CN115750196A

CN115750196A - Wind power blade and wind driven generator

Info

Publication number: CN115750196A
Application number: CN202211461641.8A
Authority: CN
Inventors: 谢喆; 张登刚
Original assignee: Sinomatech Wind Power Blade Co Ltd
Current assignee: Sinomatech Wind Power Blade Co Ltd
Priority date: 2022-11-17
Filing date: 2022-11-17
Publication date: 2023-03-07
Anticipated expiration: 2042-11-17
Also published as: CN115750196B

Abstract

The invention discloses a wind power blade and a wind power generator. Wherein, wind-powered electricity generation blade includes root of leaf, the blade middle part and the leaf point portion that sets gradually along the length direction of blade, and the root of leaf is including the relative pressure surface and the suction surface that set up, and at least one in pressure surface and the suction surface is provided with a plurality of concave part, and the concave part is sunken to the inside of root of leaf portion and is set up. The invention reduces the air resistance of the wind power blade, and the concave part is arranged at the root of the blade and has little influence on the main acting source pneumatic lift force of the wind power blade, thereby not influencing the power generation function of the wind power blade.

Description

Wind power blade and wind driven generator

Technical Field

The invention belongs to the technical field of wind power generation, and particularly relates to a wind power blade and a wind power generator.

Background

The wind power generator is an electric power device which converts wind energy into mechanical power, and the mechanical power drives a rotor to rotate so as to finally output alternating current. The principle of wind power generation is that wind power is used for driving a wind power blade to rotate, and then the rotating speed is increased through a speed increaser, so that a generator is promoted to generate electricity.

The aerodynamic appearance design of the wind power blade determines multiple economic indexes of the blade such as the utilization rate of wind energy, the manufacturing cost of the blade, the manufacturing cost of the whole machine and the like, and is one of the most important parts of the wind driven generator. The blade rotates while encountering more aerodynamic resistance, thereby increasing various loads of the blade, the unit and the tower barrel, and further increasing the manufacturing cost of other parts.

Disclosure of Invention

The invention provides a wind power blade and a wind driven generator, and aims to solve the technical problem that the conventional wind power blade is large in aerodynamic resistance.

The invention provides a wind power blade in a first aspect, which comprises a blade root part, a blade middle part and a blade tip part which are sequentially arranged along the length direction of the blade, wherein the blade root part comprises a pressure surface and a suction surface which are oppositely arranged, at least one of the pressure surface and the suction surface is provided with a plurality of concave parts, and the concave parts are sunken towards the inside of the blade root part.

In some embodiments, both the pressure and suction surfaces are provided with recesses, the number of recesses of the suction surface being greater than the number of recesses of the pressure surface.

In some embodiments, the plurality of recesses are respectively disposed in an area of the blade root portion having a relative thickness of 100% to 40%.

In some embodiments, the surface profile of the recess is hemispherical, and the diameter D of the recess and the local chord length C of the recess satisfy the following condition: d is more than 0 and less than or equal to 0.1C.

In some embodiments, the spacing distance between any two adjacent recesses is the same as the diameter of each recess.

In some embodiments, the depth H of the recess and the local chord length C of the recess satisfy the following condition: h is more than or equal to 0 and less than or equal to 0.05C.

In some embodiments, the number of the concave parts is multiple, and the multiple concave parts are arranged at intervals along the length direction to form a concave part group.

In some embodiments, the number N of recesses per column of recess groups satisfies the following condition: n is more than 1 and less than or equal to 200, the length L of each row of concave part groups and the length M from the root part of each leaf to the position of 40 percent of relative thickness meet the following conditions: l is more than 0 and less than or equal to M.

In some embodiments, the number of the recess groups is two, and the two recess groups are spaced apart along the chord length direction of the blade root.

In a second aspect, the invention provides a wind power generator, which includes a tower and the wind power blade of any of the above embodiments, wherein the plurality of wind power blades are respectively rotatably connected to the tower.

The wind power blade comprises a blade root part, a blade middle part and a blade tip part which are sequentially arranged along the length direction of the blade, wherein the aerodynamic lift force is the only energy source for the wind power blade to generate electricity, the blade middle part and the blade tip part need a large amount of aerodynamic lift force to enable the wind power blade to generate electricity, the blade root part mainly bears structural performance, the aerodynamic resistance is extremely high, the aerodynamic lift force is extremely low, the blade root part comprises a pressure surface and a suction surface which are oppositely arranged, and a plurality of concave parts are arranged on at least one of the pressure surface and the suction surface and are sunken towards the inside of the blade root part, so that the air resistance of the wind power blade is reduced. And the concave part is arranged at the root of the blade, so that the influence on the main acting source pneumatic lift force of the wind power blade is very small, and the power generation function of the wind power blade is not influenced.

Drawings

FIG. 1 is a schematic structural view of a wind turbine blade according to some embodiments of the present invention;

FIG. 2 is a schematic view of an airfoil at 70% relative thickness of a 90m class wind blade according to some embodiments of the present invention;

FIG. 3 is a schematic view of an airfoil at 70% relative thickness of a 90m class wind blade of the prior art;

FIG. 4 is a schematic view of airfoil surface flow conditions at 70% relative thickness of a 90m class wind blade of the prior art;

FIG. 5 is a schematic view of airfoil surface flow conditions at 70% relative thickness of a 90 m-class wind turbine blade provided in embodiment 1.

The reference numbers are as follows: a wind power blade 100; a leaf root 10; a mid-leaf portion 20; a tip portion 30; a pressure surface 10a; a suction surface 10b; a recess 11; a set of recesses 110; a length direction X; and a chord length direction Y.

Detailed Description

In order to make the objects, technical solutions and advantageous technical effects of the present invention clearer, the present invention is further described in detail with reference to the following embodiments. It should be understood that the embodiments described in this specification are only for the purpose of explaining the present invention and are not intended to limit the present invention.

For the sake of brevity, only some numerical ranges are explicitly disclosed herein. However, any lower limit may be combined with any upper limit to form ranges not explicitly recited; and any lower limit may be combined with any other lower limit to form a range not explicitly recited, and similarly any upper limit may be combined with any other upper limit to form a range not explicitly recited. Also, although not explicitly recited, each point or individual value between endpoints of a range is encompassed within the range. Thus, each point or individual value can form a range not explicitly recited as its own lower or upper limit in combination with any other point or individual value or in combination with other lower or upper limits.

In the description herein, it is noted that, unless otherwise specified, "a number" means one or more than one; "several" means two or more; "above" and "below" are intended to include the present numbers; the terms "upper", "lower", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present disclosure.

The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The following description more particularly exemplifies illustrative embodiments. At various points throughout this application, guidance is provided through lists of examples, which examples can be used in various combinations. In each instance, the list is merely a representative group and should not be construed as exhaustive.

The aerodynamic appearance design of the wind power blade determines multiple economic indexes of the blade such as the utilization rate of wind energy, the manufacturing cost of the blade, the manufacturing cost of the whole machine and the like, and is one of the most important parts of the wind driven generator. The blade can be divided into a blade root, a blade leaf and a blade tip according to the distance from the blade to the hub. Wherein the root of the blade provides primarily structural strength and the tip of the blade provides primarily aerodynamic properties of the blade. The root portion primarily functions to provide sufficient structural strength to resist loads experienced by the blade during operation. Since structural stiffness is generally directly proportional to the thickness of the blade, it is generally characterized by a greater thickness in the root portion. In past small size (below 60 m) model designs, the root area usually accounts for very little (within 20%), so the overall aerodynamic performance of the blade is not significantly affected. However, with the implementation of domestic flat-price internet policy, the design of large-size blades in the current environment tends to extend the use range of large-thickness airfoils (by about 25%), so as to obtain higher structural rigidity and reduce the material weight of the blades due to the limitations of the cost pressure of the whole machine. However, the area with larger thickness can not provide the lift force required by the blade to generate electricity, and on the other hand, the area with larger thickness can provide more aerodynamic resistance, so that various loads of the blade, the unit and the tower can be increased, and the manufacturing cost of other parts can be increased.

Fig. 1 is a schematic structural diagram of a wind turbine blade according to some embodiments of the present invention; FIG. 2 is a schematic view of an airfoil at 70% relative thickness of a 90m class wind blade according to some embodiments of the present invention. Referring to fig. 1 and fig. 2 in combination, an embodiment of the first aspect of the present invention provides a wind turbine blade 100, which includes a root portion 10, a middle portion 20, and a tip portion 30 sequentially arranged along a length direction X of the blade, where the root portion 10 includes a pressure surface 10a and a suction surface 10b oppositely arranged, at least one of the pressure surface 10a and the suction surface 10b is provided with a plurality of recesses 11, and the recesses 11 are recessed toward an inside of the root portion 10.

The length direction X of wind power blade 100 is wind power blade 100's extending direction, and along length direction X, wind power blade 100 is divided into the triplex, and the position of being connected with wheel hub is blade root portion 10, and the tip of keeping away from wheel hub is leaf point portion 30, and the intermediate portion that is located leaf root portion 10 and leaf point portion 30 is middle part of the blade 20. The pressure surface 10a is a windward surface, the suction surface 10b is a leeward surface, and the recess 11 is provided in the pressure surface 10a or the suction surface 10b of the blade root 10, or the recess 11 may be provided in both the pressure surface 10a and the suction surface 10b of the blade root 10. The recess 11 is recessed inward from the surface of the blade root 10, and the surface contour of the recess 11 may be in other shapes such as a hemispherical shape, a rectangular parallelepiped shape, a square shape, a triangular pyramid shape, or a truncated cone shape, and may be designed with reference to the recess 11 provided on the surface of the golf ball.

The bottom layer element of the aerodynamic design of the wind turbine blade 100 is an airfoil (a cross-sectional shape perpendicular to a leading edge or a connecting line of 1/4 chord length points, also called an airfoil section or a blade section), the wind turbine blade 100 can be considered to be formed by stacking an infinite number of airfoils in the length direction X, and because the airfoil thickness (the length of a straight line perpendicular to the chord length at each point on the airfoil chord length and cut by an airfoil contour line) of the blade root 10 is large, and the operational attack angle is high (generally above 10 deg), the flow characteristics of the wind turbine blade are different from those of a thin airfoil and are more similar to those of cylindrical bypass flow. Because aerodynamic lift is the only energy source for generating electricity by the wind power blade 100, the blade middle part 20 and the blade tip part 30 need a large amount of aerodynamic lift to enable the wind power blade 100 to generate electricity, and the blade root part 10 mainly bears structural performance, the aerodynamic resistance is extremely large, the aerodynamic lift is extremely small, the blade root part 10 comprises a pressure surface 10a and a suction surface 10b which are arranged oppositely, a plurality of concave parts 11 are arranged on at least one of the pressure surface 10a and the suction surface 10b, the concave parts 11 are arranged in a concave mode towards the inside of the blade root part 10, when airflow flows, a vortex structure can independently appear in the concave parts 11, under the influence of the vortex structure, a layer of structure similar to an aerodynamic protective film can be formed on the surface of the airfoil to avoid direct contact of external flow and the wall surface, and therefore, the friction between the aerodynamic force and the wall surface of the original airfoil is converted into the friction between gas and gas to reduce the aerodynamic resistance. This principle is completely consistent with the aerodynamic drag reduction principle of dimples on the surface of a golf ball. The present invention reduces the air resistance of the wind turbine blade 100. Moreover, the concave part 11 is arranged at the root part 10, and has very little influence on the aerodynamic lift of the main working source of the wind power blade 100, so that the power generation function of the wind power blade 100 is not influenced.

The recess 11 is preferably provided on the suction surface 10b, which is demonstrated by numerical simulation to greatly reduce the air resistance of the wind turbine blade 100.

In some embodiments, both the pressure surface 10a and the suction surface 10b are provided with recesses 11, the number of recesses 11 of the suction surface 10b being greater than the number of recesses 11 of the pressure surface 10 a. According to the embodiment, the concave parts 11 are arranged on two side surfaces of the blade root part 10, so that aerodynamic resistance is reduced, and on the premise that structural strength is guaranteed, the concave parts 11 with more quantity are arranged on the suction surface 10b, so that the aerodynamic resistance of the wind power blade 100 can be reduced to the maximum extent.

In some embodiments, the plurality of recesses 11 are respectively disposed in an area where the relative thickness of the blade root 10 is 100% to 40%. It should be noted that the relative thickness refers to the ratio of the maximum thickness to the chord length of the airfoil, wherein the thickness of the airfoil is the length of a straight line segment between the upper and lower surfaces of the airfoil perpendicular to the chord. The chord length is the length from the leading edge point to the trailing edge point of the wind turbine blade 100. In the embodiment, the area with the relative thickness of 100% -40% of the wind power blade 100 is used as the blade root part 10, and the concave part 11 can be arranged in the area according to specific conditions, so that the aerodynamic resistance of the wind power blade 100 can be reduced, the aerodynamic lift force is not influenced, and the overall aerodynamic performance of the wind power blade 100 is ensured.

In some embodiments, the surface profile of the recess 11 is hemispherical, and the diameter D of the recess 11 and the local chord length C of the recess 11 satisfy the following condition: d is more than 0 and less than or equal to 0.1C. Since the concave portion 11 is in the shape of a hemispherical concave groove, the diameter D of the concave portion 11 refers to the diameter of the opening of the concave portion 11, for example, if the concave portion 11 is semicircular along the plane of the airfoil, the diameter D of the concave portion 11 is the diameter of the semicircular opening. Because the surface profile of the concave part 11 is hemispherical, the surface is smooth, the aerodynamic resistance is small, and the size of the diameter D of the concave part 11 is limited, the structural strength of the root part 10 of the blade can be prevented from being damaged due to the overlarge diameter of the concave part 11, and the problem that the reduction amplitude of the aerodynamic resistance is limited due to the overlarge diameter of the concave part 11 can be solved.

In some embodiments, the spacing distance between any two adjacent recesses 11 is the same as the diameter of each recess 11. It should be noted that, in this embodiment, the diameter of each concave portion 11 is set to be the same, and the spacing distance between any two adjacent concave portions 11 is set to be the same as the diameter of each concave portion 11, so that the uniform arrangement is favorable for positioning the surface of the blade in the production process of the wind turbine blade 100, and the production efficiency is improved.

In some embodiments, the depth H of the recess 11 and the local chord length C of the recess 11 satisfy the following condition: h is more than or equal to 0 and less than or equal to 0.05C. The depth H of the concave portion 11 refers to the maximum vertical distance from the bottom of the concave portion 11 to the opening, for example, the surface contour of the concave portion 11 is a hemisphere, and the depth H of the concave portion 11 is marked as shown in the figure. The local chord length is the length of the cross-sectional position of the wind turbine blade 100 from the leading edge to the trailing edge, and after the spanwise position is determined, the chord length at the spanwise position is referred to as the local chord length. In the present embodiment, by limiting the depth H of the concave portion 11, it is ensured that the air resistance of the wind turbine blade 100 is reduced, and the structural strength of the root portion 10 of the wind turbine blade 100 is not damaged.

In some embodiments, the number of the concave portions 11 is plural, and the plural concave portions 11 are arranged at intervals along the length direction X to form the concave portion group 110. The plurality of concave portions 11 in the concave portion group 110 are arranged in a row along the length direction X, which not only can reduce the aerodynamic resistance of the wind turbine blade 100 to the maximum extent, but also is convenient for manufacturing. In other embodiments, the plurality of recesses 11 may also form a circle, an ellipse, or other irregular shapes.

In some embodiments, the number N of recesses 11 per column of the recess group 110 satisfies the following condition: n is more than 1 and less than or equal to 200, and the length L of each row of concave part groups 110 and the length M from the root part of each row to the position of 40 percent of relative thickness satisfy the following conditions: l is more than 0 and less than or equal to M. The term "length of the blade root to the 40% relative thickness position" means: the length from the end part of the blade root part far away from the blade tip part to the position of 40% of the relative thickness of the wind power blade. By limiting the number N of each row of the concave groups 110 and the length L of each row of the concave groups 110, the air resistance of the wind turbine blade 100 can be reduced, and the structural strength of the root 10 of the wind turbine blade 100 cannot be damaged.

In some embodiments, the number of the concave groups 110 is two, and the two concave groups 110 are spaced along the chord length direction Y of the blade root 10, so as to further reduce the aerodynamic resistance of the wind turbine blade 100. The surface contour of the concave part 11 can be set to be hemispherical, and the distance between two concave part groups 110 is set to be the same as the diameter of each concave part 11, so that the positioning on the surface of the blade in the production process of the wind power blade 100 is facilitated, and the production efficiency is improved.

In a second aspect, the present invention provides a wind power generator, which comprises a tower and the wind power blades 100 of any of the above embodiments, wherein the plurality of wind power blades 100 are respectively rotatably connected to the tower. Since the wind power generator adopts all technical solutions of all the embodiments, at least all the beneficial effects brought by the technical solutions of the embodiments are achieved, and details are not repeated herein.

Examples

Hereinafter, examples of the present application will be described. The following embodiments are described as illustrative only and are not to be construed as limiting the present application.

Example 1

Fig. 2 is a schematic view of an airfoil at 70% relative thickness of a 90 m-class wind turbine blade provided in embodiment 1, and fig. 3 is a schematic view of an airfoil at 70% relative thickness of a 90 m-class wind turbine blade in the prior art. Starting from the BEM (Blade Element moment kinematic theory) theory, the method for designing the concave portion 11 of the wind turbine Blade 100 in the Blade root according to embodiment 1 can be simplified to the aerodynamic performance influence of the concave portion 11 on the two-dimensional airfoil profile. Example 1 a simulation was carried out using an airfoil profile of a 90m class wind turbine blade at 70% relative thickness, the profile being as shown in figure 2. The BEM is a basic criterion for the aerodynamic design of the wind turbine blade 100, and divides the blade into an infinite number of mutually independent two-dimensional sections, and the aerodynamic performance of the blade is determined by the two-dimensional sections.

To illustrate the effect of the recess 11 in reducing aerodynamic drag, the larger recess 11 size is taken for illustration. Two large-sized recesses 11 are designed on the airfoil suction surface 10b near the tail, the diameter D of each recess 11 is about 0.1 chord length, and the depth H is about 0.02 chord length.

FIG. 4 is a schematic view of airfoil surface flow at 70% relative thickness of a 90m class wind turbine blade of the prior art; FIG. 5 is a schematic view of airfoil surface flow conditions at 70% relative thickness of a 90m class wind turbine blade provided in example 1. Referring to fig. 4 and 5, under actual operating conditions, the reynolds number of the airfoil region is about 3500000 according to BEM, under which CFD (Computational Fluid Dynamics) simulation, which is a numerical method of Computational Fluid Dynamics, is performed on two-dimensional airfoils, respectively. At the 20 deg. angle of attack at which a large thickness airfoil typically operates, the original smooth airfoil surface streamline distribution is shown in FIG. 4. It can be seen that the large thickness profile has a poor resistance to flow separation and therefore a large range of separation shedding vortices are present on the suction surface 10b, this region being of low velocity and high pressure and having a large gas frictional drag and therefore being the main source of aerodynamic drag.

The modified recess 11 has airfoil streamline conditions as shown in fig. 5. It can be seen that the recess 11 is not significantly improved with respect to the separation flow. However, a vortex structure independently appears in the concave portion 11, and under the influence of the vortex structure, a structure similar to a pneumatic protective film is formed on the surface of the airfoil to prevent external flow from directly contacting with the wall surface, so that the friction between the original aerodynamic surface and the wall surface is converted into the friction between gas and air to reduce aerodynamic resistance. This principle is completely consistent with the aerodynamic drag reduction principle of dimples on the surface of a golf ball. According to the calculation result, the original airfoil drag coefficient is 0.189 at 20deg, and the drag coefficient is reduced to 0.139 after the concave part 11 is added, and the reduction amplitude is 26.3%.

While the invention has been described with reference to specific embodiments, the invention is not limited thereto, and various equivalent modifications and substitutions can be easily made by those skilled in the art within the technical scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. The utility model provides a wind-powered electricity generation blade, its characterized in that includes and follows root of leaf, leaf middle part and the leaf point portion that the length direction of blade set gradually, the root of leaf portion is including the relative pressure face and the suction surface that set up, the pressure face with at least one among the suction surface is provided with a plurality of concave part, the concave part to the sunken setting in root of leaf's inside.

2. The wind turbine blade as claimed in claim 1, wherein the pressure surface and the suction surface are provided with recesses, the number of recesses of the suction surface being greater than the number of recesses of the pressure surface.

3. The wind turbine blade of claim 1, wherein the plurality of recesses are respectively disposed in an area of the blade root portion having a relative thickness of 100% to 40%.

4. The wind blade as set forth in claim 1, wherein the surface profile of the concave portion is a hemisphere, and the diameter D of the concave portion and the local chord length C of the concave portion satisfy the following condition: d is more than 0 and less than or equal to 0.1C.

5. The wind blade as set forth in claim 1 wherein the spacing distance between any two adjacent recesses is the same as the diameter of each recess.

6. The wind blade as claimed in claim 1, wherein the depth H of the recess and the local chord length C of the recess satisfy the following condition: h is more than or equal to 0 and less than or equal to 0.05C.

7. The wind turbine blade according to any one of claims 1 to 6, wherein the number of the concave portions is plural, and the plural concave portions are arranged at intervals along the length direction to form a concave portion group.

8. The wind turbine blade as claimed in claim 7, wherein the number N of recesses per row of the recess group satisfies the following condition: n is more than 1 and less than or equal to 200, and the length L of each row of the concave part group and the length M from the leaf root to the position of 40 percent of relative thickness meet the following conditions: l is more than 0 and less than or equal to M.

9. The wind turbine blade as claimed in claim 7, wherein the number of the concave groups is two, and the two concave groups are distributed at intervals along the chord length direction of the blade root.

10. A wind power generator, comprising:

a tower; and

a plurality of wind blades as defined in any one of claims 1 to 9, each rotatably connected to said tower.