Wind turbines and wind power generation equipment

Abstract

To provide a windmill which can improve the conversion efficiency of rotational energy.SOLUTION: A windmill comprises a shaft, a blade and a support material. The windmill is rotatable around a center axis of the shaft. The blade has a blade main body part extending along an axial direction being a direction of the center axis. The blade main body part includes a front edge being an end of a front side in a rotation direction of the windmill, and a rear edge being an end of a rear side in the rotation direction in a cross-sectional view perpendicular to the axial direction. The support material connects the shaft and the blade main body part. The support material has a front end being an end of a front side in the rotation direction, and a rear end being an end of a rear side in the rotation direction. A linear line passing an intermediate point between the front end and the rear end, and parallel with an extension direction of the support material intersects with a blade chord line at the rear edge side rather than a center point of the blade chord line which connects the front edge and the rear edge.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wind turbine and a wind power generating device. [Background technology]

[0002] Japanese Patent Application Laid-Open Publication No. 2011-169292 (Patent Document 1) describes a vertical wind turbine for wind power generation. The vertical wind turbine described in Patent Document 1 has a rotor, blades (wings), and horizontal support arms (support members). The rotor is rotatable around a central axis. The wings have main parts extending along the direction of the rotor's central axis (axial direction). The support members connect the main parts of the blades to the rotor by extending along a direction perpendicular to the axial direction and passing through the rotor's central axis (radial direction). The support members are approximately fish-shaped in a cross section perpendicular to the radial direction.

[0003] Japanese Patent No. 5527783 (Patent Document 2) describes a rotor for wind power generation. The rotor described in Patent Document 1 has a rotating shaft, blades (wings), and a support base (support material). The rotating shaft is rotatable around a central axis. The wings extend along the direction of the central axis of the rotating shaft (axial direction). The support material connects the blades to the rotating shaft by extending along a direction (radial direction) that is perpendicular to the axial direction and passes through the central axis of the rotating shaft. The support material is streamlined in a cross section perpendicular to the radial direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-169292 [Patent Document 2] Patent No. 5527783 Summary of the Invention [Problem to be solved by the invention]

[0005] In the wind turbine described in Patent Document 1 and the rotor described in Patent Document 2, the cross-sectional shape of the support material perpendicular to the radial direction is generally fish-shaped or streamlined, thereby reducing the air resistance of the support material itself and improving rotational energy conversion efficiency. However, the wind turbine described in Patent Document 1 and the rotor described in Patent Document 2 do not focus on airflow turbulence at the connection between the support material and the blades. Therefore, the wind turbine described in Patent Document 1 and the rotor described in Patent Document 2 leave room for improvement in rotational energy conversion efficiency.

[0006] The present invention has been made in view of the above-mentioned problems of the prior art, and more specifically, to provide a wind turbine and a wind power generation device that can improve the efficiency of rotational energy conversion. [Means for solving the problem]

[0007] The wind turbine of the present invention comprises a shaft, a blade, and a support member. The wind turbine is rotatable around the central axis of the shaft. The blade has a blade main body extending along the axial direction, which is the direction of the central axis. In a cross-sectional view perpendicular to the axial direction, the blade main body includes a leading edge, which is the end on the forward side in the direction of rotation of the wind turbine, and a trailing edge, which is the end on the rear side in the direction of rotation. The support member connects the shaft and the blade main body. The support member has a leading end, which is the end on the forward side in the direction of rotation, and a trailing end, which is the end on the rear side in the direction of rotation. A line passing through the midpoint between the leading end and the trailing end and parallel to the extension direction of the support member intersects with the chord line, connecting the leading edge and the trailing edge, closer to the trailing edge than the midpoint of the chord line. The support member has a first portion, which is the end on the blade main body side, and a second portion extending from the first portion toward the central axis. The leading end of the first portion is located closer to the trailing edge than a position, in the direction of the chord line, that is two-thirds of the length of the chord line. The boundary between the first and second portions is located inside a circle that is centered on the central axis and passes through the front end that is connected to the wing main body portion.

[0008] In the above wind turbine, the boundary between the first portion and the second portion may be perpendicular to a line that passes through an intermediate position between the front end and the rear end and is parallel to the extension direction of the support material.

[0009] A wind turbine generator according to the present invention includes the above-described wind turbine and a generator that generates electricity by rotation of the wind turbine about its central axis. [Effects of the Invention]

[0010] According to the wind turbine and wind power generation device of the present invention, the efficiency of rotational energy conversion can be improved. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a front view of a wind turbine generator 100. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] 3 is a schematic diagram showing the relationship between the azimuth angle of the blade main body 12a and the wind direction. FIG. [Figure 4] 10 is a schematic graph showing the relationship between the rotation time of the wind turbine 10 and the rotational torque applied to the wind turbine 10 when the wind turbine 10 has two blades 12. [Figure 5] FIG. 2 is a cross-sectional view of the wind turbine generator 200. [Figure 6] 1 is a graph showing the relationship between the tip speed ratio in the wind power generation plant 100 and the output increase rate of the wind turbine 10. DETAILED DESCRIPTION OF THE INVENTION

[0012] The details of an embodiment of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are given the same reference numerals, and redundant explanations will not be repeated. The wind turbine generator according to the embodiment is referred to as a wind turbine generator 100.

[0013] (Configuration of wind turbine generator 100) The configuration of the wind turbine generator 100 will be described below.

[0014] Fig. 1 is a front view of a wind turbine generator 100. As shown in Fig. 1, the wind turbine generator 100 has a wind turbine 10 and a generator 20. The generator 20 generates electricity when the wind turbine 10 rotates around a central axis A, which will be described later. The wind turbine generator 100 is installed at a high place by being attached to a support pole (not shown).

[0015] The wind turbine 10 is a vertical axis wind turbine (upright wind turbine). The wind turbine 10 has a shaft 11, blades 12, and a support member 13. The central axis of the shaft 11 is referred to as the central axis A. The direction of the central axis A is referred to as the axial direction. The direction perpendicular to the axial direction and passing through the central axis A is referred to as the radial direction. The wind turbine 10 is rotatable around the central axis A. In the example shown in FIG. 1, the wind turbine 10 has two blades 12 arranged symmetrically with respect to the central axis A. However, the number of blades 12 is not limited to this.

[0016] The shaft 11 extends in the axial direction. The shaft 11 is rotatable around a central axis A. In the example shown in FIG. 1, the wing 12 has a wing main body 12a, a wing tip inclined portion 12b, and a wing tip inclined portion 12c. However, the shape of the end of the wing 12 is not limited to the wing tip inclined portion 12b and the wing tip inclined portion 12c, and may be other shapes. The wing main body 12a extends along the axial direction. FIG. 2 is a cross-sectional view taken along II-II in FIG. 1. As shown in FIG. 2, the wing main body 12a is, for example, a lift-type wing when viewed in a cross section perpendicular to the axial direction.

[0017] In a cross-sectional view perpendicular to the axial direction, the blade main body 12a has a leading edge 12aa and a trailing edge 12ab. The leading edge 12aa is the end of the blade main body 12a that is on the forward side in the direction of rotation of the wind turbine 10 (indicated by the arrow in FIG. 2). The trailing edge 12ab is the end of the blade main body 12a that is on the rear side in the direction of rotation of the wind turbine 10. An imaginary line connecting the leading edge 12aa and the trailing edge 12ab is defined as a chord line 12ac. The direction of the chord line 12ac is defined as the chord direction.

[0018] A point on the chord line 12ac that is midway between the leading edge 12aa and the trailing edge 12ab is defined as the midway position MP. The distance in the chord direction between the midway position MP and the leading edge 12aa is equal to the distance in the chord direction between the midway position MP and the trailing edge 12ab. A position where the distance from the trailing edge 12ab in the chord direction is 2 / 3 of the chord length (the length of the chord line 12ac) is defined as position P1. Position P1 is located closer to the leading edge 12aa than the midway position MP in the chord direction.

[0019] The blade main body 12a has an inner surface 12ad and an outer surface 12ae. The inner surface 12ad is the surface of the blade main body 12a that faces the central axis A (radially inward). The outer surface 12ae is the surface of the blade main body 12a that faces the opposite side from the central axis A (radially outward). From another perspective, the outer surface 12ae is the surface opposite the inner surface 12ad in the radial direction.

[0020] In the example of Figure 1, the blade tip inclined portion 12b is connected to one axial end (upper end) of the blade main body 12a. The blade tip inclined portion 12b extends upward from the upper end of the blade main body 12a, sloping radially inward. The blade tip inclined portion 12c is connected to the other axial end (lower end) of the blade main body 12a. The blade tip inclined portion 12c extends downward from the lower end of the blade main body 12a, sloping radially inward.

[0021] The support member 13 extends in the radial direction. The support member 13 only needs to extend in the radial direction when viewed in a direction parallel to the axial direction, and may be inclined with respect to a plane perpendicular to the axial direction. The support member 13 connects the shaft 11 and the blade 12 (blade main body portion 12a). The support member 13 is connected to the inner surface 12ad of the blade main body portion 12a. As shown in FIG. 2 , the support member 13 has a front end 13a and a rear end 13b in a plan view (when viewed in the axial direction). The front end 13a is the end of the support member 13 that is on the front side in the rotation direction of the wind turbine 10. The rear end 13b is the end of the support member 13 that is on the rear side in the rotation direction of the wind turbine 10.

[0022] A virtual line 13c passes through the midpoint between the leading end 13a and the trailing end 13b and is parallel to the extension direction of the support member 13. The line 13c and the chord line 12ac intersect at an intersection point CP. The intersection point CP is located closer to the trailing edge 12ab than the midpoint MP in the chord direction. The line 13c forms an angle θ with the chord line 12ac. The angle θ is, for example, less than 90°.

[0023] The support material 13 has a first portion 13d and a second portion 13e. The first portion 13d is the end of the support material 13 connected to the wing main body portion 12a. The second portion 13e extends from the first portion 13d toward the central axis A. The width of the second portion 13e in a direction perpendicular to the extension direction of the support material 13 is greater than the width of the first portion 13d in a direction perpendicular to the extension direction of the support material 13. The boundary between the first portion 13d and the second portion 13e is referred to as boundary 13f. It is preferable that boundary 13f is perpendicular to the straight line 13c.

[0024] The leading end 13a of the first portion 13d is closer to the trailing edge 12ab than position P1 in the blade chord direction. The position of the leading end 13a connected to the blade main body 12a is defined as position P2. The trajectory of position P2 as the wind turbine 10 rotates, i.e., the circle that passes through position P2 and has its center at the central axis A, is defined as circle C. The boundary 13f is located inside circle C. It is preferable that boundary 13f is perpendicular to the straight line 13c.

[0025] Although not shown, in a cross section perpendicular to the extending direction of the support material 13, the support material 13 preferably has a smooth shape, such as a streamlined shape or an elliptical shape.

[0026] Figure 3 is a schematic diagram showing the relationship between the azimuth angle of the blade main body 12a and the wind direction. The azimuth angle of the blade main body 12a is 0° when the wind direction is rotated 90° from the direction from the trailing edge 12ab to the leading edge 12aa. In the example of Figure 3, the azimuth angle of the blade main body 12a increases as the wind turbine 10 rotates counterclockwise, and when the wind turbine 10 makes one rotation, the azimuth angle of the blade main body 12a returns to 0°.

[0027] Fig. 4 is a schematic graph showing the relationship between the rotation time of the wind turbine 10 and the rotational torque applied to the wind turbine 10 when the wind turbine 10 has two blades 12. As shown in Fig. 4, the rotational torque applied to the wind turbine 10 is maximum when the azimuth angle of the blade main body 12a is close to 0°.

[0028] (Effects of the wind power generation device 100) The effects of the wind turbine generator 100 will be described below in comparison with a wind turbine generator according to a comparative example. The wind turbine generator according to the comparative example is referred to as a wind turbine generator 200.

[0029] Fig. 5 is a cross-sectional view of wind turbine generator 200. Fig. 5 shows a cross-section of wind turbine generator 200 at a position corresponding to II-II in Fig. 1. As shown in Fig. 5, in wind turbine generator 200, boundary 13f is outside circle C. Except for this point, the configuration of wind turbine generator 200 is the same as the configuration of wind turbine generator 100.

[0030] The rotational force of the wind turbine 10 is mainly generated by negative pressure generated around the inner surface 12ad near the leading edge 12aa (hereinafter referred to as the "negative pressure generating region"). When the connection between the support material 13 and the blade main body 12a is located close to the negative pressure generating region, airflow turbulence is likely to occur at the connection between the support material 13 and the blade main body 12a. This airflow turbulence interferes with the airflow flowing through the negative pressure generating region, causing the airflow flowing through the negative pressure generating region to separate from the inner surface 12ad, reducing the rotational force of the wind turbine 10.

[0031] In wind turbine generators 100 and 200, intersection CP of straight line 13c and chord line 12ac is closer to trailing edge 12ab than midpoint MP. Also, in wind turbine generators 100 and 200, leading end 13a in first portion 13d is closer to trailing edge 12ab than position P1 in the chord direction. Therefore, in wind turbine generators 100 and 200, the connection between support member 13 and blade main body 12a can be separated from the negative pressure generating region, and airflow turbulence generated at the connection between support member 13 and blade main body 12a is less likely to interfere with the negative pressure generating region.

[0032] However, in the wind turbine generator 200, the boundary 13f is located outside the circle C, so airflow separation is likely to occur at the boundary 13f. On the other hand, in the wind turbine generator 100, the boundary 13f is located inside the circle C, so airflow separation is suppressed by the negative pressure gradient (the airflow separation position is shifted toward the trailing edge 12ab compared to the wind turbine generator 200), making it even less likely that airflow turbulence will interfere with the negative pressure generating region. Therefore, the wind turbine generator 100 can improve the rotational energy conversion efficiency compared to the wind turbine generator 200. If the boundary 13f is perpendicular to the line 13c, the wind turbine 10 can be manufactured more easily. More specifically, in this case, it becomes possible to easily manage the angle of the blade 12 relative to the support member 13, improve the assembly of the wind turbine generator 10, and improve the weldability of the support member 13 to the blade 12.

[0033] (Example) FIG. 6 is a graph showing the relationship between the tip speed ratio of the wind turbine 10 in the wind power generation device 100 and the output increase rate of the wind turbine 10. The horizontal axis in FIG. 6 represents the tip speed of the wind turbine 10, and the vertical axis in FIG. 6 represents the output increase rate of the wind turbine 10 in the wind power generation device 100. The tip speed ratio of the wind turbine 10 is calculated by multiplying the angular velocity of the wind turbine 10 by ω (unit: s -1 ), the radius of the wind turbine 10 is R (unit: m), and the wind speed is V (unit: m), then ω×R / V. If the rotation speed of the wind turbine 10 is n (unit: rps), then the tip speed ratio of the wind turbine 10 is 2π×R×n / V.

[0034] The output increase rate of wind turbine 10 in wind turbine generator 100 is the difference between the output of wind turbine 10 in wind turbine generator 100 and the output of wind turbine 10 in wind turbine generator 200 divided by the output of wind turbine 10 in wind turbine generator 200 and multiplied by 100.

[0035] As shown in Fig. 6, the output of the wind turbine 10 in the wind turbine generator 100 was greater than the output of the wind turbine 10 in the wind turbine generator 200 at all tip speed ratios. This experimentally demonstrated that the wind turbine generator 100 can improve the rotational energy conversion efficiency.

[0036] Although the embodiments of the present invention have been described above, the above-described embodiments can be modified in various ways. Furthermore, the scope of the present invention is not limited to the above-described embodiments. The scope of the present invention is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. [Industrial Applicability]

[0037] The above-described embodiment is particularly advantageously applied to a vertical axis wind turbine and a wind power generation system having a vertical axis wind turbine. [Explanation of symbols]

[0038] 100 wind power generation device, 10 wind turbine, 11 shaft, 12 blade, 12a blade body, 12aa leading edge, 12ab trailing edge, 12ad inner surface, 12ae outer surface, 12b, 12c blade tip slope, 13 support, 13a leading end, 13b trailing end, 13c straight line, 13d first part, 13e second part, 13f boundary, 20 generator, 200 wind power generation device, A central axis, C circle, CP intersection, MP intermediate position, P1, P2 positions.

Claims

1. A windmill, a shaft, a wing, and a support; The wind turbine is rotatable around a central axis of the shaft, The blade has a blade main body portion extending along an axial direction that is the direction of the central axis, the blade main body includes, in a cross-sectional view perpendicular to the axial direction, a leading edge that is an end on a front side in a rotation direction of the wind turbine and a trailing edge that is an end on a rear side in the rotation direction, the support member connects the shaft and the wing main body portion, the support member has a front end that is an end on a front side in the rotation direction and a rear end that is an end on a rear side in the rotation direction, a straight line passing through an intermediate position between the leading end and the trailing end and parallel to an extending direction of the support member intersects with the chord line connecting the leading edge and the trailing edge closer to the trailing edge than a midpoint of the chord line, the support member has a first portion which is an end portion on the blade main body side, and a second portion which extends from the first portion toward the central axis side, the leading end of the first portion is located closer to the trailing edge than a position that is two-thirds of the length of the chord line from the trailing edge in the direction of the chord line, a boundary between the first portion and the second portion is located inside a circle that is centered on the central axis and passes through the front end connected to the blade main body portion.

2. The wind turbine of claim 1 , wherein the boundary is perpendicular to the straight line.

3. The wind turbine according to claim 1 or claim 2; a generator that generates electricity by rotation of the wind turbine about the central axis.

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