing edge. In another embodiment, at least one of the parameters chosen from the group consisting of length, diameter and flexibility of the bristles varies depending on the distance of said bristle from the blade root.
According to a further aspect of the present invention, a wind turbine blade for use in a wind energy system includes a blade body having a trailing edge and a leading edge, a brush including a plurality of bristles, wherein said brush is disposed on said blade body in the vicinity of the trailing edge.
In a third aspect of the present invention, a wind turbine for use in a wind energy system includes a blade body having a trailing edge, a leading edge and a plurality of bristles disposed on an outer surface of said blade body.
Further aspects, advantages and features of the present invention are apparent from the dependent claims, the description and the accompanying drawings.
It is possible to use the wind turbine blade of the present invention in any wind energy system.
A full and enabling disclosure of the present invention, including the best mode thereof, to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures wherein:
Reference will now be made in detail to the various embodiments of the invention, one or more examples of which are illustrated in the figures. Each example is provided by way of explanation of the invention, and is not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the present invention includes such modifications and variations.
The basic configuration of a wind turbine blade or rotor blade 140 is shown in
A plurality of rows of bristles may be used in order to achieve a higher noise reduction effect. These rows, as defined by mounting points of the bristles in a longitudinal direction of the blade 140, are located close to each other and disposed in the vicinity of the trailing edge 190.
The length of the bristles 300 lies between 5 mm and 100 mm, typically between 15 mm and 80 mm, more typically between 25 mm and 70 mm, e.g., 30 mm or 50 mm. The diameter varies between 0.1 mm and 4 mm, typically between 0.2 mm and 0.8 mm, more typically between 0.3 mm and 0.6 mm, e.g. 0.3 mm or 0.5 mm. The material of the bristles 300 can be chosen from a variety of materials used for man made fibers, typically polymers like polyolefins, cyclic polyolefins, silicones, acrylic polymers, polyester, polyamides, aromatic polyamides and the like, also metal or quartz are applicable. More typically, the material is polypropylene, polyethylene, polyamide or polyvinyl chloride. Also natural or cellulose-based fibers, for example hemp jute, flax, ramie or sisal are applicable and are regarded to fall into the scope of the invention. The fibers should provide flexibility, fatigue resistance and long term stability when exposed to the ultraviolet component of the sunlight.
In an embodiment of the present invention, the brush 600 is located in the vicinity of the trailing edge 190.
In a further embodiment of the present invention, the brush 600 includes bristles 300 of different lengths and/or of different diameters and/or different flexibility, which are intermittently or randomly disposed about the brush.
In still another embodiment of the present invention, at least one of the parameters of said bristles 300, chosen from the group consisting of length, diameter and flexibility, is dependent from a chord length of the blade 140, as measured at the position of the respective bristle.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims. Especially, mutually non-exclusive features of the embodiments described above may be combined with each other. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims of they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
Claims
1. A rotor blade for use in a wind energy system, comprising:
- a blade body having a trailing edge and a leading edge, and
- a plurality of bristles disposed on an outer surface of said blade body.
2. The rotor blade of claim 1, wherein said bristles are attached to said blade body in the vicinity of said trailing edge.
3. The rotor blade of claim 1, wherein said bristles are arranged in at least one row along a longitudinal direction of said blade.
4. The rotor blade according to claim 3, wherein said at least one row of bristles has a length between 5 and 100% of the total rotor blade length.
5. The rotor blade of claim 1, further comprising a carrier element, wherein said carrier element is attached to said blade body, and said bristles are attached to said carrier element.
6. The rotor blade according to claim 1, wherein the length of said bristles lies in a range between 10 mm and 100 mm.
7. The rotor blade according to claim 1, wherein said bristles are flexible.
8. The rotor blade according to claim 1, wherein the diameter of said bristles lies in a range between 0.1 mm and 4 mm.
9. The rotor blade according to claim 1, wherein the blade comprises bristles of different lengths and/or of different diameters.
10. The rotor blade according to claim 1, wherein at least one of the parameters chosen from the group consisting of length, diameter and flexibility of the bristles varies depending on the distance of said bristle from the blade root.
11. A rotor blade for use in a wind energy system, comprising:
- a shell having a trailing edge and a leading edge,
- a brush comprising a plurality of bristles,
- wherein said brush is disposed on said shell in the vicinity of said trailing edge.
12. The rotor blade according to claim 11, wherein said brush has a length between 1 and 100% of the total rotor blade length.
13. The rotor blade according to claim 11, wherein the length of said bristles lies in a range between 10 mm and 100 mm.
14. The rotor blade according to claim 11, wherein said bristles are flexible.
15. The rotor blade according to claim 11, wherein the material of the bristles is chosen from the group consisting of synthetic polymer, silicone, metal, quartz or natural fiber.
16. The rotor blade according to claim 11, wherein the diameter of said bristles lies in a range between 0.1 mm and 4 mm.
17. The rotor blade according to claim 11, wherein a blade comprises bristles of different lengths and/or of different diameters.
18. The rotor blade according to claim 11, wherein at least one of the parameters of said bristles, chosen from the group consisting of length, diameter and flexibility, varies in accordance with a chord length of said blade.
19. The rotor blade according to claim 11, wherein a plurality of discrete brushes are disposed about the rotor blade.
20. A wind turbine for use in a wind energy system, comprising:
- a rotor blade comprising a blade body having a trailing edge and a leading edge, and
- a plurality of bristles disposed on an outer surface of said blade body.
Type: Application
Filed: Jan 4, 2007
Publication Date: Jul 10, 2008
Inventors: Stefan Herr (Greenville, SC), Klaus Koegler (Rheine), Werner Dobrzynski (Wolfenbuttel)
Application Number: 11/619,638
International Classification: F01D 5/14 (20060101); F04D 29/38 (20060101);