Turbine for wind power generation and wind power generation device
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Filing Date
- 2024-06-18
- Publication Date
- 2026-04-21
AI Technical Summary
Conventional wind turbines with high circumferential speed ratios generate excessive aerodynamic noise and are not practical for high-output wind power generation, while those with low circumferential speed ratios and high power coefficients have not been implemented due to the trade-off between noise reduction and efficiency.
A horizontal-axis wind turbine with a dual structure featuring a rotating shaft, a cylindrical ring, and both inner and outer blades arranged around the shaft, where the outer blades are fixed to the ring's outer surface, allowing for a high power coefficient and reduced noise through a low circumferential speed ratio, enhancing mechanical strength and installation flexibility.
The dual-structured turbine achieves high output and quiet operation, ensuring safety and efficiency while allowing for compact design and versatile installation, expanding wind power generation possibilities.
Abstract
Description
Wind power turbines and wind power generation equipment
[0001] The present invention relates to a turbine for wind power generation that rotates using the flow of wind, and a wind power generation device equipped with this turbine.
[0002] Turbines (also called impellers or windmills) used in wind power generation systems are broadly classified into horizontal-axis and vertical-axis types depending on the direction of their rotational axis. Of these, horizontal-axis turbines have their rotational axis positioned so that it extends horizontally, and two- or three-bladed propeller types are commonly used. The larger the turbine's wind-receiving area (swept area), the greater the amount of wind energy it can generate. For this reason, horizontal-axis turbines often have relatively large diameters, ranging from several dozen meters to over 100 meters. However, a problem with larger turbines is that their weight also increases. In response to this issue, for example, Patent Document 1 attempts to achieve a lightweight, highly rigid turbine by using hollow turbine blades (windmill blades) and optimizing their materials.
[0003] JP 2023-4899 A
[0004] A three-bladed propeller turbine, such as that exemplified in Patent Document 1, can increase the amount of wind energy it can obtain by increasing the swept area. Furthermore, a three-bladed propeller turbine is characterized by a high circumferential speed ratio, which is the ratio of the blade tip speed (the speed at the tip of the turbine blades) to the wind speed, and a high power coefficient, which is the proportion of the energy contained in the wind that can be extracted using the turbine. A high power coefficient means that the turbine is highly efficient at converting energy from natural wind into mechanical rotational force, and the higher this value, the better.
[0005] On the other hand, the tip speed ratio is a parameter that indicates how fast a turbine rotates relative to the wind speed, and a high tip speed ratio means that it can rotate at a high speed relative to the wind speed. However, a turbine with a high tip speed ratio generates a louder aerodynamic noise as the blades cut through the wind, so it cannot be said that a higher tip speed ratio is necessarily preferable. The relationship between tip speed ratio and power coefficient has long been known to indicate turbine performance, and turbines with low power coefficients exist in the low tip speed ratio range, while turbines with high power coefficients exist in the high tip speed ratio range. However, turbines with both a low tip speed ratio and a high power coefficient have not yet been put into practical use. A turbine with these characteristics would reduce aerodynamic noise and enable the realization of a high-output wind power generation system without increasing the size.
[0006] This invention was invented in light of these issues, and one of its objectives is to realize a turbine for wind power generation that has a low tip speed ratio but a high power coefficient, and another objective is to realize a quiet, safe, and high-output wind power generation device by using this turbine.
[0007] The disclosed wind power turbine is a turbine for wind power generation that rotates using the flow of wind and includes a rotating shaft having a center of rotation extending horizontally, a cylindrical ring located radially outward of the rotating shaft and concentric with the center of rotation, a plurality of inner blades arranged around the rotating shaft, one end fixed to the outer peripheral surface of the rotating shaft and the other end fixed to the inner peripheral surface of the ring, and a plurality of outer blades arranged around the rotating shaft, one end fixed to the outer peripheral surface of the ring. The disclosed wind power generation device includes the above turbine and a generator that generates electricity using the rotational force of the turbine.
[0008] The disclosed wind turbine can achieve a high power coefficient despite a low tip speed ratio, and the disclosed wind power generator is quiet, safe, and capable of achieving high output.
[0009] 2A and 2B are diagrams for explaining the configuration of a wind power generation system according to an embodiment. (a) is a front view of a turbine for wind power generation according to an embodiment, as seen from the front in the axial direction, and (b) is a cross-sectional view taken along the arrows X-X in Fig. 2A. (b) is a front perspective view of the turbine in Fig. 2. (c) is a view taken along the arrow Y in Fig. 2. (d) is a front perspective view of a turbine according to a modified example.
[0010] A wind power turbine and a wind power generating system will be described as embodiments with reference to the drawings. The embodiments described below are merely examples, and are not intended to exclude various modifications or applications of techniques not explicitly described in the following embodiments. The configurations of the embodiments can be modified in various ways without departing from the spirit of the embodiments. Furthermore, they can be selected or combined as needed.
[0011] 1 is a diagram illustrating the configuration of a wind turbine generator 1 according to an embodiment. The wind turbine generator 1 includes a turbine 2 that rotates using the flow of wind, and a generator 4 that generates electricity using the rotational force of the turbine 2. The installation location of the wind turbine generator 1 is not particularly limited, and may be any location where the turbine 2 can receive wind, such as the ground or the rooftop of a building.
[0012] As shown by the white arrow in FIG. 1 , when the turbine 2 receives wind from the front, it rotates integrally with a rotating shaft 10 having a center of rotation C extending horizontally. That is, the wind power generation system 1 includes a horizontal-axis turbine 2. Regarding the definitions of directions in this embodiment, the vertical direction (up-down direction) is defined based on the state in which the wind power generation system 1 is installed on a flat surface, and the horizontal direction is a direction perpendicular to the vertical direction (a direction parallel to the flat surface). Note that the horizontal and vertical directions do not need to be strict, and some tilt is allowed. Furthermore, the "front" here refers to the side of the turbine 2 that receives wind, and the opposite side is called the "rear." The configuration of the turbine 2 will be described later.
[0013] The generator 4 is a power generating device that generates electricity using the rotational force of the turbine 2. The generator 4 is disposed, for example, on an extension of the rotating shaft 10 (concentric with the center of rotation C). Note that, depending on the length of the rotating shaft 10 and the relative positions of the turbine 2 and the generator 4, a shaft member 3 may be provided that connects the rotating shaft 10 to a rotating shaft of the generator 4 (not shown). Furthermore, the type of the generator 4 is not particularly limited. The wind power generating device 1 of this embodiment includes a brake mechanism (not shown) that suppresses the rotation of the turbine 2, a battery 6 that stores the power generated by the generator 4, and a charging circuit 5 that controls (converts) the generated power to a current and voltage that can be charged into the battery 6.
[0014] The brake mechanism is a mechanism that limits the rotation of the turbine 2 when the wind speed exceeds a certain level, thereby preventing the turbine 2 from over-rotating and damaging the turbine 2. The charging circuit 5 and the battery 6 are not essential and may be provided as appropriate depending on the usage of the wind turbine generator 1. For example, it is possible to control only the voltage of the generated power, or to connect the generated power directly to an electrical device without storing it in the battery 6.
[0015] 2 to 4 are diagrams showing the turbine 2 according to this embodiment. The turbine 2 includes the above-described rotating shaft 10, a ring 20 positioned radially outward from the rotating shaft 10, inner blades 30 positioned radially inward from the ring 20, and outer blades 40 positioned radially outward from the ring 20. That is, the turbine 2 is a double-structure turbine in which the blades 30, 40 are provided on the inner and outer sides of the ring 20, which is concentric with the center of rotation C. Note that the "radial direction" referred to here is the radial direction based on the center of rotation C, and the direction away from the center of rotation C is referred to as the "radially outward" direction, and the direction toward the center of rotation C is referred to as the "radially inward" direction. The direction extending from the center of rotation C is referred to as the "axial direction," and the direction around the center of rotation C is referred to as the "circumferential direction."
[0016] As shown in Figure 3, the rotating shaft 10 is a shaft portion having a cylindrical outer peripheral surface 12, and has a columnar or cylindrical appearance. The corner formed by the end face of the tip side of the rotating shaft 10 (the end on the front side of the turbine 2) and the outer peripheral surface 12 is chamfered, but this chamfering shape is not essential. The shape of the rotating shaft 10 is not limited to this, and it may be tapered toward the tip side, or may be a cylindrical or columnar shape other than a cylindrical or columnar shape.
[0017] As shown in Figures 2(a) and 3, the ring 20 is a cylindrical part concentric with the center of rotation C. The ring 20 functions to connect the outer blades 40 to the rotary shaft 10 together with the inner blades 30 described later. The radial thickness of the ring 20 is constant in the radial direction as shown in Figure 2, and the axial length of the ring 20 is constant in the circumferential direction as shown in Figure 4. Hereinafter, the edge on the front side of the ring 20 will be referred to as one edge 23, and the edge on the back side of the ring 20 will be referred to as the other edge 24.
[0018] The size (diameter, radial thickness, axial length) of the ring 20 can be set as appropriate. The larger the diameter of the ring 20, the longer the circumferential length of the ring 20, and the larger the area of the outer peripheral surface 22 can be without changing the axial length. Therefore, the diameter of the ring 20 may be set depending on the number of outer blades 40 and the fixing area of the base end 41 (described later). Furthermore, the larger the radial thickness of the ring 20, the stronger the ring 20 becomes, while the smaller the wind-receiving area relative to the size of the turbine 2 becomes. Therefore, the radial thickness of the ring 20 may be set in consideration of the strength of the ring 20 and the performance of the turbine 2. Furthermore, the longer the axial length of the ring 20, the larger the axial size of the turbine 2 becomes. Therefore, the axial length of the ring 20 may be set in consideration of the size of the turbine 2.
[0019] The inner blades 30 are blade members (blades) having one end fixed to the outer peripheral surface 12 of the rotating shaft 10 and the other end fixed to the inner peripheral surface 21 of the ring 20. A plurality of inner blades 30 are arranged around the rotating shaft 10. The turbine 2 shown in FIG. 2( a) and other figures illustrates an example in which five inner blades 30 are arranged at equal intervals in the circumferential direction. A space is provided between two circumferentially adjacent inner blades 30. However, the arrangement and number of inner blades 30 are not limited to this. Since the multiple inner blades 30 have the same configuration, only one of the multiple inner blades 30 is assigned a reference symbol in the figures.
[0020] The inner blades 30 are shaped so that they can rotate independently when exposed to wind, and thus function to rotate the turbine 2. Furthermore, the inner blades 30 also function to connect the rotating shaft 10 and the ring 20. Hereinafter, one radially inner end of the inner blade 30 will be referred to as the inner end 31, and the other radially outer end of the inner blade 30 will be referred to as the outer end 32. The inner end 31, which is fixed to the outer peripheral surface 12 of the rotating shaft 10, extends obliquely with respect to both the axial and circumferential directions and is slightly curved, as shown in FIG. 3 . Similarly, the outer end 32, which is fixed to the inner peripheral surface 21 of the ring 20, also extends obliquely with respect to both the axial and circumferential directions and is slightly curved.
[0021] Both the inner end 31 and the outer end 32 are inclined so that the counterclockwise ends 31 a, 32 a are positioned closer to the front in the axial direction than the clockwise ends 31 b, 32 b, and the inner blades 30 have a three-dimensionally curved surface (plate-like) shape. Also, as shown in Fig. 4, the inner blades 30 are set to a shape and angle that prevents them from protruding axially from the one end edge 23 and the other end edge 24 of the ring 20. The specific shape of the inner blades 30 can be set as appropriate and is not limited to that shown in the figure.
[0022] The outer blades 40 are blade members (blades) having one end fixed to the outer peripheral surface 22 of the ring 20. A plurality of outer blades 40 are arranged around the rotating shaft 10. In the turbine 2 shown in FIG. 2( a ) and other figures, five outer blades 40 are arranged at equal intervals in the circumferential direction, similar to the number of inner blades 30, but the arrangement and number of outer blades 40 are not limited to this. Since the multiple outer blades 40 have the same configuration, only one of the multiple outer blades 40 is designated by a reference symbol in the figures.
[0023] The outer blade 40 has a blade cross section as shown in Figures 2(b), 3 and 4. As shown in Figure 2(b), the blade cross section of the outer blade 40 of this embodiment has a shape in which the lower surface 40b of the blade faces the front side, the upper surface 40a of the blade faces the back side, and the leading edge 40c of the blade is positioned counterclockwise and on the front side of the trailing edge 40d. As a result, when the outer blade 40 receives wind from the front as shown by the white arrow in Figure 2(b), lift is generated due to the speed difference between the lower surface 40b and the upper surface 40a of the blade, and the outer blade 40 rotates counterclockwise when viewed from the front. In this way, the outer blade 40 has the function of rotating the turbine 2.
[0024] Hereinafter, one radially inner end of the outer blade 40 will be referred to as the base end 41, and the other radially outer end of the outer blade 40 will be referred to as the tip end 42. The base ends 41 of the outer blades 40 are fixed to the outer peripheral surface 22 of the ring 20, so that a wide fixing area can be secured. This allows the size of the base ends 41 of the outer blades 40 to be increased, and therefore the size of the outer blades 40 to be enlarged. As shown in Fig. 3, the base ends 41 of the outer blades 40 extend obliquely both in the axial and circumferential directions and are slightly curved. Similarly, the tip ends 42 also extend obliquely both in the axial and circumferential directions.
[0025] The base end 41 and the tip end 42 are both inclined so that the counterclockwise end portions 41a, 42a are located closer to the front in the axial direction than the clockwise end portions 41b, 42b, and the outer blades 40 also have a three-dimensionally curved surface (plate-like) shape. As shown in Figures 3 and 4, the outer blades 40 of this embodiment are set to a shape and angle such that they do not protrude from one end edge 23 of the ring 20 but protrude from the other end edge 24 in the axial direction. Also, as shown in Figure 2(a) , the outer blades 40 have a longer circumferential length at the base end 41 than at the tip end 42 in a front view. In other words, the outer blades 40 of this embodiment have a so-called tapered shape, in which the circumferential length decreases radially outward. The specific shape of the outer blades 40 can be set as appropriate and is not limited to that shown in the figures.
[0026] 2A, in the turbine 2 of this embodiment, the radial length L1 of the outer blades 40, the radial length L2 of the inner blades 30, and the radius R of the rotating shaft 10 satisfy the relationship L1 > L2 > R.
[0027] Furthermore, in the turbine 2 of this embodiment, the inner blades 30 and the outer blades 40 are fixed to the ring 20 so that their circumferential positions partially overlap. In other words, focusing on a certain circumferential position (range) of the ring 20, there are five locations where the inner blades 30 are fixed to the inner peripheral surface 21 of the ring 20 and the outer blades 40 are fixed to the outer peripheral surface 22 of the ring 20. Fixing the inner and outer blades 30, 40 so that they partially overlap in this way ensures the strength of the ring 20 while minimizing the radial thickness of the ring 20.
[0028] Furthermore, in the turbine 2 of this embodiment, the number of inner blades 30 and the number of outer blades 40 are the same (five), and both are arranged at equal intervals in the circumferential direction. This provides a good balance when viewed from the front of the turbine 2, improving its design.
[0029] [2. Actions and Effects] (1) The above-described turbine 2 is a double-structure turbine including a rotating shaft 10 having a rotation center C, a ring 20 concentric with the rotation center C, inner blades 30 provided inside the ring 20, and outer blades 40 provided outside the ring 20. When the turbine 2 receives wind from the front, it rotates due to the inner blades 30 and the outer blades 40, and because the outer blades 40 are fixed to the outer peripheral surface 22 of the ring 20, the area on which the outer blades 40 can be fixed is larger than, for example, a conventional three-bladed propeller-type turbine.
[0030] Therefore, in the above-described turbine 2, the size or number of the outer blades 40 can be increased. This makes it possible to increase the solidity σ of the outer blades 40, which is defined as the projected area of the outer blades 40 relative to the swept area A of the turbine 2 shown by the two-dot chain line in Fig. 2(a), and to increase the torque of the turbine 2. In other words, by providing the above-described ring 20, the solidity σ of the outer blades 40 (=projected area of the outer blades 40 / swept area A) can be increased, and a torque-type turbine 2 can be realized (manufactured).
[0031] In order to increase the fixing area of the outer blades 40, it is conceivable to increase the diameter of the rotating shaft 10, but in the above-described turbine 2, the ring 20 is provided without increasing the diameter of the rotating shaft 10. In this way, a space is formed between the rotating shaft 10 and the ring 20, and by providing the inner blades 30 in this space, it is possible to obtain rotational force from the inner blades 30 as well and to avoid a decrease in the swept area A. In other words, the above-described turbine 2 makes it possible to utilize the space without waste.
[0032] The wind energy E received by the turbine 2 increases in proportion to the swept area A, as shown in the following formula 1. Therefore, preventing a reduction in the swept area A leads to preventing a reduction in the wind energy, which in turn contributes to ensuring the output of the turbine 2. This makes it easier to ensure the desired output even if the turbine 2 is made smaller. Note that c in formula 1 p is the power coefficient, ρ is the air density, and V is the wind speed.
[0033] Furthermore, because the output power P of the turbine is expressed as the product of the torque T and the rotational angular velocity ω, the output power of the turbine 2 can be ensured even at a low rotational angular velocity ω by increasing the torque T. Here, the rotational angular velocity ω can be expressed as a tip speed ratio λ (= blade tip speed U / wind speed V, blade tip speed U = radius R of turbine 2 × rotational angular velocity ω) taking into account the wind speed V. In other words, by increasing the torque T, the output power P of the turbine 2 can be ensured even at a low tip speed ratio λ.
[0034] Therefore, as described above, by increasing the solidity σ of the outer blades 40 to make it a torque type turbine and by using a double structure turbine of the inner blades 30 and the outer blades 40, it is possible to obtain a high output (i.e., a power coefficient c p A turbine 2 with a low peripheral speed ratio λ can reduce the noise of the blades cutting through the air (aerodynamic noise), thereby improving quietness and safety. This allows the turbine to be installed in homes, commercial facilities, etc., increasing the degree of freedom in installation.
[0035] Furthermore, by making the turbine 2 a double structure, mechanical strength can be ensured when braking during strong winds. Here, mechanical strength refers to the strength of the blades 30, 40 of the turbine 2. In the case of a conventional turbine that does not have a ring 20, long blades are fixed to the rotating shaft, but when a load is applied to limit rotation using a brake mechanism, a large torque acts on the base of the blade. In contrast, in the turbine 2 described above, the blades 30, 40 have a double structure via the ring 20, so the length of each blade is shorter than in conventional turbines, resulting in a structure that is advantageous in terms of strength even when subjected to a load equivalent to that of conventional turbines.
[0036] Furthermore, the above-described turbine 2 can ensure output even when it is miniaturized, which allows for greater freedom in installation. Furthermore, the fact that sufficient performance can be obtained with a small turbine 2 means that a turbine with similar high performance can be realized even if the turbine 2 is enlarged in size. Therefore, the above-described turbine 2 can expand the possibilities of wind power generation.
[0037] (2) According to the above-described turbine 2, since the outer blades 40 have a wing cross-sectional shape, it is possible to utilize lift to rotate the turbine 2. (3) Furthermore, according to the above-described turbine 2, since the inner blades 30 have a shape that allows them to rotate independently when exposed to wind, the power coefficient c p This can contribute to improving
[0038] The above-described wind power generation plant 1 is equipped with the above-described turbine 2, and therefore is quiet, safe, and can achieve high output while also increasing the degree of freedom in installation. Furthermore, the wind power generation plant 1 equipped with the above-described turbine 2 can expand the possibilities of wind power generation.
[0039] [3. Others] The configuration of the turbine 2 described above is merely an example and is not limited to the above. For example, as in the turbine 2 shown in Fig. 5 , the outer blades 40 may have a shape that does not protrude from either the one edge 23 or the other edge 24 of the ring 20. That is, the entire base end 41 of the outer blade 40 may be fixed to the outer peripheral surface 22 of the ring 20. Alternatively, the outer blades 40 may have a shape that protrudes from the one edge 23 of the ring 20 but does not protrude from the other edge 24. Furthermore, as in the turbine 2 shown in Fig. 5 , the outer blades 40 may not have a tapered shape (i.e., the outer blades 40 have a substantially constant cross-sectional shape in the radial direction). Alternatively, the outer blades 40 may have a flared shape such that the cross-sectional shape becomes larger as it goes radially outward.
[0040] Furthermore, for example, the radial length L1 of the outer blades 40, the radial length L2 of the inner blades 30, and the radius R of the rotating shaft 10 may be configured to satisfy the relationship L2 > L1 > R or the relationship L1 = L2 > R. The shapes, sizes, numbers, arrangements, angles, etc. of the inner blades 30 and the outer blades 40 may be set as appropriate. The shape and size of the rotating shaft 10 and the size of the ring 20 may also be set as appropriate.
[0041] The configuration of the wind power generation device 1 described above is also one example, and it is sufficient if it includes at least the turbine 2 described above or a turbine according to a modified example thereof, and the generator 4 that generates electricity using the rotational force of the turbine.
[0042] [4. Supplementary Notes] The following supplementary notes are disclosed regarding the above-described embodiments and modified examples. [Supplementary Note 1] A turbine for wind power generation that rotates using a wind flow, comprising: a rotating shaft having a center of rotation extending horizontally; a cylindrical ring located radially outward of the rotating shaft and concentric with the center of rotation; inner blades having one end fixed to the outer peripheral surface of the rotating shaft and the other end fixed to the inner peripheral surface of the ring, and arranged in plurality around the rotating shaft; and outer blades having one end fixed to the outer peripheral surface of the ring, and arranged in plurality around the rotating shaft. [Supplementary Note 2] The turbine for wind power generation according to Supplementary Note 1, wherein the outer blades have a wing cross section. [Supplementary Note 3] The turbine for wind power generation according to Supplementary Note 1 or 2, wherein the inner blades have a shape that allows them to rotate independently when exposed to the wind. [Supplementary Note 4] A wind power generating system comprising: the turbine according to any one of Supplementary Notes 1 to 3; and a generator that generates electricity using the rotational force of the turbine.
[0043] The present invention is applicable to the manufacturing industry of turbines (wind wheels, impellers) for wind power generation that rotate using the flow of wind, and also applicable to the manufacturing industry of wind power generation devices equipped with such turbines.
[0044] REFERENCE SIGNS LIST 1 Wind power generator 2 Turbine 4 Generator 10 Rotating shaft 12 Outer peripheral surface 20 Ring 21 Inner peripheral surface 22 Outer peripheral surface 30 Inner blade 31 Inner end (one end) 32 Outer end (other end) 40 Outer blade 41 Base end (one end) 42 Tip C Center of rotation
Claims
1. A turbine for wind power generation that rotates using the flow of air, A rotation axis having a center of rotation extending horizontally, A ring located radially outside the rotation axis and formed in a cylindrical shape concentric with the rotation center, One end is fixed to the outer circumferential surface of the rotating shaft and the other end is fixed to the inner circumferential surface of the ring, and a plurality of inner blades are arranged around the rotating shaft, It comprises an outer vane, one end of which is fixed to the outer surface of the ring, and a plurality of outer vanes arranged around the rotation axis, The aforementioned outer wing is, It has an airfoil cross-sectional shape and is a plate-like shape that is three-dimensionally curved from the base to the tip of the outer wing. The lower surface of the wing faces the front side of the turbine, the upper surface of the wing faces the rear side of the turbine, and the leading edge of the wing is positioned on the front side relative to the trailing edge. Both the base end and the tip end of the outer wing extend diagonally in both the axial and circumferential directions. The base end of the outer wing extends from one end edge to the other end edge in the axial direction of the ring. A turbine for wind power generation, characterized by the following features.
2. (delete)
3. The inner blade is shaped to be able to rotate on its own when subjected to wind. A turbine for wind power generation according to claim 1, characterized in that
4. (delete)
5. The inner wing and the outer wing are fixed to the ring such that their circumferential ranges do not completely overlap but partially overlap each other. A turbine for wind power generation according to claim 1, characterized in that
6. Each of the circumferential ranges of the plurality of outer fins is fixed to the ring such that it overlaps with a portion of the circumferential range of the inner fin. A turbine for wind power generation according to claim 5, characterized in that it is a wind turbine.
7. Each of the aforementioned plurality of inner fins is fixed to the ring such that its circumferential position partially overlaps that of the outer fin. A turbine for wind power generation according to claim 5, characterized in that it is a wind turbine.
8. The number of inner fins and the number of outer fins are the same, and the ring is fixed such that the circumferential position of each inner fin and the circumferential position of each outer fin overlap. A turbine for wind power generation according to claim 5, characterized in that it is a wind turbine.
9. The ring is fixed such that the circumferential range of each inner wing and the circumferential range of each outer wing do not completely overlap but partially overlap each other. A turbine for wind power generation according to claim 8, characterized in that it is a wind turbine.
10. The sum of the areas of all the inner fins as viewed from the axial direction is greater than the sum of the areas of the spaces formed between two adjacent inner fins as viewed from the axial direction. A turbine for wind power generation according to claim 1, characterized in that
11. The outer wing has a constant circumferential length from its base to its tip. A turbine for wind power generation according to claim 1, characterized in that
12. A turbine according to any one of claims 1, 3, 5 to 11, The system comprises a generator that generates electricity using the rotational force of the turbine. A wind power generation device characterized by the following features.