Blade manufacturing method and blade

Abstract

To provide a manufacturing method for a blade capable of rotating a wind turbine efficiently.SOLUTION: A manufacturing method for a blade mounted on a support arm attached to a vertical rotational shaft erected vertically so as to rotate on a circumference around the vertical rotational shaft, comprises: setting an attachment angle at the time when attaching a basic blade being a base to the support arm so that the angle is within a range of 0° to 90° with respect to the support arm; calculating a maximum value of a circumferential component of aerodynamic force generated in the basic blade at an azimuth angle (Ψ) of 0° to 360° of the basic blade at the attachment angle; and based on the calculated azimuth angle (Ψ) at the maximum value, searching for a cross-sectional shape of a blade with an increased circumferential component from the basic blade.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a blade manufacturing method and a blade. [Background technology]

[0002] Generally, there are two types of vertical axis wind turbines: a drag type, such as the Savonius type or paddle type, which rotates the turbine by drag acting on the blades, and a lift type, such as the Darrieus type or gyromill type, which rotates the turbine by lift acting on the blades.

[0003] The amount of power generated by a wind turbine is determined by the rotational torque multiplied by the number of rotations, but in the case of a drag-type vertical axis wind turbine, although it can rotate in low wind speeds, it cannot rotate faster than the wind. Therefore, even if the wind speed increases, it is not possible to obtain a higher rotation speed, which limits the amount of power that can be obtained.

[0004] Furthermore, in the case of lift-type vertical axis wind turbines, they can rotate at high speeds exceeding the wind speed during high wind speeds, enabling them to generate a large amount of electricity, but they do not rotate at medium to low wind speeds, meaning that they can only be used in places with extremely favorable wind conditions, such as mountainous regions or offshore.

[0005] In order to solve these problems, a vertical axis wind turbine has been proposed, as described in Patent Document 1. The vertical axis wind turbine described in Patent Document 1 can operate as either a drag type or a lift type, simply by changing the installation angle, without providing any special mechanism or the like. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5924125 Summary of the Invention [Problem to be solved by the invention]

[0007] However, although the above-mentioned vertical axis wind turbine can rotate efficiently over a wide range of wind speeds by operating as a drag type at low wind speeds and as a lift type at high wind speeds, there is still a problem that there is room for improvement.

[0008] In view of the above, an object of the present invention is to provide a blade manufacturing method and a blade that can rotate a wind turbine more efficiently. [Means for solving the problem]

[0009] The above object of the present invention can be achieved by the following means: Note that the parentheses indicate reference symbols of embodiments to be described later, but the present invention is not limited to these.

[0010] The blade manufacturing method according to claim 1 is a method for manufacturing blades (3A, 3B) attached to a support arm (4) attached to a vertical rotation shaft (2) that is erected vertically so as to rotate on a circumference (C) centered on the vertical rotation shaft (2), The magatama-shaped blade is the basic blade, The basic blade (blade 3) is attached to the support arm (4) at an angle (β) between the angle of the lift type arrangement and the angle of the drag type arrangement, At the mounting angle (β), the circumferential component (F) of the aerodynamic force (F) generated on the basic blade (blade 3) at an azimuth angle (Ψ) of 0° to 360° of the basic blade (blade 3) is θ ) is calculated as the azimuth angle (Ψ) at which the value of Furthermore, the circumferential component of the aerodynamic force (F θ ) is the maximum value of the azimuth corner (Ψ), the circumferential component (F θ The blades (3A, 3B) are manufactured by searching for a cross-sectional shape that increases the thickness of the blades (3A, 3B). The blade manufacturing method according to claim 2 is characterized in that in the blade manufacturing method according to claim 1, the angle of the lift type arrangement relative to the support arm (4) is 0°, and the angle of the drag type arrangement relative to the support arm is 90°.

[0011] Claim 3 The blade manufacturing method according to the present invention is 1 or 2 In the method for manufacturing a blade according to the above item, an attachment angle (β) when attaching the basic blade (blade 3) to the support arm (4) is set to be 50° to 70° with respect to the support arm (4), The circumferential component (F) of the aerodynamic force (F) generated on the basic blade (blade 3) θ The maximum value of the azimuth angle (Ψ) of the basic blade (blade 3) at the setting angle (β) is between 0° and 70°, or the azimuth angle (Ψ) of the basic blade (blade 3) at the setting angle (β) is between 180° and 270°, Based on the azimuth angle (Ψ) at the maximum value, the circumferential component (F θ ) is increased. and get The blades (3A, 3B) are manufactured.

[0012] The blade according to claim 4 is a blade (3A, 3B) attached to a support arm (4) attached to a vertical rotation shaft (2) that is erected vertically, at a set attachment angle (β) and azimuth angle (Ψ) so as to rotate on a circumference (C) centered on the vertical rotation shaft (2), The mounting angle (β) is The magatama-shaped blade is the basic blade, The angle at which the basic blade (3) is attached to the support arm (4) is set to an angle between the angle of the lift type arrangement and the angle of the drag type arrangement; a Jimasu corner (Ψ) is the circumferential component (F) of the aerodynamic force generated on the basic blade (blade 3) at the set mounting angle (β) in the azimuth angle range of 0° to 360° of the basic blade (blade 3).θ ) is the angle at which the value is maximum, Furthermore, the blades (3A, 3B) are configured to reduce the circumferential component (F θ ) is the maximum value of the azimuth corner In this case, the cross-sectional shape of the basic blade (blade 3) is used as a basis, and the circumferential component (F θ ) is increased. A blade according to claim 5 is the blade according to claim 4, The cross-sectional shape of the blade (3A) is a front edge portion (30A) formed in an arc shape protruding in a first outward direction (left outward direction in FIG. 4(a)); a rear edge portion (31A) formed in an arc shape protruding in a second outward direction (right outward in FIG. 4(a)) opposite to the first outward direction (left outward in FIG. 4(a)); a first side portion (32A) connecting one end (upper end 30Aa) of the front edge portion (30A) and one end (upper end 31Aa) of the rear edge portion (31A); a second side portion (33A) connecting the other end (lower end portion 30Ab) of the front edge portion (30A) and the other end (lower end portion 31Ab) of the rear edge portion (31A); The arc of the leading edge portion (30A) is formed to have a larger diameter than the arc of the trailing edge portion (31A), The arc of the rear edge portion (31A) is formed in a hook shape, the first side portion (32A) is connected to one end (upper end 30Aa) of the front edge portion (30A) and one end (upper end 31Aa) of the rear edge portion (31A) so as to form an arc shape when connecting the first side portion (32A) to one end (upper end 30Aa) of the front edge portion (30A), and further is connected to the one end (upper end 30Aa) of the front edge portion (30A) so as to form a recessed step portion (32Aa1); The second side portion (33A) ,before When the other end (lower end 30Ab) of the front edge portion 30A and the other end (lower end 31Ab) of the rear edge portion 31A are connected, they are connected to form an arc, and further, the other end (lower end 30Ab) of the front edge portion 30A is concave step (33Aa1)

[0013] A blade according to claim 6 is the blade according to claim 4, The cross-sectional shape of the blade (3B) is a front edge portion (30B) formed in an arc shape protruding in a first outward direction (left outward direction in FIG. 4(b)); a rear edge portion (31B) formed in an arc shape protruding in a second outward direction (right outward in FIG. 4(b)) opposite to the first outward direction (left outward in FIG. 4(b)); a first side portion (32B) connecting one end (upper end 30Ba) of the front edge portion (30B) and one end (upper end 31Ba) of the rear edge portion (31B); a second side portion (33B) connecting the other end (lower end 30Bb) of the front edge portion (30B) and the other end (lower end 31Bb) of the rear edge portion (31B), The arc of the front edge portion (30B) is formed to have a larger diameter than the arc of the rear edge portion (31B), the first side portion (32B) is connected to one end (upper end 30Ba) of the front edge portion (30B) and one end (upper end 31Ba) of the rear edge portion (31B) so as to form an arc when the first side portion (32B) connects the one end (upper end 30Ba) of the front edge portion (30B) and the one end (upper end 31Ba) of the rear edge portion (31B), The second side portion (33B) ,before When the other end (lower end 30Bb) of the front edge portion 30B and the other end (lower end 31Bb) of the rear edge portion 31B are connected, they are connected to form an arc, and further, the other end (lower end 30Bb) of the front edge portion 30B is concave step (33Ba1) and Convex step It is characterized by being formed by linking (33Ba2) together to form a continuous structure. [Effects of the Invention]

[0014] Next, the effects of the present invention will be described with reference to the drawings. Note that the reference symbols in parentheses are those of the embodiments described below, but the present invention is not limited to these.

[0015] According to the inventions of claims 1 and 4, the mounting angle (β) when the basic blade (blade 3) is mounted on the support arm (4) is set to be an angle between the angle of the lift type arrangement and the angle of the drag type arrangement with respect to the support arm (4), and the circumferential component (F) of the aerodynamic force (F) generated on the basic blade (blade 3) at the mounting angle (β) in the azimuth angle (Ψ) of 0° to 360° of the basic blade (blade 3) is θ ) is calculated as the azimuth angle (Ψ) at which the azimuth angle (F θ ) is the maximum azimuth corner In (Ψ), the circumferential component (F θ The blades (3A, 3B) are manufactured by searching for a cross-sectional shape that increases the circumferential component (F θ ) can be manufactured.

[0016] Thus, according to the present invention, a high performance vertical axis wind turbine can be realized, and the wind turbine can be rotated more efficiently.

[0017] In addition, in order to realize such an effect, as in the invention of claim 2, It is preferable that the angle of the lift type arrangement relative to the support arm (4) is 0°, and the angle of the drag type arrangement relative to the support arm is 90°. The mounting angle (β) of the basic blade (blade 3) when it is attached to the support arm (4) is set to 50° to 70° with respect to the support arm (4), and the circumferential component (F θ The maximum value of the circumferential component (F) is at an azimuth angle (Ψ) between 0° and 70° of the base blade (blade 3) at the setting angle (β), or at an azimuth angle (Ψ) between 180° and 270° of the base blade (blade 3) at the setting angle (β), and based on the azimuth angle (Ψ) at the maximum value, the circumferential component (F θ ) is increasing. and get It is preferable to manufacture the blades (3A, 3B) in this way. θ) can be manufactured.

[0018] Also, Claims that allow wind turbines to rotate more efficiently 5 The blade (3A) and the claim 6 The blade (3B) can be manufactured as described above. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic plan view of a vertical axis wind turbine according to an embodiment of the present invention. [Figure 2] (a-1) is an explanatory diagram showing that the mounting angle when the blade is attached to the support arm is 0°, (a-2) is an explanatory diagram showing that the mounting angle when the blade is attached to the support arm is 90°, and (b) is an explanatory diagram of the azimuth angle when the left side of the illustration of a counterclockwise rotating vertical axis wind turbine is the upwind side. [Figure 3] FIG. 10 is a graph showing the results of calculating the dimensionless circumferential component of the aerodynamic force generated on the blade at an azimuth angle Ψ of 0° to 360° for the blade at mounting angles of 50°, 60°, and 70°. [Figure 4] FIG. 1( a ) is a diagram showing the cross-sectional shape of a blade obtained by searching for a cross-sectional shape of a blade whose circumferential component increases based on an azimuth angle of Ψ=21°, and FIG. 1( b ) is a diagram showing the cross-sectional shape of a blade obtained by searching for a cross-sectional shape of a blade whose circumferential component increases based on an azimuth angle of Ψ=211°. [Figure 5] (a) is a diagram showing the simulation results when the blade shown in Figure 4(a) is used, (b) is an enlarged view of the blade located in the upper right corner of (a), and (c) is an explanatory diagram showing the aerodynamic force generated on the blade and the direction of its circumferential component. [Figure 6] (a) is a diagram showing the simulation results when the blade shown in Figure 4(b) is used, (b) is an enlarged view of the blade located at the bottom left of (a), and (c) is an explanatory diagram showing the aerodynamic force generated on the blade and the direction of its circumferential component. [Figure 7] FIG. 5 shows the results of a field experiment using the blade shown in FIG. 4(a). [Figure 8] This figure shows an enlargement of the low tip speed ratio portion (lower left portion of Fig. 7) shown in Fig. 7, with data for a lift-type wind turbine (NACA0018 blades) added. [Figure 9] FIG. 5 shows the results of a wind tunnel experiment comparing the performance of the blade shown in FIG. 4(a) with that of the blade shown in FIG. 4(b). DETAILED DESCRIPTION OF THE INVENTION

[0020] An embodiment of a blade manufacturing method according to the present invention will now be described in detail with reference to the drawings. In the following description, the directions of up, down, left, and right refer to the directions of up, down, left, and right as viewed from the front of the illustration.

[0021] The blades manufactured by the blade manufacturing method of this embodiment are used in a vertical axis wind turbine 1 as shown in Fig. 1. This vertical axis wind turbine 1 has a vertical rotation shaft 2 that stands perpendicular to the wind direction, and magatama-shaped blades 3 attached to the vertical rotation shaft 2 via support arms 4 that extend radially from the vertical rotation shaft 2. When this vertical axis wind turbine 1 receives wind, the drag acting on the blades 3 causes the support arms 4 to rotate on a circumference C centered on the vertical rotation shaft 2.

[0022] The lower end of the vertical rotation shaft 2 is connected to a generator (not shown), and the rotational force of the blades 3 obtained by wind power is transmitted to the vertical rotation shaft 2 via the support arm 4. The blades 3 are attached to one end of the support arm 4, and the other end of the support arm 4 is fixed to the vertical rotation shaft 2 by a disk-shaped fixture 5.

[0023] As explained above, the vertical axis wind turbine 1 rotates due to the rotational torque acting on the vertical rotation shaft 2. However, when viewed from the vertical axis wind turbine 1 side, the circumferential force F acting on the outer periphery of the vertical rotation shaft 2 is TOn the other hand, when viewed from the wind side, the circumferential component F of the aerodynamic force F generated on the blade 3 is θ contributes to the rotation of the vertical rotation axis 2. In this case, the circumferential component F θ The blade with a large F T This brings about a high efficiency in the vertical axis wind turbine 1, that is, the wind turbine can be rotated more efficiently.

[0024] Therefore, the inventors have focused on this point and have calculated the circumferential component F θ We have come up with a method for manufacturing a blade that increases the axial length. This will be explained in detail below.

[0025] (1) First, the circumferential component F θ In manufacturing a blade that increases the load, the mounting angle β when mounting the blade 3 shown in Fig. 1 to the support arm 4 was set to be 0° to 90° with respect to the support arm 4. As shown in Patent Document 1, when the mounting angle β when mounting the blade 3 to the support arm 4 is 0° (see Fig. 2(a-1)), a lift-type arrangement is achieved, and when the mounting angle β is 90° (see Fig. 2(a-2)), a drag-type arrangement is achieved. Therefore, the mounting angle β was set to be 0° to 90° with respect to the support arm 4 so that the blade can operate in either case.

[0026] (2) Next, the circumferential component F of the aerodynamic force F generated on the blade 3 at the azimuth angle of 0° to 360° of the blade 3 at the mounting angle β θ C, which is a non-dimensional Fθ In this embodiment, as shown in Fig. 2(b), the left side of the vertical axis wind turbine 1 rotating counterclockwise is the upwind side. Therefore, the range of azimuth angle Ψ, 0°≦Ψ≦180°, is the return side where the blade 3 advances in the upwind direction, and the range of 180°≦Ψ≦360° is the advance side in the opposite direction.

[0027] (3) Next, based on the calculated azimuth angle Ψ at the maximum value, the circumferential component F θA genetic algorithm was used to search for a blade cross-sectional shape that increases the circumferential component F. That is, the cross-sectional shape of the magatama-shaped blade 3 was used as a base, and the genetic algorithm was used to search for a blade cross-sectional shape that increases the circumferential component F based on the azimuth angle Ψ at the calculated maximum value. θ In this embodiment, the cross-sectional shape of the blade that increases the circumferential component F is calculated by a numerical analysis of the flow that takes viscosity into consideration. θ We are looking for...

[0028] By the way, the circumferential component F θ The cross-sectional shape of the blade where the azimuth angle Ψ increases is thought to differ depending on the azimuth angle Ψ. On the other hand, the cross-sectional shape of the blade needs to be fixed to a single value regardless of the azimuth angle Ψ. Therefore, it is necessary to select in advance the position of the azimuth angle Ψ of the blade 3 shown in Figure 1 where the genetic algorithm will be used for the study. The criterion for selecting the position of the azimuth angle Ψ is the circumferential component F at that position. θ C, which is a non-dimensional Fθ That thing, C Fθ In this embodiment, the azimuth angle Ψ direction change rate is θ C, which is a non-dimensional Fθ The azimuth angle Ψ was selected so that

[0029] Thus, through the above steps (1) to (3), the circumferential component F θ This makes it possible to manufacture a blade with an increased circumferential component F. This makes it possible to realize a high-performance vertical axis wind turbine 1, which in turn makes it possible to rotate the vertical axis wind turbine 1 more efficiently. θ In order to obtain the circumferential component F of the aerodynamic force F generated by the blade, a numerical analysis of the flow that takes viscosity into account is used. θ This improves the calculation accuracy, thereby realizing a higher performance vertical axis wind turbine 1. This allows the vertical axis wind turbine 1 to rotate more efficiently.

[0030] Here, for easier understanding, the above steps (1) to (3) will be explained using a concrete example.

[0031] First, the circumferential component F θ In manufacturing a blade with increased force, the mounting angle β when mounting the blade 3 shown in FIG. 1 to the support arm 4 was set to 50°, 60°, and 70°. Then, the circumferential component F of the aerodynamic force F generated on the blade 3 at the mounting angle β (50°, 60°, 70°) in the azimuth angle Ψ of the blade 3 from 0° to 360° was calculated. θ C, which is a non-dimensional Fθ The results are shown in Figure 3. As shown in Figure 3, at an installation angle β (50°), C Fθ The negative value of C is limited to a narrow range of about 100°, 70°≦Ψ≦170°, which is a part of the return side shown in Figure 2(b). In the other range of about 260°, C Fθ becomes positive, and a driving force is generated that rotates the vertical rotation axis 2 counterclockwise. In particular, at two points, Ψ=41° at the return side entrance and Ψ=211° at the advance side entrance, C Fθ As shown in Figure 3, at the mounting angle β (60°), C Fθ The negative value of C is limited to a narrow range of about 90°, 70°≦Ψ≦160°, which is a part of the return side shown in Figure 2(b). In the other range of about 270°, C Fθ becomes positive, and a driving force is generated that rotates the vertical rotation axis 2 counterclockwise. In particular, at two points, Ψ=21° at the return side entrance and Ψ=211° at the advance side entrance, C Fθ Furthermore, as shown in Figure 3, at the mounting angle β (70°), C Fθ The negative value of C is limited to a narrow range of approximately 100°, 30°≦Ψ≦40°, 60°≦Ψ≦150°, which is a part of the return side shown in Figure 2(b). In the other range of approximately 260°, C Fθ becomes positive, and a driving force is generated that rotates the vertical rotation axis 2 counterclockwise. In particular, at two points, Ψ=55° at the return side entrance and Ψ=211° at the advance side entrance, C Fθ is the maximum value.

[0032] Thus, for the installation angle β (50° to 70°), CFθ The maximum value of is between azimuth angles Ψ0° and 70° and between azimuth angles Ψ180° and 270°.

[0033] Incidentally, among the maximum values ​​shown in Fig. 3, at mounting angle β (50°), the maximum values ​​are lower at point X and point Y compared to mounting angle β (60°). Also, at mounting angle β (70°), the maximum value at point Y is larger than at mounting angle β (60°), but the maximum value at point X is lower. As a result, mounting angle β (60°) is considered to be optimal.

[0034] Therefore, in this embodiment, the azimuth angles Ψ=21° and Ψ=211° are selected as the maximum values ​​at the mounting angle β (60°).

[0035] Next, based on the cross-sectional shape of the blade 3 shown in FIG. 1, a genetic algorithm was used to calculate the circumferential component F θ In this embodiment, a cross-sectional shape of the blade that increases the circumferential component F was searched for by a numerical analysis of the flow taking viscosity into consideration. θ asked for.

[0036] As a result of the above search, the cross-sectional shape of the blade 3A shown in Figure 4(a) was obtained. Furthermore, using the cross-sectional shape of the blade 3 shown in Figure 1 as a base, a genetic algorithm was used to find the circumferential component F θ In this embodiment, a cross-sectional shape of the blade that increases the circumferential component F was searched for by a numerical analysis of the flow taking viscosity into consideration. θ asked for.

[0037] As a result of the above search, the cross-sectional shape of blade 3B shown in Fig. 4(b) was obtained. Note that, hereinafter, blade 3A may be referred to as MT-C, and blade 3B may be referred to as MT-D.

[0038] As shown in Fig. 4(a), the blade 3A is composed of a leading edge portion 30A, a trailing edge portion 31A, an upper portion 32A, and a lower portion 33A. As shown in Fig. 4(a), the leading edge portion 30A is formed in an arc shape that protrudes outward to the left in the figure. Also, as shown in Fig. 4(a), the trailing edge portion 31A is formed in an arc shape that protrudes outward to the right in the figure. As shown in Fig. 4(a), the arc shape of the trailing edge portion 31A is formed to have a smaller diameter than the arc shape of the leading edge portion 30A, and is formed in a hook shape.

[0039] 4(a), the upper portion 32A is formed in an arc shape and serves to connect the upper end 30Aa of the leading edge 30A and the upper end 31Aa of the trailing edge 31A. The upper end 30Aa of the leading edge 30A and the left end 32Aa of the upper portion 32A are connected to each other so as to form a recessed step 32Aa1.

[0040] On the other hand, as shown in Fig. 4(a), the lower portion 33A serves to connect the lower end 30Ab of the leading edge portion 30A and the lower end 31Ab of the trailing edge portion 31A, and is formed in an arc shape so as to be parallel to the upper portion 32A. In addition, when connecting the lower end 30Ab of the leading edge portion 30A and the left end 33Aa of the lower portion 33A, concave step They are connected to form 33Aa1.

[0041] As shown in FIG. 4(b), the blade 3B is composed of a leading edge portion 30B, a trailing edge portion 31B, an upper portion 32B, and a lower portion 33B. As shown in FIG. 4(b), the leading edge portion 30B is formed in an arc shape that protrudes outward to the left in the figure. Also, as shown in FIG. 4(b), the trailing edge portion 31B is formed in an arc shape that protrudes outward to the right in the figure. As shown in FIG. 4(b), the arc shape of this trailing edge portion 31A is formed to have a smaller diameter than the arc shape of the leading edge portion 30A.

[0042] On the other hand, as shown in FIG. 4(b), the upper side portion 32B serves to connect the upper end portion 30Ba of the leading edge portion 30B and the upper end portion 31Ba of the trailing edge portion 31B, and is formed in an arc shape.

[0043] 4(b), the lower portion 33B serves to connect the lower end 30Bb of the leading edge portion 30B and the lower end 31Bb of the trailing edge portion 31B, and is formed in an arc shape so as to be parallel to the upper portion 32B. In addition, when connecting the lower end 30Bb of the leading edge portion 30B and the left end 33Ba of the lower portion 33B, concave step 33Ba1 and Convex step They are connected to form a continuous chain of 33Ba2.

[0044] Here, the inventors have found that the blade 3A shown in FIG. 4(a) and the blade 3B shown in FIG. 4(b) have a circumferential component F θ To check whether the cross-sectional shape of the blade increases the wind speed, we used numerical analysis software COSMOL Multiphysics (COSMOL Inc.) to simulate wind passing through the rotating vertical axis wind turbine 1. The results are shown in Figures 5 and 6.

[0045] Figure 5 shows the results of a simulation using the blade 3A shown in Figure 4(a), which is indicated as MT-C in the figure. Figures 5(a) and 5(b) show wind speed (indicated by red arrows in the figure) and pressure (in the figure, blue indicates the lowest pressure, and red indicates increasing pressure). As shown in Figure 5(a), it can be seen that the wind flowing in from the left side of the figure passes through the rotating vertical axis wind turbine 1 and flows downward while meandering. It can also be seen that multiple low-pressure areas (indicated by A to G in the figure) generated by the passing of the rotating blade 3A flow downward downstream of the vertical axis wind turbine 1. The velocity vector also meanders in accordance with these low-pressure areas.

[0046] Meanwhile, FIG. 5(a) shows the moment when blade 3A located at the upper right of the figure is positioned at an azimuth angle Ψ=21° using a genetic algorithm, and FIG. 5(b) is an enlarged view of blade 3A located at the upper right of the figure. As shown in FIG. 5(b), the wind speed is high and the pressure is low on the upper side 32A of blade 3A. Therefore, as shown in FIG. 5(c), an aerodynamic force F is generated that pushes blade 3A upward to the upper right of the figure. As shown in FIG. 5(c), this aerodynamic force F has a rotational component, i.e., a circumferential component F. θ , which rotates the support arm 4 to which the blade 3A is attached, and thus the vertical rotation shaft 2 rotates.

[0047] By the way, the circumferential component F θ increases, the aerodynamic force F and the circumferential component F θ Therefore, as shown in Figure 5(c), the aerodynamic force F and the circumferential component F θ Since the direction of the circumferential component F is closer than 90°, the blade 3A shown in FIG. 4(a) θ As a result, the blade 3A shown in FIG. 4(a) has a circumferential component F θ It was confirmed that the cross-sectional shape of the blade increases.

[0048] Figure 6 shows the results of a simulation using blade 3B shown in Figure 4(b), which is indicated as MT-D in the figure. Figures 6(a) and 6(b) show wind speed (indicated by red arrows in the figure) and pressure (in the figure, blue indicates the lowest pressure, and red indicates increasing pressure). As shown in Figure 6(a), it can be seen that the wind flowing in from the left side of the figure passes through the rotating vertical axis wind turbine 1 and flows downward while meandering. It can also be seen that multiple low-pressure areas (indicated by H to O in the figure) generated by the passing of rotating blade 3B flow downward downstream of the vertical axis wind turbine 1. The velocity vector also meanders in accordance with these low-pressure areas.

[0049] Meanwhile, Fig. 6(a) shows the moment when blade 3B located at the bottom left of the figure is positioned at an azimuth angle Ψ = 211° using the genetic algorithm, and Fig. 6(b) is an enlarged view of blade 3B located at the bottom left of the figure. As can be seen from Fig. 6(b), the wind speed is high and the pressure is low at the upper part 32B of blade 3B. Therefore, as shown in Fig. 6(c), an aerodynamic force F is generated that pushes blade 3B upward to the bottom right of the figure. As shown in Fig. 6(c), this aerodynamic force F has a rotational component, i.e., a circumferential component F θ , which rotates the support arm 4 to which the blade 3B is attached, and thus the vertical rotation shaft 2 rotates.

[0050] Here, as shown in Figure 6(c), the aerodynamic force F and the circumferential component F θ The direction of the circumferential component F θ As a result, the blade 3B shown in FIG. 4(b) has a circumferential component F θ It was confirmed that the cross-sectional shape of the blade increases.

[0051] From the above, it can be seen that the blade 3A shown in FIG. 4(a) and the blade 3B shown in FIG. 4(b) have a circumferential component F θ It was confirmed that the cross-sectional shape of the blade increases.

[0052] Furthermore, the inventors conducted the following experiment to confirm that the blade 3A shown in FIG. 4(a) and the blade 3B shown in FIG. 4(b) are superior to drag-type wind turbines and lift-type wind turbines.

[0053] Figure 7 shows the results of a field experiment in which the blades 3A shown in Figure 4(a) were attached to the vertical axis wind turbine 1 shown in Figure 1. In Figure 7, the horizontal axis represents the tip speed ratio, and the vertical axis represents the wind turbine output. Figure 7 shows that when the blades 3A shown in Figure 4(a) are attached, the turbine not only rotates at a tip speed ratio of 1.0 or less, but also rotates at a tip speed ratio that far exceeds 1.0. In contrast, a drag-type wind turbine cannot rotate at a tip speed that exceeds the wind speed, and therefore will not rotate at a tip speed ratio that exceeds 1.0. Therefore, it can be seen that the vertical axis wind turbine 1 attached with the blades 3A shown in Figure 4(a) is superior to a drag-type wind turbine.

[0054] On the other hand, Figure 8 is an enlarged view of the low tip speed ratio portion shown in Figure 7 (the lower left portion of Figure 7), and in this Figure 8, data for a lift-type wind turbine (NACA0018 blades) has also been added. As is clear from Figure 8, the vertical axis wind turbine 1 equipped with the blades 3A shown in Figure 4(a) has a higher wind turbine output than the lift-type wind turbine (NACA0018 blades). Therefore, it can be seen that the vertical axis wind turbine 1 equipped with the blades 3A shown in Figure 4(a) is superior to the lift-type wind turbine.

[0055] On the other hand, Figure 9 shows the results of a wind tunnel experiment comparing the performance of blade 3A shown in Figure 4(a) and blade 3B shown in Figure 4(b). As is clear from Figure 9, blade 3B shown in Figure 4(b) and blade 3A shown in Figure 4(a) have almost the same performance. Therefore, it can be seen that blade 3B shown in Figure 4(b) is also superior to both drag-type wind turbines and lift-type wind turbines.

[0056] From the above, it was confirmed that the blade 3A shown in FIG. 4(a) and the blade 3B shown in FIG. 4(b) are superior to the drag type wind turbine and the lift type wind turbine.

[0057] According to the blade manufacturing method as described above in this embodiment, it is possible to manufacture blades that can rotate a wind turbine more efficiently.

[0058] It should be noted that the shapes and the like shown in this embodiment are merely examples, and various modifications and alterations are possible within the scope of the gist of the present invention as set forth in the claims. For example, in this embodiment, the cross-sectional shape of the blade 3 shown in FIG. 1 is used as a base and a genetic algorithm is applied thereto, but it is also possible to use a different shape as a base and a genetic algorithm therefrom. Also, while this embodiment shows an example in which a genetic algorithm is used, the present invention is not limited to this, and any other method, such as machine learning or reinforcement learning, may be used. [Explanation of symbols]

[0059] 1 vertical axis windmill 2 vertical rotation axis 3 Blade (Basic Blade) 3A, 3B blades 4 support arms 30A leading edge 30Aa Upper end (one end) 30Ab lower end (other end) 31A Trailing edge 31Aa Upper end (one end) 31Ab Lower end (other end) 32A First Side 32Aa1 Concave step 33A Second side 33Aa1 concave step 30B leading edge 30Ba Upper end (one end) 30Bb Lower end (other end) 31B Trailing edge 31Ba Upper end (one end) 31Bb Lower end (other end) 32B First side 33B Second side 33Ba1 concave step 33Ba2 Convex step F aerodynamic force F θ Circumferential component Ψ Azimuth angle

Claims

1. A method for manufacturing a blade attached to a support arm attached to a vertical rotation shaft so as to rotate on a circumference centered on the vertical rotation shaft, the method comprising: a magatama-shaped blade is used as a basic blade, and an angle between an angle of a lift type arrangement and an angle of a drag type arrangement of the basic blade relative to the support arm is set as an attachment angle for attaching the basic blade to the support arm; Calculating an azimuth angle at which a circumferential component of an aerodynamic force generated on the basic blade has a maximum value among azimuth angles of 0° to 360° of the basic blade at the mounting angle; Furthermore, a blade manufacturing method is provided in which the blade is manufactured by searching for a cross-sectional shape that increases the circumferential component of the aerodynamic force at the azimuth angle where the circumferential component of the aerodynamic force is at its maximum value, based on the cross-sectional shape of the basic blade.

2. 2. The method of claim 1, wherein the angle of the lift type arrangement relative to the support arm is 0 degrees and the angle of the drag type arrangement relative to the support arm is 90 degrees.

3. The mounting angle of the basic blade when mounted on the support arm is set to 50° to 70° with respect to the support arm, The maximum value of the circumferential component of the aerodynamic force generated on the basic blade is at an azimuth angle between 0° and 70° of the basic blade at the setting angle, or at an azimuth angle between 180° and 270° of the basic blade at the setting angle, 3. A method for manufacturing a blade according to claim 1, wherein the blade is manufactured by searching for a cross-sectional shape of the blade in which the circumferential component increases from the basic blade based on the azimuth angle at the maximum value.

4. A blade is attached at a set angle to a support arm attached to a vertical rotation shaft so as to rotate on a circumference centered on the vertical rotation shaft, the mounting angle is set to an angle between an angle for a lift type arrangement and an angle for a drag type arrangement when a magatama-shaped blade is used as a basic blade and the basic blade is mounted on the support arm; the azimuth angle is an angle at which the circumferential component of the aerodynamic force generated on the basic blade reaches a maximum value in an azimuth angle of 0° to 360° of the basic blade at the set mounting angle, Furthermore, the blade has a cross-sectional shape obtained by searching for an increase in the circumferential component of the aerodynamic force at the azimuth angle where the circumferential component of the aerodynamic force is at its maximum value, based on the cross-sectional shape of the basic blade.

5. The cross-sectional shape of the blade is a front edge portion formed in an arc shape protruding in a first outward direction; a trailing edge portion formed in an arc shape protruding toward a second outward direction opposite to the first outward direction; a first side portion connecting one end of the leading edge portion and one end of the trailing edge portion; a second side portion connecting the other end of the leading edge portion and the other end of the trailing edge portion, The arc of the leading edge portion is formed to have a larger diameter than the arc of the trailing edge portion, The arc of the trailing edge is formed in a hook shape, the first side portion is connected to one end of the leading edge portion and one end of the trailing edge portion so as to form an arc shape when connecting the first side portion and the one end of the leading edge portion, and further is connected to the one end of the leading edge portion so as to form a recessed step portion, 5. The blade according to claim 4, wherein the second side portion is connected to the other end of the leading edge portion so as to form an arc when the other end of the leading edge portion is connected to the other end of the trailing edge portion, and further, the second side portion is connected to the other end of the leading edge portion so as to form a recessed step portion.

6. The cross-sectional shape of the blade is a front edge portion formed in an arc shape protruding in a first outward direction; a trailing edge portion formed in an arc shape protruding toward a second outward direction opposite to the first outward direction; a first side portion connecting one end of the leading edge portion and one end of the trailing edge portion; a second side portion connecting the other end of the leading edge portion and the other end of the trailing edge portion, The arc of the leading edge portion is formed to have a larger diameter than the arc of the trailing edge portion, The first side portion is connected to one end of the leading edge portion and one end of the trailing edge portion so as to form an arc shape, 5. The blade according to claim 4, wherein the second side portion is connected to the other end of the leading edge portion so as to form an arc when the other end of the leading edge portion is connected to the other end of the trailing edge portion, and further, the second side portion is connected to the other end of the leading edge portion so as to form a continuous concave step portion and a convex step portion.

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