JP2012211588A - Windmill blade and wind power generation apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively reduce noises due to a turbulent boundary layer generated in a tip rear edge of a windmill blade, in a wind power generation apparatus using the windmill blade to generate electrical power.SOLUTION: In the windmill blade, an elevation angle reducing part 19 for reducing an elevation angle defined when rotating at a predetermined rotation number, is provided across a predetermined range on a side from a blade tip 20 to a blade root 21 of the windmill blade 9 that is radially mounted around a rotation axis line of a rotor head. The elevation angle reducing part 19 is gradually decreased toward the blade tip 20 and formed by applying a twisting angle to at most 20% of a blade length.

Description

  The present invention relates to a wind turbine blade and a wind turbine generator that generates power using the wind turbine blade.

In wind power generators, noise generated from the blades is a problem. The main factors of the noise generated from the blade are the noise caused by the tip vortex and the noise caused by the turbulent boundary layer generated on the blade surface.
Conventionally, in order to reduce this noise level, it has been effective to reduce the rotational speed of the rotor. That is, when the rotational speed of the rotor is lowered, the inflow speed of air into the blades is reduced, so that aerodynamic noise can be reduced. However, when the rotational speed of the rotor is lowered, there is a problem that the power generation efficiency is lowered.

In particular, for example, a technique disclosed in Patent Document 1 has been proposed for reducing noise at a blade tip portion where noise is high.
This is because a wing tip portion is bent or bent (so-called retracted wing) on the trailing edge side at the wing surface of the wing and / or a small wing (so-called, so-called retreat wing) bent to the pressure side so as to intersect the wing tip. A winglet is provided to reduce noise by reducing the vortex at the blade tip.

JP-T-2006-521383

By the way, in recent years, wind turbine generators are required to have a large output, and have become larger. Along with this, the rotor diameter, that is, the blade length of the wind turbine blade is increasing.
As the blade length increases, the moving speed of the blade tip increases. For this reason, since the generated noise becomes large, further noise reduction is required.
In addition, since the influence of noise due to the turbulent boundary layer generated on the blade surface in the vicinity of the blade tip increases due to the increase in blade length, for example, in the case of suppressing noise only at the blade tip as in Patent Document 1, Sufficient noise suppression cannot be expected.

  The present invention has been made in view of the above circumstances, and the object of the present invention is to reduce the thickness of the turbulent boundary layer generated on the blade surface at the tip of the blade and reduce the noise generated at the trailing edge. An object of the present invention is to provide a wind turbine blade that can be suppressed and a wind power generator using the same.

The present invention employs the following means in order to solve the above problems.
A first aspect of the present invention is a wind turbine blade having a blade shape in cross section, and the angle of attack that reduces the angle of attack when rotating at a predetermined rotation speed over a predetermined range from the blade tip to the blade root side. A reduction portion is provided, and the predetermined range is within 20% of the length of the wind turbine blade, and the attack angle reduction portion provides a wind turbine blade formed by adding a twist angle to the predetermined range To do.

According to the wind turbine blade according to this aspect, the angle-of-attack reduction unit reduces the angle of attack when rotating at a predetermined rotational speed over a predetermined range from the blade tip to the blade root side. It is possible to reduce the thickness of the boundary layer of the blade surface in a predetermined range on the blade root side.
As described above, when the boundary layer is thinned, generation of vortices at the trailing edge of the blade can be suppressed, so that noise can be reduced.
Since the angle-of-attack reduction part is provided in the front-end | tip part of a windmill blade with large generation | occurrence | production of noise, a noise can be reduced efficiently. Thereby, since it is not necessary to suppress the rotation speed for noise reduction, it is possible to suppress a decrease in performance such as power generation efficiency.
If the cross-sectional shape of the wings is the same, the lift force that is generated decreases as the angle of attack decreases, so the range where the angle-of-attack reduction part is provided is set in consideration of the effect on blade performance and the noise reduction effect. It is preferable to do this. This range is, for example, within 20% of the blade length, and preferably within 10%.
Further, the predetermined rotational speed is, for example, a rotational speed at which the wind turbine generator has a rated output, that is, a rated rotational speed.

In the above aspect, the angle-of-attack reduction unit may be formed such that the angle of attack gradually decreases from the angle of attack on the blade root side toward the blade tip.
In other words, the angle-of-attack reduction portion is formed by being twisted so as to gradually reduce the angle of the blade with respect to the wind inflow direction toward the blade tip, that is, by adding a twist angle to the blade tip portion.
In this way, the angle-of-attack reduction unit always has a different angle of attack compared to the blade root side regardless of the rotational speed, so that noise can be reduced in a wide rotational speed range.

In the above aspect, the angle-of-attack reduction portion may be configured to be a substantially extended portion of the blade surface on the blade root side when rotating at the predetermined rotational speed.
In other words, the surface of the angle-of-attack reduction portion is formed so as to be substantially flush with the blade surface on the blade root side when rotating at a predetermined rotational speed.

As the wing rotates, the wing is deformed by the wind. This deformation increases at the tip of the wing. As a result of this deformation, the angle of attack at the tip of the wind turbine blade is larger than the design value, resulting in increased noise.
In this configuration, the angle-of-attack reduction unit is a substantially extended portion of the blade surface on the blade root side when the blade rotates at a predetermined rotational speed and is deformed by the wind, that is, the blade surface on the blade root side and the angle-of-attack reduction unit. The angle of attack of the angle-of-attack reduction part does not become larger than the design value, in other words, compared to a wing that does not have an angle-of-attack reduction part. The angle of attack at a predetermined rotation can be reduced.
Thereby, the noise at the time of predetermined rotation speed can be reduced, and a performance fall can be controlled.

  In the above-mentioned configuration, it is preferable that the angle-of-attack reducing portion is smoothly bent so that the bending gradually increases from the blade surface on the blade root side to the pressure surface side.

  According to the 2nd aspect of this invention, the wind power generator which performs electric power generation using the windmill blade which can suppress generation | occurrence | production of the vortex in the trailing edge of the blade at the time of rotating at a predetermined rotation speed is provided.

  In this way, the wind turbine generator can reduce the generation of noise during operation. Thereby, since the restriction | limiting by noise is eased, the freedom degree of an installation place is securable, for example, it can install in the vicinity of a residence.

According to the present invention, the angle-of-attack reduction part reduces the angle of attack when rotating at a predetermined rotational speed over a predetermined range from the blade tip to the blade root side. Generation can be suppressed and noise can be reduced.
Moreover, since the angle-of-attack reduction part is provided in the front-end | tip part of a windmill blade with large generation | occurrence | production of noise, a noise can be reduced efficiently. Thereby, since it is not necessary to suppress the rotation speed for noise reduction, it is possible to suppress a decrease in performance such as power generation efficiency.

It is a side view which shows the whole schematic structure of the wind power generator concerning 1st embodiment of this invention. It is a front view of the windmill blade concerning 1st embodiment of this invention. It is a graph which shows the change of the angle of attack of the windmill blade concerning 1st embodiment of this invention. It is a front view of the windmill blade concerning 2nd embodiment of this invention. It is a side view which shows the state at the time of the rated rotation speed of the windmill blade concerning 2nd embodiment of this invention. It is a side view which shows the state at the time of the stop of the windmill blade concerning 2nd embodiment of this invention.

(First embodiment)
Hereinafter, a wind turbine generator 1 according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a side view showing an overall schematic configuration of the wind turbine generator 1.
As shown in FIG. 1, the wind power generator 1 includes a support column 3 that is erected on a foundation 11, a nacelle 5 that is installed on the upper end of the support column 3 so as to be rotatable substantially horizontally with the support column 3 as a fulcrum, A rotor head 7 provided in the nacelle 5 so as to be rotatable around a horizontal axis, and a plurality of wind turbine blades 9 mounted so as to be rotatable around the rotation axis of the rotor head 7 about the blade length direction. It has been.
The force of the wind striking the wind turbine blade 9 from the direction of the rotation axis of the rotor head 7 is converted into power for rotating the rotor head 7 around the rotation axis.

An anemometer 13 that measures the peripheral wind speed value, an anemometer 15 that measures the wind direction, and a lightning rod (not shown) are provided at appropriate locations on the outer peripheral surface of the nacelle 5 (for example, the upper part).
Inside the nacelle 5, although not shown, a generator connected to the rotor head 7 via a coaxial gearbox is installed. That is, the generator output is obtained from the generator by driving the generator by increasing the rotation of the rotor head 7 with a speed increaser.

FIG. 2 is a front view of the wind turbine blade 9. FIG. 2 shows a cross-sectional view of the wind turbine blade 9 at that position.
The wind turbine blade 9 is a hollow body having a wing shape in cross section. The wind turbine blade 9 has a blade shape defined by an outer skin 17 formed of, for example, glass fiber reinforced plastic. The strength of the outer skin 17 is reinforced from the inside by a main girder or the like.

  An angle-of-attack reduction unit 19 is provided at the blade tip 20 side portion of the wind turbine blade 9. The angle-of-attack reduction unit 19 is configured such that the angle of attack, which is the angle formed between the chord 23 and the wind direction 25, gradually decreases from the angle of attack α on the blade root 21 side toward the blade tip 20. In other words, the angle-of-attack reduction portion 19 is formed by being twisted toward the blade tip 20 so as to gradually reduce the angle of the blade with respect to the wind inflow direction, that is, by adding a twist angle to the blade tip.

FIG. 3 shows a change in the angle of attack of the wind turbine blade 9 in the blade length direction.
The length in the blade length direction of the angle-of-attack reduction unit 19 is set in consideration of the influence on the blade performance and the noise reduction effect, and is approximately 10% of the blade length L here. In consideration of a decrease in performance, it is preferable to keep it within 20%.
The angle of attack at the blade tip 20 of the angle-of-attack reduction unit 19 is, for example, 0 ° at the rotational speed (rated rotational speed) at which the rated output is achieved.
The angle of attack at the blade tip 20 is not limited to 0 °, and may be a value other than 0 ° in consideration of conditions other than noise.
In addition, depending on the airfoil (for example, with a camber or the like), the value at which the boundary layer becomes the thinnest may be other than 0 °.

The operation of the wind turbine generator 1 configured as described above will be described.
The wind power generator 1 measures the wind direction with the anemometer 15 during operation. According to the measurement result, the nacelle 5 rotates and the wind blows from the rotation axis direction of the rotor head 7. That is, the wind is blown against the wind turbine blade 9 in a certain direction.
When wind hits the wind turbine blade 9, lift is generated in a direction intersecting the blade surface. Since the wind turbine blades 9 are moved by this lift, the rotor head 7 rotates around the rotation axis.
Electric power is generated by driving the generator by increasing the rotation of the rotor head 7 with a gearbox.

  The windmill blade 9 is rotated around the blade length direction by the wind speed measured by the anemometer 13 to adjust the pitch angle. When the wind speed is low, the pitch angle is increased so that the area receiving the wind is increased. When the wind speed exceeds the speed at which the rated output can be obtained (rated speed), the pitch angle is reduced and the area that receives the wind is reduced.

At this time, for example, at the rated rotational speed, the attack angle reduction unit 19 has an attack angle smaller than the attack angle on the blade root 21 side. It is smaller than one having the same angle of attack as the root 21 side. As a result, the wind flows more smoothly along the blade surface, so that the thickness of the boundary layer formed on the blade surface is thinner than that in which the blade tip portion has the same angle of attack as the blade root 21 side.
As described above, when the boundary layer becomes thin, the generation of vortices at the trailing edge of the wind turbine blade 9 can be suppressed, so that noise can be reduced.
Since the angle-of-attack reduction part 19 is provided at the front-end | tip part of the windmill blade 9 with large generation | occurrence | production of a noise because the moving speed is large, it can reduce a noise efficiently. Thereby, since it is not necessary to suppress the rotation speed for noise reduction, it is possible to suppress a decrease in performance such as power generation efficiency.

Further, since the angle of attack of the angle-of-attack reduction unit 19 is fixed, the mutual relationship does not always change even if the rotational speed changes.
For this reason, since the angle-of-attack reduction unit 19 always has a different angle of attack compared to the blade root 21 side regardless of the rotational speed, noise can be reduced in a wide rotational speed range.

  Thus, the wind power generator 1 can reduce the generation of noise during operation. Thereby, since the restriction | limiting by noise is eased, the freedom degree of an installation place is securable, for example, it can install in the vicinity of a residence.

(Second embodiment)
Next, 2nd embodiment of this invention is described using FIGS.
In the present embodiment, the basic configuration is the same as that of the first embodiment, and the configuration of the wind turbine blade 9 is different. Therefore, in this embodiment, this difference is demonstrated and the overlapping description is abbreviate | omitted about another part.
In addition, the same code | symbol is attached | subjected to the component same as 1st embodiment, and the detailed description is abbreviate | omitted.
FIG. 4 is a front view of the wind turbine blade 9. FIG. 5 is a side view showing a state of the wind turbine blade 9 at the rated rotational speed. FIG. 6 is a side view showing a state when the wind turbine blade 9 is stopped.

An angle-of-attack reduction unit 19 is provided at the tip side portion of the wind turbine blade 9. As shown in FIG. 6, the angle-of-attack reduction portion 19 is formed by being smoothly bent so that the bending gradually increases from the blade surface on the blade root 21 side toward the blade tip 20 toward the positive pressure surface 27 side. .
This bending occurs when the wind turbine blade 9 rotates at a predetermined rotational speed and is deformed by the wind, as shown in FIG. 5, the angle-of-attack reduction portion 19 is a substantially extended portion of the blade surface on the blade root 21 side, that is, the blade The blade surface on the root 21 side and the blade surface of the angle-of-attack reduction unit 19 are substantially flush with each other. The angle-of-attack reduction unit 19 at this time may be represented by reference numeral 19B. Moreover, the angle-of-attack reduction part 19 at the time of a stop (namely at the time of manufacture) may be represented with the code | symbol 19A.

Since the operation | movement operation | movement of the wind power generator 1 comprised as mentioned above is substantially the same as 1st embodiment, the overlapping description is abbreviate | omitted and a different part is demonstrated.
When the windmill blade 9 rotates, the windmill blade 9 is deformed by a force (lift, drag) caused by the action of wind. This deformation becomes large at the blade tip portion of the wind turbine blade 9, that is, at the attack angle reducing portion 19.
When the rotational speed of the wind turbine blade 9 reaches the rated rotational speed, the angle-of-attack reduction unit 19 changes from the angle-of-attack reduction unit 19A shown in FIG. 6 to the state of the angle-of-attack reduction unit 19B shown in FIG. That is, the angle-of-attack reduction part 19B becomes a substantially extended part of the blade surface on the blade root 21 side, and therefore the angle of attack of the angle-of-attack reduction part 19B does not become larger than the design value.

That is, in the wind turbine blade 9 having no angle-of-attack reduction portion 19, the angle of attack at the tip portion is larger than the design value and the noise is increased due to this deformation, but in the wind turbine blade 9 of the present embodiment, In comparison, the angle of attack at the rated rotation can be reduced.
Therefore, in this embodiment, compared with the wind turbine blade 9 that does not have the angle-of-attack reduction unit 19, it is possible to reduce the noise at the rated rotation speed and to suppress the performance degradation.

  In the present embodiment, the angle-of-attack reduction unit 19 is configured to be a substantially extended portion of the blade surface on the blade root 21 side at the rated rotational speed, but is not limited to this. The portion 19 may be twisted so that the angle of attack is smaller than the angle of attack on the blade root 21 side.

In addition, this invention is not limited to each embodiment mentioned above, In the range which does not deviate from the summary, it can change suitably.
For example, it is good also as a structure which has the structure which uses the deformation | transformation at the time of rotation of 2nd embodiment, and the structure which makes the angle of attack of 1st embodiment small toward the blade tip 20 of the windmill blade 9 sequentially.

DESCRIPTION OF SYMBOLS 1 Wind power generator 9 Windmill blade 19 Angle-of-attack reduction part 20 Blade tip 21 Blade root 27 Pressure surface

Claims (4)

A wind turbine blade with a wing-shaped cross section,
An angle-of-attack reduction unit is provided for reducing the angle of attack when rotating at a predetermined rotational speed over a predetermined range from the blade tip to the blade root side,
The predetermined range is within 20% of the length of the wind turbine blade,
The angle-of-attack reduction unit is a wind turbine blade formed by adding a twist angle to the predetermined range.   The wind turbine blade according to claim 1, wherein the angle-of-attack reduction unit is formed so that the angle of attack gradually decreases from the angle of attack on the blade root side toward the blade tip.   3. The wind turbine blade according to claim 1, wherein the angle-of-attack reduction portion is formed to be a substantially extended portion of the blade surface on the blade root side when rotating at the predetermined number of rotations.   A wind turbine generator that generates power using the wind turbine blade according to any one of claims 1 to 3.

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