JP5433553B2 - Wind turbine blade, wind power generator equipped with the wind turbine blade, and wind turbine blade design method - Google Patents

Description

  The present invention relates to a wind turbine blade, a wind turbine generator including the wind turbine blade, and a wind turbine blade design method.

In recent years, wind power generators have attracted attention as clean energy that does not emit greenhouse gases during power generation. A wind turbine generator rotates wind turbine blades around an axis by wind power, and converts the rotational force into electric power to obtain a power generation output.
The power generation output of the wind turbine generator is represented by the product of the shaft end output (output generated by the blade) and the conversion efficiency (efficiency of bearings, generators, etc.). Further, the shaft end output is expressed by the following formula, and if the blade has high blade efficiency and a large blade diameter, the power generation amount is improved.
Shaft end output = 1/2 x air density x wind speed ³ x blade efficiency x π x (blade diameter / 2) ²

The blade efficiency has a theoretical upper limit (Betz limit = 0.593). In practice, the upper limit is about 0.5 due to the influence of the wind turbine wake and the air resistance of the blade. Therefore, further significant improvement in blade efficiency is difficult.
On the other hand, since the blade diameter has an influence on the output by its square, it is effective to increase the blade diameter to improve the power generation amount. However, the expansion of the blade diameter leads to an increase in aerodynamic load (thrust force acting in the inflow direction and moment transmitted to the blade root), which increases the size and weight of equipment such as the rotor head, nacelle, and tower, which in turn increases costs. There are concerns / trends to connect. Therefore, a technique for increasing the length of the blade while suppressing an increase in the aerodynamic load of the blade is essential. In order to avoid the problem of increased load, aerodynamic (blade shape) methods can be considered: shorter chord length (ie chord length) (ie greater aspect ratio or less solidity). Thus, a method of reducing the aerodynamic load by reducing the wing projection area is conceivable.
Here, the aspect ratio and the solidity are expressed by the following equations.
Aspect ratio = Wing length ² / Wing projected area (1)
Solidity = total wing projection area / wing sweep area
= (Number of blades x average cord length) / (π x (blade diameter / 2) ² ) (2)

In general, a wind turbine blade has a predetermined optimum cord length for a predetermined peripheral speed ratio, and has a relationship expressed by the following equation (Wind Energy Handbook, John Wiley & Sons, p378).
Copt / R × λ ² × CLdesign × r / R≈16 / 9 × π / n (3)
Where Copt is the optimum code length, R (blade radius) is half the blade diameter, λ is the design peripheral speed ratio, CLdesign is the design lift coefficient, r is the radial position of the blade cross section, and n is the number of blades. .
The design peripheral speed ratio is the tip peripheral speed / infinite upstream wind speed. The design lift coefficient is the lift coefficient at the angle of attack at which the lift / drag ratio (lift / drag) of the airfoil (blade cross section) is maximum, and the (aerodynamic) shape and inflow conditions (Reynolds number) It depends on.
FIG. 13 shows the definition of the Reynolds number used in this specification. As shown in the figure, the Reynolds number in the windmill is obtained by considering the relative wind speed in the predetermined section AA of the blade rotating at the predetermined rotational speed, and is expressed by the following equation.
Reynolds number = Air density x Relative wind speed on blade cross section x Cord length of blade cross section / Air viscosity coefficient

In order to maintain the aerodynamic efficiency of the wing, it is desirable that the wing shape (wing cross section) has the following characteristics.
1. 1. High design lift coefficient The design lift coefficient “combination” is optimized. Here, the design lift coefficient “combination” means different blade thickness ratios (maximum blade thickness divided by code length) applied to one wind turbine blade. This is a combination of the design lift coefficients of a series of airfoil series / family / set. For example, as a blade thickness ratio of an airfoil applied to a wind turbine, a combination of 12, 15, 18, 21, 24, 30, 36, and 42% can be given.

  Patent Document 1 below discloses an airfoil for improving wind turbine output. Specifically, an aerofoil having a blade thickness ratio in the range of 14% to 45% and a design lift coefficient in the range of 1.10 to 1.25 is disclosed (see claim 1).

European Patent Application No. 1152148

  However, even if a desired design lift coefficient is defined, how to define the airfoil that realizes the design lift coefficient is not currently organized in a unified manner.

On the other hand, when determining the airfoil, the back bulge YS and the ventral bulge YP are used. Here, the back-side swelling YS is a percentage of a value obtained by dividing the distance from the cord on the blade back side at the maximum blade thickness position by the cord length. Further, the ventral bulge YP is a percentage of a value obtained by dividing the distance from the cord on the blade ventral side at the maximum blade thickness position by the cord length.
However, the relationship between the dorsal bulge YS and ventral bulge YP and the design lift coefficient is not studied at all.

  This invention is made | formed in view of such a situation, Comprising: It aims at providing the wind turbine blade which can implement | achieve a desired design lift coefficient, the wind power generator provided with the same, and the design method of a wind turbine blade. .

In order to solve the above problems, the wind turbine blade and the design method thereof of the present invention employ the following means.
That is, the wind turbine blade according to the present invention includes a blade body portion in which the cord length and the blade thickness ratio increase from the blade tip side to the blade root side, and the blade body portion is obtained by dividing the maximum value of the blade thickness by the cord length. The blade thickness ratio is 21% when expressed by the blade thickness ratio, which is a percentage of the value, and the back bulge YS, which is the percentage of the value obtained by dividing the distance from the blade back cord at the maximum blade thickness position by the cord length. In position, dorsal swollen YS is 12.0 ± 0.6%, blade thickness ratio 24% position, dorsal swollen YS is 12.3 ± 0.7%, blade thickness ratio 30% position, dorsal swollen YS is 13.3 ± 1.2%, preferably 13.3 ± 1.0%, more preferably 13.3 ± 0.8%.

The wind turbine blade of the present invention includes a blade main body portion whose cord length increases from the blade tip side to the blade root side, and the blade cross-sectional shape of the blade main body portion is given by the back-side bulge YS. This is based on the good correlation between the design lift coefficient and the back bulge YS. Thereby, it is possible to obtain a blade shape that satisfies a desired design lift coefficient.
In particular, in the present invention, by defining the combination of the blade thickness ratio and the backside bulge as described above, the change in the design lift coefficient of the blade cross section between the blade thickness ratio of 21% and 30% can be reduced. Desired aerodynamic characteristics can be obtained.
Further, by defining the back-side bulge, it is possible to provide a thin blade that achieves a high design lift coefficient, and it is possible to reduce the load applied to the wind turbine blade. Thereby, a windmill blade can be lengthened and a power generation amount can be improved as a result.
Preferably, the design peripheral speed ratio (blade tip peripheral speed / inflow wind speed) is 6 or more (more preferably 8.0 or more and 9.0 or less), and the Reynolds number is 3 to 10 million.

  Further, the blade body portion has a blade thickness ratio in the range of 21% to 35%, the YS value at the blade thickness ratio 21% position, the YS value at the blade thickness ratio 24% position, and It is preferable to have YS obtained by an interpolation curve that passes through the YS value at the blade thickness ratio of 30%.

  Further, the blade main body portion has a blade thickness ratio of 18%, YS of 11.7 ± 0.5%, blade thickness ratio of 36%, and YS of 14.6 ± 2.0%, preferably 14.5%. 6 ± 1.2%, more preferably 14.6 ± 1.0%, blade thickness ratio 42% position, YS 16.6 ± 3.0%, preferably 16.6 ± 2.0% It is preferably 16.6 ± 1.5%.

  By defining the blade cross section as described above, a wind turbine blade having a small change in the design lift coefficient over the region from the blade tip side (blade thickness ratio 18%) to the blade root side (blade thickness ratio 42%) is provided. be able to.

  Further, the blade main body portion has a blade thickness ratio in the range of 18% to 42%, the YS value at the blade thickness ratio of 18%, the YS value at the blade thickness ratio of 21%, the blade The YS value at the 24% thickness ratio, the YS value at the 30% blade thickness position, the YS value at the 36% blade thickness ratio position, and the YS value at the 42% blade thickness ratio position. It is preferred to have YS obtained by an interpolation curve that passes through the values.

Further, the wind turbine blade of the present invention includes a blade body portion in which the cord length and the blade thickness ratio increase from the blade tip side to the blade root side, the blade body portion is a value obtained by dividing the maximum value of the blade thickness by the cord length. The blade thickness ratio, which is the percentage of the blade, and the ventral bulge YP, which is the percentage of the value obtained by dividing the distance from the blade ventral cord at the maximum blade thickness by the cord length, is a blade thickness ratio of 21%. Then, when the ventral bulge YP is 9.0 ± 0.6% and the blade thickness ratio is 24%, the ventral bulge YP is 11.7 ± 0.7% and the blade thickness ratio is 30%, the ventral bulge YP is Is 16.7 ± 1.2%, preferably 16.7 ± 1.0%, more preferably 16.7 ± 0.8%.

The wind turbine blade of the present invention includes a blade main body portion whose cord length increases from the blade tip side to the blade root side, and the blade cross-sectional shape of the blade main body portion is given by the ventral bulge YP. This is based on the good correlation between the design lift coefficient and the ventral bulge YP. Thereby, it is possible to obtain a blade shape that satisfies a desired design lift coefficient.
In particular, in the present invention, by defining the combination of the blade thickness ratio and the ventral bulge as described above, the change in the design lift coefficient of the blade cross section between the blade thickness ratio of 21% and 30% can be reduced, Desired aerodynamic characteristics can be obtained.
Further, by defining the ventral bulge, it is possible to provide a thin blade that achieves a high design lift coefficient, and to reduce the load that the wind turbine blade receives. Thereby, a windmill blade can be lengthened and a power generation amount can be improved as a result.
Preferably, the design peripheral speed ratio (blade tip peripheral speed / inflow wind speed) is 6 or more (more preferably 8.0 or more and 9.0 or less), and the Reynolds number is 3 to 10 million.

  Further, the blade main body portion has a blade thickness ratio in the range of 21% to 35%, the YP value at the blade thickness ratio 21% position, the YP value at the blade thickness ratio 24% position, and It is preferable to have YP obtained by an interpolation curve that passes through the value of YP at the blade thickness ratio of 30%.

  Further, in the wind turbine blade of the present invention, the blade body portion has a blade thickness ratio of 18%, YP of 6.3 ± 0.5%, blade thickness ratio of 36%, and YP of 21.4 ± 2. 0%, preferably 21.4 ± 1.2%, more preferably 21.4 ± 1.0%, blade thickness ratio 42% position, YP 25.4 ± 3.0%, preferably 25.4 It is characterized by being set to ± 2.0%, more preferably 25.4 ± 1.5%.

  Furthermore, by defining the blade cross section as described above, a wind turbine blade having a small change in the design lift coefficient over the region from the blade tip side (blade thickness ratio 18%) to the blade root side (blade thickness ratio 42%) can be obtained. Can be provided.

  Further, the blade main body portion has a blade thickness ratio in the range of 18% to 42%, the YP value at the blade thickness ratio of 18%, the YP value at the blade thickness ratio of 21%, the blade The YP value at the 24% thickness ratio, the YP value at the 30% blade thickness position, the YP value at the 36% blade thickness position, and the YP value at the 42% blade thickness ratio position. It is preferable to have YP obtained by an interpolation curve that passes through the value.

  The wind turbine generator according to the present invention includes a wind turbine blade described in any of the above, a rotor connected to the blade root side of the wind turbine blade and rotated by the wind turbine blade, and a rotation obtained by the rotor. And a generator for converting power into electrical output.

  Since it is set as the wind power generator provided with the above-mentioned windmill blade, an output increase can be aimed at by lengthening.

Further, the wind turbine blade design method of the present invention is a wind turbine blade design method including a blade main body portion in which a cord length and a blade thickness ratio increase from the blade tip side to the blade root side. A design lift coefficient determination step for determining a predetermined design lift coefficient in the engine, and a distance from the blade back side code at the maximum blade thickness position so as to satisfy the design lift coefficient determined in the design lift coefficient determination step And a YS determination step for determining a dorsal bulge YS which is a percentage of the value divided by the length.

  As a result of intensive studies by the present inventors, it was found that the correlation between the design lift coefficient and the back bulge YS is strong. Therefore, in the present invention, since YS is determined so as to satisfy a predetermined design lift coefficient, it is possible to realize a wind turbine blade having desired aerodynamic characteristics.

Further, the wind turbine blade design method of the present invention is a wind turbine blade design method including a blade main body portion in which a cord length and a blade thickness ratio increase from the blade tip side to the blade root side. A design lift coefficient determination step for determining a predetermined design lift coefficient in the step, and a distance from the blade ventral side code at the maximum blade thickness position so as to satisfy the design lift coefficient determined in the design lift coefficient determination step And a YP determination step for determining a ventral bulge YP that is a percentage of the value divided by the length.

  As a result of intensive studies by the present inventors, it has been found that the correlation between the design lift coefficient and the ventral bulge YP is strong. Therefore, in the present invention, since YP is determined so as to satisfy a predetermined design lift coefficient, it is possible to realize a wind turbine blade having desired aerodynamic characteristics.

  Since the dorsal bulge YS and ventral bulge YP correlated with the design lift coefficient are defined, it is possible to obtain a blade shape that satisfies the desired design lift coefficient. Therefore, it is possible to provide a thin blade that achieves a high design lift coefficient, and to reduce the load applied to the wind turbine blade. Thereby, a windmill blade can be lengthened and a power generation amount can be improved as a result.

It is the perspective view which showed the typical shape of the windmill blade. It is the figure which showed the cross section in each blade thickness ratio of FIG. It is the figure which showed the airfoil in each blade thickness ratio of FIG. It is explanatory drawing at the time of designing the windmill blade concerning one Embodiment of this invention. It is the figure which showed distribution of the design lift coefficient with respect to the dimensionless radius. It is the figure which showed distribution of the design lift coefficient with respect to blade thickness ratio. It is the wing | blade sectional drawing which showed the back side swelling YS and the ventral side swelling YP. It is the figure which showed distribution of the back side swelling YS with respect to blade thickness ratio. It is the figure which showed the correlation with a design lift coefficient and the back side swelling YS. It is the figure which showed distribution of the bulge YP on the ventral side with respect to blade thickness ratio. It is the figure which showed the correlation with a design lift coefficient and back side swelling YP. It is the graph which showed the effect at the time of optimizing a design lift coefficient like this invention. It is explanatory drawing which showed the definition of the Reynolds number.

Embodiments according to the present invention will be described below with reference to the drawings.
[First Embodiment]
The wind turbine blade according to the present embodiment is suitably used as a blade of a wind power generator. For example, three wind turbine blades are provided, and each is connected to the rotor with an interval of about 120 °. Preferably, the rotational diameter (blade diameter) of the wind turbine blade is 60 m or more, and the blade has a solidity of 0.2 to 0.6. The wind turbine blades may have a variable pitch or a fixed pitch.

As shown in FIG. 1, the wind turbine blade 1 is a three-dimensional blade, and extends from the blade root 1a side, which is the rotation center side, toward the blade tip 1b side.
When defining the blade shape, as shown in the figure, the radial position (corresponding to the distance from the rotation center of the blade) of each blade thickness ratio (percentage of the maximum blade thickness divided by the cord length) Z (the longitudinal axis direction of the blade) at the position of the blade) = represented by using a blade element section cut by a constant section. FIG. 1 shows that blade element cross sections cut at radial positions with blade thickness ratios of 18%, 21%, 24%, 30%, 36%, and 42% are used as the definition of the shape of the wind turbine blade. ing. When the radial position of the wind turbine blade 1 is indicated, instead of the blade thickness ratio, a radial position r corresponding to the distance from the rotation center of the blade (or a dimensionless radial position r / R obtained by dividing the radial position by the blade radius). ) May be used.

In FIG. 2, the blade element cross section of FIG. 1 is projected onto the XY plane (a plane perpendicular to the Z axis). When viewed from the longitudinal tip of the wind turbine blade 1 as shown in the figure, the right side is the blade leading edge and the left side is the blade trailing edge.
FIG. 3 is a diagram in which the leading edge is normalized with X = 0, Y = 0 and the trailing edge is normalized with X = 1, Y = 0 with respect to the blade cross-section at each blade thickness ratio of the wind turbine blade 1. The shape shown in the figure is called an airfoil.

FIG. 4 shows an explanatory diagram when designing the wind turbine blade 1 according to the present embodiment.
In the figure, the horizontal axis represents the dimensionless radius and the vertical axis represents the dimensionless code length. The dimensionless radius is a value (r / R) obtained by dividing the radial position r of the blade cross section from the rotation center by the blade radius R of the wind turbine blade 1 as described above. Here, the blade radius is one half of the diameter (blade diameter) of the locus circle drawn by the tip of the blade as the wind turbine blade 1 rotates. The dimensionless code length is a value (c / R) obtained by dividing the code length c of the blade cross section by the blade radius R.

FIG. 4 shows a plurality of curves (thin lines) in which the design lift coefficient CLdesign obtained from the above equation (3) is constant. Since the curve with the constant design lift coefficient CLdesign satisfies the above equation (3), the optimum code length (vertical axis) at the design peripheral speed ratio is given from the viewpoint of aerodynamic characteristics.
In FIG. 4, the design peripheral speed ratio is 8.0 or more and 8.5 or less, and the Reynolds number is 3 million or more and 10 million or less.

The wind turbine blade 1 according to the present embodiment includes a blade body portion 3 that increases in cord length from the blade tip 1b side to the blade root 1a side, as indicated by a thick line in FIG. In the present embodiment, the dimensionless radius of the wing body 3 is 0.2 or more and 0.95 or less.
The blade body 3 is located on the blade tip 1b side, and the blade tip region 1c where the cord length gradually increases, the maximum cord position 1d located on the blade root 1a side and having the maximum cord length, and the blade tip region 1c. And a transition area 1e located between the maximum code length position 1d.

  In the present embodiment, the dimensionless radius of the blade tip region 1c is 0.5 or more and 0.95 or less, the dimensionless radius of the maximum code length position 1d is (0.25 ± 0.05), and the transition region 1e. The dimensionless radius of is 0.2 or more (excluding 0.2) and less than 0.5.

  As shown in FIG. 4, the blade tip region 1c has a substantially constant first design lift coefficient (1.15 in this embodiment). The first design lift coefficient of the blade tip region 1c is a practical upper limit that can be realized from the blade thickness ratio (for example, about 18%) of the blade tip region 1c that is a thin blade. The upper limit of the design lift coefficient should be large if the aerodynamic characteristics are taken into consideration, so that the warp will be increased in the case of thin blades. Is generated and the loss becomes large, so that the predetermined value is determined. As described above, since the blade tip region 1c has a substantially constant first design lift coefficient, desired aerodynamic characteristics can be exhibited in the blade tip region 1c that can receive a large amount of wind force and can expect an output. .

  The maximum code length position 1d is a second design lift coefficient (1.45 in the present embodiment) having a value larger than the first design lift coefficient. The second design lift coefficient is determined from the maximum code length that is limited by transportation reasons and the like. For example, as shown in FIG. 4, when the dimensionless maximum code length is limited to 0.08 due to the width of the road that transports the wind turbine blade 1, the design lift coefficient that takes this dimensionless code length is: A dimensionless radius of 0.2 given as the maximum code length position 1d is determined to be 1.45.

  The transition region 1e has a design lift coefficient that gradually increases from the first design lift coefficient (1.15) to the second design lift coefficient (1.45). That is, the blade root side of the blade tip region 1c having the first design lift coefficient and the maximum cord length position 1d having the second design lift coefficient were smoothly connected. As a result, even when the cord length is increased from the blade tip region 1c to the maximum cord length position 1d, the change range of the design lift coefficient can be kept small, so that the aerodynamic performance is not greatly impaired. In particular, it is possible to maintain a desired aerodynamic characteristic even in a thick wing portion that has not been considered in the past (a portion that is thicker than the blade tip region 1c; a region from the transition region 1e to the maximum cord length position 1d). it can.

FIG. 5 shows the distribution of the design lift coefficient with respect to each dimensionless radial position for the wind turbine blade 1 whose shape is determined as described above.
The blade tip region 1c in which the dimensionless radial position is 0.5 or more and 0.95 or less has a first design lift coefficient in the range of 1.15 ± 0.05.
The second design lift coefficient at the maximum code length position 1d where the dimensionless radius position is (0.25 ± 0.05) is 1.45 ± 0.1.
The transition region 1e in which the dimensionless radius position is 0.2 or more (excluding 0.2) and less than 0.5 is the blade root side end of the blade tip region 1c (position where the dimensionless radius is 0.5). And the maximum code length position 1d is 1.30 ± 0.075 in the design lift coefficient at the center position (the position where the dimensionless radius is 0.35 in the figure).

FIG. 6 shows the distribution of the design lift coefficient with respect to each blade thickness ratio for the wind turbine blade 1 whose shape is determined as described above. In other words, in FIG. 5, the horizontal axis is shown as a dimensionless radius, but in FIG. 6, the horizontal axis is shown as a blade thickness ratio.
The blade tip region 1c having a blade thickness ratio of 12% or more and 30 or less has a first design lift coefficient in the range of 1.15 ± 0.05.
The second design lift coefficient at the maximum cord length position 1d where the blade thickness ratio is 42% is 1.45 ± 0.1.
The transition region 1e in which the blade thickness ratio is 30% or more (not including 30%) and less than 42% is the blade root side end of the blade tip region 1c (position where the blade thickness ratio is 30%) and the maximum cord length position The design lift coefficient at the center position between 1d (the position where the blade thickness ratio is 36% in the figure) is 1.30 ± 0.075.

Next, after the desired design lift coefficient is determined at each blade thickness position (or radial position) as described above (design lift coefficient determination step), the shape of the wind turbine blade 1 that realizes this design lift coefficient is defined. A method will be described.
Specifically, by determining the wing dorsal bulge YS (YS determination step), the airfoil at each blade thickness position is defined. As shown in FIG. 7, YS is a percentage of a value obtained by dividing the distance from the chord (blade chord) on the blade back side at the maximum blade thickness position by the chord length.

すなわち、背側膨らみＹＳは、（ａ）の範囲で規定され、好ましくは（ｂ）の範囲で規定され、さらに好ましくは（ｃ）の範囲で規定される。
図８に示すように、風車翼１は、各翼断面にて、上表に示した各翼厚比における背側膨らみＹＳを通過する補間曲線によって得られる背側膨らみＹＳを有する。 FIG. 8 shows the distribution of the back swell YS with respect to the blade thickness ratio.
YS in FIGS. 8A, 8B, and 8C is defined as shown in the table below.

That is, the back bulge YS is defined within the range (a), preferably defined within the range (b), and more preferably defined within the range (c).
As shown in FIG. 8, the wind turbine blade 1 has a back-side bulge YS obtained by an interpolation curve passing through the back-side bulge YS at each blade thickness ratio shown in the above table in each blade cross section.

  In FIG. 8, as a comparative example with respect to the present embodiment, a back-side bulge YS of a wind turbine blade obtained based on a conventional NACA blade is indicated by a square mark. As described above, the wind turbine blade according to the present embodiment has a different back-side bulge YS from the conventional wind turbine blade.

FIG. 9 shows data as a basis for obtaining a desired design lift coefficient by the back bulge YS.
9A to 9E show the results when the blade thickness ratio is 21%, 24%, 30%, 36%, and 42%, respectively. These figures are obtained as a result of changing the back bulge YS by numerical simulation.
As shown in each figure, it can be seen that there is a strong correlation between the design lift coefficient and the back bulge YS.

As described above, according to the present embodiment, the following operational effects are obtained.
Since the dorsal bulge YS correlated with the design lift coefficient is defined, a blade shape satisfying the desired design lift coefficient can be obtained. Therefore, it is possible to provide a thin blade that achieves a high design lift coefficient, and to reduce the load applied to the wind turbine blade. Thereby, a windmill blade can be lengthened and a power generation amount can be improved as a result.

[Second Embodiment]
The present embodiment is different from the first embodiment in that the wing shape is determined using the dorsal bulge YS while the wing shape is determined using the ventral bulge YP. Since other points are the same as those of the first embodiment, description thereof will be omitted.

After a desired design lift coefficient is determined at each blade thickness position (or radial position) as shown in FIG. 6 (design lift coefficient determination step), a method of defining the shape of the wind turbine blade 1 that realizes this design lift coefficient explain.
More specifically, by determining the ventral bulge YP of the wing (YP determination step), the wing shape at each blade thickness position is defined. As shown in FIG. 7, YP is a percentage of a value obtained by dividing the distance from the chord (blade chord) on the blade ventral side at the maximum blade thickness position by the chord length.

すなわち、腹側膨らみＹＰは、（ａ）の範囲で規定され、好ましくは（ｂ）の範囲で規定され、さらに好ましくは（ｃ）の範囲で規定される。
図１０に示すように、風車翼１は、各翼断面にて、上表に示した各翼厚比における腹側膨らみＹＰを通過する補間曲線によって得られる腹側膨らみＹＰを有する。 FIG. 10 shows the distribution of the ventral bulge YP with respect to the blade thickness ratio.
YP in FIGS. 10A, 10B, and 10C is defined as shown in the table below.

That is, the ventral bulge YP is defined within the range (a), preferably defined within the range (b), and more preferably defined within the range (c).
As shown in FIG. 10, the wind turbine blade 1 has a ventral bulge YP obtained by an interpolation curve passing through the ventral bulge YP at each blade thickness ratio shown in the above table in each blade cross section.

  In FIG. 10, as a comparative example with respect to the present embodiment, a back-side bulge YS of a wind turbine blade obtained based on a conventional NACA blade is indicated by a square mark. As described above, the wind turbine blade according to the present embodiment has a different back-side bulge YS from the conventional wind turbine blade.

FIG. 11 shows data as a basis for obtaining a desired design lift coefficient by the ventral bulge YP.
11A to 11E show the results when the blade thickness ratio is 21%, 24%, 30%, 36%, and 42%, respectively. These figures are obtained as a result of changing the ventral bulge YP by numerical simulation.
As shown in each figure, it can be seen that there is a strong correlation between the design lift coefficient and the ventral bulge YP.

As described above, according to the present embodiment, the following operational effects are obtained.
Since the dorsal bulge YS correlated with the design lift coefficient is defined, a blade shape satisfying the desired design lift coefficient can be obtained. Therefore, it is possible to provide a thin blade that achieves a high design lift coefficient, and to reduce the load applied to the wind turbine blade. Thereby, a windmill blade can be lengthened and a power generation amount can be improved as a result.

FIG. 12 shows the effect of this embodiment.
As shown in FIG. 12 (a), the A wing is a reference wing to be compared, the design lift coefficient at the wing tip is set to about 0.8, and the design lift coefficient is not optimized in the blade length (radius) direction. The B wing is obtained by increasing the design lift coefficient by 40% with respect to the A wing. The C wing corresponds to this embodiment. ) Optimized in the direction.
When the design lift coefficient is increased as in the B blade, the optimum cord length can be reduced by 30% as shown in FIG. 12B, thereby extending the blade diameter by 7% as shown in FIG. 12C. As a result, the power generation amount is increased by 6.5% as shown in FIG. 12 (d). Since the design lift coefficient of blade C is optimized in the blade length direction, the blade efficiency is further improved by 2% compared to blade B, and the power generation amount is further 1 than that of blade B as shown in FIG. % (7.5% for A wing).

In addition, the back swell YS and the ventral swell YP of each embodiment described above are defined by an interpolation curve that passes through the back swell YS and the ventral swell YP in each phrase blade thickness ratio shown in Tables 1 and 2. However, the wind turbine blade of the present invention is not limited to this, and an interpolation curve that passes through the values of the back-side swelling YS and the ventral-side swelling YP in Tables 1 and 2 when the blade thickness ratio is 21% to 35%. It only has to be. This is because the characteristics of the wind turbine are mainly determined within the range of the blade thickness ratio.
In each embodiment, the design peripheral speed ratio is set to 8.0 or more and 8.5 or less, but the present invention is not limited to this. For example, the design peripheral speed ratio is 6.0 or more and 9.0 or less. Can also be applied.
Further, the blade tip region 1c, the transition region 1e, and the maximum code length position are not limited to the dimensionless radial position and blade thickness ratio range shown in the present embodiment, but in a range where the effects of the present invention are exhibited. It can be changed as appropriate.

DESCRIPTION OF SYMBOLS 1 Windmill blade 1a Blade root 1b Blade tip 1c Blade tip region 1d Maximum cord length position 1e Transition region 3 Blade body

Claims (11)

It has a blade body part that increases the cord length and blade thickness ratio from the blade tip side to the blade root side,
The wing body is
The blade thickness ratio, which is the percentage of the value obtained by dividing the maximum blade thickness by the cord length,
When expressed by the back swell YS, which is a percentage of the value obtained by dividing the distance from the cord on the blade back side at the maximum blade thickness position by the cord length,
At the blade thickness ratio of 21%, the back bulge YS is 12.0 ± 0.6%.
At the blade thickness ratio of 24%, the back bulge YS is 12.3 ± 0.7%.
When the blade thickness ratio is 30%, the back bulge YS is 13.3 ± 1.2%, preferably 13.3 ± 1.0%, more preferably 13.3 ± 0.8%,
It is said that the wind turbine wing. The wing body part is
In the range where the blade thickness ratio is 21% or more and 35% or less,
The YS value at the blade thickness ratio of 21%;
The YS value at the blade thickness ratio of 24%, and
The YS value at the blade thickness ratio of 30%;
The wind turbine blade according to claim 1, which has YS obtained by an interpolation curve passing through. The wing body part is
YS is 11.7 ± 0.5% at the blade thickness ratio of 18%.
At a blade thickness ratio of 36%, YS is 14.6 ± 2.0%, preferably 14.6 ± 1.2%, more preferably 14.6 ± 1.0%,
At a blade thickness ratio of 42%, YS is 16.6 ± 3.0%, preferably 16.6 ± 2.0%, more preferably 16.6 ± 1.5%,
The wind turbine blade according to claim 1 or 2, wherein The wing body part is
In the range where the blade thickness ratio is 18% or more and 42% or less,
The YS value at the blade thickness ratio of 18%;
The YS value at the blade thickness ratio of 21%;
The YS value at the blade thickness ratio of 24%;
The YS value at the blade thickness ratio of 30%;
The YS value at the blade thickness ratio of 36%, and
The YS value at the blade thickness ratio of 42%;
The wind turbine blade according to claim 3, which has YS obtained by an interpolation curve passing through. It has a blade body part that increases the cord length and blade thickness ratio from the blade tip side to the blade root side,
The wing body is
The blade thickness ratio, which is the percentage of the value obtained by dividing the maximum blade thickness by the cord length,
When represented by the ventral bulge YP, which is the percentage of the value obtained by dividing the distance from the blade ventral cord at the maximum blade thickness position by the cord length,
At the blade thickness ratio of 21%, ventral bulge YP is 9.0 ± 0.6%,
At the blade thickness ratio of 24%, the ventral bulge YP is 11.7 ± 0.7%,
At the blade thickness ratio of 30%, the ventral bulge YP is 16.7 ± 1.2%, preferably 16.7 ± 1.0%, more preferably 16.7 ± 0.8%,
It is said that the wind turbine wing. The wing body part is
In the range where the blade thickness ratio is 21% or more and 35% or less,
The YP value at the blade thickness ratio of 21%;
The value of YP at the blade thickness ratio of 24%, and
The YP value at the blade thickness ratio of 30%;
The wind turbine blade according to claim 5, which has YP obtained by an interpolation curve passing through. The wing body part is
YP is 6.3 ± 0.5% at the blade thickness ratio of 18%.
At a blade thickness ratio of 36%, YP is 21.4 ± 2.0%, preferably 21.4 ± 1.2%, more preferably 21.4 ± 1.0%,
At a blade thickness ratio of 42%, YP is 25.4 ± 3.0%, preferably 25.4 ± 2.0%, more preferably 25.4 ± 1.5%,
The wind turbine blade according to claim 5 or 6, wherein The wing body part is
In the range where the blade thickness ratio is 18% or more and 42% or less,
The YP value at the blade thickness ratio of 18%;
The YP value at the blade thickness ratio of 21%;
The YP value at the blade thickness ratio of 24%;
The YP value at the blade thickness ratio of 30%;
The YP value at the blade thickness ratio of 36%, and
The YP value at the blade thickness ratio of 42%;
The wind turbine blade according to claim 7, which has YP obtained by an interpolation curve passing through. A wind turbine blade according to any one of claims 1 to 8,
A rotor connected to the blade root side of the wind turbine blade and rotated by the wind turbine blade;
A generator that converts the rotational force obtained by the rotor into an electrical output;
A wind turbine generator comprising: In the design method of a wind turbine blade having a blade body portion in which the cord length and blade thickness ratio increase from the blade tip side to the blade root side,
A design lift coefficient determination step for determining a predetermined design lift coefficient in each blade cross section of the blade body portion;
In order to satisfy the design lift coefficient determined in the design lift coefficient determination step, the back side bulge YS, which is a percentage of the value obtained by dividing the distance from the blade back side code at the maximum blade thickness position by the code length, is determined. YS determination step;
A method for designing a wind turbine blade, comprising: In the design method of a wind turbine blade having a blade body portion in which the cord length and blade thickness ratio increase from the blade tip side to the blade root side,
A design lift coefficient determination step for determining a predetermined design lift coefficient in each blade cross section of the blade body portion;
In order to satisfy the design lift coefficient determined in the design lift coefficient determination step, the ventral bulge YP which is a percentage of the value obtained by dividing the distance from the blade ventral cord at the maximum blade thickness position by the cord length is determined. A YP determination step;
A method for designing a wind turbine blade, comprising:

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