JP7089848B2 - Vertical axis wind turbine and wind power generator - Google Patents

Description

The present invention relates to a vertical axis wind turbine having a vertical spindle, and a wind power generator including the vertical axis wind turbine.

Wind turbines used for wind power generation equipment are roughly classified into horizontal shaft type and vertical shaft type. The vertical axis type is often used for relatively small wind turbines because it can obtain rotational force regardless of the wind direction and does not require control of the wind direction. It is known that the amount of power generation of a vertical axis type wind turbine depends on the shape of the blade, and the development of a blade capable of efficient power generation is underway. One of them is a wing provided with a winglet at the tip of the wing (for example, Patent Documents 1 to 4). A winglet is a wing tip plate that is tilted so that the tip side is closer to the vertical main axis. By providing a winglet, the generation of vortices at the wing tip is suppressed. This makes it possible to improve the rotational energy conversion efficiency of converting the energy received from the wind into rotational energy, and to reduce the noise caused by the wind noise.

Japanese Unexamined Patent Publication No. 2004-204801 Japanese Unexamined Patent Publication No. 2004-293409 Japanese Unexamined Patent Publication No. 2011-169267 Japanese Unexamined Patent Publication No. 2016-20204

The effect of the above-mentioned winglet is known empirically, but how is the shape of the entire wing related to the shape of the winglet, and what shape of the winglet should be used to obtain the optimum effect? There are some things that have not been fully researched yet. For example, the relationship between the ratio of the length of the winglet to the total length of the wing and the rotational energy conversion efficiency has not been clarified. Therefore, the vertical axis wind turbine equipped with the conventional winglet does not have sufficient rotational energy conversion efficiency.

An object of the present invention is to provide a vertical axis wind turbine in which the ratio of the length of the winglet to the total length of the blade is optimized so that the rotational energy conversion efficiency is good.
Another object of the present invention is to provide a wind power generation device having good power generation efficiency.

The vertical axis wind turbine of the present invention has a rotatably provided vertical spindle, a support provided on the vertical spindle, and the axis of the vertical spindle connected to the vertical spindle via the support and receiving wind. Equipped with wings that rotate around,
The wing has a main wing portion extending parallel to the vertical main axis and a winglet extending diagonally from both ends of the main wing portion toward the vertical main axis, and the wing crosses the main wing portion and the winglet. As for the surface shape, the outer or inner surface in the radial direction is gradually outer in the radial direction from the front and rear ends in the rotation traveling direction of the wing so that the thickness in the radial direction becomes the thickest at the portion near the front end in the rotation traveling direction of the wing. The winglet has a shape that bulges inward, and the winglet has a shape in which the amount of bulge on the outer surface in the radial direction gradually decreases toward the tip side, and the winglet has a shape in which the rotation of the wing progresses toward the tip side. It has a shape that narrows the width in the direction.
It is characterized in that the ratio of the length of the winglet in the axial direction to the half length of the entire blade in the axial direction is in the range of 10% to 20%.

The ratio of the axial length of each winglet to half the axial length of the entire wing is more preferably in the range of 16% to 18%.

The winglet is a part intended to suppress the wing tip vortex, but the ratio of the total length of the wing to the length of the winglet affects the rotational energy conversion efficiency of converting wind energy into the rotational energy of the wing.

A fluid analysis of the relationship between the total length of the wing and the length of the winglet and the rotational energy conversion efficiency revealed that the ratio of the length of the winglet to half the length of the entire wing in the axial direction was 17 It was found that the rotational efficiency was the highest at around%, and that the rotational energy conversion efficiency decreased regardless of whether it was larger or smaller than this. Further, it was found that a certain high rotational efficiency was maintained when the ratio was in the range of 10% to 20%. From this, it can be said that the ratio of the length of the winglet to the total length of the wing is preferably in the range of 10% to 20 °, and more preferably in the range of 16% to 18 °.

In the present invention, the bending angle of the winglet with respect to the main wing portion is preferably in the range of 20 ° to 55 °.
When the bending angle of the winglet is within the above range, the above-mentioned action / effect often appears.

The wind power generator of the present invention includes the vertical axis wind turbine and a generator that generates electricity by the rotation of the vertical spindle of the vertical axis wind turbine.
As described above, the vertical axis wind turbine used in this wind power generation device has good rotational energy conversion efficiency. Therefore, this wind power generation device has good power generation efficiency.

The vertical axis wind turbine of the present invention has a rotatably provided vertical spindle, a support provided on the vertical spindle, and the axis of the vertical spindle connected to the vertical spindle via the support and receiving wind. The wing comprises a wing that rotates around, the wing having a wing portion extending parallel to the vertical spindle and a winglet extending diagonally from both ends of the wing portion toward the vertical spindle. The cross-sectional shape of the wing over the portion and the winglet has the radial outer or inner surface in the direction of rotation of the wing so that the thickness in the radial direction is the thickest at the portion near the front end in the direction of rotation of the wing. The winglet has a shape that gradually bulges outward or inward in the radial direction from both front and rear ends, and the winglet has a shape in which the amount of bulge on the outer surface in the radial direction gradually decreases toward the tip side, and the winglet has a tip. The width of the wing in the rotational traveling direction becomes narrower toward the side, and the ratio of the length of the winglet in the axial direction to half the length of the entire wing in the axial direction is 10. Since it is in the range of% to 20%, the rotational energy conversion efficiency is good.

Since the vertical axis wind turbine of the present invention includes the vertical axis wind turbine and a generator that generates electricity by the rotation of the vertical spindle of the vertical axis wind turbine, the power generation efficiency is high.

It is a front view of the wind power generation apparatus provided with the vertical axis wind turbine which concerns on one Embodiment of this invention. It is a plan view of the wind power generation device. (A) is a front view of the blade of the vertical axis wind turbine, and (B) is a side view thereof. (A) is a partially enlarged view of FIG. 3 (A), and (B) is a partially enlarged view of FIG. 3 (B). (A) is a VA-VA cross-sectional view of FIG. 4 (B), (B) is a VB-VB cross-sectional view of FIG. 4 (B), and a VC-VC cross-sectional view. (A) to (E) are front views showing a part of the wing used for the analysis of the bending angle of the winglet, respectively. It is a graph which shows the relationship between the bending angle of a winglet, and the rotational moment which acts on a vertical spindle when a wing is rotated by the wind. It is a graph which shows the relationship between the bending angle of a winglet, and the rotational moment which acts on a vertical spindle at the time of idling of a wing. It is a graph which shows the relationship between the bending angle of a winglet and noise. (A) to (E) are diagrams showing the maximum sound generation location at the wing tip and the magnitude of the sound. (A) to (C) are front views of the wing used for the analysis of the length of the winglet with respect to the total length of the wing, respectively. It is a graph which shows the relationship between the length of a winglet with respect to the total length of a wing, and the rotational moment which acts on a wing when a vertical axis wind turbine is rotated by the wind. (A) to (D) are plan views showing a part of the wing used for the analysis of the apex position of the winglet in cross section. It is a graph which shows the relationship between the apex position of a winglet and noise. (A) to (D) are diagrams showing the maximum sound generation location at the wing tip and the magnitude of the sound. It is a graph which shows the relationship between the apex position of a winglet and the rotational moment which acts on a wing at the time of idling of a vertical axis wind turbine.

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a front view of a wind power generator provided with a vertical axis wind turbine according to an embodiment of the present invention, and FIG. 2 is a plan view thereof. A steel tower 2 is constructed on a foundation 1 built on the ground, and a wind power generation device 3 is installed on the steel tower 2. The wind power generation device 3 includes a vertical axis wind turbine 4, a generator 6 that generates electricity by rotation of the vertical spindle 5 of the vertical axis wind turbine 4, and other devices for power distribution, control, and the like. The vertical spindle 5 is a shaft extending in the vertical direction, is rotatably supported by bearings, and its lower portion is connected to the generator 6. The vertical spindle 5, the generator 6, and other equipment are covered by a cover 7.

In the vertical axis wind turbine 4, a plurality of blades 9 are attached to the vertical main shaft 5 via a support 8. In the example of the figure, the number of blades 9 is two, and each blade 9 is provided at a position different in phase by 180 ° with respect to the vertical main axis 5. The number of wings 9 may be 3 or more. The support 8 has one horizontal arm 8a horizontally fixed to the upper end of the vertical spindle 5, and diagonally upward and diagonally downward from the vicinity of the center of the horizontal arm 8a toward the left and right sides of the figure, respectively. It consists of a total of four slanted arms 8b that extend. The left wing 9 is connected to the tip of the two diagonal arms 8b on the left end and the left side of the horizontal arm 8a, and the right wing 9 is connected to the tip of the two diagonal arms 8b on the right end and the right side of the horizontal arm 8a. There is. When the vertical axis wind turbine 4 receives wind, it rotates around the axis O of the vertical spindle 5 in the direction of the arrow in FIG.

3 (A) and 3 (B) are a front view and a side view of the wing 9. The wing 9 has a main wing portion 10 extending parallel to the vertical main shaft 5 (see FIG. 1), that is, extending in the vertical direction, and upper and lower winglets extending diagonally from both upper and lower ends of the main wing portion 10 toward the vertical main shaft 5, respectively. It consists of 11. The winglets 11 may extend linearly or curvedly. When it is curved, the curve may be arcuate or a combination of a plurality of arcs having different curvatures. The upper and lower winglets 11 are formed in the same shape that is line-symmetrical with respect to the center line CL of the intermediate portion in the longitudinal direction of the main wing portion 10.

In the following description, the axial direction of the vertical spindle 5 is referred to as the "vertical direction". Further, the outer diameter side in the radial direction is defined as "outside" and the inner diameter side is defined as "inside" about the axis O of the vertical spindle 5. Further, the side on which the blade 9 advances when the vertical axis wind turbine 4 rotates in the direction of the arrow in FIG. 2 is referred to as the "front side", and the opposite side thereof is referred to as the "rear side". The direction of rotation of the blade 9 is determined by the cross-sectional shape of the blade 9, which will be described later.

As shown in FIG. 3A, the cross-sectional shape and the cross-sectional dimension of the main wing portion 10 are constant over the entire upper and lower sides, and the winglet 11 becomes thinner toward the tip side. However, the thickness of both the main wing portion 10 and the winglet 11 differs depending on the position in the rotation traveling direction, as will be described later. The thickness of the winglet 11 described above is about the thickness of the maximum thickness portion in the rotation traveling direction.

In FIG. 3B, the positions of the maximum thickness portions of the main wing portion 10 and the winglet 11 are shown by lines A1 and A2. The line A1 indicating the maximum thickness portion of the main wing portion 10 is a straight line. The line A2 indicating the maximum thickness portion of the winglet 11 changes depending on the apex position P, which is the most advanced position in the vertical direction of the winglet 11. The vertex position P is located on the line A2. As in the example shown in FIG. 3B, when the apex position P is located on the extension line of the line A1 indicating the maximum thickness portion of the main wing portion 10, the line A2 indicating the maximum thickness portion of the winglet 11 is a straight line. When the apex position P deviates from the extension line of the line A1 indicating the maximum thickness portion of the main wing portion 10, the line A2 indicating the maximum thickness portion of the winglet 11 is relative to the line A1 indicating the maximum thickness portion of the main wing portion 10. It becomes a curved line. In this case, the line A2 may be a curved line or a straight line, but in either case, it is desirable that the tip of the line A1 and the base end of the line A2 are smoothly connected to each other.

As shown in FIG. 4 (B), which is a partially enlarged view of FIG. 3 (B), the front and rear edges 13F and 13R of the main wing portion 10 are formed in a straight line, and the width B1 in the rotation traveling direction is constant. The front and rear edges 14F and 14R of the winglet 11 are formed by curves that are smoothly connected to the front and rear edges 13F and 13R of the main wing portion 10, respectively, and the width in the rotation traveling direction is continuously and gradually narrowed toward the tip side. It has become. The front and rear edges 14F and 14R of the winglet 11 are smoothly connected to each other, and the connected portion is the apex position P. The curves forming the front and rear edges 14F and 14R of the winglet 11 consist of, for example, an arc and an elliptical arc. The curve forming the edges 14F and 14R may be a single curve or a combination of a plurality of curves. Further, the front and rear edges 14F and 14R may be configured by combining a straight line and a curved line.

As shown in FIG. 4 (A), which is a partially enlarged view of FIG. 3 (A), the winglet 11 includes a bent portion 11a that continues to the upper and lower ends of the main wing portion 10 and an inclined portion 11b that extends diagonally from the bent portion 11a. Consists of. The front edge 13F of the main wing portion 10 is linear when viewed from the front. In this example, the front edge 14F of the winglet 11 has an arc shape that smoothly connects to the edge 14F of the main wing portion 10 at the bent portion 11a, and is linear at the inclined portion 11b. The rear edges 13R and 14R of the main wing portion 10 and the winglets 11 overlap with the front edges 13F and 14F in front view.

The outer surface 15 of the main wing portion 10 and the outer surface 16a of the bent portion 11a of the winglet 11 are smoothly connected, and the outer surface 16a of the bent portion 11a of the winglet 11 and the outer surface 17 of the inclined portion 11b are smoothly connected. The outer surface 16a of the bent portion 11a and the outer surface 16b of the inclined portion 11b form the outer surface 16 of the winglet 11. The outer outlines of the main wing portion 10 and the winglet 11 in FIGS. 3 (A) and 4 (A) correspond to the lines A1 and A2 in FIGS. 3 (B) and 4 (B), and the main wing portion 10 and the winglet 11 correspond to the lines A1 and A2. The maximum thickness portion of 11 is shown. In the front view shown in FIG. 4A, the outer outline of the main wing portion 10 is a straight line, and the outer outline of the winglet 11 is an arc shape at the bent portion 11a and a smooth arc at the inclined portion 11b. It is a connecting curve or straight line.

Further, the inner side surface 17 of the main wing portion 10 and the inner side surface 18a of the bent portion 11a of the winglet 11 are smoothly connected, and the inner side surface 18a of the bent portion 11a of the winglet 11 and the inner side surface 18b of the inclined portion 11b are smoothly connected. There is. In this example, the inner side surface 18b of the inclined portion 11b of the winglet 11 is planar except for the tip portion, and the tip portion is curved. The inner side surface 18a of the bent portion 11a and the inner side surface 18b of the inclined portion 11b form the inner side surface 18 of the winglet 11.

5 (A), (B), and (C) are a VA-VA sectional view, a VB-VB sectional view, and a VC-VC sectional view of FIG. 4 (B). In each of these cross-sectional views, the wing portion 10 and the winglets 11 are shown solid, but in reality they are made of various materials for weight reduction. For example, it is formed in a hollow shape with a fiber reinforced resin or the like, or is formed with a lightweight material such as a foam or aluminum.

As shown in FIGS. 5A, 5B, and 5C, the outer surface 15 of the main wing portion 10 and the winglet 11 have the thickest radial thickness at a portion near the front end in the rotational traveling direction. The 16 (16a, 16b) and the inner side surfaces 17, 18 (18a, 18b) have a shape that gradually bulges outward and inward in the radial direction from both front and rear ends with respect to the chord length 19. The chord length 19 refers to a straight line passing through the front end QF and the rear end QR of the blade 9. In other words, the outer surfaces 15 and 16 bulge outward with respect to the chord length 19, and the inner surfaces 17 and 18 bulge inward with respect to the chord length 19. Only one of the outer side surfaces 15, 16 and the inner side surfaces 17, 18 may be inflated with respect to the chord length 19.
In the case of the example of FIG. 5, the inner side surfaces 17, 18 (18a, 18b) of the main wing portion 10 and the winglet 11 have a curved shape that bulges inward near the front end, and becomes a straight line from the end to the rear end of the curved portion. However, the shape may be such that the entire shape bulges inward in the radial direction from the front end to the rear end due to a curved line, or the central portion in the radial direction may be recessed. The rotation locus C of the wing 9 is a locus through which the front end QF and the rear end QR of the wing 9 pass.

As shown in FIG. 5A, the outer surface 15 of the main wing portion 10 and the front end side of the inner side surface 17 are connected to each other by a smooth curved surface, and the front end QF of the main wing portion 10 is located on this curved surface. Further, the rear end sides of the outer surface 15 and the inner surface 17 intersect each other at an acute angle, and this intersection serves as the rear end QR of the main wing portion 10. Similarly, as shown in FIGS. 5 (B) and 5 (C), the front end sides of the outer surface 16 (16a, 16b) and the inner surface 18 (18a, 18b) of the winglet 11 are connected to each other by a smooth curved surface. The front end QF of the winglet 11 is located on this curved surface. Further, the rear end sides of the outer surface 16 and the inner surface 18 intersect with each other at an acute angle, and this intersection serves as the rear end QR of the winglet 11.

The cross-sectional shape of the tip of the main wing portion 10 and the cross-sectional shape of the base end of the winglet 11 are the same as each other. The cross-sectional shape of each part of the winglet 11 in the inclined direction may be a similar shape in which only the dimensions change depending on the position in the inclined direction, or may be a non-similar shape in which not only the dimensions but also the shape changes. In this embodiment, since the positions of the main wing portion 10 and the maximum thickness portion of the winglet 11 are at the same position in the rotation traveling direction, the cross-sectional shapes of the respective portions in the winglet 11 in the inclined direction are substantially similar to each other, but the main wing portion 10 When the position of the maximum thickness portion of the winglet 11 is deviated from the position of the maximum thickness portion of the winglet 11 in the rotation traveling direction, the cross-sectional shapes of the respective portions of the winglet 11 in the inclined direction are not similar to each other.

The action / effect of the vertical axis wind turbine 4 having this configuration, and a specific configuration will be described.
The outer surface 15, 16a, 16b or the inner side surface 17, 18a, 18b of the wing 9 is such that the cross-sectional shape of the wing 9 has the thickest radial thickness at a portion near the front end in the rotation traveling direction of the wing 9. It has a shape that gradually swells outward or inward in the radial direction from both front and rear ends in the direction of rotation. Therefore, when the blade 9 receives the wind, a lift is generated on the blade 9, and the lift causes the vertical axis wind turbine 4 to rotate around the axis O of the vertical main shaft 5 in the direction of the arrow in FIG.

When the winglets 11 are provided at both ends of the wing 9, the pressure difference between the inner side surfaces 17 and 18 and the outer surfaces 15 and 16 of the wing 9 becomes small, and the entrainment of airflow is suppressed, so that a vortex is generated near the wing tip. It is hard to generate and the generation of noise is suppressed.

By making the cross-sectional shape of the wing 9 the thickest in the radial direction near the front end in the rotation traveling direction, a strong lift is generated in front of the rotation traveling direction, and the front end of the wing 9 is on the rotation locus C. The wing 9 can rotate even when the pitch angle at which the QF and the rear end QR are arranged is 0 °. When the pitch angle becomes 0 °, the resistance during rotation, particularly the resistance during idling, becomes small, and the rotation of the vertical axis wind turbine 4 is difficult to stop.

Further, since the winglet 11 has a shape in which the width in the rotation traveling direction of the wing 9 becomes narrower toward the tip side, the air flow around the wing tip becomes smooth when the wing 9 is rotating and traveling, and noise is generated. Can be suppressed.

In the vertical axis wind turbine 4 of this embodiment, the detailed shape of the winglet 11 is defined as follows in order to further improve the rotational energy conversion efficiency, reduce the resistance at the time of idling, and suppress noise.

[Bending angle of winglet]
The bending angle θ (FIG. 3A) of the upper and lower winglets 11 with respect to the main wing portion 10 is in the range of 20 ° to 55 °, more preferably in the range of 40 ° to 50 °. Here, the bending angle θ is an angle formed by the radial center of the main wing portion 10 (center of the cross section) and the radial center of the winglet 11 (center of the cross section), and in this example, the main wing portion. The front and rear edges 13F and 13R of 10 and the front and rear edges 14F and 14R of the inclined portion 11b of the winglet 11 coincide with the angle formed by each other. The desired bending angle θ described above was obtained by the following fluid analysis.

The analysis was performed assuming the five wings shown in FIG. 6 as the specimen. The wing 9A shown in (A) is composed of only the main wing portion 10 and has no winglet. The bending angles θ of the winglets 11 of the wings 9B, 9C, 9D, and 9E shown in (B), (C), (D), and (E) are 0 °, 20 °, 45 °, and 60 °, respectively. The total length of the wing 9A and the total length of the wing 9B are the same. The wings 9B, 9C, 9D, and 9E have the same length of the main wing portion 10 and the same length of the winglets 11 of each other. The size of the wings 9B, 9C, 9D, 9E was set to a total length of about 2800 mm.

(1) Relationship between the bending angle of the winglet and the rotational energy conversion efficiency For each wing 9B, 9C, 9D, 9E having the winglet 11, the rotation acting on the vertical spindle 5 when the wing 9 is rotated by the wind blowing in a certain direction. The moment was calculated. The calculation is performed by changing the rotation speed of the blade 9 in four ways, and the analysis result of the rotation speed at which the most efficient result is obtained is shown in FIG. From this analysis result, the rotational energy conversion efficiency decreases as the bending angle θ increases as a whole, but the rotational energy conversion efficiency is kept high until the bending angle θ is around 50 °, and when it exceeds 50 °, the rotational energy conversion efficiency. It was found that the rate of decrease in energy was large.

(2) Relationship between the bending angle of the winglet and the resistance at the time of idling The wing 9 was rotated in a windless environment, and the rotational moment acting on the vertical spindle 5 at this time was calculated. From this, it can be seen that the resistance at the time of idling, that is, the difficulty in stopping the rotation of the wing 9 when the wind weakens. The rotation speed of the blade 9 is the most efficient rotation speed obtained by the analysis of the above-mentioned "relationship between the bending angle of the winglet and the rotation energy conversion efficiency". The analysis result is shown in FIG. From this analysis result, it was found that the resistance at idling is the smallest when the bending angle θ is around 20 °, and the resistance at idling is large regardless of whether the bending angle θ is larger or smaller than this. It was also found that when the bending angle θ is around 45 °, the rate of increase in resistance during idling becomes loose. For reference, the rotational moment was calculated for the wing 9A without winglets under the same conditions, but the wing 9A has extremely high resistance during idling compared to the wings 9B, 9C, 9D, 9E with winglets 11. I understand.

(3) Relationship between the bending angle of the winglet and noise The wing 9 was rotated in a windless environment, and the sound at the wing tip was calculated. The rotation speed of the blade 9 is the most efficient rotation speed obtained by the analysis of the above-mentioned "relationship between the bending angle of the winglet and the rotation energy conversion efficiency". The analysis result is shown in FIG. Further, for the wing 9A having no winglet and the wing 9B, 9C, 9D, 9E in which the bending angles θ of the winglet 11 are 0 °, 20 °, 45 °, and 60 °, respectively, the maximum sound generation points at the wing tip and their portions thereof. The magnitude of the sound is shown in FIG. From these analysis results, the noise gradually decreases from 0 ° to around 45 °, but the noise does not decrease when the bending angle θ exceeds 45 °, and the noise tends to increase when the bending angle θ exceeds a certain bending angle θ. It turned out that there was.

From the analysis results of (1) to (3), it is preferable that the bending angle θ is less than 55 ° for the rotational energy conversion efficiency, it is sufficient to have the winglet 11 for the resistance at the time of idling, and for the noise, it is sufficient. It can be said that it is preferable that the bending angle θ is 20 ° or more. Judging from these factors in a complex manner, the bending angle θ of the winglet 11 with respect to the main wing portion 10 is preferably in the range of 20 ° to 55 °, more preferably 40 ° to 50 °. By setting the bending angle θ of the winglet 11 in this way, the vertical axis wind turbine 4 that can satisfy all of the rotational energy conversion efficiency, the resistance at the time of idling, and the noise can be obtained.

[Winglet length for half the total length of the wing]
The ratio of the vertical length L2 (FIG. 3 (A)) of the winglet 11 to the length L1 (FIG. 3 (A)) which is half of the vertical total length of the entire wing 9 is in the range of 10% to 20 °. It is preferably in the range of 16% to 18 °. Here, the vertical length L2 of the winglet 11 refers to the vertical length from the base end of the bent portion 11a of the winglet 11 to the apex position P of the winglet 11. The above desirable percentages were obtained by the following fluid analysis.

The analysis was performed assuming the three wings shown in FIG. 11 as the specimen. The wing 9F shown in (A) has (L2 / L1) 11.4%, the wing 9G shown in (B) has (L2 / L1) 17.0%, and the wing 9H shown in (C) has. (L2 / L1) is 26.8%. The total lengths of the wings 9F, 9G, and 9H are the same (for example, L1 is about 1400 mm), and the bending angle θ of the winglet 11 is 45 °.

For each blade 9F, 9G, 9H, the rotational moment acting on the vertical spindle 5 when the blade 9 is rotated by the wind was calculated. The calculation is performed by changing the rotation speed of the blade 9 in four ways, and the analysis result of the rotation speed at which the most efficient result is obtained is shown in FIG. From this analysis result, it was found that (L2 / L1) had the highest rotational energy conversion efficiency at around 17%, and that the rotational energy conversion efficiency decreased regardless of whether it was larger or smaller than this. Further, it was found that a certain high rotational energy conversion efficiency was maintained in the range of (L2 / L1) of 10% to 20%. From these, the desired ratio between the length of the wing 9 and the length of the winglet 11 is derived.

[Winglet vertex position]
At the apex position P of the winglet 11 (FIG. 3B), the ratio of the distance B2 from the rear end of the blade 9 in the rotational traveling direction to the width B1 in the rotational traveling direction of the wing 9 is within the range of 50% to 83%. More preferably, it is in the range of 60% to 75%. The apex position P of this desirable winglet 11 was obtained by the following fluid analysis.

The analysis was performed assuming the four wings shown in FIG. 13 as the specimen. The wing 9I shown in (A) has (B2 / B1) 83%, the wing 9J shown in (B) has (B2 / B1) 75%, and the wing 9K shown in (C) has (B2 / B1). ) Is 53%, and (B2 / B1) is 33% in the wing 9L shown in (D). The width B1 in the traveling direction of each blade 9I, 9J, 9K, 9L is the same, and the thickness is also the same.

(1) Relationship between the apex position of the winglet and noise The wing 9 was rotated in a windless environment, and the sound at the wing tip was calculated. The analysis result is shown in FIG. Further, for each blade 9I, 9J, 9K, 9L, the maximum sound generation location at the wing tip and the magnitude of the sound are shown in FIGS. 15 (A), (B), (C), and (D), respectively. From this analysis result, the larger the overall (B2 / B1), that is, the smaller the noise is as the apex position P of the winglet 11 is located on the front side in the rotation traveling direction, and the (B2 / B1) is about 50% or less. It was found that the noise level was kept at a high level, and when (B2 / B1) exceeded about 50%, the noise level decreased in a quadratic curve.

(2) Relationship between the apex position of the winglet and the resistance at the time of idling The blade 9 was rotated in a windless environment, and the rotational moment acting on the vertical spindle 5 at this time was calculated. From this, it can be seen that the resistance at the time of idling, that is, the difficulty in stopping the rotation of the wing 9 when the wind weakens due to the fluctuating wind. The analysis result is shown in FIG. From this analysis result, it was found that the larger (B2 / B1) is, that is, the more the apex position P of the winglet 11 is located on the front side in the rotation traveling direction, the smaller the resistance at the time of idling. Further, it was found that when (B2 / B1) was around 50% or more, the resistance at idling was suppressed to some extent, and when it was around 50% or less, the resistance at idling was sharply increased.

From the analysis results of (1) and (2), it is preferable that (B2 / B1) is 50% or more for noise, and (B2 / B1) is 50% or more for resistance during idling. It can be said that it is preferable. However, if the apex position P of the winglet 11 is too far forward, the surface of the front end of the winglet 11 becomes wide and the air resistance becomes large. As a result of these combined judgments, the B2 / B1 value is preferably in the range of 50% to 83%, more preferably in the range of 60% to 75%. By setting the apex position P of the winglet in this way, a vertical axis wind turbine 4 that can satisfy both noise and resistance at the time of idling can be obtained.

As described above, the vertical axis wind turbine 4 has good rotational energy conversion efficiency. Therefore, the wind power generation device 3 using the vertical axis wind turbine 4 has good power generation efficiency and low noise.

Although the embodiments for carrying out the present invention have been described above based on the examples, the embodiments disclosed here are exemplary in all respects and are not limiting. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

3 ... Wind power generator 4 ... Vertical axis wind turbine 5 ... Vertical spindle 6 ... Generator 8 ... Support 9 ... Wing 10 ... Main wing 11 ... Winglet 15 ... Outer surface of main wing 16 ... Outer surface of winglet L1 ... Overall wing Half the length in the axial direction L2 ... The length in the axial direction of the winglet O ... Axial center

Claims (2)

A vertical spindle provided rotatably, a support provided on the vertical spindle, and a wing connected to the vertical spindle via the support and receiving wind to rotate around the axis of the vertical spindle. It ’s a vertical axis windmill.
The wing has a wing portion extending parallel to the vertical main axis and a winglet extending diagonally from both ends of the main wing portion toward the vertical main axis, and the wing extends over the main wing portion and the uniglet. In the cross-sectional shape, the outer surface in the radial direction gradually becomes outward in the radial direction from both front and rear ends in the rotational traveling direction of the wing so that the thickness in the radial direction becomes the thickest at the portion near the front end in the rotational traveling direction of the wing. The winglet has a bulging shape, and the winglet has a shape in which the amount of bulging of the radial outer surface gradually decreases toward the tip side, and the winglet has a width in the rotational traveling direction of the wing toward the tip side. Is a shape that narrows
The ratio of the axial length of the winglet to half the axial length of the entire wing is in the range of 16% to 18%.
The bending angle of the winglet with respect to the main wing portion is larger than 45 ° and within the range of 55 ° or less.
A vertical axis wind turbine that features that. A wind power generator comprising the vertical axis wind turbine according to claim 1 and a generator that generates electricity by the rotation of the vertical spindle of the vertical axis wind turbine.

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