Wind turbine, blade of wind turbine, and structure attached to wind turbine

Abstract

A blade of a wind turbine comprises a first end that is a portion on the rotor-shaft side of the blade in the longitudinal direction, and a second end that is positioned on the side opposite from the first end. The blade includes, in a chord direction from the leading edge of the blade to the trailing edge thereof, a separation portion that is a portion between the leading edge of the blade and an intermediate point bisecting a line segment by which the leading edge and the trailing edge are connected. The blade includes a structure that is positioned at least partially on the upper surface or the lower surface of the blade in the separation portion. The structure includes at least two friction parts that are aligned in the longitudinal direction, and a smooth part that is positioned between the friction parts in the longitudinal direction. Each of the friction parts includes a plurality of disturbing structures that disturb an airflow and are aligned in the chord direction from the leading edge toward the trailing edge.

Description

Wind turbines, wind turbine blades, and structures attached to wind turbines

[0001] Embodiments of this disclosure relate to wind turbines, wind turbine blades, and structures attached to wind turbines.

[0002] Wind turbines are used for purposes such as wind power generation. When a wind turbine blade is subjected to airflow, lift and drag are generated on the blade. Lift is generated perpendicular to the relative direction of the airflow to the blade. Drag is generated parallel to the relative direction of the airflow to the blade. Wind turbines that rotate using the lift generated on the blade are called lift-type wind turbines.

[0003] A boundary layer is formed between the main airflow and the surface of the wing. The phenomenon of this boundary layer separating from the wing surface is called separation. When separation occurs, the rotational efficiency of the wind turbine decreases and noise is generated. To prevent separation, for example, Patent Document 1 proposes providing a structure for generating vortices on the trailing edge of the wing.

[0004] Japanese Patent Publication No. 2003-254225

[0005] Conventional wind turbines have the problem of low power generation efficiency. To increase power generation efficiency, it is necessary to increase the lift-to-drag ratio of the blades, which means increasing lift or decreasing drag.

[0006] The first embodiment of this disclosure aims to reduce the drag of a wind turbine and improve the power generation efficiency of the wind turbine.

[0007] The first embodiment of this disclosure relates to the following [1] to

[35] .

[0008] [1] A wind turbine comprising: a rotor shaft; and a plurality of blades arranged in the direction of rotation of the rotor shaft and receiving airflow, wherein each blade includes a first end which is the part of the blade on the rotor shaft side in the longitudinal direction of the blade, and a second end located opposite to the first end, and the blade includes a separation portion which is the part between the leading edge and the midpoint which is the point that bisects the line segment connecting the leading edge and the trailing edge in the chord direction from the leading edge to the trailing edge, and the leading edge, and the blade includes a structure located at least partially on the upper or lower surface of the blade in the separation portion, and the structure includes at least two friction portions arranged in the longitudinal direction, and a smooth portion located between the friction portions in the longitudinal direction, and each friction portion includes a plurality of disturbance structures arranged in the chord direction that disturb the airflow.

[0009] [2] In the wind turbine described in [1], the structure may include a first structure located at least partially on the upper surface or the lower surface in the first separation portion, and the first separation portion may be a portion of the separation portion in which the ratio of the distance from the first end to the length of the blade in the longitudinal direction is 0.40 or less.

[0010] [3] In the wind turbine described in [1], the structure may include a second structure located at least partially on the upper or lower surface in the second separation portion, and the second separation portion may be the portion of the separation portion in which the ratio of the distance from the first end to the length of the blade in the longitudinal direction is greater than 0.40.

[0011] [4] In the wind turbine described in [3], the structure may include the second structure which is at least partially located on the upper surface in the second peeled portion.

[0012] [5] In the wind turbine described in [3] or [4], the structure may include the second structure located at least partially on the lower surface in the second peeled portion.

[0013] [6] In the wind turbine described in [1], the structure may include a first structure located at least partially on the lower surface in the first detached portion, and a second structure located at least partially on the upper surface in the second detached portion, wherein the first detached portion may be a portion of the detached portion in which the ratio of the distance from the first end to the length of the blade in the longitudinal direction is 0.40 or less, and the second detached portion may be a portion of the detached portion in which the ratio of the distance from the first end to the length of the blade in the longitudinal direction is greater than 0.40.

[0014] [7] In the wind turbine described in any one of [1] to [6], each of the multiple disturbance structures may have a disturbance thickness in the thickness direction of the blade, and the ratio of the disturbance thickness to the chord length of the blade may be 0.00025 or less.

[0015] [8] In the wind turbine described in any one of [1] to [7], each friction portion may include at least 50 of the disturbance structures arranged in the direction of the code.

[0016] [9] In the wind turbine according to any one of [1] to [8], the blade may include the structure located at least partially on the lower surface in the separated portion.

[0017] In the wind turbine described in

[10] and [9], the structure may be arranged to overlap the position of maximum thickness. The position of maximum thickness is the position where the blade has the greatest thickness.

[0018]

[11] In the wind turbine described in [9] or

[10] , the structure may be at least partially arranged in the longitudinal direction in a portion where the ratio of the distance from the first end to the length of the blade is 0.2516 or less.

[0019]

[12] In the wind turbine described in any one of [9] to

[11] , each of the multiple disturbance structures may have a disturbance thickness in the thickness direction of the blade, and the ratio of the disturbance thickness to the chord length of the blade may be 0.00015 or more and 0.00025 or less.

[0020]

[13] In the windmill according to any one of [1] to

[12] , the blade may include the structure that is at least partially located on the upper surface at the peeling portion.

[0021]

[14] In the windmill according to

[13] , the structure may be at least partially arranged in a portion where the ratio of the distance from the leading edge to the chord length of the blade is 0.10 or less in the chord direction.

[0022]

[15] In the windmill according to

[13] or

[14] , the structure may be at least partially arranged in a portion where the ratio of the distance from the first end to the length of the blade is 0.2516 or less in the longitudinal direction.

[0023]

[16] In the windmill according to any one of

[13] to

[15] , each of the plurality of disturbing structures may have a disturbing thickness in the thickness direction of the blade, and the ratio of the disturbing thickness to the chord length of the blade may be 0.00015 or less.

[0024]

[17] In the windmill according to any one of [l] to

[16] , the upper surface or the lower surface may include a base surface, and the disturbing structure may protrude with respect to the base surface in the thickness direction of the blade.

[0025]

[18] In the windmill according to any one of [1] to

[16] , the upper surface or the lower surface may include a base surface, and the disturbing structure may be recessed with respect to the base surface in the thickness direction of the blade.

[0026]

[19] In the windmill according to any one of [1] to

[18] , the friction portion may include a first friction portion including the plurality of disturbing structures having a first dimension in the thickness direction of the blade, and a second friction portion located outside the first friction portion in the longitudinal direction of the blade and including the plurality of disturbing structures having a second dimension in the thickness direction of the blade, and the second dimension may be smaller than the first dimension.

[0027]

[20] In the windmill described in

[19] , the second friction part may be the friction part among the plurality of friction parts whose distance from the first friction part in the longitudinal direction is closest to the reference distance, and the reference distance may be 0.2 times the dimension of the blade in the longitudinal direction.

[0028]

[21] In the windmill described in

[20] , the first friction part may be the friction part among the plurality of friction parts whose distance from the first end in the longitudinal direction is closest to the first reference distance, and the first reference distance may be 0.2 times the dimension of the blade in the longitudinal direction.

[0029]

[22] In the windmill described in

[21] , the ratio of the second dimension to the first dimension may be 0.60 or less.

[0030]

[23] In the windmill described in

[21] or

[22] , the ratio of the second dimension to the first dimension may be 0.04 or more.

[0031]

[24] In the windmill described in any one of

[21] to

[23] , the first friction part may have a first width in the longitudinal direction, the second friction part may have a second width in the longitudinal direction, and the ratio of the second width to the first width may be 0.75 or less.

[0032]

[25] In the windmill described in any one of

[21] to

[24] , the first friction part and the second friction part may be located in the first cord region on the upper surface. The first cord region is a region on the upper surface where the distance from the leading edge is more than 0.0 times and less than or equal to 0.5 times the cord length. The cord length is the distance from the leading edge to the trailing edge.

[0033]

[26] In the windmill described in

[19] or

[20] , the first friction part may be the friction part among the plurality of friction parts whose distance from the first end in the longitudinal direction is closest to the second reference distance. The second reference distance is 0.6 times the dimension of the blade in the longitudinal direction.

[0034]

[27] In the wind turbine described in

[26] , the ratio of the second dimension to the first dimension may be 0.80 or less.

[0035]

[28] In the wind turbine described in

[26] or

[27] , the ratio of the second dimension to the first dimension may be 0.10 or more.

[0036]

[29] In the wind turbine described in any one of

[26] to

[28] , the first friction portion has a first width in the longitudinal direction, and the second friction portion has a second width in the longitudinal direction, and the ratio of the second width to the first width may be 0.75 or less.

[0037]

[30] In the wind turbine described in any one of

[19] to

[29] , the blades may have a sufficiency ratio of 0.80 or more. The sufficiency ratio is the ratio of the number of sufficient pairs to the total number of pairs. The total number of pairs is the number of pairs of the friction parts selected based on the reference interval. The number of sufficient pairs is the number of pairs of the friction parts selected based on the reference interval that satisfy the relationship between the first dimension of the first friction part and the second dimension of the second friction part.

[0038]

[31] A wind turbine blade, comprising: a first end which is the part of the blade on the rotor axis side in the longitudinal direction of the blade; and a second end located opposite to the first end, wherein the blade includes a separation portion which is the portion between the leading edge and the midpoint which is the point that bisects the line segment connecting the leading edge and the trailing edge in the chord direction from the leading edge to the trailing edge, and the leading edge, wherein the blade includes a structure located at least partially on the upper or lower surface of the blade in the separation portion, wherein the structure includes at least two friction portions aligned in the longitudinal direction and a smooth portion located between the friction portions in the longitudinal direction, and each of the friction portions is aligned in the chord direction and includes a plurality of disturbance structures that disturb the airflow.

[0039]

[32] A structure to be attached to a wind turbine, the wind turbine comprising a rotor shaft and a plurality of blades aligned in the direction of rotation of the rotor shaft and receiving airflow, the blades including a first end which is the part of the blade on the rotor shaft side in the longitudinal direction of the blade and a second end located opposite to the first end, the blades including a separation portion which is the part between a midpoint which is the point that bisects the line segment connecting the leading edge and the trailing edge in the chord direction from the leading edge to the trailing edge of the blade and the leading edge, the structure to be attached to the wind turbine such that it is located at least partially on the upper or lower surface of the blade in the separation portion, the structure to include at least two friction portions aligned in the longitudinal direction and a smooth portion located between the friction portions in the longitudinal direction, the friction portions each including a plurality of disturbance structures aligned in the chord direction that disturb the airflow.

[0040]

[33] A molded article comprising the structure described in

[32] .

[0041]

[34] A film comprising the structure described in

[32] .

[0042]

[35] A transfer sheet for transferring multiple disturbance structures of the structure in

[32] to a molded product.

[0043] According to the first embodiment of this disclosure, the resistance force caused by the structure can be reduced.

[0044] This figure shows an example of a wind turbine in the first embodiment. This figure shows an example of a wind turbine nacelle. This is a plan view showing an example of a wind turbine blade. This is a plan view showing an example of a wind turbine blade. This is a plan view showing an example of a wind turbine blade. This is a cross-sectional view showing an example of the blade of Figure 3A viewed from the IVA-IVA direction. This is a cross-sectional view showing an example of the blade of Figure 3A viewed from the IVB-IVB direction. This is a plan view showing an example of a structure. This is a cross-sectional view showing the structure of Figure 5 viewed from the VI-VI direction. This is a cross-sectional view showing a modified example of a structure. This is a cross-sectional view showing an example of a structure before it is attached to an object. This figure illustrates a method for measuring the position and shape of the components of a friction part. This figure shows an example of a vortex generated in a structure. This is a cross-sectional view showing an example of airflow around a blade. This is a cross-sectional view showing an example of airflow around a blade in a comparative form. This is a cross-sectional view showing a blade in the first modified example. This is a cross-sectional view showing an example of airflow around a blade in the first modified example. This is a cross-sectional view showing a blade in the second modified example. This is a cross-sectional view showing an example of airflow around a blade in the second modified example. This is a cross-sectional view showing an example of a structure in the third modified example. This is a plan view showing an example of a structure in the fourth modified example. This is a plan view showing an enlarged view of the structure in Figure 18. This is a cross-sectional view showing the structure in Figure 18 as viewed from the XX-XX direction. This is a plan view showing an example of a disturbance structure in the fifth modified example. This is a plan view showing an example of a disturbance structure in the sixth modified example. This is a plan view showing an example of a disturbance structure in the seventh modified example. This is a plan view showing an example of a disturbance structure in the eighth modified example. This is a plan view showing an example of a disturbance structure in the ninth modified example. This is a plan view showing an example of a disturbance structure in the tenth modified example. This is a plan view showing an example of a structure in the eleventh modified example. This is a plan view showing an example of a structure in the twelfth modified example. This is a plan view showing an example of a wing in the thirteenth modified example. This is a plan view showing an example of a wing in the thirteenth modified example. This is a plan view showing an example of a wing in the fourteenth modified example. This is a plan view showing the positions of the first and second samples. This is a table showing the relationship between the height of the protrusions and the width and spacing of the protrusions in Examples 1 to 5.This table shows the relationship between the height of the protrusion and the minimum value of the drag coefficient when the structure is attached to the upper surface of the wing in Examples 1A to 1C. This graph shows the relationship between the drag coefficient and the angle of attack in Example 1A. This table shows the relationship between the height of the protrusion and the minimum value of the drag coefficient when the structure is attached to the lower surface of the wing in Examples 2A to 2B. This table shows the relationship between the position of the structure and the minimum value of the drag coefficient when the structure is attached to the upper surface of the wing in Example 3. This table shows the relationship between the position of the structure and the minimum value of the drag coefficient when the structure is attached to the lower surface of the wing in Example 4. This table shows the relationship between the position of the structure and the minimum value of the drag coefficient when the structure is attached to the lower surface of the wing in Example 5. This table shows the relationship between the position of the structure and the minimum value of the drag coefficient when the structure is attached to the lower surface of the wing in Example 6. This table shows the relationship between the position of the structure and the minimum value of the drag coefficient when the structure is attached to the upper surface of the wing in Example 7. This table shows the relationship between the height of the protrusions of the structure and the minimum value of the drag coefficient when the structure is attached to the upper surface of the wing in Example 8. This table shows the relationship between the height of the protrusions of the structure and the minimum value of the drag coefficient when the structure is attached to the upper surface of the wing in Example 9. This table shows the relationship between the height of the protrusions of the structure and the minimum value of the drag coefficient when the structure is attached to both the upper and lower surfaces of the wing in Example 10. This table shows the relationship between the height of the protrusions of the structure and the minimum value of the drag coefficient when the structure is attached to the lower surface of the wing in Example 11. This table shows the relationship between the height of the protrusions of the structure and the minimum value of the drag coefficient when the structure is attached to the lower surface of the wing in Example 12. This table shows the relationship between the arrangement of the structure in the longitudinal direction and the minimum value of the drag coefficient in Example 13. This table shows the wing parameters in Example 14. This table shows the calculation results of the torque change at each position in the longitudinal direction in Example 14. This table shows the calculation results of the torque change for the entire wing in Example 14. This is a plan view showing an example of a wind turbine blade in the second embodiment. This is a cross-sectional view showing the blade of Figure 50 as viewed from the LI-LI direction. This is a cross-sectional view showing an example of a boundary layer formed around a structure. This is a plan view showing an example of a first friction section and a second friction section.This is a diagram illustrating a pair of friction parts. In the first modified example, this is a plan view showing the structure. In the first modified example, this is a diagram illustrating a pair of friction parts. In the fifth modified example, this is a plan view showing an example of a wing. In the sixth modified example, this is a plan view showing an example of a wing. In the embodiment, this is a table showing the relationship between the position of the friction parts and the dimensions of the disturbance structure. In the embodiment, this is a table showing the relationship between the position of the friction parts and the width of the friction parts.

[0045] In this specification, unless otherwise specified, terms meaning base materials such as "substrate," "base material," "board," "sheet," and "film" are not distinguished from each other solely on the basis of differences in name. For example, "substrate" is a concept that includes materials that may be called sheets or films.

[0046] In this specification, unless otherwise specified, the term "plane" refers to the plane of a plate-like member in question that coincides with the planar direction of the member when viewed as a whole and in a broad sense. The term "normal direction" as used with respect to a plate-like member refers to the direction normal to the plane of the member.

[0047] In this specification, unless otherwise specified, terms relating to shape and geometric conditions, as well as values ​​that specify the degree of shape and geometric conditions, may be interpreted based on the function they achieve, without being bound by their strict meaning. Examples of terms relating to shape and geometric conditions include "parallel" and "orthogonal." Examples of values ​​that specify the degree of shape and geometric conditions include length values ​​and angle values.

[0048] In this specification and these drawings, unless otherwise specified, when the positional relationship of a second component to a first component is described using terms such as "above," "below," "upper side," "lower side," "upward," or "downward," the second component may or may not be in contact with the first component. In this specification and these drawings, unless otherwise specified, when the positional relationship of a second component to a first component is described using terms such as "above," "upper side," or "upward," depending on the usage conditions of the product, the second component may be located "below," "downward," or "downward" of the first component.

[0049] In this specification, if there are multiple candidate upper limits and multiple candidate lower limits for a given parameter, the numerical range of that parameter may be constructed by combining any one candidate upper limit and any one candidate lower limit. For example, consider the case where it is stated that "Parameter B is, for example, A1 or greater, may be A2 or greater, or A3 or greater. Parameter B is, for example, A4 or less, may be A5 or less, or A6 or less." In this case, the numerical range of parameter B may be A1 or greater and A4 or less, A1 or greater and A5 or less, A1 or greater and A6 or less, A2 or greater and A4 or less, A2 or greater and A5 or less, A2 or greater and A6 or less, A3 or greater and A4 or less, A3 or greater and A5 or less, or A3 or greater and A6 or less.

[0050] In this specification and these drawings, unless otherwise specified, identical parts or components having similar functions are denoted by the same or similar reference numerals. Dimensional ratios in the drawings may differ from actual ratios for illustrative purposes. In this specification and these drawings, some components may be omitted from the drawings.

[0051] In this specification and these drawings, unless otherwise specified, one embodiment of this specification may be combined with other embodiments or modifications, to the extent that it does not contradict. Other embodiments or modifications may also be combined with each other, to the extent that it does not contradict.

[0052] In this specification and these drawings, unless otherwise specified, when multiple steps are disclosed regarding a method such as a manufacturing method, other steps not disclosed may be performed between the disclosed steps. The order of the disclosed steps may be changed to the extent that it does not create a contradiction.

[0053] The structures and the configurations of the blades and wind turbines equipped with the structures according to the embodiments of this disclosure will be described in detail with reference to the drawings. The embodiments shown below are examples of the technical concept of this application, and the technical concept of this application is not limited to these embodiments.

[0054] (First Embodiment) The first embodiment is based on Japanese Patent Application No. 2024-165663 filed on 24 September 2024 and Japanese Patent Application No. 2025-102727 filed on 18 June 2025, and claims priority thereto. Figure 1 is a side view showing an example of a wind turbine 1. The wind turbine 1 comprises a tower 1A extending in the vertical direction and a rotor 1B located at the upper end of the tower 1A. The rotor 1B includes a nacelle 2 and a plurality of blades 10 that receive the airflow. The plurality of blades 10 may be fixed to a hub 7.

[0055] Figure 2 shows an example of a nacelle 2. The nacelle 2 houses the rotor shaft 3 and the generator 4. The rotor shaft 3 is connected to the hub 7. The multiple blades 10 described above are arranged along the direction of rotation of the rotor shaft. The generator 4 generates electricity using the rotation of the rotor shaft 3.

[0056] An airflow monitor 5 may be positioned on the outer surface of the nacelle 2. The airflow monitor 5 may include an anemometer for measuring the speed of the airflow. The airflow monitor 5 may also include a wind vane for measuring the direction of the airflow.

[0057] A speed increaser 6 may be positioned between the hub 7 and the generator 4. The speed increaser 6 can increase the rotational speed of the blade 10.

[0058] The wind turbine 1 may be equipped with a control device 8. The control device 8 may include a first control device 8A and a second control device 8B. The first control device 8A may adjust the direction of the rotor 1B according to the direction of the airflow. The second control device 8B may adjust the angle of the blades 10 according to the speed of the airflow.

[0059] Figure 3A is a plan view showing an example of a wing 10. The wing 10 includes a first end 11, a second end 12, a leading edge 13, and a trailing edge 14. The first end 11 and the second end 12 are the ends of the wing 10 in the longitudinal direction D1. The first end 11 is the end of the wing 10 facing the rotor shaft 3. The first end 11 may be connected to the hub 7. The second end 12 is the end of the wing 10 located opposite the first end 11 in the longitudinal direction D1.

[0060] As shown in Figure 3A, the leading edge 13 and trailing edge 14 extend from the first end 11 to the second end 12. The leading edge 13 is located upstream of the airflow F compared to the trailing edge 14. The longitudinal direction D1 described above is defined as the direction in which the leading edge 13 extends. Specifically, the longitudinal direction D1 is the direction of the straight line connecting the intersection point 131 between the leading edge 13 and the first end 11 and the intersection point 132 between the leading edge 13 and the second end 12.

[0061] Figure 4A is a cross-sectional view showing an example of the wing 10 in Figure 3A viewed from the IVA-IVA direction. A cross-sectional view of the wing 10 as shown in Figure 4A is obtained by cutting the wing 10 along a plane perpendicular to the longitudinal direction D1. As shown in Figure 4A, the trailing edge 14 may have a sharper profile than the leading edge 13. For example, the radius of curvature of the cross-sectional profile of the wing 10 at the trailing edge 14 may be smaller than the radius of curvature of the cross-sectional profile of the wing 10 at the leading edge 13.

[0062] The surface direction of the wing 10 may change discontinuously at the trailing edge 14. That is, the trailing edge 14 may be defined as the portion where the surface direction of the wing 10 changes discontinuously. The leading edge 13 may be defined as the portion furthest from the trailing edge 14 in a cross-sectional view of the wing 10 with respect to a plane perpendicular to the longitudinal direction D1.

[0063] As shown in Figure 4A, the blade 10 includes an upper surface 15 and a lower surface 16 that extend from the leading edge 13 to the trailing edge 14. The upper surface 15 and the lower surface 16 are distinguished by a code line 17. The code line 17 is a hypothetical straight line in the cross-sectional view of the blade 10 that extends from the leading edge 13 to the trailing edge 14. The direction of the code line 17 is also referred to as the code direction D2. The upper surface 15 and the lower surface 16 may be distinguished based on the pressure applied to the blade 10 when an article comprising the blade 10 is in operation. For example, the upper surface 15 and the lower surface 16 may be distinguished based on the pressure applied to the blade 10 when a wind turbine 1 comprising the blade 10 is rotating. When the wind turbine 1 is rotating, the pressure on the upper surface 15 is mainly negative, and the pressure on the lower surface 16 is mainly positive.

[0064] The upper surface 15 includes the maximum thickness position 15M. The wing 10 has its maximum thickness T0 at the maximum thickness position 15M. The thickness of the wing 10 is the dimension of the wing 10 in the direction perpendicular to the longitudinal direction D1 and the chord direction D2.

[0065] The thickness T0 of the wing 10 at the position where the structure 20 described later is placed may be determined relative to the chord length C0 of the wing 10. The chord length C0 is the distance in the chord direction D2 from the leading edge 13 to the trailing edge 14. The chord length C0 may vary depending on the position in the longitudinal direction D1 of the wing 10.

[0066] The ratio T0 / C0, which is the ratio of the thickness T0 to the code length C0, is, for example, 0.50 or less, may be 0.45 or less, or 0.40 or less. T0 / C0 is, for example, 0.10 or more, may be 0.15 or more, or 0.20 or more.

[0067] Figure 4B is a cross-sectional view showing an example of the wing 10 of Figure 3A viewed from the IVB-IVB direction. The cross-section of the wing 10 shown in Figure 4B is located further from the first end 11 in the longitudinal direction D1 compared to the cross-section of the wing 10 shown in Figure 4A. That is, the distance from the cross-section of the wing 10 shown in Figure 4B to the first end 11 is longer than the distance from the cross-section of the wing 10 shown in Figure 4A to the first end 11.

[0068] As shown in Figure 4B, the cross-sectional shape of the wing 10 shown in Figure 4B may differ from the cross-sectional shape of the wing 10 shown in Figure 4A. That is, the cross-sectional shape of the wing 10 may differ depending on its position in the longitudinal direction D1.

[0069] For example, the cross-sectional thickness T0 of the wing 10 shown in Figure 4B may be smaller than the cross-sectional thickness T0 of the wing 10 shown in Figure 4A. For example, the cross-sectional thickness T0 of the wing 10 may decrease as it moves away from the first end 11 in the longitudinal direction D1.

[0070] For example, the T0 / C0 of the cross-section of the wing 10 shown in Figure 4B may be smaller than the T0 / C0 of the cross-section of the wing 10 shown in Figure 4A. For example, the T0 / C0 of the cross-section of the wing 10 may decrease as it moves away from the first end 11 in the longitudinal direction D1.

[0071] Although not shown in Figure 4B, the structure 20 may be positioned on the upper surface 15 or lower surface 16 at a location where the cross-section has a small thickness T0 or T0 / C0, as shown in Figure 4B.

[0072] The structure 20 will now be described. As shown in Figures 3A and 4A, the wind turbine 1 includes a structure 20 located on the surface of the blade 10. The structure 20 is located on at least one of the upper surface 15 or the lower surface 16 of the blade 10. In the example shown in Figures 3A and 4A, the structure 20 is located on the upper surface 15 of the blade 10.

[0073] Patent Document 1 proposes providing a structure on the trailing edge of the blade to suppress boundary layer separation. However, simply providing a structure on the trailing edge of the blade may not be sufficient to sufficiently improve the rotational efficiency of the wind turbine. Through the inventors' research, it was found that one of the causes is boundary layer separation occurring in the forward portion of the blade 10. Specifically, it was found that the shape of the forward portion of the blade 10 can cause boundary layer separation.

[0074] The forward portion of the wing 10 is the part located between the second boundary L2 and the leading edge 13 in the cross-sectional view of the wing 10, as shown in Figure 4A. The second boundary L2 is, for example, a plane that passes through the midpoint 171 and is perpendicular to the chord direction D2. The midpoint 171 is located midway between the leading edge 13 and the trailing edge 14 in the chord direction D2.

[0075] Through the inventors' research, it has been found that the structure 20 of this embodiment functions effectively against separation occurring in the forward portion of the wing 10. Therefore, in this embodiment, it is proposed to provide the structure 20 in the forward portion of the wing 10. In this embodiment, the forward portion of the wing 10 is referred to as the separation portion and is represented by reference numeral 18. The structure 20 provided in the separation portion 18 can effectively suppress airflow separation.

[0076] As shown in Figure 3A, the wing 10 has a length L0. The length L0 of the wing 10 is the dimension of the wing 10 along the longitudinal direction D1. The length L0 of the wing 10 is, for example, 1 m or more, may be 50 m or more, or 100 m or more. The length L0 of the wing 10 is, for example, 200 m or less, may be 160 m or less, or 130 m or less.

[0077] As will be described later, the effect of the structure 20 may differ depending on its position. The options for the placement of the structure 20 are, for example, the following (1) to (3): (1) Position of the structure 20 in the longitudinal direction D1 (2) Position of the structure 20 in the code direction D2 (3) Surface on which the structure 20 is placed (top surface 15 or bottom surface 16)

[0078] Figure 3B is a plan view showing an example of a wing 10. As shown in Figure 3B, the structure 20 may be located in the first delamination portion 18A. In this case, although not shown in Figure 3B, it is preferable that the structure 20 be located on the lower surface 16. Of course, as shown in Figure 3B, the structure 20 may also be located on the upper surface 15 in the first delamination portion 18A. The structure 20 located in the first delamination portion 18A may be referred to as the first structure.

[0079] As shown in Figure 3B, the first delamination portion 18A is the portion of the forward part of the wing 10 located between the first A boundary L1A and the first end 11 in the longitudinal direction D1. That is, the first delamination portion 18A is the portion of the wing 10 located between the first A boundary L1A and the first end 11 in the longitudinal direction D1, and between the leading edge 13 and the second boundary L2 in the chord direction D2.

[0080] In Figure 3B, the symbol L10A represents the distance from the first end 11 to the first A boundary L1A in the longitudinal direction D1. The ratio of the distance L10A to the length L0 of the wing 10 is, for example, 0.60. In this case, at each position of the first separation portion 18A, the ratio of the distance from the first end 11 to the length L0 of the wing 10 is 0.60 or less. In this case, the first separation portion 18A is defined as "the portion between the leading edge 13 and the midpoint 171 in the code direction D2, and in the longitudinal direction D1, the ratio of the distance from the first end 11 to the length L0 of the wing 10 is 0.60 or less."

[0081] The distance L10A between the first A boundary L1A of the first peeled portion 18A and the first end 11 may be set to a smaller value. The ratio of the distance L10A to the length L0, L10A / L0, is, for example, 0.40 or less, and may be 0.30 or less. As supported by the embodiments described later, L10A / L0 may be 0.2516 or less. L10A / L0 is, for example, greater than 0.00, may be 0.01 or more, may be 0.10 or more, and may be 0.15 or more. As supported by the embodiments described later, L10A / L0 may be 0.1865 or more.

[0082] The symbol L11 represents the distance in the longitudinal direction D1 between the center point Pc of the structure 20 in a plan view and the first end 11. A hypothetical straight line extending in the code direction D2, which is at an equal distance in the longitudinal direction D1 from both the part of the structure 20 closest to the first end 11 and the part of the structure 20 closest to the second end 12 in the longitudinal direction D1, is called the first hypothetical straight line. The intersection of the first hypothetical straight line and the front end 201 is called the first hypothetical point. The intersection of the first hypothetical straight line and the rear end 202 is called the second hypothetical point. The center point Pc is located midway between the first hypothetical point and the second hypothetical point. In the example shown in Figure 3B, the structure 20 is provided on the wing 10 such that the center point Pc is located in the first delamination portion 18A. The structure 20 may be partially located outside the first delamination portion 18A, as long as the center point Pc is located in the first delamination portion 18A.

[0083] Figure 3C is a plan view showing an example of a wing 10. As shown in Figure 3C, the structure 20 may be located in the second separation portion 18B. In this case, it is preferable that the structure 20 is located on the upper surface 15. Although not shown in Figure 3C, the structure 20 may also be located on the lower surface 16 in the second separation portion 18B. The structure 20 located in the second separation portion 18B may be referred to as the second structure.

[0084] As shown in Figure 3C, the second separation portion 18B is the portion of the forward part of the wing 10 located between the first B boundary L1B and the second end 12 in the longitudinal direction D1. That is, the second separation portion 18B is the portion of the wing 10 located between the first B boundary L1B and the second end 12 in the longitudinal direction D1, and between the leading edge 13 and the second boundary L2 in the chord direction D2.

[0085] In Figure 3C, the symbol L10B represents the distance from the first end 11 to the first B boundary L1B in the longitudinal direction D1. Distance L10B may be equal to or greater than the distance L10A described above.

[0086] The ratio of the distance L10B to the length L0 of the wing 10 is, for example, 0.60. In this case, at each position of the second separation portion 18B, the ratio of the distance from the first end 11 to the length L0 of the wing 10 is greater than 0.60. In this case, the second separation portion 18B is defined as "the portion between the leading edge 13 and the midpoint 171 in the chord direction D2, and in the longitudinal direction D1, the ratio of the distance from the first end 11 to the length L0 of the wing 10 is greater than 0.60."

[0087] The distance L10B between the first B boundary L1B of the second peeled portion 18B and the first end 11 may be set to be smaller or larger. The ratio of the distance L10B to the length L0, L10B / L0, may be greater than 0.40, greater than 0.50, or greater than 0.70. As supported by the embodiments described later, L10B / L0 may be greater than 0.4469, greater than 0.5770, or greater than 0.7072.

[0088] In the example shown in Figure 3C, the structure 20 is provided on the wing 10 such that its center point Pc is located in the second delamination portion 18B. The structure 20 may be partially located outside the second delamination portion 18B, as long as its center point Pc is located in the second delamination portion 18B.

[0089] The reason why the effect of the structure 20 differs depending on its position in the longitudinal direction D1 may be due to differences in the cross-sectional shape of the wing 10. As described above, the T0 / C0 of the cross-section of the wing 10 may decrease as it moves away from the first end 11 in the longitudinal direction D1. In this case, the T0 / C0 of the cross-section of the wing 10 in the second delamination portion 18B is smaller than the T0 / C0 of the cross-section of the wing 10 in the first delamination portion 18A. As a result, the preferred placement surface of the structure 20 in the second delamination portion 18B may be different from the preferred placement surface of the structure 20 in the first delamination portion 18A. For example, the preferred placement surface of the structure 20 in the second delamination portion 18B may be the upper surface 15, and the preferred placement surface of the structure 20 in the first delamination portion 18A may be the lower surface 16.

[0090] The T0 / C0 of the cross-section of the blade 10 in the first delamination portion 18A is, for example, 0.30 or more, may be 0.35 or more, or may be 0.40 or more. The T0 / C0 of the cross-section of the blade 10 in the first delamination portion 18A is, for example, 1.00 or less, may be 0.50 or less, or may be 0.42 or less.

[0091] The T0 / C0 of the cross-section of the blade 10 in the second delamination portion 18B is, for example, 0.32 or less, may be 0.30 or less, may be 0.25 or less, or may be 0.22 or less. The T0 / C0 of the cross-section of the blade 10 in the second delamination portion 18B is, for example, 0.10 or more, may be 0.14 or more, or may be 0.18 or more.

[0092] The preferred placement surface for the structure 20 may be determined according to the T0 / C0 of the cross-section of the wing 10. For example, in positions where the cross-section is thick, the structure 20 may be placed on the lower surface 16, and in positions where the cross-section is thin, the structure 20 may be placed on the upper surface 15. The range of T0 / C0 in positions where the cross-section is thick may be the same as the above-mentioned range of T0 / C0 of the cross-section of the wing 10 in the first delamination portion 18A. The range of T0 / C0 in positions where the cross-section is thin may be the same as the above-mentioned range of T0 / C0 of the cross-section of the wing 10 in the second delamination portion 18B.

[0093] Both the first peeled portion 18A and the second peeled portion 18B are part of the peeled portion 18. In the following description, unless otherwise specified, the configurations and effects described using the term "peeled portion 18" apply to all cases: when the structure 20 is located in the peeled portion 18, when the structure 20 is located in the first peeled portion 18A, and when the structure 20 is located in the second peeled portion 18B.

[0094] The structure 20 may be a member that can be detached from the wing 10. For example, the structure 20 may be a member attached to the upper surface 15 or lower surface 16 of the detached portion 18 of the wing 10. Alternatively, the structure 20 may be a member firmly fixed to the detached portion 18 of the wing 10 by fasteners such as bolts. Alternatively, the structure 20 may be an integral component of the detached portion 18 of the wing 10.

[0095] When the wing 10 is subjected to airflow, lift and drag are generated on the wing 10. The structure 20 is a component for reducing drag. The structure 20 can reduce drag, for example, by suppressing boundary layer separation.

[0096] Referring to Figure 4A, the arrangement of the structure 20 in the code direction D2 will be described. The structure 20 includes a front end 201 and a rear end 202. The front end 201 and the rear end 202 are the ends of the structure 20 in the code direction D2. The first distance C1, which is the distance from the front edge 13 to the front end 201 in the code direction D2, is smaller than the second distance C2, which is the distance from the front edge 13 to the rear end 202 in the code direction D2.

[0097] As shown in Figure 4A, the structure 20 may be positioned such that both its front end 201 and rear end 202 are located in the peeling portion 18. When the structure 20 is located on the upper surface 15, the second distance C2 may be less than or equal to the distance Cm. The distance Cm is the distance from the front edge 13 to the maximum thickness position 15M in the cord direction D2. By adjusting the position of the structure 20 in the cord direction D2, peeling can be appropriately suppressed.

[0098] The distance Cm may be determined relative to the chord length C0 of the wing 10. The ratio of the distance Cm to the chord length C0, Cm / C0, may be, for example, 0.40 or less, and may be 0.35 or less. Cm / C0 may be, for example, 0.20 or more, and may be 0.25 or more.

[0099] The first distance C1 and the second distance C2 may be determined relative to the chord length C0 of the wing 10. When the structure 20 is located on the upper surface 15, the ratio of the first distance C1 to the chord length C0, C1 / C0, may be less than 0.10, and the ratio of the second distance C2 to the chord length C0, C2 / C0, may be 0.10 or more. That is, the structure 20 may be positioned at least partially in the chord direction D2 in a portion where the ratio of the distance from the leading edge 13 to the chord length C0 is 0.10 or less.

[0100] The structure of the structure 20 will now be described. Figure 5 is a plan view showing an example of the structure 20. The structure 20 may include a plurality of friction parts 25 and a plurality of smooth parts 26. The plurality of friction parts 25 may be arranged in the longitudinal direction D1. Each of the plurality of friction parts 25 may extend in the cord direction D2. Each of the plurality of smooth parts 26 may be located between two adjacent friction parts 25 in the longitudinal direction D1. For example, the plurality of friction parts 25 and smooth parts 26 may be arranged alternately along the longitudinal direction D1. Each of the plurality of smooth parts 26 may extend in the cord direction D2.

[0101] In Figure 5, the dotted line labeled 27 indicates the boundary between the friction portion 25 and the smooth portion 26. The imaginary line indicating the boundary is also called the boundary line. The boundary line 27 may extend parallel to the code direction D2. For example, the angle between the direction in which the boundary line 27 extends and the code direction D2 may be less than or equal to the first threshold TH1. The first threshold TH1 is, for example, 10°, but may also be 5° or 3°.

[0102] The friction section 25 may include a plurality of disturbance structures 30 that disrupt the airflow. The plurality of disturbance structures 30 may be arranged in the code direction D2. The disturbance structures 30 may extend along the longitudinal direction D1. In this case, the boundary line 27 may be defined as a line passing through the ends of the plurality of disturbance structures 30. "Extending along the longitudinal direction D1" means that the dimensions of the disturbance structures 30 in the longitudinal direction D1 are greater than the dimensions of the disturbance structures 30 in the code direction D2.

[0103] In Figure 5, the symbol S1 represents the dimension of the friction portion 25 in the code direction D2. Dimension S1 is also referred to as length S1. Length S1 may be set so that a sufficient number of disturbance structures 30 are aligned in the code direction D2. Length S1 is, for example, 10 mm or more, but may also be 25 mm or more, or 50 mm or more. By aligning a sufficient number of disturbance structures 30 in the code direction D2, the airflow along the friction portion 25 can be repeatedly disturbed by the multiple disturbance structures 30. As a result, mixing of airflows in the boundary layer is promoted. Therefore, separation can be suppressed.

[0104] In this application, the number of disturbance structures 30 arranged in the code direction D2, which is required to suppress delamination, is also called the number of repetitions. The friction portion 25 includes disturbance structures 30 equal to or greater than the number of repetitions. Preferably, the friction portion 25 includes disturbance structures 30 located in the delamination portion 18 equal to or greater than the number of repetitions. If the number of disturbance structures 30 located in the delamination portion 18 is equal to or greater than the number of repetitions, the friction portion 25 may also include disturbance structures 30 located outside the delamination portion 18.

[0105] The number of repetitions is, for example, 10, but it could also be 30, 50, or 100.

[0106] If the length S1 becomes too large, the frictional resistance that the airflow receives from the structure 20 increases, and the airflow is obstructed. Taking this into consideration, the length S1 is 25 m or less, may be 10 m or less, or may be 1 m or less.

[0107] In Figure 5, the reference numeral S2 represents the dimension of the region where the disturbance structure 30 is distributed in the longitudinal direction D1. The reference numeral S2 is set such that at least two friction portions 25 are aligned in the longitudinal direction D1.

[0108] In Figure 5, the reference numeral S21 represents the dimension of the friction portion 25 in the longitudinal direction D1. Dimension S21 is also referred to as width S21. The width S21 may be set so that the friction portion 25 can sufficiently disturb the airflow. The width S21 is, for example, 1 mm or more, may be 5 mm or more, 10 mm or more, or 50 mm or more.

[0109] On the other hand, if the width S21 becomes too large, the ratio of the size of the vortex generated at the boundary between the friction portion 25 and the smooth portion 26 to the width S21 becomes smaller. As a result, the proportion of airflow that is less affected by vortices increases. Taking this into consideration, the width S21 may be, for example, 500 mm or less, 300 mm or less, 100 mm or less, or 90 mm or less.

[0110] The width S22 of the smooth portion 26 in the longitudinal direction D1 may be the same as the width S21 of the friction portion 25, or it may be different from the width S21. The numerical range of the width S22 of the smooth portion 26 may be the same as the above-mentioned numerical range of the width S21 of the friction portion 25, or it may be different.

[0111] One reason for the generation of vortices at the boundary between the friction portion 25 and the smooth portion 26 is the difference between the resistance the airflow F experiences in the friction portion 25 and the resistance the airflow F experiences in the smooth portion 26. The larger the width S22 of the smooth portion 26, the more the airflow in the smooth portion 26 is promoted, and the lower the resistance the airflow experiences in the smooth portion 26. The smaller the resistance in the smooth portion 26, the larger the difference between the resistance in the friction portion 25 and the resistance in the smooth portion 26, and the more vortex generation is promoted. It is preferable that the width S22 of the smooth portion 26 has a certain ratio or higher to the width S21 of the friction portion 25. The ratio S22 / S21, which is the ratio of the width S22 of the smooth portion 26 to the width S21 of the friction portion 25, is, for example, 0.20 or more, may be 0.50 or more, or may be 1.00 or more. S22 / S21 is, for example, 10.00 or less, may be 5.00 or less, or may be 2.00 or less.

[0112] Figure 6 is a cross-sectional view of the structure 20 of Figure 5 as seen from the VI-VI direction. The structure 20 may include a first surface 21 and a second surface 22. The second surface 22 is the surface located on the opposite side of the first surface 21 in the thickness direction D3 of the structure 20. The second surface 22 may be a flat surface.

[0113] The first surface 21 may include a base surface 21B. For example, the structure 20 may include a base body 40 that includes a base surface 21B. The base surface 21B is the region on the first surface 21 that has the largest occupancy rate. The base surface 21B is distinguished from other regions of the first surface 21 based on its distance from the second surface 22 in the thickness direction of the structure 20. The occupancy rate of the base surface 21B on the first surface 21 may be, for example, 50% or more, 60% or more, or 70% or more.

[0114] As shown in Figure 6, the disturbance structure 30 may protrude from the base surface 21B in the thickness direction of the structure 20. Such a disturbance structure 30 is also referred to as a convex portion 301. The convex portion 301 may have a trapezoidal cross-sectional shape.

[0115] The disturbance structure 30, such as the protrusion 301, has a dimension H in the thickness direction D3 of the wing 10. The dimension of the disturbance structure 30 in the thickness direction D3 is also called the disturbance thickness. Dimension H is the distance between the base surface 21B and the tip of the disturbance structure 30 in the thickness direction D3. If the disturbance structure 30 is a protrusion 301, then dimension H, i.e., the disturbance thickness, is the height of the protrusion 301. The thickness direction D3 of the wing 10 is defined as the normal direction of the upper surface 15 at each position on the upper surface 15 of the wing 10.

[0116] Dimension H is, for example, 1.0 mm or less, but may also be 0.7 mm or less, 0.6 mm (600 μm) or less, 0.4 mm or less, 0.3 mm (300 μm) or less, or 0.2 mm (200 μm) or less. By reducing dimension H, the frictional resistance that the airflow F receives from the structure 20 can be reduced. Dimension H is, for example, 0.01 mm or more, but may also be 0.05 mm or more, 0.1 mm or more, or 0.2 mm or more.

[0117] The dimension H of the disturbance structure 30 may be determined relative to the chord length C0 of the wing 10. The ratio H / C0, which is the ratio of dimension H to chord length C0, may be, for example, 0.00030 or less, 0.00025 or less, or 0.00020 or less. When the structure 20 is located on the upper surface 15, H / C0 may be 0.00015 or less. H / C0 may be, for example, 0.00005 or more, or 0.00010 or more.

[0118] In Figure 6, the symbol W represents the dimension of the disturbance structure 30 in the code direction D2. Dimension W may be measured at the position where the disturbance structure 30 is in contact with the base surface 21B. Dimension W may also be determined in relation to dimension H. The ratio W / H, which is the ratio of dimension W to dimension H, is, for example, 0.1 or more, may be 0.3 or more, or may be 0.7 or more. W / H is, for example, 10.0 or less, may be 7.0 or less, may be 5.0 or less, may be 3.0 or less, or may be 1.5 or less.

[0119] In Figure 6, the symbol G represents the distance between two disturbance structures 30 aligned in the code direction D2. The distance G may be determined in relation to the dimension H. The ratio of the distance G to the dimension H, G / H, is, for example, 1.0 or more, may be 2.0 or more, or may be 3.0 or more. By making G / H sufficiently large, as shown in Figure 6, the airflow F1 deflected upward by colliding with the protrusion 301 can collide again with the downstream protrusion 301. As a result, the airflow along the friction portion 25 can repeatedly collide with the disturbance structure 30. G / H is, for example, 11.0 or less, may be 10.0 or less, or may be 8.0 or less. The smaller G / H, the higher the frequency with which the airflow collides with the disturbance structure 30. By appropriately setting G / H, mixing of the airflow F in the boundary layer is promoted. Therefore, the occurrence of airflow separation can be suppressed.

[0120] In Figure 6, the symbol P represents the period of multiple disturbance structures 30 arranged in the code direction D2. The period P is the sum of the dimension W and the interval G. The ratio of the period P to the dimension H, P / H, is, for example, 2.0 or more, may be 3.0 or more, or 4.0 or more. The ratio G / H is, for example, 12.0 or less, may be 11.0 or less, or 9.0 or less.

[0121] As described above, it is preferable that the airflow F1, which is deflected upward by colliding with the upstream disturbance structure 30, collides again with the downstream disturbance structure 30. The base surface 21B located between the two disturbance structures 30 aligned in the code direction D2 is also referred to as the valley region 21B1. In order for the airflow to collide again with the downstream disturbance structure 30, it is preferable that no large protrusions are placed in the valley region 21B1. This configuration suppresses disturbance of the airflow by the valley region 21B1. The spacing G described above corresponds to the dimensions of the valley region 21B1 in the code direction D2.

[0122] Figure 7 is a cross-sectional view showing one modified example of the structure 20. Small protrusions 34s may be placed on the base surface 21B located between two disturbance structures 30 aligned in the code direction D2. If the height of the small protrusions 34s is small, the airflow will hardly be disturbed by the small protrusions 34s. In this case, the airflow that collides with the upstream disturbance structure 30 can collide with the downstream disturbance structure 30 again.

[0123] In Figure 7, the symbol Hd represents the distance in the thickness direction D3 from the tip of the protrusion 301 of the disturbance structure 30 to the tip of the small projection 34s. The preferred range of distance Hd may be determined relative to the dimension H of the disturbance structure 30. The ratio of distance Hd to dimension H, Hd / H, is, for example, 0.50 or more, may be 0.60 or more, may be 0.70 or more, may be 0.80 or more, or may be 0.90 or more. Hd / H is, for example, 1.00 or less, may be 0.99 or less, or may be 0.98 or less.

[0124] The layer structure of the structure 20 will now be described. The base body 40 that constitutes the base surface 21B may include multiple layers. For example, the base body 40 may include a first substrate 41 that constitutes the base surface 21B. The first substrate 41 may be a plastic film. The plastic film may be a stretched plastic film or an unstretched plastic film. The material of the first substrate 41 may be, for example, polyvinyl chloride, polypropylene, polyethylene, polyester, polyurethane, etc.

[0125] Polyethylene resins include not only ordinary polyethylene obtained by polymerizing ethylene, but also copolymers of ethylene and α-olefins. The α-olefin is preferably one having 3 to 12 carbon atoms. Specifically, examples include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methylpentene-1, 4-methylhexene-1, and 4,4-dimethylpentene-1. The α-olefin may be used alone or in combination of two or more. Among these, unbranched α-olefins are preferred, and unbranched α-olefins with 3 to 8 carbon atoms are more preferred. Specifically, examples include 1-propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene. Having 3 to 8 carbon atoms in the α-olefin provides both good flexibility and good strength.

[0126] Examples of polyethylene resins include high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), metallocene-based linear low-density polyethylene (M-LLDPE), and very low-density polyethylene (VLDPE). Polyethylene resins may be used individually or in combination of two or more types. Among polyethylene resins, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), metallocene-based linear low-density polyethylene (M-LLDPE), and very low-density polyethylene (VLDPE) are preferred due to their good flexibility, transparency, and processability. Polyolefin resins may be crosslinked polyolefin resins or non-crosslinked polyolefin resins.

[0127] The first substrate 41 may contain additives as needed. Examples of additives include light stabilizers, ultraviolet absorbers, antioxidants, heat stabilizers, nucleating agents, dispersants, leveling agents, plasticizers, defoamers, flame retardants, fillers, and catalysts. The content of these additives is preferably 10% by mass or less, and more preferably 5% by mass or less, based on the total mass of the polyurethane resin. If the amount of these additives is greater than the above range, sufficient weather resistance may not be ensured. Examples of light stabilizers include hindered amine light stabilizers (HALS). Hindered amine light stabilizers are broadly classified into three types depending on the bonding partner of the nitrogen atom in the piperidine skeleton: N-H type (hydrogen bonded to the nitrogen atom), N-R type (alkyl group (R) bonded to the nitrogen atom), and N-OR type (alkoxy group (OR) bonded to the nitrogen atom). Among hindered amine light stabilizers, the N-OR type hindered amine light stabilizer is preferred. N-OR type HALS capture radicals faster than N-H type and N-R type. Furthermore, N-OR type low molecular weight HALS, which migrate to the surface faster than polymer HALS, capture radicals in a shorter time than N-H type and N-CH3 type HALS. Therefore, degradation of the protective layer can be suppressed. The above-mentioned weather-resistant agents such as light stabilizers, ultraviolet absorbers, and antioxidants may be added to the resin composition as a weather-resistant masterbatch dispersed in the resin. The weather-resistant masterbatch may be prepared as appropriate, or a commercially available product may be used.

[0128] The thickness of the first base material 41 is, for example, 50 μm or more, may be 80 μm or more, or may be 100 μm or more. If the thickness of the first base material 41 is above a predetermined value, sufficient erosion resistance can be obtained, and the wing 10 can be protected from sand, etc. The thickness of the first base material 41 is, for example, 700 μm or less, may be 600 μm or less, or may be 500 μm or less. If the thickness of the first base material 41 is below a predetermined value, the structure 20 becomes more stretchable, so the adhesion and conformability of the structure 20 to uneven and curved surfaces can be improved. The first base material 41 may consist of one layer, or it may consist of two or more layers. The first base material 41, which includes two or more layers, may be formed by bonding two or more layers together. Regardless of the layer configuration of the first base material 41, it is preferable that the thickness of the first base material 41 is within the above range.

[0129] The base body 40 may include an adhesive layer 42 that constitutes the second surface 22. The adhesive layer 42 may be tacky to the surface of the wing 10. The structure 20 can be attached to the surface of the wing 10 using the adhesive layer 42.

[0130] The base body 40 may include a printing layer 44 located between the first substrate 41 and the adhesive layer 42. The printing layer 44 is a layer for displaying characters, images, etc., on the structure 20. The base body 40 may include a second substrate 45 that supports the printing layer 44. The base body 40 may include an adhesive layer 46 located between the printing layer 44 and the first substrate 41. The adhesive layer 46 can bond the first substrate 41 and the second substrate 45 on which the printing layer 44 is provided.

[0131] The thickness of the base body 40 is, for example, 1 mm or less, may be 500 μm or less, or 250 μm or less. When the thickness of the base body 40 is small, the base body 40 can deform to conform to the shape of the surface of the wing 10. The thickness of the base body 40 is, for example, 50 μm or more, may be 70 μm or more, or 100 μm or more.

[0132] The method for forming the disturbance structure 30 is not particularly limited. For example, a film including the disturbance structure 30 may be formed by forming a resin layer on the base surface 21B of the base body 40 and then processing the resin layer using a mold such as a shaping roll. If the disturbance structure 30 is a convex portion, a film including the convex portion may be formed by selectively applying the material constituting the convex portion onto the base surface 21B using an inkjet method or the like. After performing a step to define the shape of the disturbance structure 30, such as the convex portion, the disturbance structure 30 may be subjected to a curing treatment. For example, if the material of the disturbance structure 30 is UV curable, the disturbance structure 30 may be irradiated with UV light.

[0133] Although not shown in the diagram, the disturbance structure 30 may be integrally constructed with the first base material 41. "Integrated" means that there is no interface between the disturbance structure 30 and the first base material 41. For example, first, a first base material 41 having a thickness greater than the dimension H of the disturbance structure 30 may be prepared, and then the first base material 41 may be processed using a shaping roll or the like. This will result in a disturbance structure 30 that is integral with the first base material 41.

[0134] For example, first, a mold is prepared. Next, a fluid raw material is poured into the mold. The raw material may contain a resin. The raw material may contain both a resin and a solvent. Next, the raw material is solidified in the mold. For example, the solvent is evaporated by heating the raw material. This forms the structure 20 inside the mold. After that, the structure 20 is removed from the mold. This gives an integrated disturbance structure 30 with the first base material 41. Thus, the structure 20 including the disturbance structure 30 may be a molded product produced by molding using a mold.

[0135] The disturbance structure 30 may be realized by molding using a transfer sheet. The transfer sheet includes, for example, a female water-soluble resin layer and a coating material layer. The female water-soluble resin layer has a pattern corresponding to the disturbance structure 30. The coating material layer is positioned on top of the pattern of the female water-soluble resin layer. After the coating material layer and the female water-soluble resin layer are transferred to the surface of the blade 10 or the surface of the first substrate 41, the female water-soluble resin layer is removed. This forms the disturbance structure 30 on the surface of the blade 10 or the surface of the first substrate 41.

[0136] Figure 8 is a cross-sectional view showing an example of the structure 20 before it is attached to the wing 10. The structure 20 may include a separator 43 that is in contact with the adhesive layer 42. The structure 20 may be distributed with the separator 43 attached. In the process of attaching the structure 20 to the wing 10, the separator 43 is removed, and then the structure 20 is attached to the wing 10.

[0137] The smooth portion 26 may include the base surface 21B described above. The occupancy rate of the base surface 21B in the friction portion 25 is referred to as the first base ratio R1. The occupancy rate of the base surface 21B in the smooth portion 26 is referred to as the second base ratio R2. The second base ratio R2 is higher than the first base ratio R1. The second base ratio R2 is, for example, 70% or more, may be 80% or more, 90% or more, 95% or more, 99% or more, or 100%.

[0138] The position and shape of the components on the first surface 21 of the structure 20 are measured using a laser displacement sensor. Based on the measurement results, the length S1, dimension S2, width S21, width S22, dimension H, dimension W, and spacing G are calculated.

[0139] The dimensions H, W, and spacing G of a single friction section 25 are calculated by averaging the measurements in three measurement areas. As shown in Figure 9, a single friction section 25 includes a first test area Sq1, a second test area Sq2, and a third test area Sq3. The first test area Sq1 is located at a distance Sc in the code direction D2 from the end of the friction section 25 on the upstream side of the code direction D2. The third test area Sq3 is located at a distance Sc in the code direction D2 from the end of the friction section 25 on the downstream side of the code direction D2. The distance Sc is determined relative to the length S1 of the friction section 25. Specifically, the distance Sc is 0.1 × S1. The second test area Sq2 is located in the center of the friction section 25 in the code direction D2. The first test area Sq1, the second test area Sq2, and the third test area Sq3 each include five disturbance structures 30 aligned in the code direction D2. Therefore, in one friction section 25, 15 disturbance structures 30 are measured. If the number of disturbance structures 30 in one friction section 25 is less than 15, all disturbance structures 30 are measured.

[0140] In the first test area Sq1, as shown in Figure 9, measurements are performed along a single scanline SL located in the center of the first test area Sq1 in the longitudinal direction D1 and parallel to the code direction D2. The single scanline SL overlaps with five disturbance structures 30 aligned in the code direction D2. The average values ​​of the dimensions H and spacing G measured along the single scanline SL are the measured values ​​of dimensions H, W, and spacing G in the first test area Sq1.

[0141] In the second test area Sq2 and the third test area Sq3, measurements are performed along a single scanline SL parallel to the code direction D2, similar to the first test area Sq1. The average values ​​of the measurements from the three measurement areas are used as the dimensions H, W, and G of this application.

[0142] The dimensions H, W, and G are measured using a sample on which the shape of the wing structure 20 has been transferred. The sample preparation process includes a coating step, a curing step, and a peeling step.

[0143] In the coating process, a resin solution containing a polymer and a curing agent is applied to the structure 20 of the wing 10. The resin solution is obtained by placing a cartridge containing the polymer and a cartridge containing the curing agent in a dispenser and mixing the polymer and curing agent in the mixing nozzle of the dispenser. The dispenser is, for example, a mixing gun.

[0144] In the curing process, the resin solution applied to the structure 20 of the wing 10 hardens. The hardened resin solution is the sample described above. In the peeling process, the sample is peeled off the structure 20 of the wing 10. The sample is made of, for example, two-component curing silicone rubber.

[0145] The sample has a structure corresponding to the disturbance structure 30 of the structure 20. For example, if the disturbance structure 30 includes a plurality of protrusions 301, the sample includes a plurality of recesses corresponding to the plurality of protrusions 301.

[0146] The measurements of dimensions H, W, and G are performed with the sample placed on a horizontal surface.

[0147] Figure 10 is a plan view showing an example of a vortex generated in the structure 20. The friction portion 25 and the smooth portion 26 extend along the chord direction D2. As shown in Figure 10, a vortex F2 of the airflow F is generated along the boundary line 27 between the friction portion 25 and the smooth portion 26. The vortex F2 can suppress the occurrence of separation in the forward portion of the blade 10.

[0148] As shown in Figure 10, the energy of the vortex F2 may increase as it moves downstream. As a result, separation is further suppressed. Preferably, as described above, the friction portion 25 includes a disturbance structure 30 located in the separated portion 18, with a number of repetitions equal to or greater than the specified number. As a result, separation is more reliably suppressed in the forward portion of the blade 10.

[0149] Figure 11 is a cross-sectional view showing an example of the airflow F around the wing 10. In the example shown in Figure 11, the wing 10 is positioned to form an angle of attack α with respect to the airflow F. The angle of attack α represents the inclination of the wing 10 with respect to the airflow F.

[0150] A boundary layer is formed around the wing 10. In the boundary layer, the airflow velocity decreases due to friction between the airflow F and the surface of the wing 10. When the wing 10 is subjected to airflow, a lift FL and a drag FD are generated on the wing 10.

[0151] The lift force FL is generated perpendicular to the relative direction of the airflow with respect to the wing 10. The lift force FL is caused by the fact that the pressure of the airflow along the upper surface 15 is lower than the pressure of the airflow along the lower surface 16. The pressure difference in the airflow is caused by the fact that the velocity of the airflow along the upper surface 15 is higher than the velocity of the airflow along the lower surface 16.

[0152] The drag force FD occurs parallel to the relative direction of the airflow with respect to the wing 10. The structure 20 is a component for reducing drag.

[0153] The structure 20 located on the upper surface 15 repeatedly disturbs the airflow F along the friction portion 25 with multiple disturbance structures 30. As a result, mixing of the airflow in the boundary layer is promoted. Therefore, as shown in Figure 11, separation around the structure 20 is suppressed. As a result, the drag force FD on the upper surface 15 is reduced.

[0154] Figure 12 is a cross-sectional view showing an example of the airflow F around the wing in the comparative configuration. In the comparative configuration, the structure 20 is not provided in the forward portion of the wing. In this case, as shown in Figure 12, a separation layer 181 is formed around the forward portion of the upper surface 15 of the wing. The separation layer 181 increases the drag force FD.

[0155] According to this embodiment, by providing the structure 20 in the forward portion of the upper surface 15 of the wing, separation around the forward portion of the upper surface 15 of the wing is suppressed. Therefore, the drag force FD can be reduced.

[0156] The first embodiment described above can be modified in various ways. Other embodiments or modifications will be described with reference to the drawings as needed. In the following description and the drawings used therein, parts that can be configured similarly to the first embodiment described above will be given the same reference numerals as those used for the corresponding parts in the first embodiment described above. Duplication of explanation will be omitted. In addition, if it is clear that the effects and advantages obtained in the first embodiment described above can also be obtained in other embodiments or modifications, the explanation may be omitted.

[0157] (First Modification) Figure 13 is a cross-sectional view showing the wing 10 in the first modification. The wing 10 may include a structure 20 located on the lower surface 16 in the separation portion 18. The structure 20 located on the lower surface 16 can contribute to reducing drag, similar to the structure 20 located on the upper surface 15.

[0158] When the structure 20 is located on the lower surface 16, the structure 20 may be positioned to overlap the maximum thickness position 15M, as shown in Figure 13. For example, the first distance C1 may be less than the distance Cm, and the second distance C2 may be greater than or equal to the distance Cm. In the example shown in Figure 13, the second distance C2 is equal to the distance Cm. Alternatively, the first distance C1 may coincide with the distance Cm. In this case, the ratio of the second distance C2 to the code length C0, C2 / C0, may be 0.50 or less, or greater than 0.50.

[0159] On the lower surface 16 of the wing 10, delamination is likely to occur downstream of the maximum thickness position 15M. By positioning the structure 20 so as to overlap the maximum thickness position 15M, delamination on the lower surface 16 of the forward portion of the wing 10 is suppressed.

[0160] When the structure 20 is located on the lower surface 16, the friction portion 25 of the structure 20 includes a disturbance structure 30 located on the peeling portion 18, with a number of repetitions equal to or greater than the specified number. The friction portion 25 may also include a disturbance structure 30 located on the lower surface 16 between the leading edge 13 and the maximum thickness position 15M, with a number of repetitions equal to or greater than the specified number. The friction portion 25 may also include a disturbance structure 30 located on the lower surface 16 between the maximum thickness position 15M and the midpoint 171, with a number of repetitions equal to or greater than the specified number.

[0161] Even when the structure 20 is located on the lower surface 16, the dimension H of the disturbance structure 30 may be determined relative to the chord length C0 of the wing 10. The ratio H / C0, which is the ratio of dimension H to chord length C0, is, for example, 0.00030 or less, may be 0.00025 or less, or may be 0.00020 or less. H / C0 is, for example, 0.00005 or more, may be 0.00010 or more, or may be 0.00015 or more.

[0162] Figure 14 is a cross-sectional view showing an example of the airflow F around the wing 10 in the first modified example. The structure 20 located on the lower surface 16 repeatedly disturbs the airflow F along the friction portion 25 with multiple disturbance structures 30. As a result, mixing of the airflow in the boundary layer is promoted. Therefore, as shown in Figure 14, separation around the structure 20 is suppressed. As a result, the drag force FD on the lower surface 16 is reduced.

[0163] As described above, the placement plane of the structure 20 may be determined according to the position of the structure 20 in the longitudinal direction D1, or it may be determined according to the T0 / C0 of the cross-section of the wing 10.

[0164] (Second Modification) Figure 15 is a cross-sectional view showing the wing 10 in the second modification. The wing 10 may include a structure 20 located on the upper surface 15 in the peeling portion 18, and a structure 20 located on the lower surface 16 in the peeling portion 18. The structure 20 located on the upper surface 15 may be referred to as the upper structure 20A, and the structure 20 located on the lower surface 16 may be referred to as the lower structure 20B.

[0165] Figure 16 is a cross-sectional view showing an example of the airflow F around the wing 10 in a second modified example. The upper structure 20A located on the upper surface 15 repeatedly disturbs the airflow F along the friction portion 25 on the upper surface 15 with multiple disturbance structures 30. The lower structure 20B located on the lower surface 16 also repeatedly disturbs the airflow F along the friction portion 25 on the lower surface 16 with multiple disturbance structures 30. As a result, mixing of airflows in the boundary layer is promoted on the upper surface 15 and the lower surface 16. Therefore, as shown in Figure 16, separation around the upper structure 20A and the lower structure 20B is suppressed on the upper surface 15 and the lower surface 16. As a result, the drag force FD on the upper surface 15 and the lower surface 16 is reduced.

[0166] (Third Modification) Figure 17 is a cross-sectional view showing the structure 20 in the third modification. As shown in Figure 17, the disturbance structure 30 may be recessed in the thickness direction of the structure 20 relative to the base surface 21B. Such a disturbance structure 30 is also referred to as a recess 302. By using the recess 302, the increase in frictional resistance caused by the structure 20 can be suppressed. In addition, damage to the disturbance structure 30 can be suppressed compared to the case in which the convex portion 301 is used.

[0167] The recess 302 has a dimension H in the thickness direction D3. Dimension H is the distance between the base surface 21B and the bottom surface of the recess 302 in the thickness direction D3. Dimension H is, for example, 1.0 mm or less, but may also be 0.7 mm or less, 0.6 mm (600 μm) or less, 0.4 mm or less, 0.3 mm (300 μm) or less, or 0.2 mm (200 μm) or less. By reducing the dimension H, the frictional resistance that the airflow F receives from the structure 20 can be reduced. Dimension H is, for example, 0.01 mm or more, but may also be 0.05 mm or more, 0.1 mm or more, or 0.2 mm or more.

[0168] (Fourth Modification) Figure 18 is a plan view showing the structure 20 in the fourth modification. As shown in Figure 18, each of the multiple disturbance structures 30 may include a first guidance structure 31 and a second guidance structure 32. The multiple first guidance structures 31 and the multiple second guidance structures 32 are each arranged in the code direction D2. Each of the multiple disturbance structures 30 may include a connecting portion 33 that connects the first guidance structure 31 and the second guidance structure 32.

[0169] Figure 19 is a plan view showing an enlarged view of the disturbance structure 30. Each of the multiple disturbance structures 30 may include a connecting portion 33 that connects the first induction structure 31 and the second induction structure 32.

[0170] The two smooth portions 26 that are in contact with the friction portion 25 are also referred to as the first smooth portion 26A and the second smooth portion 26B. The first guide structure 31 includes a first end portion 311 adjacent to the first smooth portion 26A. The first end portion 311 is a portion of the first guide structure 31 adjacent to the first smooth portion 26A and having a dimension K in the longitudinal direction D1. Dimension K is 10% of the width S21 described above.

[0171] The first end portion 311 extends toward the first smooth portion 26A along a direction inclined with respect to the code direction D2. The angle that the first end portion 311 makes with respect to the code direction D2 is also called the first inclination angle and is denoted by the symbol φ1. The first inclination angle φ1 is less than 90°. Therefore, the first induction structure 31 can impart a velocity component toward the first smooth portion 26A to the airflow F that collides with the first induction structure 31.

[0172] The first inclination angle φ1 is, for example, greater than 0°, may be 15° or more, or 30° or more. The first inclination angle φ1 is, for example, less than 90°, may be 75° or less, or 60° or less. When the first inclination angle φ1 is 15° or more and 75° or less, the force of the airflow F directed toward the first smooth section 26A can be made to be about 25% or more of the total force of the airflow F. When the first inclination angle φ1 is 30° or more and 60° or less, the force of the airflow F directed toward the first smooth section 26A can be made to be about 50% or more of the total force of the airflow F. The force of the airflow F directed toward the first smooth section 26A is proportional to the product of sinφ1 and cosφ1.

[0173] As shown in Figure 19, the first guide structure 31 includes a first upstream surface 313 and a first downstream surface 314. The first upstream surface 313 is a side surface of the first guide structure 31 located on the upstream side in the code direction D2. The first downstream surface 314 is a side surface of the first guide structure 31 located on the downstream side in the code direction D2. The first inclination angle φ1 is the angle formed by the intersection line of the first upstream surface 313 and the base surface 21B of the first end portion 311 with respect to the code direction D2.

[0174] As shown in Figure 19, the first guide structure 31 may extend linearly toward the first smooth section 26A. For example, the end of the first upstream surface 313 of the first guide structure 31 in a plan view may extend toward the first smooth section 26A at a first inclination angle φ1. The airflow F that collides with the first guide structure 31 is efficiently guided toward the first smooth section 26A. The reference numeral K1 represents the dimension in the longitudinal direction D1 of the portion of the first guide structure 31 that extends linearly toward the first smooth section 26A. The ratio of the dimension K1 to the width S21 described above, K1 / S21, is, for example, 0.20 or more, may be 0.30 or more, or may be 0.40 or more.

[0175] The first guide structure 31 may extend linearly from the connection portion 33 toward the first smooth portion 26A. For example, the first guide structure 31 may have a deviation distance of 0.1 mm or less. The deviation distance is the distance in the code direction D2 between the third virtual line IL3 and the first guide structure 31. The third virtual line IL3 is a straight line that passes through the part of one first guide structure 31 that is located furthest upstream in the code direction D2 and the part that is located furthest downstream in the code direction D2.

[0176] The structure of the second guide structure 32 will now be described. As shown in Figure 19, the second guide structure 32 includes a second end portion 321 adjacent to the second smooth portion 26B. The second end portion 321 is a part of the second guide structure 32 that is adjacent to the second smooth portion 26B and has a dimension K in the longitudinal direction D1.

[0177] The second end portion 321 extends toward the second smooth portion 26B along a direction inclined with respect to the code direction D2. The angle that the second end portion 321 makes with respect to the code direction D2 is also called the second inclination angle and is denoted by the symbol φ2. The second inclination angle φ2 is less than 90°. Therefore, the second induction structure 32 can impart a velocity component toward the second smooth portion 26B to the airflow F that collides with the second induction structure 32. The second inclination angle φ2 may be the same as or different from the first inclination angle φ1. The numerical range of the second inclination angle φ2 can be the same as the numerical range of the first inclination angle φ1 described above.

[0178] As shown in Figure 19, the second guide structure 32 includes a second upstream surface 323 and a second downstream surface 324. The second upstream surface 323 is a side surface of the second guide structure 32 located on the upstream side in the code direction D2. The first downstream surface 314 is a side surface of the second guide structure 32 located on the downstream side in the code direction D2. The second inclination angle φ2 is the angle formed by the intersection line of the second upstream surface 323 and the base surface 21B of the second end portion 321 with respect to the code direction D2.

[0179] Similar to the first guide structure 31, the second guide structure 32 may extend linearly toward the second smooth section 26B. For example, the end of the second upstream surface 323 of the second guide structure 32 in a plan view may extend toward the second smooth section 26B at a second inclination angle φ2. This allows the airflow F that collides with the second guide structure 32 to be efficiently guided toward the second smooth section 26B. The reference numeral K2 represents the dimension in the longitudinal direction D1 of the portion of the second guide structure 32 that extends linearly toward the second smooth section 26B. The ratio of the dimension K2 to the width S21 described above, K2 / S21, is, for example, 0.20 or more, may be 0.30 or more, or may be 0.40 or more.

[0180] Similar to the first guide structure 31, the second guide structure 32 may extend linearly from the connection portion 33 toward the second smooth portion 26B. For example, the second guide structure 32 may have a deviation distance of 0.1 mm or less. The deviation distance is the distance in the code direction D2 between the fourth virtual line IL4 and the second guide structure 32. The fourth virtual line IL4 is a straight line that passes through the part of a single second guide structure 32 that is located furthest upstream in the code direction D2 and the part that is located furthest downstream in the code direction D2.

[0181] Figure 20 is a cross-sectional view of the structure 20 of Figure 18 as seen from the XX-XX direction. The first guiding structure 31 includes a protrusion 301. Although not shown, if the first guiding structure 31 includes a protrusion 301, the second guiding structure 32 also includes a protrusion 301.

[0182] As shown in Figure 20, in this modified example as well, the airflow F1 that is deflected upward by colliding with the protrusion 301 can collide again with the downstream protrusion 301. As a result, the airflow along the friction portion 25 can repeatedly collide with the disturbance structure 30. The higher the frequency with which the airflow collides with the disturbance structure 30, the more the mixing of the airflow F1 in the boundary layer is promoted.

[0183] (Fifth Modification) Figure 21 is a plan view showing the disturbance structure 30 in the fifth modification. As shown in Figure 21, the connecting portion 33 that connects the first induction structure 31 and the second induction structure 32 may extend in the longitudinal direction D1. The connecting portion 33 has a dimension K3 in the longitudinal direction D1. The ratio of the dimension K3 to the width S21 described above, K3 / S21, is for example 0.20 or more, may be 0.30 or more, or may be 0.40 or more.

[0184] (Sixth Modification) Figure 22 is a plan view showing the disturbance structure 30 in the sixth modification. As shown in Figure 22, the first guide structure 31 may include a portion whose width increases as it approaches the first end portion 311. For example, the first guide structure 31 may include a portion in which the distance between the first upstream surface 313 and the first downstream surface 314 increases as it approaches the first end portion 311. Similarly, the second guide structure 32 may include a portion in which the distance between the second upstream surface 323 and the second downstream surface 324 increases as it approaches the second end portion 321.

[0185] (Seventh Modification) Figure 23 is a plan view showing the disturbance structure 30 in the seventh modification. As shown in Figure 23, the first guide structure 31 may include a portion in which the width decreases as it approaches the first end portion 311. For example, the first guide structure 31 may include a portion in which the distance between the first upstream surface 313 and the first downstream surface 314 decreases as it approaches the first end portion 311. Similarly, the second guide structure 32 may include a portion in which the distance between the second upstream surface 323 and the second downstream surface 324 decreases as it approaches the second end portion 321.

[0186] (Eighth Modification) Figure 24 is a plan view showing the disturbance structure 30 in the eighth modification. As shown in Figure 24, the disturbance structure 30 may have a curved shape in plan view. For example, the disturbance structure 30 may have a curved shape that is convex to the upstream side in plan view. In this case, the first inclination angle φ1 of the first guide structure 31 is calculated as the average value of the inclination angle with respect to the code direction D2 at each position of the first end portion 311 having dimension K. For example, the inclination angle may be measured at each position of the first end portion 311 which is divided into 10 equal parts in the code direction D2. Similarly, the second inclination angle φ2 of the second guide structure 32 is calculated as the average value of the inclination angle with respect to the code direction D2 at each position of the second end portion 321 having dimension K.

[0187] (Ninth Modification) Figure 25 is a plan view showing the disturbance structure 30 in the ninth modification. Similar to the example shown in Figure 24, the disturbance structure 30 may have a curved shape in plan view. Furthermore, the first guide structure 31 may include a portion in which the distance between the first upstream surface 313 and the first downstream surface 314 decreases as it approaches the first end portion 311, similar to the example shown in Figure 23. The second guide structure 32 may similarly include a portion in which the distance between the second upstream surface 323 and the second downstream surface 324 decreases as it approaches the second end portion 321.

[0188] (Tenth Modification) Figure 26 is a plan view showing the disturbance structure 30 in the tenth modification. As shown in Figure 26, the first guide structure 31 and the second guide structure 32 do not have to be connected. That is, the disturbance structure 30 may include a gap 34 located between the first guide structure 31 and the second guide structure 32 in the longitudinal direction D1. Reference numeral 312 represents the end portion of the first guide structure 31 facing the second guide structure 32 in the longitudinal direction D1 (also referred to as the third end portion). Reference numeral 322 represents the end portion of the second guide structure 32 facing the first guide structure 31 in the longitudinal direction D1 (also referred to as the fourth end portion).

[0189] When the dimension U of the gap 34 in the longitudinal direction D1 is small, the effect of the gap 34 on the airflow F is negligible. When the dimension U is small, the region including the gap 34 is interpreted as part of the friction portion 25 including the first guide structure 31 and the second guide structure 32, rather than the smooth portion 26. The dimension U may be, for example, 5.0 mm or less, 3.0 mm or less, 1.0 mm or less, 0.5 mm or less, or 0.1 mm or less. The dimension U may also be determined in relation to the width S22 of the smooth portion 26. The ratio U / S22, which is the ratio of the dimension U to the width S22, may be, for example, 1 / 5 or less, 1 / 10 or less, or 1 / 20 or less.

[0190] (Eleventh Modification) Figure 27 is a plan view showing the structure 20 in the eleventh modification. As shown in Figure 27, the structure 20 includes a first guide structure 31, but does not include a second guide structure 32. For example, the first end portion 311 of the first guide structure 31, which extends at a first inclination angle φ1 with respect to the chord direction D2, may be in contact with the first smooth portion 26, and the third end portion 312 of the first guide structure 31 may be in contact with the second smooth portion 26. In this modification as well, the generation of vortices at the boundary between the friction portion 25 and the first smooth portion 26 is promoted. Therefore, the pressure resistance that the blade 10 receives from the airflow F can be reduced.

[0191] (Twelfth Modification) Figure 28 is a plan view showing the structure 20 in the fourth modification. As shown in Figure 28, one friction section 25 may include a plurality of disturbance structures 30 arranged in the longitudinal direction D1 and the cord direction D2. The distance Y between two disturbance structures 30 arranged in the longitudinal direction D1 may be, for example, 5.0 mm or less, 3.0 mm or less, 1.0 mm or less, 0.5 mm or less, or 0.1 mm or less. The disturbance structure 30 is, for example, a protrusion 301. According to the example shown in Figure 28, foreign matter such as dirt can pass between two disturbance structures 30 arranged in the longitudinal direction D1. Therefore, the accumulation of foreign matter in the friction section 25 can be suppressed.

[0192] The disturbance structure 30 may also be a recess 302.

[0193] The spacing Y may be determined in relation to the width S22 of the smoothed portion 26. The ratio of the spacing Y to the width S22, Y / S22, is, for example, 1 / 5 or less, may be 1 / 10 or less, or 1 / 20 or less.

[0194] (13th Modification) Figure 29A is a plan view showing an example of a wing 10 in the 13th modification. The wing 10 may include a plurality of structures 20 located on the upper surface 15 of the peeling portion 18. Although not shown, the wing 10 may also include a plurality of structures 20 located on the lower surface 16 of the peeling portion 18. The plurality of structures 20 may be arranged in the longitudinal direction D1. The plurality of structures 20 may be arranged in the first peeling portion 18A described above. Although not shown, the plurality of structures 20 may be arranged in the second peeling portion 18B described above.

[0195] As shown in Figure 29B, the plurality of structures 20 may include at least one structure 20 located in the first peeled portion 18A and at least one structure 20 located in the second peeled portion 18B.

[0196] As shown in Figure 29C, the plurality of structures 20 may include at least one structure 20 located on the lower surface 16 in the first peeled portion 18A, and at least one structure 20 located on the upper surface 15 in the second peeled portion 18B.

[0197] (14th Modification) Figure 30 is a plan view showing an example of the wing 10 in the 14th modification. The structure 20 may be located at least partially outside the delamination portion 18. For example, the structure 20 may overlap the second boundary L2. The portion of the structure 20 located in the delamination portion 18 can suppress the occurrence of delamination. Therefore, drag can be reduced.

[0198] Although several modifications of the first embodiment described above have been explained, it is also possible to combine multiple modifications as appropriate and apply them to the first embodiment described above.

[0199] [Examples] The embodiments of the present disclosure will now be described in more detail by examples, but the embodiments of the present disclosure are not limited to the following examples unless they exceed the gist of the disclosure.

[0200] (Example 1A) A first sample SA1 and a second sample SA2 were fabricated, which constitute a portion of a wind turbine model that is a scaled-down version of the blade 10 of an actual wind turbine 1. The actual wind turbine 1 was assumed to be an NREL5MW wind turbine. The first sample SA1 includes a portion in which the ratio of the distance SL11 from the first end 11 to the length L0 is 0.1865. The second sample SA2 includes a portion in which the ratio of the distance SL12 from the first end 11 to the length L0 is 0.2516. Figure 31 is a plan view showing the positions of the first sample SA1 and the second sample SA2. In each of the first sample SA1 and the second sample SA2, the dimension SL1 in the longitudinal direction D1 was 0.65 m, and the cord length C0 in the cord direction D2 was 0.20 m. The thickness T0 of the first sample SA1 was 81 mm, and T0 / C0 was 0.405. The thickness T0 of the second sample SA2 was 70 mm, and the T0 / C0 ratio was 0.351.

[0201] Structure 20 was attached to the upper surface 15 of the first sample SA1 and the second sample SA2, respectively. The first sample SA1 and the second sample SA2, to which structure 20 was attached, are also referred to as the first evaluation sample and the second evaluation sample, respectively. The configuration of structure 20 was as follows: - Ratio of first distance C1 to code length C0: 0.00 - Ratio of second distance C2 to code length C0: 0.10 - Length S1 of structure 20 in code direction D2: 20 mm - Dimension S2 of structure 20 in longitudinal direction D1: 650 mm - Ratio of distance Cm to code length C0: 0.29 - Width S21 of friction part 25: 3 mm - Width S22 of smooth part 26: 3 mm - Structure of disturbance structure 30: convex part 301 - Height H of convex part 301: 0.01 mm or 0.03 mm

[0202] In Example 1A and Examples 1B-1C and 2A-14 described later, the width W and spacing G of the protrusions 301 were determined depending on the height H of the protrusions 301. Figure 32 shows the relationship between the height H of the protrusions 301 and the width W and spacing G of the protrusions 301.

[0203] When the height H of the protrusion 301 is 0.01 mm, the width W is 0.01 mm and the spacing G is 0.07 mm. Therefore, the period P of the protrusion 301 is 0.08 mm. As described above, the length S1 of the structure 20 in the code direction D2 is 20 mm. Therefore, when the height H of the protrusion 301 is 0.01 mm, the structure 20 contains approximately 250 disturbance structures 30 arranged in the code direction D2.

[0204] The effectiveness of the structure 20 was evaluated by wind tunnel experiments in which airflow was applied to the first and second evaluation samples. Specifically, the angle of attack of the wing 10 was varied, and the load acting on the pitch axis of the wing 10 was measured. The load was measured using a three-component force balance. The ratio of the distance from the leading edge 13 to the pitch axis in the chord direction D2 to the chord length C0 was 0.40. The conditions for the wind tunnel experiment were as follows: • Airflow velocity: 48 m / s or 36 m / s • Angle of attack: -5° to +30° (resolution: 1°) • Number of load measurements: 10,000 (measurement cycle of 1000 Hz for 10 seconds)

[0205] The average of 10,000 measurements was adopted as the load value for the first and second evaluation samples. A wind speed of 48 m / s corresponds to a Reynolds number Re = 600,000. A wind speed of 36 m / s corresponds to a Reynolds number Re = 450,000.

[0206] Based on the load values, lift and drag were calculated for the first and second evaluation samples. Based on the lift and drag, the lift coefficient and drag coefficient were calculated. The lift coefficient and drag coefficient are calculated by converting lift and drag into dimensionless parameters based on dynamic pressure and wing projected area.

[0207] Figure 34 is a graph showing the drag coefficient calculated for a first evaluation sample, which includes a structure 20 with a protrusion 301 having a height H of 0.03 mm, when the Reynolds number Re = 450,000. The horizontal axis represents the angle of attack, and the vertical axis represents the drag coefficient. The drag coefficient shows its minimum value at a specific angle of attack. In the example shown in Figure 34, the drag coefficient of the first evaluation sample showed a minimum value of 0.045 when the angle of attack was 6°.

[0208] The minimum drag coefficient calculated for the first and second evaluation samples is shown in the "Evaluation Value" row of Figure 33.

[0209] A film was attached to the upper surface 15 of the first sample SA1 and the second sample SA2. The first sample SA1 and the second sample SA2, with the film attached, are also referred to as the first reference sample and the second reference sample, respectively. The film of the reference sample is identical to the structure 20 of the evaluation sample, except that it does not contain multiple disturbance structures 30.

[0210] Wind tunnel experiments were conducted in which airflow was applied to the first and second reference samples. The conditions for the wind tunnel experiments were the same as those for the first and second evaluation samples. The minimum drag coefficients calculated for the first and second reference samples are shown in the "Reference Value" row of Figure 33.

[0211] A lower "evaluation value" than the "reference value" indicates that the structure 20 contributed to reducing the drag force. For example, in Figure 33, when H = 0.03 mm, Re = 450000, and L11 / L0 = 0.1865, the evaluation value is 0.0451 and the reference value is 0.0489. In the case of H = 0.03 mm, Re = 450000, and L11 / L0 = 0.1865, it can be seen that the structure 20 contributed to reducing the drag force.

[0212] When the height H of the protrusion 301 was 0.01 mm and 0.03 mm, the structure 20 was able to contribute to reducing the drag force.

[0213] (Example 1B) Similar to Example 1A, a second sample SA2, i.e., a second evaluation sample, was prepared with the structure 20 attached to the upper surface 15. The configuration of the structure 20 was the same as in Example 1A, except that the height H of the protrusion 301 was 0.05 mm.

[0214] Similar to Example 1A, the effect of the structure 20 was evaluated by wind tunnel experiments in which airflow was made to collide with the second evaluation sample. Subsequently, the lift and drag in the second evaluation sample were calculated based on the load values. Based on the lift and drag, the lift coefficient and drag coefficient were calculated. The minimum value of the drag coefficient calculated for the second evaluation sample is shown in the "Evaluation Value" row of Figure 33.

[0215] As shown in Figure 33, when the height H of the protrusion 301 is 0.05 mm, the structure 20 was able to contribute more significantly to reducing the drag force compared to when the height H of the protrusion 301 is 0.01 mm and 0.03 mm.

[0216] (Example 1C) Third sample SA3 and fifth sample SA5 were fabricated, which constitute a portion of a wind turbine model that is a scaled-down version of the blade 10 of an actual wind turbine 1. The actual wind turbine 1 was assumed to be the NREL5MW wind turbine. The locations of the third sample SA3 and fifth sample SA5 are shown in Figure 31. The third sample SA3 includes a portion in which the ratio of the distance SL13 from the first end 11 to the length L0 is 0.3818. The fifth sample SA5 includes a portion in which the ratio of the distance SL15 from the first end 11 to the length L0 is 0.5770. In each of the third sample SA3 and fifth sample SA5, the dimension SL1 in the longitudinal direction D1 was 0.65 m, and the cord length C0 in the cord direction D2 was 0.20 m. The thickness T0 of the third sample SA3 was 60 mm, and T0 / C0 was 0.30. The thickness T0 of the fifth sample, SA5, was 42 mm, and the T0 / C0 ratio was 0.21.

[0217] Structure 20 was attached to the upper surface 15 of the third sample SA3 and the fifth sample SA5, respectively. The third sample SA3 and the fifth sample SA5, to which structure 20 was attached, are also referred to as the third evaluation sample and the fifth evaluation sample, respectively. The configuration of structure 20 was as follows: • Ratio of the first distance C1 to the code length C0: 0.00 • Ratio of the second distance C2 to the code length C0: 0.10 • Length S1 of structure 20 in the code direction D2: 20 mm • Dimension S2 of structure 20 in the longitudinal direction D1: 650 mm • Ratio of distance Cm to code length C0: 0.29 (third sample), 0.34 (fifth sample) • Width S21 of friction part 25: 3 mm • Width S22 of smooth part 26: 3 mm • Structure of disturbance structure 30: convex part 301 • Height H of convex part 301: 0.01 mm

[0218] Similar to Example 1A, the effect of the structure 20 was evaluated by wind tunnel experiments in which airflow was applied to the third and fifth evaluation samples. Subsequently, the lift and drag in the third and fifth evaluation samples were calculated based on the load values. Based on the lift and drag, the lift coefficient and drag coefficient were calculated. The minimum value of the drag coefficient calculated for the third and fifth evaluation samples is shown in the "Evaluation Value" row of Figure 33.

[0219] A film was attached to the upper surface 15 of the third sample SA3 and the fifth sample SA5. The third sample SA3 and the fifth sample SA5, with the film attached, are also referred to as the third reference sample and the fifth reference sample, respectively. The film of the reference samples is identical to the structure 20 of the evaluation samples, except that it does not contain multiple disturbance structures 30.

[0220] Wind tunnel experiments were conducted in which airflow was applied to the third and fifth reference samples. The conditions for the wind tunnel experiments were the same as those for the third and fifth evaluation samples. The minimum drag coefficients calculated for the third and fifth reference samples are shown in the "Reference Value" row of Figure 33.

[0221] In Example 1C, when the Reynolds number Re = 600,000, the "evaluation value" was lower than the "reference value." On the other hand, when the Reynolds number Re = 450,000, the "evaluation value" was higher than the "reference value."

[0222] (Example 2A) A first evaluation sample and a second evaluation sample were prepared by attaching a structure 20 to the lower surface 16 of the first sample SA1 and the second sample SA2, respectively. The structure 20 was configured as follows: • Ratio of the first distance C1 to the code length C0: 0.15 • Ratio of the second distance C2 to the code length C0: 0.29 • Length S1 of the structure 20 in the code direction D2: 28 mm • Dimension S2 of the structure 20 in the longitudinal direction D1: 650 mm • Ratio of the distance Cm to the code length C0: 0.29 • Width S21 of the friction portion 25: 3 mm • Width S22 of the smooth portion 26: 3 mm • Structure of the disturbance structure 30: convex portion 301 • Height H of the convex portion 301: 0.01 mm, 0.03 mm, 0.05 mm, or 1.00 mm

[0223] Similar to Example 1A, the effect of the structure 20 was evaluated by wind tunnel experiments in which airflow was applied to the first and second evaluation samples. The minimum drag coefficients calculated for the first and second evaluation samples are shown in the "Evaluation Value" row of Figure 35.

[0224] First and second reference samples were prepared by attaching films to the lower surfaces 16 of the first sample SA1 and second sample SA2, respectively. Similar to Example 1A, wind tunnel experiments were conducted in which airflow was applied to the first and second reference samples. The minimum drag coefficients calculated for the first and second reference samples are shown in the "Reference Value" row of Figure 35.

[0225] The structure 20 was able to contribute to reducing the drag force when the height H of the protrusion 301 was 0.01 mm, 0.03 mm, and 0.05 mm.

[0226] (Example 2B) The third, fourth, and fifth evaluation samples were prepared by attaching the structure 20 to the lower surface 16 of the third sample SA3, the fourth sample SA4, and the fifth sample SA5, respectively. The position of the fourth sample SA4 is shown in Figure 31. The fourth sample SA4 includes a portion in which the ratio of the distance SL14 from the first end 11 to the length L0 is 0.4469. In the fourth sample SA4, the dimension SL1 in the longitudinal direction D1 was 0.65 m, and the cord length C0 in the cord direction D2 was 0.20 m. The thickness T0 of the fourth sample SA4 was 50 mm, and T0 / C0 was 0.25.

[0227] The structure 20 was configured as follows: • Ratio of the first distance C1 to the code length C0: 0.15 • Ratio of the second distance C2 to the code length C0: 0.29 • Length S1 of the structure 20 in the code direction D2: 28 mm • Dimension S2 of the structure 20 in the longitudinal direction D1: 650 mm • Ratio of the distance Cm to the code length C0: 0.29 (third sample), 0.32 (fourth sample), 0.34 (fifth sample) • Width S21 of the friction portion 25: 3 mm • Width S22 of the smooth portion 26: 3 mm • Structure of the disturbance structure 30: protrusion 301 • Height H of the protrusion 301: 0.03 mm or 0.04 mm

[0228] Similar to Example 1A, the effect of the structure 20 was evaluated by wind tunnel experiments in which airflow was applied to the third, fourth, and fifth evaluation samples. Subsequently, the lift and drag were calculated for the third, fourth, and fifth evaluation samples based on the load values. The lift coefficient and drag coefficient were calculated based on the lift and drag. The minimum value of the drag coefficient calculated for the third, fourth, and fifth evaluation samples is shown in the "Evaluation Value" row of Figure 35.

[0229] The third, fourth, and fifth reference samples were prepared by attaching films to the lower surfaces 16 of the third sample SA3, fourth sample SA4, and fifth sample SA5, respectively. Similar to Example 1A, wind tunnel experiments were conducted in which airflow was applied to the third, fourth, and fifth reference samples. The minimum drag coefficients calculated for the third, fourth, and fifth reference samples are shown in the "Reference Value" row of Figure 35.

[0230] In Example 2B, when the Reynolds number Re = 600,000, the "evaluation value" was lower than the "reference value." On the other hand, when the Reynolds number Re = 450,000, the "evaluation value" was either higher than or the same as the "reference value."

[0231] (Example 3) A first evaluation sample was prepared by attaching the structure 20 to the upper surface 15 of the first sample SA1. In Example 3, five types of first evaluation samples with different first distances C1 and C2 were prepared. The examples using the five types of first evaluation samples are referred to as Example 3-1, Example 3-2, Example 3-3, Example 3-4, and Example 3-5, respectively. The configuration of the structure 20 was as follows. - C1 / C0 and C2 / C0: 0.00 and 0.10 (Example 3-1), 0.15 and 0.29 (Example 3-2), 0.20 and 0.25 (Example 3-3), 0.29 and 0.60 (Example 3-4), and 0.60 and 1.00 (Example 3-5) - Dimension S2 of structure 20 in longitudinal direction D1: 650 mm - Ratio of distance Cm to code length C0: 0.29 - Width S21 of friction section 25: 3 mm (Examples 3-1, 3-2, 3-3), 6 mm (Examples 3-4, 3-5) - Width S22 of smooth section 26: 3 mm (Examples 3-1, 3-2, 3-3), 6 mm (Examples 3-4, 3-5) - Structure of disturbance structure 30: protrusion 301 - Height H of protrusion 301: 0.03 mm

[0232] Similar to Example 1A, the effect of the structure 20 was evaluated by wind tunnel experiments in which airflow was made to collide with the first evaluation sample. The minimum value of the drag coefficient calculated for the first evaluation sample is shown in the "Evaluation Value" row of Figure 36.

[0233] A first reference sample was prepared by attaching a film to the upper surface 15 of the first sample SA1. Similar to Example 1A, a wind tunnel experiment was conducted in which airflow was applied to the first reference sample. The minimum value of the drag coefficient calculated for the first reference sample is shown in the "Reference Value" row of Figure 36.

[0234] When multiple disturbance structures 30 are aligned along the code direction D2 between the leading edge 13 and the midpoint 171, the structure 20 was able to contribute to reducing drag.

[0235] For reference, it is explained that when C1 / C0 and C2 / C0 are 0.29 and 0.60, a sufficient number of disturbance structures 30 are arranged along the code direction D2 between the leading edge 13 and the midpoint 171. When C1 / C0 and C2 / C0 are 0.29 and 0.60, the length of the structure 20 located between the leading edge 13 and the midpoint 171 in the code direction D2 is (0.50 - 0.29) × C0 = 42 mm. When the height H of the protrusion 301 is 0.03 mm, the width W is 0.03 mm, the spacing G is 0.21 mm, and the period P of the protrusion 301 is 0.24 mm. Therefore, between the leading edge 13 and the midpoint 171, the structure 20 contains approximately 175 disturbance structures 30 arranged in the code direction D2.

[0236] (Example 4) A first evaluation sample was prepared by attaching a structure 20 to the lower surface 16 of the first sample SA1. In Example 4, six types of first evaluation samples with different first distances C1 and C2 were prepared. The examples using the six types of first evaluation samples are referred to as Example 4-1, Example 4-2, Example 4-3, Example 4-4, Example 4-5, and Example 4-6, respectively. The configuration of the structure 20 was as follows. - C1 / C0 and C2 / C0: 0.06 and 0.20 (Example 4-1), 0.15 and 0.29 (Example 4-2), 0.29 and 0.44 (Example 4-3), 0.29 and 0.52 (Example 4-4), 0.35 and 0.49 (Example 4-5), and 0.70 and 1.00 (Example 4-6) - Dimension S2 of the structure 20 in the longitudinal direction D1: 650 mm - Ratio of distance Cm to code length C0: 0.29 - Width S21 of friction part 25: 3 mm (Examples 4-1, 4-2), 6 mm (Examples 4-3, 4-4, 4-5, 4-6) - Width S22 of smooth part 26: 3 mm (Examples 4-1, 4-2), 6 mm (Examples 4-3, 4-4, 4-5, 4-6) - Structure of the disturbance structure 30: protrusion 301 - Height H of the protrusion 301: 0.03 mm

[0237] Similar to Example 1A, the effect of the structure 20 was evaluated by wind tunnel experiments in which airflow was made to collide with the first evaluation sample. The minimum value of the drag coefficient calculated for the first evaluation sample is shown in the "Evaluation Value" row of Figure 37.

[0238] A first reference sample was prepared by attaching a film to the lower surface 16 of the first sample SA1. Similar to Example 1A, a wind tunnel experiment was conducted in which airflow was applied to the first reference sample. The minimum value of the drag coefficient calculated for the first reference sample is shown in the "Reference Value" row of Figure 37.

[0239] When multiple disturbance structures 30 are aligned along the code direction D2 between the leading edge 13 and the midpoint 171, the structure 20 was able to contribute to reducing drag.

[0240] For reference, it is explained that when C1 / C0 and C2 / C0 are 0.29 and 0.52, a sufficient number of disturbance structures 30 are arranged along the code direction D2 between the leading edge 13 and the midpoint 171. When C1 / C0 and C2 / C0 are 0.29 and 0.52, the length of the structure 20 located between the leading edge 13 and the midpoint 171 in the code direction D2 is (0.50 - 0.29) × C0 = 42 mm. When the height H of the protrusion 301 is 0.03 mm, the width W is 0.03 mm, the spacing G is 0.21 mm, and the period P of the protrusion 301 is 0.24 mm. Therefore, between the leading edge 13 and the midpoint 171, the structure 20 contains approximately 175 disturbance structures 30 arranged in the code direction D2.

[0241] (Example 5) A second evaluation sample was prepared by attaching the structure 20 to the lower surface 16 of the second sample SA2. In Example 5, three types of second evaluation samples with different first distances C1 and C2 were prepared. The examples using the three types of first evaluation samples are referred to as Example 5-1, Example 5-2, and Example 5-3, respectively. The configuration of the structure 20 was as follows. - C1 / C0 and C2 / C0: 0.14 and 0.28 (Example 5-1), 0.28 and 0.36 (Example 5-2), and 0.31 and 0.39 (Example 5-3) - Dimension S2 of structure 20 in longitudinal direction D1: 650 mm - Ratio of distance Cm to code length C0: 0.29 - Width S21 of friction section 25: 3 mm (Example 5-1), 6 mm (Examples 5-2, 5-3) - Width S22 of smooth section 26: 3 mm (Example 5-1), 6 mm (Examples 5-2, 5-3) - Structure of disturbance structure 30: protrusion 301 - Height H of protrusion 301: 0.03 mm

[0242] Similar to Example 1A, the effect of the structure 20 was evaluated by wind tunnel experiments in which airflow was made to collide with the second evaluation sample. The minimum value of the drag coefficient calculated for the second evaluation sample is shown in the "Evaluation Value" row of Figure 38.

[0243] A second reference sample was prepared by attaching a film to the lower surface 16 of the second sample SA2. Similar to Example 1A, a wind tunnel experiment was conducted in which airflow was directed onto the second reference sample. The minimum drag coefficient calculated for the second reference sample is shown in the "Reference Value" row of Figure 38.

[0244] When multiple disturbance structures 30 are aligned along the code direction D2 between the leading edge 13 and the midpoint 171, the structure 20 was able to contribute to reducing drag.

[0245] (Example 6) A third evaluation sample was prepared by attaching the structure 20 to the upper surface 15 of the third sample SA3. In Example 6, two types of third evaluation samples with different first distances C1 and second distances C2 were prepared. The examples using the two types of third evaluation samples are referred to as Example 6-1 and Example 6-2, respectively. The configuration of the structure 20 was as follows. - C1 / C0 and C2 / C0: 0.15 and 0.29 (Example 6-1), and 0.29 and 0.34 (Example 6-2) - Dimension S2 of structure 20 in longitudinal direction D1: 650 mm - Ratio of distance Cm to code length C0: 0.29 - Width S21 of friction section 25: 3 mm (Example 6-1), 6 mm (Example 6-2) - Width S22 of smooth section 26: 3 mm (Example 6-1), 6 mm (Example 6-2) - Structure of disturbance structure 30: protrusion 301 - Height H of protrusion 301: 0.03 mm

[0246] Similar to Example 1A, the effect of the structure 20 was evaluated by wind tunnel experiments in which airflow was made to collide with the third evaluation sample. The minimum value of the drag coefficient calculated for the third evaluation sample is shown in the "Evaluation Value" row of Figure 39.

[0247] A third reference sample was prepared by attaching a film to the upper surface 15 of the third sample SA3. Similar to Example 1A, a wind tunnel experiment was conducted in which airflow was directed onto the third reference sample. The minimum drag coefficient calculated for the third reference sample is shown in the "Reference Value" row of Figure 39.

[0248] As shown in Figure 39, the evaluation value in Example 6-1 was superior to the evaluation value in Example 6-2 and the evaluation value in Example 1C described above, especially when the Reynolds number Re = 450,000. When the structure 20 is positioned on the upper surface 15 at a position L11 / L0 = 0.3818, it is considered preferable that C1 / C0 is 0.10 or greater and C2 / C0 is 0.30 or less.

[0249] (Example 7) A third evaluation sample was prepared by attaching the structure 20 to the lower surface 16 of the third sample SA3. In Example 7, three types of third evaluation samples with different first distances C1 and second distances C2 were prepared. The examples using the three types of third evaluation samples are referred to as Example 7-1, Example 7-2, and Example 7-3, respectively. The configuration of the structure 20 was as follows. - C1 / C0 and C2 / C0: 0.15 and 0.29 (Example 7-1), 0.29 and 0.40 (Example 7-2), and 0.70 and 1.00 (Example 7-3) - Dimension S2 of structure 20 in longitudinal direction D1: 650 mm - Ratio of distance Cm to code length C0: 0.29 - Width S21 of friction section 25: 3 mm (Example 7-1), 6 mm (Examples 7-2, 7-3) - Width S22 of smooth section 26: 3 mm (Example 7-1), 6 mm (Examples 7-2, 7-3) - Structure of disturbance structure 30: protrusion 301 - Height H of protrusion 301: 0.03 mm

[0250] Similar to Example 1A, the effect of the structure 20 was evaluated by wind tunnel experiments in which airflow was made to collide with the third evaluation sample. The minimum value of the drag coefficient calculated for the third evaluation sample is shown in the "Evaluation Value" row of Figure 40.

[0251] A third reference sample was prepared by attaching a film to the lower surface 16 of the third sample SA3. Similar to Example 1A, a wind tunnel experiment was conducted in which airflow was directed onto the third reference sample. The minimum value of the drag coefficient calculated for the third reference sample is shown in the "Reference Value" row of Figure 40.

[0252] As shown in Figure 40, the evaluation values ​​in Examples 7-1 and 7-2 were superior to the evaluation values ​​in Example 7-3 and the evaluation values ​​in Example 2B described above, especially when the Reynolds number Re = 450,000. When the structure 20 is positioned on the lower surface 16 at a position L11 / L0 = 0.3818, it is considered preferable that C1 / C0 is 0.10 or greater and C2 / C0 is 0.50 or less.

[0253] (Example 8) A sixth evaluation sample was prepared by attaching a structure 20 to the upper surface 15 of the sixth sample SA6. The location of the sixth sample SA6 is shown in Figure 31. The sixth sample SA6 includes a portion in which the ratio of the distance SL16 from the first end 11 to the length L0 is 0.7072. In the sixth sample SA6, the dimension SL1 in the longitudinal direction D1 was 0.65 m, the cord length C0 in the cord direction D2 was 0.20 m, the thickness T0 was 36 mm, and T0 / C0 was 0.18.

[0254] In Example 8, three types of sixth evaluation samples with different heights H of the protrusions were prepared. The examples using the three types of sixth evaluation samples are referred to as Example 8-1, Example 8-2, and Example 8-3, respectively. The structure 20 was configured as follows. - C1 / C0 and C2 / C0: 0.09 and 0.37 (Examples 8-1, 8-2, 8-3) - Dimension S2 of structure 20 in longitudinal direction D1: 650 mm - Ratio of distance Cm to code length C0: 0.37 (Examples 8-1, 8-2, 8-3) - Width S21 of friction part 25: 3 mm (Examples 8-1, 8-2, 8-3) - Width S22 of smooth part 26: 3 mm (Examples 8-1, 8-2, 8-3) - Structure of disturbance structure 30: protrusion 301 - Height H of protrusion 301: 0.01 mm (Example 8-1), 0.03 mm (Example 8-2), or 0.05 mm (Example 8-3)

[0255] Similar to Example 1A, the effect of the structure 20 was evaluated by a wind tunnel experiment in which airflow was made to collide with the sixth evaluation sample. The minimum value of the drag coefficient calculated for the sixth evaluation sample is shown in the "Evaluation Value" row of Figure 41.

[0256] A sixth reference sample was prepared by attaching a film to the upper surface 15 of the sixth sample SA6. Similar to Example 1A, a wind tunnel experiment was conducted in which airflow was directed onto the sixth reference sample. The minimum drag coefficient calculated for the sixth reference sample is shown in the "Reference Value" row of Figure 41.

[0257] (Example 9) A sixth evaluation sample was prepared in the same manner as in Example 8, except that the first distance C1 and the second distance C2 were different, by attaching the structure 20 to the upper surface 15 of the sixth sample SA6. In Example 9, as in Example 8, three types of sixth evaluation samples with different heights H of the protrusions were prepared. The examples using the three types of sixth evaluation samples are referred to as Example 9-1, Example 9-2, and Example 9-3, respectively. The configuration of the structure 20 was as follows. - C1 / C0 and C2 / C0: 0.45 and 0.55 (Examples 9-1, 9-2, 9-3) - Dimension S2 of structure 20 in longitudinal direction D1: 650 mm - Ratio of distance Cm to code length C0: 0.29 - Width S21 of friction section 25: 6 mm (Examples 9-1, 9-2, 9-3) - Width S22 of smooth section 26: 6 mm (Examples 9-1, 9-2, 9-3) - Structure of disturbance structure 30: protrusion 301 - Height H of protrusion 301: 0.01 mm (Example 9-1), 0.03 mm (Example 9-2), or 0.05 mm (Example 9-3)

[0258] Similar to Example 1A, the effect of the structure 20 was evaluated by a wind tunnel experiment in which airflow was made to collide with the sixth evaluation sample. The minimum value of the drag coefficient calculated for the sixth evaluation sample is shown in the "Evaluation Value" row of Figure 42.

[0259] A sixth reference sample was prepared by attaching a film to the upper surface 15 of the sixth sample SA6. Similar to Example 1A, a wind tunnel experiment was conducted in which airflow was directed onto the sixth reference sample. The minimum drag coefficient calculated for the sixth reference sample is shown in the "Reference Value" row of Figure 42.

[0260] (Example 10) A sixth evaluation sample was prepared by attaching the structure 20 to the upper surface 15 and lower surface 16 of the sixth sample SA6, respectively. In Example 10, as in Example 8, three types of sixth evaluation samples with different heights H of the protrusions were prepared. The examples using the three types of sixth evaluation samples are referred to as Example 10-1, Example 10-2, and Example 10-3, respectively. The configuration of the structure 20 was as follows. - C1 / C0 and C2 / C0: 0.09 and 0.37 (Examples 10-1, 10-2, 10-3) - Dimension S2 of structure 20 in longitudinal direction D1: 650 mm - Ratio of distance Cm to code length C0: 0.37 (Examples 10-1, 10-2, 10-3) - Width S21 of friction part 25: 3 mm (Examples 10-1, 10-2, 10-3) - Width S22 of smooth part 26: 3 mm (Examples 10-1, 10-2, 10-3) - Structure of disturbance structure 30: protrusion 301 - Height H of protrusion 301: 0.01 mm (Example 10-1), 0.03 mm (Example 10-2), or 0.05 mm (Example 10-3)

[0261] Similar to Example 1A, the effect of the structure 20 was evaluated by a wind tunnel experiment in which airflow was made to collide with the sixth evaluation sample. The minimum value of the drag coefficient calculated for the sixth evaluation sample is shown in the "Evaluation Value" row of Figure 43.

[0262] A sixth reference sample was prepared by attaching films to the upper surface 15 and lower surface 16 of the sixth sample SA6. Similar to Example 1A, a wind tunnel experiment was conducted in which airflow was directed onto the sixth reference sample. The minimum drag coefficient calculated for the sixth reference sample is shown in the "Reference Value" row of Figure 43.

[0263] (Example 11) A sixth evaluation sample was prepared by attaching the structure 20 to the lower surface 16 of the sixth sample SA6. In Example 11, as in Example 8, three types of sixth evaluation samples with different heights H of the protrusions were prepared. The examples using the three types of sixth evaluation samples are referred to as Example 11-1, Example 11-2, and Example 11-3, respectively. The configuration of the structure 20 was as follows. - C1 / C0 and C2 / C0: 0.09 and 0.37 (Examples 11-1, 11-2, 11-3) - Dimension S2 of structure 20 in longitudinal direction D1: 650 mm - Ratio of distance Cm to code length C0: 0.37 (Examples 11-1, 11-2, 11-3) - Width S21 of friction part 25: 3 mm (Examples 11-1, 11-2, 11-3) - Width S22 of smooth part 26: 3 mm (Examples 11-1, 11-2, 11-3) - Structure of disturbance structure 30: protrusion 301 - Height H of protrusion 301: 0.01 mm (Example 11-1), 0.03 mm (Example 11-2), or 0.05 mm (Example 11-3)

[0264] Similar to Example 1A, the effect of the structure 20 was evaluated by a wind tunnel experiment in which airflow was made to collide with the sixth evaluation sample. The minimum value of the drag coefficient calculated for the sixth evaluation sample is shown in the "Evaluation Value" row of Figure 44.

[0265] A sixth reference sample was prepared by attaching a film to the lower surface 16 of the sixth sample SA6. Similar to Example 1A, a wind tunnel experiment was conducted in which airflow was directed onto the sixth reference sample. The minimum drag coefficient calculated for the sixth reference sample is shown in the "Reference Value" row of Figure 44.

[0266] (Example 12) A sixth evaluation sample was prepared in the same manner as in Example 11, except that the first distance C1 and the second distance C2 were different, by attaching the structure 20 to the lower surface 16 of the sixth sample SA6. In Example 12, as in Example 11, three types of sixth evaluation samples with different heights H of the protrusions were prepared. The examples using the three types of sixth evaluation samples are referred to as Example 12-1, Example 12-2, and Example 12-3, respectively. The configuration of the structure 20 was as follows. - C1 / C0 and C2 / C0: 0.37 and 0.65 (Examples 12-1, 12-2, 12-3) - Dimension S2 of structure 20 in longitudinal direction D1: 650 mm - Ratio of distance Cm to code length C0: 0.37 (Examples 12-1, 12-2, 12-3) - Width S21 of friction part 25: 6 mm (Examples 12-1, 12-2, 12-3) - Width S22 of smooth part 26: 6 mm (Examples 12-1, 12-2, 12-3) Example - Structure of disturbance structure 30: protrusion 301 - Height H of protrusion 301: 0.01 mm (Example 12-1), 0.03 mm (Example 12-2), or 0.05 mm (Example 12-3)

[0267] Similar to Example 1A, the effect of the structure 20 was evaluated by a wind tunnel experiment in which airflow was made to collide with the sixth evaluation sample. The minimum value of the drag coefficient calculated for the sixth evaluation sample is shown in the "Evaluation Value" row of Figure 45.

[0268] As can be seen from Figures 41 to 45, even when the structure 20 is positioned on the upper surface 15 or lower surface 16 at a position L11 / L0 = 0.7072, the structure 20 was able to contribute to reducing the drag force.

[0269] (Example 13) Figure 46 is a table showing the relationship between the arrangement of the structure 20 in the longitudinal direction D1 and the minimum value of the drag coefficient. The minimum value of the drag coefficient for each arrangement is the minimum value of the drag coefficient of the evaluation sample evaluated under various conditions relating to the height H of the protrusion, the first distance C1, and the second distance C2. The table in Figure 46 also shows the T0 / C0 of the cross section of the wing 10 at the position where the structure 20 is arranged in the longitudinal direction D1. As shown in Figure 46, in Example 13, a wing 10 is assumed in which the T0 / C0 of the cross section decreases as it moves away from the first end 11 in the longitudinal direction D1.

[0270] In the "Placement Surface of Structure" column of Figure 46, "Top Surface" means that the structure 20 is placed on the top surface 15, and "Bottom Surface" means that the structure 20 is placed on the bottom surface 16.

[0271] As shown in Figure 46, when L11 / L0 is 0.40 or less or 0.30 or less, it is preferable that the placement surface of the structure 20 is the bottom surface 16. On the other hand, when L11 / L0 is greater than 0.40 or greater than 0.50, it is preferable that the placement surface of the structure 20 is the top surface 15.

[0272] As shown in Figure 46, when T0 / C0 is 0.30 or greater, or 0.35 or greater, it is preferable that the placement surface of the structure 20 is the bottom surface 16. On the other hand, when T0 / C0 is less than 0.35, or less than 0.30, it is preferable that the placement surface of the structure 20 is the top surface 15.

[0273] As shown in Figure 46, it is preferable that the structure 20 be at least partially positioned in the code direction D2 in a portion where the ratio of the distance from the leading edge 13 to the code length C0 is 0.00 or more and 0.50 or less.

[0274] (Example 14) At various positions on the blade 10 in the longitudinal direction D1, the structure 20 was placed on the upper surface 15 or the lower surface 16, and the lift coefficient and drag coefficient at the most frequent angle of attack were calculated. Based on the calculation results of the lift coefficient and drag coefficient, the torque generated on the blade 10 due to the structure 20 when the structure 20 is applied to a 5MW class wind turbine was calculated.

[0275] The formula for calculating torque is shown below.

[0276] The meaning of the symbols in the above formula is as follows: Q: Torque [N・m] r min : Minimum radius position [m] for each airfoil shape max : Maximum radius position for each airfoil [m] L': Lift acting per unit length [N / m] D': Drag acting per unit length [N / m]

[0277] L' and D' are expressed by the following formulas.

[0278] The symbols in the above formula have the following meanings: ρ: air density = 1.225 [kg / m³] 3 ] c': Chord length at the center of each airfoil in the span direction (longitudinal direction D1) [m] W: Relative inflow velocity [m / s] U R :Rated wind speed=12.5[m / s] 30ω / π:Rated rotation speed=12.1[min -1 ] φ: Relative inflow angle [°] θ Twist : Wing twist angle [°] α mode :Mode angle of attack [°]

[0279] Figure 47 is a table showing the parameters used to calculate the torque for each airfoil. Figure 48 is a table showing the results of calculating the change in torque at each position in the longitudinal direction D1, attributable to the structure 20.

[0280] As shown in Figure 48, when the structure 20 is placed in the first peeling portion 18A, for example, when L11 / L0 is 0.40 or less, it is preferable that the placement surface of the structure 20 be the lower surface 16. On the other hand, when the structure 20 is placed in the second peeling portion 18B, for example, when L11 / L0 is greater than 0.40, it is preferable that the placement surface of the structure 20 be the upper surface 15. When L11 / L0 is greater than 0.70, it can be said that the placement surface of the structure 20 may be both the upper surface 15 and the lower surface 16.

[0281] Figure 49 is a table showing the results of calculating the change in torque across the entire blade 10 under conditions 1 to 5, based on the evaluation results shown in Figure 48. The details of conditions 1 to 5 are as follows: Condition 1: In the first peeled portion 18A, the structure 20 is placed on the lower surface 16, and in the second peeled portion 18B, the structure 20 is placed on the upper surface 15. Condition 2: In the first peeled portion 18A, the structure 20 is placed on the lower surface 16, and in the second peeled portion 18B, the structure 20 is placed on the upper surface 15 or on both the upper surface 15 and the lower surface 16. Condition 3: In the first peeled portion 18A, the structure 20 is placed on the lower surface 16, and in the second peeled portion 18B, the structure 20 is placed on the lower surface 16. Condition 4: In the first peeled portion 18A, the structure 20 is placed on the upper surface 15, and in the second peeled portion 18B, the structure 20 is placed on the upper surface 15. Condition 5: In the first peeled portion 18A, the structure 20 is placed on the upper surface 15, and in the second peeled portion 18B, the structure 20 is placed on the lower surface 16.

[0282] As can be seen from Figure 49, it is preferable to place the structure 20 on the lower surface 16 in the first peeled portion 18A, and on the upper surface 15 or on both the upper surface 15 and the lower surface 16 in the second peeled portion 18B.

[0283] (Second Embodiment) The second embodiment is based on Japanese Patent Application No. 2024-165679, filed on 24 September 2024, and claims priority thereunder. The second embodiment relates to a wind turbine and a structure attached to the wind turbine.

[0284] As disclosed in Patent Document 1 mentioned above, it is known to provide a structure for generating vortices on the trailing edge of a wing. However, the structure provided on the wing itself may increase drag.

[0285] A second embodiment of this disclosure aims to provide a wind turbine capable of reducing drag caused by the structure.

[0286] A second embodiment of the present disclosure is a wind turbine comprising: a rotor shaft; and a plurality of blades aligned in the rotational direction of the rotor shaft and receiving airflow, wherein each blade includes a first end toward the rotor shaft; a second end located opposite the first end in the longitudinal direction of the blade; a leading edge and a trailing edge extending from the first end to the second end; and an upper surface and a lower surface extending from the leading edge to the trailing edge; the blade includes a plurality of friction portions located at least on the upper surface and aligned in the longitudinal direction; and a smooth portion located between the friction portions in the longitudinal direction; each of the plurality of friction portions includes a plurality of disturbance structures aligned in the chord direction from the leading edge to the trailing edge and disturbing the airflow; the plurality of friction portions includes a first friction portion having a first dimension in the thickness direction of the blade and containing the plurality of disturbance structures; and a second friction portion located outside the first friction portion in the longitudinal direction of the blade and containing a second dimension in the thickness direction of the blade. The second dimension is smaller than the first dimension and relates to a wind turbine.

[0287] According to the second embodiment of this disclosure, the resistance force caused by the structure can be reduced.

[0288] A second embodiment of this disclosure will be described in detail with reference to the drawings. The second embodiment shown below is an example of an embodiment of this disclosure, and this disclosure is not to be construed as being limited to these embodiments only. In the following description and in the drawings used therein, parts that can be configured in the same way as in the first embodiment described above will be given the same reference numerals as those used for the corresponding parts in the first embodiment described above. Duplication of explanation will be omitted. In addition, if it is clear that the effects and advantages obtained in the first embodiment described above can also be obtained in the second embodiment or a modified example, that explanation may be omitted.

[0289] Figure 50 is a plan view showing an example of the wing 10. Figure 51 is a cross-sectional view showing the wing 10 of Figure 50 as viewed from the LI-LI direction. As described above, the wing 10 includes an upper surface 15 and a lower surface 16 that extend from the leading edge 13 to the trailing edge 14. The upper surface 15 and the lower surface 16 may be distinguished based on their distance from the chord wire 17. The distance between the upper surface 15 and the chord wire 17 may be greater than the distance between the lower surface 16 and the chord wire 17.

[0290] As shown in Figures 50 and 51, in the second embodiment as well, the wind turbine 1 includes a structure 20 located on the surface of the blade 10. The structure 20 may be located at least on the upper surface 15 of the blade 10. The structure 20 is a component for reducing drag, as in the first embodiment.

[0291] Referring to Figure 50, the arrangement of the structure 20 in the longitudinal direction D1 will be described. The structure 20 may be located in a first length region 151 on the upper surface 15. The first length region 151 is a region on the upper surface 15 where the distance from the first end 11 is between a distance L01 and a distance L02. By arranging the structure 20 in the first length region 151, the drag force FD generated on the blade 10 can be reduced. By reducing the drag force FD, the rotational efficiency of the wind turbine 1 can be increased. For example, the rotational speed of the wind turbine 1 can be increased when the blade 10 is subjected to a constant airflow.

[0292] The distance L01 may be determined relative to the length L0 of the wing 10. The ratio L01 / L0, which is the ratio of the distance L01 to the length L0, may be greater than 0.00, 0.10 or more, or 0.20 or more.

[0293] The distance L02 may be determined relative to the length L0 of the wing 10. The ratio of the distance L02 to the length L0, L02 / L0, is, for example, 0.60 or less, may be 0.55 or less, or may be 0.50 or less.

[0294] The length L0 of the wing 10 is the dimension of the wing 10 along the longitudinal direction D1. The numerical range of the length L0 of the wing 10 may be the same as the numerical range described above in the first embodiment.

[0295] Referring to Figure 51, the arrangement of the structure 20 in the code direction D2 will be explained. The structure 20 may be located in the first code region 153 on the upper surface 15. The first code region 153 is an area on the upper surface 15 where the distance from the leading edge 13 is between a distance C11 and a distance C12. By arranging the structure 20 in the first code region 153, it is possible to suppress the structure 20 itself from acting as resistance to the airflow.

[0296] The distance C11 may be determined relative to the chord length C0 of the wing 10. The chord length C0 is the distance in the chord direction D2 from the leading edge 13 to the trailing edge 14. The chord length C0 may vary depending on the position in the longitudinal direction D1 of the wing 10. At each position in the longitudinal direction D1 of the wing 10, the ratio of the distance C11 to the chord length C0, C11 / C0, is, for example, greater than 0.00, may be 0.10 or greater, or may be 0.20 or greater.

[0297] The distance C12 may be determined relative to the chord length C0 of the wing 10. At each position in the longitudinal direction D1 of the wing 10, the ratio of the distance C12 to the chord length C0, C12 / C0, is, for example, 0.50 or less, may be 0.40 or less, or may be 0.30 or less. As shown in Figure 51, the structure 20 may be located at least at the maximum thickness position 15M.

[0298] The basic configuration of structure 20 is the same as that of structure 20 in the first embodiment shown in Figures 5 to 10, so a detailed explanation is omitted. The numerical ranges of each component of structure 20 included in the explanation of Figures 5 to 10 are also applicable to the second embodiment.

[0299] Figure 52 is a cross-sectional view showing an example of a boundary layer 50 formed around the structure 20. In the boundary layer 50, the velocity of the airflow is reduced due to friction between the airflow and the surface of the wing 10.

[0300] In FIG. 52, reference numeral 51 represents the separation point 51 where the boundary layer 50 separates from the surface of the blade 10. By providing the structure 20 on the surface of the blade 10, the separation point 51 can be shifted downstream compared to the case where the structure 20 is not provided on the blade 10. Therefore, the pressure resistance that the blade 10 receives from the airflow can be reduced.

[0301] In FIG. 52, reference numeral δ represents the thickness of the boundary layer 50 at the maximum thickness position 15M. The thickness δ of the boundary layer 50 is calculated by the following formula. δ = 0.37 × Cm × ((U × Cm) / ν) －０．２ Cm is the distance from the leading edge 13 to the maximum thickness position 15M in the chord direction D2. U is the relative velocity of the airflow with respect to the blade 10. ν is the kinematic viscosity of air.

[0302] Incidentally, in the wind turbine 1, the moving speed of the blade 10 in the rotational direction changes according to the position of the surface of the blade 10 in the longitudinal direction D1. Specifically, the moving speed of the blade 10 increases as it goes from the first end 11 to the second end 12. Therefore, the relative velocity U of the airflow with respect to the blade 10 also changes according to the position of the surface of the blade 10 in the longitudinal direction D1.

[0303] When the velocity U changes, the influence that the friction part 25 exerts on the airflow also changes. The influence that the friction part 25 exerts on the airflow can be expressed, for example, by the roughness Reynolds number k + and can be expressed. The roughness Reynolds number k + is calculated by the following formula. k + = (H × u * ) / ν H is the dimension of the disturbance structure 30 in the thickness direction D3. u * is the velocity of the airflow turbulence. u * is, for example, U / 20. U is the relative velocity of the airflow with respect to the blade 10. ν is the kinematic viscosity of air.

[0304] In the present embodiment, it is proposed to adjust the dimension H of the disturbance structure 30 of the friction part 25 according to the position of the surface of the blade 10 in the longitudinal direction D1 so that the roughness Reynolds number k + is, for example, not less than 5.0 and not more than 20.0. k +If the value is less than 5.0, the friction portion 25 becomes a smooth surface with respect to the airflow, which may result in insufficient vortex generation. + If the value is greater than 20.0, the disturbance structure 30 of the friction section 25 itself may become a resistance to the airflow, potentially increasing the drag force FD. + When the value is between 5.0 and 20.0, it is possible to suppress the increase in the drag force FD while appropriately generating vortices around the friction portion 25.

[0305] Figure 53 is a plan view showing an example of a friction portion 25 proposed in this embodiment. The plurality of friction portions 25 include at least one first friction portion 25A and a second friction portion 25B corresponding to the first friction portion 25A. The second friction portion 25B is located outward from the first friction portion 25A in the longitudinal direction D1. "Outward in the longitudinal direction D1" means the side away from the first end 11 in the longitudinal direction D1. Therefore, the distance between the first end 11 and the second friction portion 25B is longer than the distance between the first end 11 and the first friction portion 25A.

[0306] The second friction portion 25B may be the friction portion 25 among the multiple friction portions 25 whose distance from the first friction portion 25A in the longitudinal direction D1 is closest to the reference distance Sln. In Figure 53, the distances between the first friction portion 25A and the three friction portions 25 located further outward in the longitudinal direction D1 than the first friction portion 25A are represented by the symbols In1, In2, and In3. The absolute value of the difference between distance In2 and the reference distance Sln is smaller than the absolute value of the difference between distance In1 and the reference distance Sln, and also smaller than the absolute value of the difference between distance In3 and the reference distance Sln. Therefore, the friction portion 25 whose distance from the first friction portion 25A is distance In2 is defined as the second friction portion 25B.

[0307] The reference interval Sln may be determined relative to the length L0 of the wing 10. For example, the reference interval Sln may be 0.2 times the length L0.

[0308] As shown in Figure 53, the relative velocity U2 of the airflow with respect to the second friction section 25B is greater than the relative velocity U1 of the airflow with respect to the first friction section 25A.

[0309] The first friction section 25A and the second friction section 25B each include a plurality of disturbance structures 30. The plurality of disturbance structures 30 of the first friction section 25A have a first dimension H1 in the thickness direction D3. The plurality of disturbance structures 30 of the second friction section 25B have a second dimension H2 in the thickness direction D3. The second dimension H2 is smaller than the first dimension H1. By introducing such a difference in dimensions, the roughness Reynolds number k corresponding to the position of the surface of the blade 10 in the longitudinal direction D1 is increased compared to the case where the plurality of friction sections 25 have the same dimension H. + The amount of change can be reduced. This makes it possible to suppress the increase in drag force FD while generating vortices around the friction part 25.

[0310] The ratio of the second dimension H2 to the first dimension H1 is, for example, 0.70 or less, may be 0.60 or less, or 0.50 or less. The ratio of the second dimension H2 to the first dimension H1 is, for example, 0.04 or more, may be 0.10 or more, or 0.20 or more.

[0311] The first friction portion 25A may be the friction portion 25 among the multiple friction portions 25 that is closest to the first reference distance in the longitudinal direction D1 from the first end 11. In Figure 53, the first reference line, which is at the first reference distance from the first end 11 in the longitudinal direction D1, is represented by the symbol SL1. The friction portion 25 closest to the first reference line SL1 is determined to be the first friction portion 25A.

[0312] The first reference distance may be determined relative to the length L0 of the wing 10. For example, the first reference distance may be 0.2 times the length L0.

[0313] Figure 54 is a plan view showing another example of the friction portion 25. The relationship between the first dimension H1 of the first friction portion 25A and the second dimension H2 of the second friction portion 25B may be satisfied in multiple friction portion pairs. A friction portion pair includes two friction portions 25 determined based on the reference interval Sln described above.

[0314] In the example shown in Figure 54, the structure 20 includes friction parts 251, 252, 253, 254, and 255 arranged from the inside to the outside in the longitudinal direction D1. Each of the friction parts 251, 252, 253, 254, and 255 includes a plurality of disturbance structures 30.

[0315] The friction portion 253 is the friction portion 25 located outside the friction portion 251, and whose distance from the friction portion 251 in the longitudinal direction D1 is closest to the reference distance Sln. Therefore, the friction portion 251 and the friction portion 253 constitute a single friction portion pair FP1.

[0316] The friction portion 254 is the friction portion 25 located outside the friction portion 252, and the distance between it and the friction portion 252 in the longitudinal direction D1 is closest to the reference distance Sln. Therefore, the friction portion 252 and the friction portion 254 constitute a single friction portion pair FP2.

[0317] The friction portion 255 is the friction portion 25 located outside the friction portion 253, and whose distance from the friction portion 253 in the longitudinal direction D1 is closest to the reference distance Sln. Therefore, the friction portion 253 and the friction portion 255 constitute a single friction portion pair FP3.

[0318] The relationship between the first dimension H1 of the first friction part 25A and the second dimension H2 of the second friction part 25B may be satisfied in friction part pairs FP1, FP2, and FP3. For example, the following relationships may be satisfied: • Dimension H of the disturbance structure 30 of friction part 253 < Dimension H of the disturbance structure 30 of friction part 251 • Dimension H of the disturbance structure 30 of friction part 254 < Dimension H of the disturbance structure 30 of friction part 252 • Dimension H of the disturbance structure 30 of friction part 255 < Dimension H of the disturbance structure 30 of friction part 253

[0319] The above-mentioned numerical range for the ratio of the second dimension H2 to the first dimension H1 may also be satisfied in the ratio of the dimension H of the disturbance structure 30 of friction part 253 to the dimension H of the disturbance structure 30 of friction part 251. The above-mentioned numerical range for the ratio of the second dimension H2 to the first dimension H1 may also be satisfied in the ratio of the dimension H of the disturbance structure 30 of friction part 254 to the dimension H of the disturbance structure 30 of friction part 252. The above-mentioned numerical range for the ratio of the second dimension H2 to the first dimension H1 may also be satisfied in the ratio of the dimension H of the disturbance structure 30 of friction part 255 to the dimension H of the disturbance structure 30 of friction part 253.

[0320] The number of friction part pairs selected based on the reference interval Sln is called the total number of pairs. For example, if 100 friction parts 25 are arranged regularly in the longitudinal direction D1 with a period P1, and the reference interval Sln is equal to 5 × P1, then the total number of pairs is 95.

[0321] Among the friction part pairs selected based on the reference interval Sln, friction part pairs that satisfy the relationship between the first dimension H1 of the first friction part 25A and the second dimension H2 of the second friction part 25B are called first-satisfying pairs. The number of first-satisfying pairs is called the number of first-satisfying pairs. The ratio of the number of first-satisfying pairs to the total number of pairs is also called the first-satisfaction rate. For example, if the relationship second dimension H2 < first dimension H1 is satisfied in 90 out of 95 friction part pairs, the first-satisfaction rate is 90 / 95. If the dimension H of 100 friction part 25s decreases monotonically from the first end 11 to the second end 12, the first-satisfaction rate is 95 / 95.

[0322] A pair of friction parts that satisfies the above-mentioned numerical range for the ratio of the second dimension H2 to the first dimension H1 may be called the first satisfactory pair.

[0323] The first satisfaction rate is, for example, 0.80 or higher, may be 0.85 or higher, or 0.90 or higher. The first satisfaction rate is, for example, 1.00 or less, may be 0.99 or less, or 0.95 or less.

[0324] According to this embodiment, by adjusting the dimension H1 of the disturbance structure 30 of the friction portion 25 according to its position in the longitudinal direction D1, it is possible to appropriately generate vortices around the friction portion 25 while suppressing the increase in drag force FD.

[0325] The second embodiment described above can be modified in various ways. Other embodiments or modifications will be described with reference to the drawings as needed. In the following description and the drawings used therein, parts that can be configured similarly to the first or second embodiment described above will be given the same reference numerals as those used for the corresponding parts in the first or second embodiment described above. Duplication of explanation will be omitted. In addition, if it is clear that the effects and advantages obtained in the first or second embodiment described above can also be obtained in other embodiments or modifications, the explanation may be omitted.

[0326] (First Modification) As can be seen from the above equation, the greater the relative velocity U of the airflow with respect to the wing 10, the greater the thickness δ of the boundary layer 50. In this modification, we propose adjusting the width S21 of the friction portion 25 according to the position of the surface of the wing 10 in the longitudinal direction D1, so that the ratio of the width S21 of the friction portion 25 to the thickness δ of the boundary layer 50 is, for example, 1.0 or more and 8.0 or less. If S21 / δ, which is the width S21 of the friction portion 25 with respect to the thickness δ of the boundary layer 50, is less than 1.0, vortex generation may be insufficient. If S21 / δ is greater than 8.0, vortex generation may also be insufficient, and the drag force FD may increase. When S21 / δ is between 1.0 and 8.0, it is possible to appropriately generate vortices around the friction portion 25 while suppressing the increase in drag force FD.

[0327] Figure 55 is a plan view showing the structure 20 in the first modified example. As shown in Figure 55, the width (second width) S21B of the second friction section 25B may be smaller than the width (first width) S21A of the first friction section 25A. By introducing such a difference in width, the amount of change in the thickness δ of the boundary layer 50 according to the position of the surface of the wing 10 in the longitudinal direction D1 can be reduced compared to the case in which multiple friction sections 25 have the same width S21. This makes it possible to suppress the increase in drag force FD while appropriately generating vortices around the friction section 25.

[0328] The ratio of width S21B to width S21A is, for example, 0.85 or less, may be 0.75 or less, or 0.60 or less. The ratio of width S21B to width S21A is, for example, 0.05 or more, may be 0.10 or more, or 0.20 or more.

[0329] Figure 56 is a plan view showing another example of the friction portion 25. The relationship between the width S21A of the first friction portion 25A and the width S21B of the second friction portion 25B may be satisfied in multiple friction portion pairs. A friction portion pair includes two friction portions 25 determined based on the reference interval Sln described above.

[0330] The relationship between the width S21A of the first friction part 25A and the width S21B of the second friction part 25B may be satisfied in friction part pairs FP1, FP2, and FP3. For example, the following relationships may be satisfied: • Width S213 of friction part 253 < Width S211 of friction part 251 • Width S214 of friction part 254 < Width S212 of friction part 252 • Width S215 of friction part 255 < Width S213 of friction part 253

[0331] The above-mentioned numerical range for the ratio of width S21B to width S21A may be satisfied in the ratio of width S213 of friction part 253 to width S211 of friction part 251. The above-mentioned numerical range for the ratio of width S21B to width S21A may be satisfied in the ratio of width S214 of friction part 254 to width S212 of friction part 252. The above-mentioned numerical range for the ratio of width S21B to width S21A may be satisfied in the ratio of width S215 of friction part 255 to width S213 of friction part 253.

[0332] Among the friction part pairs selected based on the reference interval Sln, friction part pairs that satisfy the relationship between the width S21A of the first friction part 25A and the width S21B of the second friction part 25B are called second-satisfying pairs. The number of second-satisfying pairs is called the number of second-satisfying pairs. The ratio of the number of second-satisfying pairs to the total number of pairs is also called the second-satisfaction rate. For example, if the relationship width S21B < width S21A is satisfied in 90 out of 95 friction part pairs, the second-satisfaction rate is 90 / 95. If the width S21 of 100 friction part pairs decreases monotonically from the first end 11 to the second end 12, the second-satisfaction rate is 95 / 95.

[0333] A pair of friction parts that satisfies the above-mentioned numerical range for the ratio of width S21B to width S21A may be called a second sufficient pair.

[0334] The second satisfaction rate is, for example, 0.80 or higher, may be 0.85 or higher, or 0.90 or higher. The second satisfaction rate is, for example, 1.00 or lower, may be 0.99 or lower, or 0.95 or lower.

[0335] According to this modified example, by adjusting the width S21 of the friction portion 25 according to its position in the longitudinal direction D1, it is possible to appropriately generate vortices around the friction portion 25 while suppressing the increase in the drag force FD.

[0336] (Second Modification) Similar to the third modification of the first embodiment shown in Figure 17 above, the disturbance structure 30 may be recessed relative to the base surface 21B in the thickness direction of the structure 20.

[0337] (Third Modification) Similar to the twelfth modification of the first embodiment shown in Figure 28 above, one friction portion 25 may include a plurality of disturbance structures 30 arranged in the longitudinal direction D1 and the cord direction D2.

[0338] (Fourth Modification) The structure 20 may be located on the peeling portion 18 shown in Figure 3A, the first peeling portion 18A shown in Figure 3B, or the second peeling portion 18B shown in Figure 3C, as in the first embodiment. The structure 20 may be located on the upper surface 15 or on the lower surface 16. In other words, the arrangement of the structure 20 in the first embodiment or its modification may be adopted in the second embodiment or its modification. Conversely, the configuration of the structure 20 having the first friction portion 25A and the second friction portion 25B in the second embodiment or its modification may be adopted in the first embodiment or its modification.

[0339] The arrangement of the structure 20 in the code direction D2 in the first embodiment or its modified form, as shown in Figure 4A or Figure 4B above, may be adopted in the second embodiment or its modified form. Conversely, the configuration of the structure 20 having the first friction portion 25A and the second friction portion 25B in the second embodiment or its modified form may be adopted in the first embodiment or its modified form, as shown in Figure 4A or Figure 4B.

[0340] (Fifth Modification) Figure 57 is a plan view showing an example of a wing 10 in the fifth modification. The wing 10 may include a structure 20 located in a first length region 151 and a structure 20 located in a second length region 152. The second length region 152 is a region on the upper surface 15 where the distance from the first end 11 is between a distance L03 and a distance L04. The structure 20 located in the second length region 152 may be separated from the structure 20 located in the first length region 151.

[0341] The distance L03 may be determined relative to the length L0 of the wing 10. The ratio of distance L03 to length L0, L03 / L0, is, for example, greater than 0.00, may be 0.30 or more, or 0.50 or more. The distance L04 may be determined relative to the length L0 of the wing 10. The ratio of distance L04 to length L0, L04 / L0, is, for example, less than 1.00, may be 0.99 or less, or 0.95 or less.

[0342] In the structure 20 located in the second length region 152, the first friction portion 25A may be the friction portion 25 among a plurality of friction portions 25 that is closest to the second reference distance in the longitudinal direction D1 from the first end 11. The second reference distance may be determined relative to the length L0 of the wing 10. The second reference distance is, for example, 0.6 times the length L0.

[0343] Although not shown in the figures, the wing 10 includes a structure 20 located in the second length region 152, but does not necessarily include a structure 20 located in the first length region 151.

[0344] (Sixth Modification) Figure 58 is a plan view showing an example of the wing 10 in the sixth modification. The wing 10 may include two structures 20 located in the first length region 151. The two structures 20 may be separated from each other in the longitudinal direction D1. The two structures 20 may be located in the first delamination portion 18A described above.

[0345] The wing 10 may include two structures 20 located in the second length region 152. The two structures 20 may be separated from each other in the longitudinal direction D1. The two structures 20 may be located in the second separation portion 18B described above.

[0346] As shown in Figure 29B above, the plurality of structures 20 may include at least one structure 20 located in the first peeling portion 18A and at least one structure 20 located in the second peeling portion 18B. As shown in Figure 29C above, the plurality of structures 20 may include at least one structure 20 located on the lower surface 16 in the first peeling portion 18A and at least one structure 20 located on the upper surface 15 in the second peeling portion 18B.

[0347] Although several modifications of the second embodiment described above have been explained, it is also possible to combine multiple modifications as appropriate and apply them to the second embodiment described above. Furthermore, it is also possible to combine the first embodiment or its modifications as appropriate and apply them to the second embodiment described above. Furthermore, it is also possible to combine the second embodiment or its modifications as appropriate and apply them to the first embodiment described above.

[0348] [Examples] Next, a second embodiment of the present disclosure will be described in more detail by reference to examples, but the second embodiment of the present disclosure is not limited to the following examples unless it exceeds the gist of the disclosure.

[0349] (Example 2.1) The friction portions 25 at each position of the blade 10 in the longitudinal direction D1 have a first roughness Reynolds number k + The dimensions H of the disturbance structure 30 were calculated to achieve this. The first roughness Reynolds number k + It is 5. Also, the friction portion 25 at each position of the wing 10 in the longitudinal direction D1 has a second roughness Reynolds number k. + The dimensions H of the disturbance structure 30 were calculated to achieve the second roughness Reynolds number k. + The answer is 20.

[0350] The calculation conditions are as follows: • Length L0 of the wing 10 in the longitudinal direction D1: 110 mm • Position Lx of the friction section 25 in the longitudinal direction D1: 11 m, 22 m, 33 m, 44 m, 55 m, 66 m, 77 m, 88 m, 99 m, or 110 m • Airflow velocity V: 12 m / s • Peripheral speed ratio λ: 4, 6, or 8 • Kinematic viscosity ν of air: 0.000015 m ２ The position Lx of the friction portion 25 represents the distance from the first end 11 to the friction portion 25 in the longitudinal direction D1. The peripheral speed ratio λ is the ratio of the airflow velocity V to the velocity of the second end 12 of the blade 10 in the direction of rotation.

[0351] The calculation results are shown in Figure 59. ω is the angular velocity of the wing 10. U is the relative velocity of the airflow to the wing 10 at the friction points 25 at each position of the wing 10. The relative velocity U is calculated by the following formula: U = (V ２ + (L0 × ω) ２ ) ０．５

[0352] As can be seen from Figure 59, when the peripheral speed ratio λ = 4, the second roughness Reynolds number k is at the position where Lx / L0 = 0.2. + The dimension H of the disturbance structure 30 to achieve =20 was 3.90E-04 [m] = 390 μm. When the peripheral speed ratio λ = 8, the first roughness Reynolds number k is at the position where Lx / L0 = 0.4. +The dimension H of the disturbance structure 30 required to achieve Lx / L0 = 5 was 3.73E-05 [m] = 37.3 μm. In this case, the ratio of the dimension H of the disturbance structure 30 at position Lx / L0 = 0.4 to the dimension H of the disturbance structure 30 at position Lx / L0 = 0.2 is 37.3 μm / 390 μm = 0.09.

[0353] As can be seen from Figure 59, when the peripheral speed ratio λ = 6, the first roughness Reynolds number k is at the position where Lx / L0 = 0.2. + The dimension H of the disturbance structure 30 to achieve =5 was 8.00E-05 [m] = 80.0 μm. When the peripheral speed ratio λ = 6, the first roughness Reynolds number k is at the position where Lx / L0 = 0.4. + The dimension H of the disturbance structure 30 required to achieve Lx / L0 = 5 was 4.81E-05 [m] = 48.1 μm. In this case, the ratio of the dimension H of the disturbance structure 30 at position Lx / L0 = 0.4 to the dimension H of the disturbance structure 30 at position Lx / L0 = 0.2 is 48.1 μm / 80.0 μm = 0.60.

[0354] As can be seen from Figure 59, when the peripheral speed ratio λ = 4, the second roughness Reynolds number k is at the position where Lx / L0 = 0.6. + The dimension H of the disturbance structure 30 to achieve =20 was 1.92E-04 [m] = 192 μm. When the peripheral speed ratio λ = 8, the first roughness Reynolds number k is at the position where Lx / L0 = 0.8. + The dimension H of the disturbance structure 30 required to achieve Lx / L0 = 5 was 1.93E-05 [m] = 19.3 μm. In this case, the ratio of the dimension H of the disturbance structure 30 at position Lx / L0 = 0.8 to the dimension H of the disturbance structure 30 at position Lx / L0 = 0.6 is 19.3 μm / 192 μm = 0.10.

[0355] As can be seen from Figure 59, when the peripheral speed ratio λ = 6, the first roughness Reynolds number k is at the position Lx / L0 = 0.6. + The dimension H of the disturbance structure 30 to achieve =5 was 3.35E-05 [m] = 33.5 μm. When the peripheral speed ratio λ = 6, the first roughness Reynolds number k is at the position where Lx / L0 = 0.8. +The dimension H of the disturbance structure 30 required to achieve Lx / L0 = 5 was 2.55E-05 [m] = 25.5 μm. In this case, the ratio of the dimension H of the disturbance structure 30 at the position Lx / L0 = 0.8 to the dimension H of the disturbance structure 30 at the position Lx / L0 = 0.6 is 25.5 μm / 33.5 μm = 0.76.

[0356] (Example 2.2) At each position of the wing 10 in the longitudinal direction D1, the width S21 of the friction portion 25 was calculated to make the ratio S21 / δ, which is the ratio of the width S21 of the friction portion 25 to the thickness δ of the boundary layer 50, between 1.0 and 8.0. Specifically, the width S21 of the friction portion 25 to achieve S21 / δ = 1.0, 2.0, or 8.0 was calculated at each position of the wing 10 in the longitudinal direction D1.

[0357] The calculation conditions are as follows: • Length L0 of the wing 10 in the longitudinal direction D1: 110 mm • Position Lx of the friction section 25 in the longitudinal direction D1: 22 m or 44 m • Airflow velocity V: 12 m / s • Kinematic viscosity ν of air: 0.000015 m ２ / s • Code length C0 at Lx = 22m: 10m • Code length C0 at Lx = 44m: 8m • Distance Cm from leading edge 13 to maximum thickness position 15M at Lx = 22m: 2.5m • Distance Cm from leading edge 13 to maximum thickness position 15M at Lx = 44m: 2.0m

[0358] The calculation results are shown in Figure 60. δ is the thickness of the boundary layer 50 at the maximum thickness position of 15M. The thickness δ of the boundary layer 50 is calculated using the following formula: δ = 0.37 × Cm × ((U × Cm) / ν) －０．２

[0359] As can be seen from Figure 60, the width S21 of the friction section 25 required to achieve S21 / δ = 8.0 at the position Lx / L0 = 0.2 was 372 mm. The width S21 of the friction section 25 required to achieve S21 / δ = 1.0 at the position Lx / L0 = 0.4 was 35 mm. In this case, the ratio of the width S21 of the friction section 25 at Lx / L0 = 0.4 to the width S21 of the friction section 25 at Lx / L0 = 0.2 is 35 mm / 3372 mm = 0.09.

[0360] As can be seen from Figure 60, the width S21 of the friction portion 25 required to achieve S21 / δ = 1.0 at the position Lx / L0 = 0.2 was 47 mm. The width S21 of the friction portion 25 required to achieve S21 / δ = 1.0 at the position Lx / L0 = 0.4 was 35 mm. In this case, the ratio of the width S21 of the friction portion 25 at Lx / L0 = 0.4 to the width S21 of the friction portion 25 at Lx / L0 = 0.2 is 35 mm / 47 mm = 0.74.

[0361] 1 Wind turbine 1A Tower 1B Rotor 2 Nacelle 3 Rotor shaft 4 Generator 5 Airflow monitor 6 Speed ​​increaser 7 Hub 8 Control device 8A First control device 8B Second control device 10 Blade 11 First end 12 Second end 13 Leading edge 14 Trailing edge 15 Upper surface 15M Maximum thickness position 151 First length region 152 Second length region 153 First code region 154 Second code region 16 Lower surface 17 Code line 171 Midpoint 18 Detachment section 18A First detachment section 18B Second detachment section 181 Detachment layer 20 Structure 201 Front end 202 Rear end 21 First surface 21B Base surface 21B1 Valley region 22 Second surface 25 Friction section 25A First friction section 25B Second friction section 26 Smooth section 27 Boundary line 30 Disturbance structure 301 Convex section 302 Concave section 34s Small protrusion 40 Base body 41 First substrate 42 Adhesive layer 43 Separator 44 Printed layer 45 Second substrate 46 Adhesive layer 50 Boundary layer 51 Detachment point D1 Longitudinal direction D2 Code direction D3 Thickness direction F Airflow

Claims

It is a windmill, Rotor shaft and The rotor comprises a plurality of blades arranged in the direction of rotation of the rotor shaft and receiving the airflow, The blade includes a first end which is the part of the blade on the rotor axis side in the longitudinal direction of the blade, and a second end which is located on the opposite side of the first end. The wing includes a separation portion which is the portion between the leading edge and the midpoint, which is the point that bisects the line segment connecting the leading edge and the trailing edge in the chord direction from the leading edge to the trailing edge of the wing, The wing includes a structure located at least partially on the upper or lower surface of the wing in the separated portion, The structure includes at least two friction portions arranged in the longitudinal direction, and a smooth portion located between the friction portions in the longitudinal direction. Each of the friction parts is arranged in the direction of the cord and includes a plurality of disturbance structures that disrupt the airflow, in a wind turbine. 　 The structure includes a first structure located at least partially on the upper or lower surface in the first peeled portion. The wind turbine according to claim 1, wherein the first detached portion is the portion of the detached portion in which the ratio of the distance from the first end to the length of the blade in the longitudinal direction is 0.40 or less. 　 The structure includes a second structure located at least partially on the upper or lower surface in the second peeled portion. The wind turbine according to claim 1, wherein the second peeled portion is the portion of the peeled portion in which the ratio of the distance from the first end to the length of the blade in the longitudinal direction is greater than 0.

40. The wind turbine according to claim 3, wherein the structure includes the second structure located at least partially on the upper surface in the second peeled portion. 　 The wind turbine according to claim 3, wherein the structure includes the second structure located at least partially on the lower surface in the second peeled portion. 　 The structure includes a first structure located at least partially on the lower surface in the first peeled portion, and a second structure located at least partially on the upper surface in the second peeled portion. The first detached portion is the portion of the detached portion in which the ratio of the distance from the first end to the length of the wing in the longitudinal direction is 0.40 or less. The wind turbine according to claim 1, wherein the second peeled portion is the portion of the peeled portion in which the ratio of the distance from the first end to the length of the blade in the longitudinal direction is greater than 0.

40. Each of the aforementioned disturbance structures has a disturbance thickness in the thickness direction of the wing, The wind turbine according to claim 1, wherein the ratio of the disturbance thickness to the chord length of the blade is 0.00025 or less. 　 The wind turbine according to claim 1, wherein each of the friction portions includes at least 50 of the disturbance structures arranged in the direction of the code. 　 The wind turbine according to any one of claims 1 to 8, wherein the wing includes the structure located at least partially on the lower surface in the separated portion. 　 The aforementioned structure is positioned so as to overlap the position of maximum thickness. The wind turbine according to claim 9, wherein the position of maximum thickness is the position where the wing has the greatest thickness. 　 The wind turbine according to claim 9, wherein the structure is at least partially located in the longitudinal direction in a portion where the ratio of the distance from the first end to the length of the wing is 0.2516 or less. 　 Each of the aforementioned disturbance structures has a disturbance thickness in the thickness direction of the wing, The wind turbine according to claim 9, wherein the ratio of the disturbance thickness to the chord length of the blade is 0.00015 or more and 0.00025 or less. 　 The wind turbine according to any one of claims 1 to 8, wherein the wing includes the structure located at least partially on the upper surface in the separated portion. 　 The wind turbine according to claim 13, wherein the structure is at least partially located in the portion of the chord direction where the ratio of the distance from the leading edge to the chord length of the blade is 0.10 or less. 　 The wind turbine according to claim 13, wherein the structure is at least partially located in the longitudinal direction in a portion where the ratio of the distance from the first end to the length of the wing is 0.2516 or less. 　 Each of the aforementioned disturbance structures has a disturbance thickness in the thickness direction of the wing, The wind turbine according to claim 13, wherein the ratio of the disturbance thickness to the chord length of the blade is 0.00015 or less. 　 The aforementioned upper surface or lower surface includes the base surface, The wind turbine according to any one of claims 1 to 8, wherein the disturbance structure protrudes from the base surface in the thickness direction of the blade. 　 The aforementioned upper surface or lower surface includes the base surface, The wind turbine according to any one of claims 1 to 8, wherein the disturbance structure is recessed relative to the base surface in the thickness direction of the blade. 　 The friction portion includes a first friction portion comprising a plurality of disturbance structures having a first dimension in the thickness direction of the wing, and a second friction portion comprising a plurality of disturbance structures located outside the first friction portion in the longitudinal direction of the wing and having a second dimension in the thickness direction of the wing. The wind turbine according to any one of claims 1 to 8, wherein the second dimension is smaller than the first dimension. 　 The second friction portion is the friction portion among the plurality of friction portions that has the closest distance to the reference distance between it and the first friction portion in the longitudinal direction. The wind turbine according to claim 19, wherein the reference interval is 0.2 times the dimension of the blade in the longitudinal direction. 　 The first friction portion is the friction portion among the plurality of friction portions that is closest to the first reference distance in the longitudinal direction from the first end, The wind turbine according to claim 20, wherein the first reference distance is 0.2 times the dimension of the blade in the longitudinal direction. 　 The wind turbine according to claim 21, wherein the ratio of the second dimension to the first dimension is 0.60 or less. 　 The wind turbine according to claim 21, wherein the ratio of the second dimension to the first dimension is 0.04 or more. 　 The first friction portion has a first width in the longitudinal direction, The second friction portion has a second width in the longitudinal direction, The wind turbine according to claim 21, wherein the ratio of the second width to the first width is 0.75 or less. 　 The first friction portion and the second friction portion are located in the first code region of the upper surface, The first code region is a region on the upper surface whose distance from the leading edge is greater than 0.0 times and less than or equal to 0.5 times the code length. The wind turbine according to claim 21, wherein the code length is the distance from the leading edge to the trailing edge. 　 The first friction portion is the friction portion among the plurality of friction portions that is closest in distance from the first end in the longitudinal direction to the second reference distance. The wind turbine according to claim 20, wherein the second reference distance is 0.6 times the dimension of the blade in the longitudinal direction. 　 The wind turbine according to claim 26, wherein the ratio of the second dimension to the first dimension is 0.80 or less. 　 The wind turbine according to claim 26, wherein the ratio of the second dimension to the first dimension is 0.10 or more. 　 The first friction portion has a first width in the longitudinal direction, The second friction portion has a second width in the longitudinal direction, The wind turbine according to claim 26, wherein the ratio of the second width to the first width is 0.75 or less. 　 The aforementioned wing has a sufficiency ratio of 0.80 or higher. The aforementioned satisfaction rate is the ratio of the number of satisfied pairs to the total number of pairs. The total number of pairs is the number of pairs of friction parts selected based on the reference interval. The wind turbine according to claim 20, wherein the number of satisfying pairs is the number of pairs of friction parts selected based on the reference interval that satisfy the relationship between the first dimension of the first friction part and the second dimension of the second friction part. 　 The wings of a windmill, The first end, which is the part of the blade on the rotor axis side in the longitudinal direction, A second end located opposite the first end, The wing includes a separation portion which is the portion between the leading edge and the midpoint, which is the point that bisects the line segment connecting the leading edge and the trailing edge in the chord direction from the leading edge to the trailing edge of the wing, The wing includes a structure located at least partially on the upper or lower surface of the wing in the separated portion, The structure includes at least two friction portions arranged in the longitudinal direction, and a smooth portion located between the friction portions in the longitudinal direction. Each of the friction portions is arranged in the direction of the code and includes a wing with multiple disturbance structures that disrupt the airflow. 　 A structure attached to a wind turbine, The wind turbine comprises a rotor shaft and a plurality of blades arranged in the direction of rotation of the rotor shaft and receiving the airflow. The blade includes a first end which is the part of the blade on the rotor axis side in the longitudinal direction of the blade, and a second end which is located on the opposite side of the first end. The wing includes a separation portion which is the portion between the leading edge and the midpoint, which is the point that bisects the line segment connecting the leading edge and the trailing edge in the chord direction from the leading edge to the trailing edge of the wing, The structure is attached to the wind turbine so as to be located at least partially on the upper or lower surface of the wing in the detached portion. The structure includes at least two friction portions arranged in the longitudinal direction, and a smooth portion located between the friction portions in the longitudinal direction. Each of the friction portions is a structure that includes a plurality of disturbance structures arranged in the direction of the code and that disrupt the airflow. 　 A molded article comprising the structure of claim 32. 　 A film comprising the structure of claim 32. 　 A transfer sheet for transferring multiple disturbance structures of the structure according to claim 32 to a molded product.

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