JP4676228B2 - Windmill wing - Google Patents

Description

  The present invention relates to a wind turbine blade used for wind power generation and the like, and more particularly, to a wind turbine blade configured using a skin material made of a fiber reinforced plastic containing carbon fiber (hereinafter also simply referred to as CFRP).

  In recent years, wind power generation technology that converts the rotational energy of a windmill rotated by wind power into electric energy has attracted attention as a clean power generation method. In addition, in order to reduce the weight of the wind turbine blade, a part or the whole of the blade is being made of fiber reinforced plastic (hereinafter also simply referred to as FRP).

  However, in such a windmill, with increasing rotor diameter and speed, windmill blade noise, for example, fluttering, airflow noise due to Karman vortices, blade vibration noise, and the like becomes a problem.

  For example, if the tip of the blade is easily twisted and the bending rigidity is small, the blade is likely to cause a flutter phenomenon and cause noise. In order to solve such problems, Patent Document 1 discloses that a blade tip portion is reinforced with a metal material having a high elastic modulus and high specific gravity, and is connected to a blade-side blade mounting member with a light and high-strength tension rod. However, there is a problem in that providing a high specific gravity reinforcing material at the tip of the blade causes an increase in the weight of the entire blade, thereby reducing the power generation efficiency. Further, problems such as the reliability of joining of the reinforcing material remain, and if the joining strength is insufficient, the blade may be damaged.

In order to ensure the strength and rigidity of the wing, it is conceivable to increase the thickness of the wing or its constituent parts. However, especially when the thickness of the wing edge is large, a Karman vortex is generated behind the wing trailing edge. Easy and leads to noise problems. To deal with such a problem, Patent Document 2 discloses a wind turbine blade provided with a separate reinforcing material made of a material different from the blade main body along the longitudinal direction of the blade trailing edge. However, if such a reinforcing material is provided, the problem of an increase in the weight of the blades still occurs, and problems such as reliability of the bonding of the reinforcing material remain, and if the bonding strength is insufficient, the blades may be damaged. .
JP 2001-289151 A JP 2000-120524 A

  Therefore, the problem of the present invention is to focus on the above-mentioned problems, suppress the noise due to the vibration of the wing while achieving weight reduction of the wing without depending on the reinforcement by the reinforcing material made of different materials, and An object of the present invention is to provide a wind turbine blade capable of suppressing noise caused by Karman vortex generation.

In order to solve the above problems, a wind turbine blade according to the present invention includes a skin material made of fiber-reinforced plastic containing at least carbon fiber, and a gas and / or solid having a lower bulk density than the skin material surrounded by the skin material. The following constituent element [A] and condition [B] are satisfied simultaneously over the length of 3 to 30% of the entire length of the blade from the blade tip to the rotation center direction.
[A] Skin material whose product E ₀ × D of flexural modulus E ₀ (N / mm ² ) and thickness D (mm) in the blade longitudinal direction is 25,000 to 600,000 N / mm [B] Skin material The ratio T / W of the thickness T (mm) and the width W (mm) of the entire blade including the blade is in the range of 0.05 to 0.15.

  Here, the fiber reinforced plastic (FRP) including at least carbon fiber is a concept including both the case where the entire reinforcing fiber is made of carbon fiber and the case where the fiber is made of carbon fiber and another reinforcing fiber. Examples of other reinforcing fibers include inorganic fibers such as glass fibers, and reinforcing fibers made of organic fibers such as Kevlar fibers, polyethylene fibers, and polyamide fibers. Carbon fiber is particularly preferable from the viewpoint of controllability of the blade strength and rigidity. Examples of the FRP matrix resin include thermosetting resins such as epoxy resins, unsaturated polyester resins, vinyl ester resins, phenol resins, and further, polyamide resins, polyolefin resins, dicyclopentadiene resins, polyurethanes. A thermoplastic resin such as a resin can also be used.

  Further, the portion surrounded by the skin material is composed of a gas and / or solid having a lower bulk density than the skin material. The internal portion surrounded by the skin material may be configured in a hollow structure, It is a concept that it may be configured in a structure including a core material having a high density. As the core material, an elastic body, a foam material, and a honeycomb material can be used, and a foam material is particularly preferable for reducing the weight. The material of the foam material is not particularly limited, and for example, a low-density foam material made of a polymer material such as polyurethane, acrylic, polystyrene, polyimide, vinyl chloride, or phenol can be used. The honeycomb material is not particularly limited, and for example, aluminum alloy, paper, aramid paper or the like can be used.

By setting the product E ₀ × D of the flexural modulus E ₀ (N / mm ² ) and thickness D (mm) in the blade longitudinal direction to 25,000 to 600,000 N / mm as in [A] above. In addition, while maintaining the light weight, it is possible to achieve a sufficiently high bending rigidity in the longitudinal direction of the blade, and it is possible to suppress the vibration of the blade and suppress the noise caused thereby. In addition, as described in [B] above, when the ratio T / W of the thickness T (mm) to the width W (mm) is in the range of 0.05 to 0.15, the lightness and bending rigidity are increased. The generation of Karman vortices can be effectively suppressed by using thin wings while maintaining noise, and in particular, noise caused by Karman vortices can be suppressed. When T / W is smaller than 0.05, the bending rigidity in the longitudinal direction becomes too small, and when it is larger than 0.15, the effect of suppressing Karman vortices becomes small. The area satisfying the configuration and conditions of [A] and [B] is sufficient in the area extending from 3 to 30% of the entire length of the blade in the direction of the rotation center from the blade tip. The noise suppression effect is obtained. If such a configuration and conditions are satisfied even over other regions, the lightness of the entire blade may be impaired.

  In such a wind turbine blade according to the present invention, the skin material [A] may have a location having a thickness of 1.1 to 3.0 times the average thickness of the entire skin material. That is, the thickness of the skin material is increased in at least a part of a region extending from the blade tip to the rotation center direction in a length of 3 to 30% of the entire blade length.

  Moreover, the said skin material [A] can also be set as the structure provided with the location which has 1.1-3.0 times the elasticity modulus of the skin material of parts other than this skin material [A]. That is, the elastic modulus of the skin material is increased in at least a part of a region extending from the blade tip to the rotation center direction in a length of 3 to 30% of the entire blade length.

In the skin material [A], the product E ₄₅ × D of the flexural modulus E ₄₅ (N / mm ² ) and thickness D (mm) in the direction of ± 45 ° on the blade rotation surface with respect to the blade longitudinal direction. Can be configured to be 25,000 to 600,000 N / mm. In such a configuration, the torsional rigidity in this region can be increased, and thereby fluttering of the blades can be effectively suppressed, and noise caused by fluttering can be suppressed.

Further, in the skin material [A], the bending elastic modulus E ₀ (N / mm ² ) in the blade longitudinal direction and the bending elastic modulus E ₄₅ (N / in the direction of ± 45 ° on the blade rotation surface with respect to the blade longitudinal direction). It is preferable that the ratio E ₀ / E ₄₅ to mm ² ) be in the range of 0.2 to _5.0 . In other words, the bending elastic modulus in the longitudinal direction and the bending elastic modulus in the direction of ± 45 ° (elastic modulus in the torsional direction) are appropriately balanced, and both the vibration caused by bending in the blade longitudinal direction and the vibration in the torsional direction are efficient. It is a configuration that can be reduced well, and is a configuration that attempts to suppress noise caused by these vibrations as a whole.

The average density ρ of the entire blade is preferably in the range of 0.15 to 1.5 (g / cm ³ ). When the average density ρ is lower than 0.15 g / cm ^3, it is difficult to ensure the strength of the entire blade, and when it is higher than 1.5 g / cm ³ , the lightness of the entire blade may be impaired.

  The type of wind turbine to which the wind turbine blade according to the present invention is applied is not particularly limited, but the present invention is particularly suitable for a horizontal axis type wind turbine in which the wind turbine shaft extends in the horizontal direction.

  Thus, according to the present invention, it is possible to provide a wind turbine blade that can efficiently suppress noise caused by vibrations and Karman vortices without being dependent on reinforcement by a reinforcing material made of a different material, with light weight, high strength, and high rigidity. .

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
1 to 3 show a wind turbine blade according to an embodiment of the present invention, and show a case where the present invention is applied to a blade of a horizontal axis type wind turbine. In FIG. 1, reference numeral 1 denotes an entire wind turbine blade, and the wind turbine blade 1 is covered with a skin material 2 over substantially the entire front and back surfaces. In this embodiment, the skin material 2 is made of carbon fiber reinforced plastic (the reinforcing fiber is carbon fiber, and the matrix resin is epoxy resin), and the core material made of the low density foam as described above (this embodiment) Then, a core material made of urethane foam is included.

The cross section CC in the windmill blade 1 of FIG. 1 is comprised as shown in FIG. 2, and DD cross section is comprised as shown in FIG. As shown in FIG. 2, a core material 3 made of a low-density foam is included inside the skin material 2. In the region portion 5 that extends from the blade tip 4 of the wind turbine blade 1 toward the center of rotation (that is, in the direction toward the blade root) and 3 to 30% of the blade total length, the skin material 2 is in the blade longitudinal direction. The product E ₀ × D of the flexural modulus E ₀ (N / mm ² ) and the thickness D (mm) is in the range of 25,000 to 600,000 N / mm, and the thickness T (mm ) And width W (mm) ratio T / W is in the range of 0.05 to 0.15. In particular, in the present embodiment, the thickness of the skin material 2 is increased in the region portion 5 that extends from 3 to 30% of the entire length of the blade, and the average thickness of the entire skin material 2 is 1.1 to 3.0. The thickness is set within the double range.

  While satisfying such a configuration and conditions, a DD section (blade transverse section) in the wind turbine blade 1 of FIG. 1 is configured as shown in FIG. As shown in FIG. 3, the entire wind turbine blade 1 is covered with a skin material 2, and a core material 3 made of a low-density foam is included in the interior surrounded by the skin material 2. . Reference numeral 6 denotes a front edge portion in the rotation direction of the blade 1, and 7 denotes a rear edge portion.

  The wind turbine blade according to the present invention configured as described above will be described based on an example while comparing with a comparative example.

Example 1
Carbon fiber reinforced epoxy resin was used for the skin material, and urethane foam was used for the core material. The total length of the wings was 1,000 mm, the total width was 250 mm, and the average thickness of the entire skin material was 0.75 mm. The blade thickness in the range of 3 to 30% of the blade total length from the blade tip to the center of rotation varies in the range of 2 to 6 mm, the thickness D of the skin material is 0.95 mm, a substantially constant thickness, and the elastic modulus E ₀ was set as high as 75,000 N / mm ² , and the elastic modulus E ₄₅ was set as high as 50,000 N / mm ^2, and E ₀ × D was set as 71,250 N / mm. The ratio T / W of the blade thickness T (mm) to the width W (mm) is 0.1 to 0.13, E ₄₅ × D is 47,500 N / mm, and E ₀ / E ₄₅ is 1. It was set to 5. The elastic modulus corresponding to E ₀ was in the range of 55,000 to 60,000 N / mm ² in the portion of 30% or more of the blade total length from the blade tip to the rotation center direction. The average density ρ of the entire blade was 0.3 g / cm ³ .

  When three wind turbine blades were attached to a horizontal axis type wind turbine and the noise was measured, the sound pressure level was 20 to 40 dB, which was sufficiently low. In addition, there is almost no fluttering, noise caused by the fluttering is not generated, and it is considered that the strength instability due to fluttering is sufficiently removed. The results are summarized in Table 1.

Comparative Examples 1 and 2
In Comparative Example 1, glass fiber reinforced epoxy resin was used as the skin material, and the same urethane foam as in Example 1 was used as the core material. In Comparative Example 2, the entire blade was composed of carbon fiber reinforced nylon resin without using a core material. Table 1 also shows the characteristics of the blades, the measurement results of the sound pressure level when the same test as in Example 1 was performed, and the observation results of fluttering.

  As is clear from the results shown in Table 1, in the wind turbine blades according to Example 1, both noise and fluttering were significantly improved as compared with the wind turbine blades of Comparative Examples 1 and 2.

  The present invention can be applied to any wind turbine blade formed of a skin material made of fiber reinforced plastic including carbon fiber, and is particularly suitable for a horizontal axis wind turbine blade.

It is a top view of the wing | blade part wing | blade of the windmill which concerns on one embodiment of this invention. It is a fragmentary sectional view of the windmill blade which follows the CC line of FIG. It is a cross-sectional view of the windmill blade which follows the DD line | wire of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Windmill blade 2 Skin material 3 Core material 4 Blade | tip tip 5 The area | region part 6 to 3-30% of the wing | blade full length from a blade tip to the rotation center direction 6 Leading edge part 7 Trailing edge part

Claims (7)

At least the skin material made of a fiber-reinforced plastic comprising carbon fibers (2) is constituted by said surface skin material said surface skin material surrounded by (2) a small Mocha bulk density than (2) gas and / or solids (3), A wind turbine blade (1) characterized by simultaneously satisfying the following component [A] and condition [B] over a length of 3 to 30% of the total blade length from the blade tip (4) to the rotation center direction.
[A] Skin material (2) in which the product E ₀ × D of the flexural modulus E ₀ (N / mm ² ) and thickness D (mm) in the blade longitudinal direction is 25,000 to 600,000 N / mm
[B] The ratio T / W between the thickness T (mm) and the width W (mm) of the entire blade including the skin material (2) is in the range of 0.05 to 0.15. The windmill blade (1) according to claim 1, wherein the skin material [A] includes a portion having a thickness 1.1 to 3.0 times the average thickness of the entire skin material. The windmill blade according to claim 1 or 2, wherein the skin material [A] includes a portion having a modulus of elasticity 1.1 to 3.0 times that of the skin material other than the skin material [A]. (1) In the skin material [A], the product E ₄₅ × D of the bending elastic modulus E ₄₅ (N / mm ² ) and the thickness D (mm) in the direction of ± 45 ° on the blade rotation surface with respect to the blade longitudinal direction is 25. The wind turbine blade (1) according to any one of claims 1 to 3, wherein the wind turbine blade (1) is characterized in that it is 1,000,000 to 600,000 N / mm. In the skin material [A], the bending elastic modulus E ₀ (N / mm ² ) in the blade longitudinal direction and the bending elastic modulus E ₄₅ (N / mm ^{2) in} the direction of ± 45 ° on the blade rotation surface with respect to the blade longitudinal direction. The wind turbine blade (1) according to any one of claims 1 to 4, wherein a ratio E ₀ / E ₄₅ to the range of 0.2 to _5.0 is present. The wind turbine blade (1) according to any one of claims 1 to 5, wherein an average density ρ of the entire blade is in a range of 0.15 to 1.5 (g / cm ³ ) . The wind turbine blade (1) according to any one of claims 1 to 6, which is a blade used for a horizontal axis wind turbine.

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