JP5433554B2 - 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, power generation by windmills has been promoted as clean energy. A windmill rotates a blade | wing around an axis | shaft with a wind force, converts this rotational force into electric power, and obtains an electric power generation output.
The power generation output of the windmill is represented by the product of the shaft end output (output generated by the blades) 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 × air density × wind speed ³ × blade efficiency × π × (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. 11 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).

  Patent Document 2 below defines the shape of the blade leading edge in order to suppress performance degradation due to the roughness of the blade leading edge (dust attachment, scratches, manufacturing errors, etc. on the blade leading edge). Specifically, when the cord length position of the blade leading edge is 0% and the cord length position of the blade trailing edge is 100%, the distance from the cord on the blade back side at the 2% position is divided by the cord length. The percentage is specified as 7% or more and 9% or less.

European Patent Application No. 1152148 International Publication No. 2007/010329

  However, even if a desired design lift coefficient is determined as in Patent Document 1 to improve the wind turbine output, and performance degradation due to roughness can be suppressed as in Patent Document 2, there are the following problems.

In general, there are a maximum lift-drag ratio and a maximum lift coefficient as performance evaluation of a blade. In particular, from the viewpoint of the wind turbine blade, the maximum lift-drag ratio is a parameter that affects the aerodynamic performance of the blade when the wind turbine is operating at a variable speed (design point). The maximum lift coefficient is a parameter that affects the blade aerodynamic performance in a transition state from when the wind turbine reaches the maximum rotational speed until it reaches the rated output. Therefore, it is important for the wind turbine blade to improve both the maximum lift-drag ratio and the maximum lift coefficient.
On the other hand, even if the wind turbine blade exhibits desired aerodynamic performance, if the aerodynamic noise of the wind turbine blade is not taken into consideration at the same time, the surrounding environment where the wind turbine is installed is adversely affected.

  The present invention has been made in view of such circumstances, and achieves high performance with an appropriate design lift coefficient that improves the maximum lift-drag ratio and the maximum lift coefficient, and is a low-noise wind turbine blade. An object of the present invention is to provide a wind turbine generator equipped with the same and a method for designing a wind turbine blade.

In order to solve the above-mentioned problems, the wind turbine blade of the present invention, the wind turbine generator equipped with the wind turbine blade, and the wind turbine blade design method employ the following means.
That is, the wind turbine blade according to the present invention is a wind turbine blade in which the blade thickness ratio increases from the blade tip side to the blade root side, and the chord length position obtained by dividing the distance X from the leading edge along the chord line by the cord length C. The maximum blade thickness position where the blade thickness is maximum is provided in the range of X / C of 0.28 or more and 0.32 or less, and the chord direction position X / C is in the range of 0.45 or more and 0.55 or less. A blade section having a maximum camber position where the camber is maximum is provided.

As a result of studying various numerical calculations and wind tunnel tests on the blade section of the wind turbine blade, the present inventor has achieved high performance (that is, a design lift coefficient in the optimum range) and low aerodynamic noise (that is, a boundary layer at the blade trailing edge) by the following combination. It was found that (thickness reduction) can be realized.
The chord direction position X / C is set within the range of 0.28 or more and 0.32 or less (more preferably 0.29 or more and 0.31 or less), and the maximum blade thickness position is arranged forward (front edge side) The arrangement) tends to improve the design lift coefficient, improve the maximum lift-drag ratio, and reduce the boundary layer thickness at the blade trailing edge as compared to the rear arrangement.
Also, in the case of the front camber where the maximum camber position is located on the leading edge side of the chord center, the maximum lift-drag ratio is improved and the boundary layer thickness at the blade trailing edge is reduced compared to the rear camber. However, the maximum lift coefficient tends to decrease. On the other hand, in the case of the rear camber, the maximum lift coefficient tends to be improved, but the maximum lift / drag ratio tends to decrease. Thus, since there is a trade-off relationship between the front camber and the rear camber, the chord direction position X / C is 0.45 or more and 0.55 or less so that the maximum camber position is intermediate between the front camber and the rear camber. It was determined to be.
With the above combination, a high-performance and low-noise wind turbine blade can be realized.
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.

  Furthermore, the distribution of the camber is characterized by being substantially symmetric in the chord direction about the maximum camber position.

  By making the distribution in the chord direction of the camber symmetrical about the maximum camber position, the advantages of the front camber and the rear camber can be taken in, and the maximum lift-drag ratio and the maximum lift coefficient can be improved.

  Furthermore, the blade cross section is provided at a wind turbine blade tip in which a blade thickness ratio obtained by dividing the maximum blade thickness by the cord length is in a range of 12% to 21%.

  A high-performance and low-noise wind turbine blade can be realized by providing the blade cross section within a blade thickness ratio of 12% or more and 21% or less that functions as a main part that converts wind power into rotation of the wind turbine blade.

  Further, the wind power generator of the present invention is the wind turbine blade described above, a rotor connected to the blade root side of the wind turbine blade and rotated by the wind turbine blade, and a rotational force obtained by the rotor is converted into an electric output. It is characterized by having a generator.

The wind turbine blade design method of the present invention is a wind turbine blade design method in which the blade thickness ratio increases from the blade tip side to the blade root side, and the distance X from the leading edge along the chord line is divided by the cord length C. In the range where the chord direction position X / C is 0.28 or more and 0.32 or less, a maximum blade thickness position where the blade thickness is maximum is provided, and the chord direction position X / C is 0.45 or more and 0.00. A maximum camber position where the camber is maximized is provided within a range of 55 or less.

As a result of studying various numerical calculations and wind tunnel tests on the blade section of the wind turbine blade, the present inventor has achieved high performance (that is, a design lift coefficient in the optimum range) and low aerodynamic noise (that is, a boundary layer at the blade trailing edge) by the following combination. It was found that (thickness reduction) can be realized.
The chord direction position X / C is set within the range of 0.28 or more and 0.32 or less (more preferably 0.29 or more and 0.31 or less), and the maximum blade thickness position is arranged forward (front edge side) The arrangement) tends to improve the design lift coefficient, improve the maximum lift-drag ratio, and reduce the boundary layer thickness at the blade trailing edge as compared to the rear arrangement.
Also, in the case of the front camber where the maximum camber position is located on the leading edge side of the chord center, the maximum lift-drag ratio is improved and the boundary layer thickness at the blade trailing edge is reduced compared to the rear camber. However, the maximum lift coefficient tends to decrease. On the other hand, in the case of the rear camber, the maximum lift coefficient tends to be improved, but the maximum lift / drag ratio tends to decrease. Thus, since there is a trade-off relationship between the front camber and the rear camber, the chord direction position X / C is 0.45 or more and 0.55 or less so that the maximum camber position is intermediate between the front camber and the rear camber. It was determined to be.
With the above combination, a high-performance and low-noise wind turbine blade can be realized.
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.

  According to the present invention, a wind turbine blade having high performance and low noise can be provided by appropriately determining the maximum blade thickness position and the maximum camber position.

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 a windmill blade. 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 figure which showed the blade | wing cross section concerning one Embodiment of this invention. It is a figure explaining the parameter regarding the performance of a windmill blade. It is the graph which showed the change of the design lift coefficient and boundary layer thickness with respect to the maximum blade thickness position. It is the graph which showed the change of the maximum lift coefficient and the maximum lift-drag ratio with respect to the maximum camber position. 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.
The wind turbine blade according to the present embodiment is suitably used for a wind turbine for power generation. 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 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. 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, at the radial position of each blade thickness ratio (percentage obtained by dividing the maximum value of the blade thickness by the cord length), Z (in the longitudinal axis direction of the blade) = It is expressed using a blade 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.
FIG. 3 shows the blade element cross section at each blade thickness ratio of the wind turbine blade 1 with the leading edge X = 0, Y = 0 and the trailing edge X = 1, Y = 0, normalized by the code length. Is. 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 maximum code length is From the dimensionless radius (0.25 ± 0.05) given as the maximum code length position 1d, 1.45 is determined.

  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. That is, while the horizontal axis is shown as a dimensionless radius in FIG. 5, the horizontal axis is shown as a blade thickness ratio in FIG.
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, the design lift coefficient optimally determined as described above is realized, the maximum lift coefficient is improved, the maximum lift-drag ratio is improved, and the turbulent boundary layer thickness at the blade trailing edge is reduced. Consider the blade cross section.

FIG. 7 shows an airfoil according to the present embodiment. The airfoil is normalized with respect to the blade cross-section at each blade thickness ratio of the wind turbine blade 1 using a cord length C that is a length on the chord line 7 passing from the leading edge 6 to the trailing edge 4. . Specifically, the front edge is normalized with X / C = 0 and Y / C = 0, and the rear edge is normalized with X / C = 1 and Y / C = 0.
In the figure, the wind inflow angle is represented by θ, the drag coefficient is represented by CD, and the lift coefficient is represented by CL.
Further, as shown in the figure, a turbulent boundary layer 5 develops from the maximum blade thickness position 2 on the back side to the trailing edge 4. Aerodynamic noise is caused by vortices in the boundary layer discharged from the turbulent boundary layer 5. Therefore, aerodynamic noise can be reduced by reducing the turbulent boundary layer thickness DSTAR at the trailing edge 4.

In the present embodiment, the airfoil shown in the figure is provided in a range where the blade thickness ratio is 12% or more and 21% or less. The range of the blade thickness ratio is defined as a range that functions as a main part that converts wind power into rotation of a wind turbine blade.
Further, the maximum blade thickness position 2 is provided in the range where the chord direction position X / C is 0.28 or more and 0.32 or less (more preferably 0.29 or more and 0.31 or less).
Further, the maximum camber position where the camber is maximum is provided in the range where the chord direction position X / C is 0.45 or more and 0.55 or less.
Further, the camber distribution is substantially symmetrical in the chord direction about the maximum camber position.

In FIG. 8, each parameter characterizing the performance of the wind turbine blade is shown with respect to the wind inflow angle θ.
FIG. 8A shows a change in the lift coefficient CL with respect to the wind inflow angle θ. As shown in the figure, the lift coefficient CL increases as the wind inflow angle θ increases, and decreases after showing the maximum lift coefficient CLmax, which is the maximum value. The maximum lift coefficient CLmax is preferably as large as possible in relation to performance improvement in a high wind speed region and prevention of stall caused by fluctuation or turbulence of inflow air. The maximum lift coefficient CLmax is a parameter that affects the blade aerodynamic performance in the transition state from when the wind turbine reaches the maximum rotational speed until it reaches the rated output. Further, as shown in the figure, the design lift coefficient CLdesign is desired to have a large value in order to exhibit high performance with an elongated blade such as a wind turbine blade of a large wind turbine.

  FIG. 8B shows a change in the lift / drag ratio with respect to the wind inflow angle θ. As shown in the figure, the lift / drag ratio L / D increases as the wind inflow angle θ increases, and decreases after the maximum lift / drag ratio L / Cmax is shown. The maximum lift / drag ratio L / Dmax is a parameter that affects the aerodynamic performance of the blade when the wind turbine is operating at a variable speed (design point), and it is desired to have a large value.

  FIG. 8C shows a change in position of the transition position XTR with respect to the wind inflow angle θ. As shown in the figure, when the wind inflow angle θ is small, the transition position XTR is located approximately at the center of the chord, and when the wind inflow angle θ exceeds a predetermined value, it moves toward the blade leading edge (LE) side. And move. That is, if the transition position XTR is positioned forward (front edge side), it means that roughness characteristics and stall characteristics are improved.

  FIG. 8D shows a change in boundary layer thickness (exclusion thickness) DSTAR at the trailing edge of the blade with respect to the wind inflow angle θ. The boundary layer thickness DSTAR increases as the wind inflow angle θ increases. Since this boundary layer thickness DSTAR is considered to be the main cause of the generation of aerodynamic noise, it is desired to make it smaller.

As a result of examining various numerical calculations and wind tunnel tests on the blade cross section of the wind turbine blade, the present inventor has found that there is a tendency shown in the following table. In the table, high camber means that the camber amount is relatively large.

  As shown in the above table, the maximum blade thickness position is improved in the design lift coefficient CLdesign and the maximum lift-drag ratio compared to the rear position by placing it at the front position (the leading edge side of the center position of the chord). This tends to improve L / Dmax and reduce the boundary layer thickness DSTAR. Therefore, it is preferable to provide the maximum blade thickness position within the range where the chord direction position X / C is 0.28 or more and 0.32 or less (more preferably 0.29 or more and 0.31 or less).

In addition, in the case of the camber at the front (front edge side of the center position of the chord), the maximum camber position tends to improve the maximum lift / drag ratio L / Dmax and reduce the boundary layer thickness DSTAR compared to the rear camber. However, the maximum lift coefficient CLmax tends to decrease. On the other hand, the rear camber tends to increase the maximum lift coefficient CLmax, but tends to decrease the maximum lift / drag ratio L / Dmax. Thus, since there is a trade-off relationship between the front camber and the rear camber, the chord direction position X / C is 0.45 or more and 0.55 or less so that the maximum camber position is intermediate between the front camber and the rear camber. It is preferable to determine so that Further, it is preferable that the camber distribution is substantially symmetric in the chord direction about the maximum camber position.
Regarding the camber amount, when the high camber was used, the design lift coefficient CLdesign, the maximum lift coefficient CLmax, and the maximum lift / drag ratio L / Dmax tended to improve.

  FIG. 9 shows the grounds for setting the chord direction position X / C of the maximum blade thickness position to 0.28 or more and 0.32 or less (more preferably 0.29 or more and 0.31 or less). In the figure, the results obtained by numerical simulation under a plurality of conditions are plotted. As shown in FIG. 4, in order to satisfy 1.15 ± 0.05, which is the range of the high design lift coefficient CLdesign, the chord direction position x / c needs to be at least 32% (0.32) or less. Since the boundary layer thickness DSTAR tends to be thinner (noise reduction) when the maximum blade thickness position is in front, it is preferable to dispose the boundary layer as much as possible. On the other hand, if the maximum blade thickness position is placed too far forward, the design lift coefficient CLdesign may become too high and may deviate from the optimum range, the stall characteristics may deteriorate, and the trailing edge against the edge moment Since the buckling strength may decrease, the lower limit of the chord direction position X / C is preferably 0.28.

  In FIG. 10, the chord direction position X / C of the maximum camber position is set to 0.45 or more and 0.55 or less, and the camber distribution is substantially symmetrical in the chord direction about the maximum camber position. The reason for this is shown. Similar to FIG. 9, the results obtained by numerical simulation under a plurality of conditions are plotted in the same figure. As shown in FIG. 10A, it is shown that the maximum lift coefficient CLmax increases as the maximum camber position changes from the trailing edge side to the leading edge side. That is, the front camber is preferable from the viewpoint of the maximum lift coefficient CLmax. On the other hand, as shown in FIG. 10B, it is shown that the maximum lift / drag ratio L / Dmax increases as the maximum camber position changes from the front edge side to the rear edge side. That is, from the viewpoint of the maximum lift / drag ratio L / Dmax, the rear camber is preferable. Therefore, in order to satisfy both the high maximum lift coefficient CLmax and the maximum lift / drag ratio L / Dmax, the chord direction position X / C of the maximum camber position is not less than 0.45 and not more than 0.55 (preferably Is preferably 0.5).

  As described above, according to the present embodiment, the maximum blade thickness position is the forward arrangement, the maximum camber position is arranged in the center of the chord direction, and the camber distribution is symmetrical in the chord direction with the maximum camber position being the center. Therefore, a high-performance and low-noise wind turbine blade can be realized.

DESCRIPTION OF SYMBOLS 1 Windmill blade 1a Blade root 1b Blade tip 2 Maximum blade thickness position 3 Blade body part 4 Trailing edge 6 Leading edge

Claims (5)

In wind turbine blades where the blade thickness ratio increases from the blade tip side to the blade root side,
The maximum blade thickness position where the blade thickness is the maximum is within the range of the chord direction position X / C obtained by dividing the distance X from the leading edge along the chord line by the chord length C within the range of 0.28 to 0.32. Provided,
In the range where the chord direction position X / C is 0.45 or more and 0.55 or less, a maximum camber position where the camber is maximum is provided ,
The wind turbine blade according to claim 1, wherein the camber distribution is substantially symmetrical with respect to the chord direction about the maximum camber position . In wind turbine blades where the blade thickness ratio increases from the blade tip side to the blade root side,
The maximum blade thickness position where the blade thickness is the maximum is within the range of the chord direction position X / C obtained by dividing the distance X from the leading edge along the chord line by the chord length C within the range of 0.28 to 0.32. Provided,
In the range where the chord direction position X / C is 0.45 or more and 0.55 or less, a maximum camber position where the camber is maximum is provided ,
The wind turbine blade, wherein the blade cross section is provided at a wind turbine blade end in which a blade thickness ratio obtained by dividing the maximum blade thickness by the cord length is in a range of 12% to 21% . A wind turbine blade according to claim 1 or 2 ,
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 a wind turbine blade design method in which the blade thickness ratio increases from the blade tip side to the blade root side,
The maximum blade thickness position where the blade thickness is maximum is within the range where the chord length position X / C, which is obtained by dividing the distance X from the leading edge along the chord line by the cord length C, is 0.28 or more and 0.32 or less. Provided,
In the range where the chord direction position X / C is 0.45 or more and 0.55 or less, a maximum camber position where the camber is maximum is provided ,
A wind turbine blade design method characterized in that the camber distribution is substantially symmetrical in the chord direction about the maximum camber position . In a wind turbine blade design method in which the blade thickness ratio increases from the blade tip side to the blade root side,
The maximum blade thickness position where the blade thickness is maximum is within the range where the chord length position X / C, which is obtained by dividing the distance X from the leading edge along the chord line by the cord length C, is 0.28 to 0.32. Provided,
In the range where the chord direction position X / C is 0.45 or more and 0.55 or less, a maximum camber position where the camber is maximum is provided ,
A design method of a wind turbine blade , wherein the blade cross section is provided at a wind turbine blade tip in which a blade thickness ratio obtained by dividing the maximum blade thickness by the cord length is in a range of 12% to 21% .

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