A wind turbine blade attachment to inhibit flow separation

Abstract

The present application relates to a kind of wind turbine blade attachments for inhibiting flow separation, which is installed above suction surface of airfoil region of wind turbine blade or above suction surface of transition region between circular region and airfoil region of wind turbine blade by support structure;The wind turbine blade attachment is curved surface structure with certain camber, and has smooth outer surface;The shape of its curved surface structure is the same as the shape of blade surface at the position of the orthographic projection of wind turbine blade attachment in wind turbine blade.The present application improves the aerodynamic performance of root region of wind turbine blade by wind turbine blade attachment, and improves the output power of wind turbine, changes the flow direction above suction surface of wind turbine blade when incoming flow blows through wind turbine blade, forces fluid to deflect towards the surface of suction surface of wind turbine blade, prevents the generation of flow separation phenomenon on the surface of wind turbine blade, optimizes the aerodynamic performance of root region of wind turbine blade, and increases the power of wind turbine.

Description

Technical Field

[0001] This invention relates to the field of wind power generation, and more specifically to a wind turbine blade accessory for suppressing flow separation. Background Technology

[0002] Wind turbine blades are a crucial component of wind turbine units, their function being to capture wind energy. Their aerodynamic performance directly impacts the power generation of the wind turbine. Many factors influence the aerodynamic performance of wind turbine blades, the most important being their aerodynamic shape. Wind turbine blades can be defined into three regions based on their cross-sectional shape: the circular region closest to the hub (where the blade cross-section is nearly circular), the transition region between the circular and airfoil regions, and the airfoil region itself. Since unilateral optimization of the blade's aerodynamic shape has become relatively stable, recent research has shifted towards adding auxiliary devices to the blades, such as vortex generators, Gurney flaps, and tip winglets. However, the optimization of these auxiliary control devices primarily focuses on the mid-section or tip of the blade, with limited exploration of aerodynamic optimization at the blade root.

[0003] To reduce the cost per kilowatt-hour of wind power generation, the size of wind turbine rotors and the length of blades are continuously increasing. Larger wind turbine blades face severe challenges in terms of load, structural strength, and aeroelastic stability. To ensure the structural stability of long blades, the transition regions of large wind turbine blades typically employ thick airfoils with poor aerodynamic performance. This is especially true in the transition region from the blade root to the maximum chord length, where the aerodynamic performance of the thick airfoils is particularly poor. This makes the airfoil closer to the blade root more prone to stall during wind turbine operation, resulting in a decrease in overall wind turbine power. Furthermore, the angle of attack of the airfoil near the blade root during wind turbine operation is typically between 10° and 30°, leading to severe flow separation and further deteriorating the aerodynamic performance of the region near the blade root.

[0004] To improve the aerodynamic performance of blades, methods such as optimizing the blade's aerodynamic shape, for example, using various algorithms to optimize the chord length and twist angle distribution, can be employed. Furthermore, to reduce reliance on thick airfoils, blade stiffness can be increased by improving blade layup, cross-sectional topology, and composite materials. However, this method is limited by the cantilever beam structure of the blade and cannot fundamentally reduce wind power companies' dependence on thick airfoils. Additionally, accessories and devices such as vortex generators and trailing edge flaps can be used to improve the aerodynamic performance of fluid airfoils and blades; however, these are subject to various operating conditions, resulting in limited improvements in aerodynamic performance. Summary of the Invention

[0005] The purpose of this invention is to provide a wind turbine blade accessory that suppresses flow separation, in order to solve the problems of aerodynamic loss, aerodynamic separation and stall caused by premature airflow separation near the suction surface of the blade in the prior art.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0007] A wind turbine blade accessory for suppressing flow separation is mounted above the suction surface of the airfoil region of the wind turbine blade, or above the suction surface of the transition region between the circular region and the airfoil region of the wind turbine blade, via a support structure. The wind turbine blade accessory has a curved surface structure with a certain curvature and a smooth outer surface. The shape of its curved surface structure is the same as the shape of the blade surface at the position of the wind turbine blade accessory's orthographic projection, wherein the orthographic projection is the projection perpendicular to the plane formed by the wind turbine blade's axial direction and the wind turbine blade's chord direction.

[0008] To optimize the above technical solution, the specific measures also include:

[0009] Furthermore, the wind turbine blade accessory is installed above the suction surface of the airfoil region of the wind turbine blade near the transition region.

[0010] Furthermore, the wind turbine blade accessory is located above the suction surface at the leading edge, middle, or trailing edge of the airfoil region or transition region of the wind turbine blade.

[0011] Furthermore, the wind turbine blade accessory is in the form of a thin plate.

[0012] Furthermore, the leading edge and trailing edge of the wind turbine blade accessory are both rounded ends.

[0013] Furthermore, the wind turbine blade accessory has a rotating shaft in the middle along the axial direction of the wind turbine blade. The wind turbine blade accessory can be fixed after rotating around the rotating shaft within a certain angle range on the support structure. The rotation angle is θ, where θ = -60° to 60°.

[0014] As a preferred embodiment, the rotation angle θ is -15° to 15°.

[0015] Furthermore, a pivot is provided on the support structure, passing through the centerline of the wind turbine blade accessory along the axial direction of the wind turbine blade. A first buckle and a second buckle are provided on the edge of the support structure. The first buckle is used to fix the wind turbine blade accessory to a non-rotating part, and the second buckle is used to fix the wind turbine blade accessory to a rotating part.

[0016] As a preferred embodiment, the chord length of the wind turbine blade accessory corresponding to the chord direction of the wind turbine blade is l, l = 0.05C~0.5C, and the maximum thickness of the wind turbine blade accessory is M, M = 0.005C~0.2C; the chord installation position of the wind turbine blade accessory is: the distance d, d = 0~0.7C, from the leading edge of the middle part of the wind turbine blade accessory in the orthographic projection position of the wind turbine blade to the leading edge end of the airfoil region or transition region of the wind turbine blade where it is located; the installation height of the wind turbine blade accessory above the suction surface of the wind turbine blade is: the vertical height of the wind turbine blade accessory from its orthographic projection on the wind turbine blade is h, h = 0.01C~2C; where C is the chord length of the wind turbine blade airfoil region or transition region at the orthographic projection position of the middle part of the wind turbine blade accessory.

[0017] As a preferred embodiment, the chordal length of the wind turbine blade accessory corresponding to the chordal direction of the wind turbine blade is l, l = 0.15C to 0.35C; the axial length of the wind turbine blade accessory corresponding to the axial direction of the wind turbine blade is V, V = 0.1R to 0.2R; the maximum thickness of the wind turbine blade accessory is M, M = 0.01C to 0.02C; the chordal installation position of the wind turbine blade accessory is: the distance from the leading edge of the middle part of the wind turbine blade accessory in the orthographic projection position of the wind turbine blade to the leading edge end of the airfoil area or transition area of ​​the wind turbine blade where it is located is d, d = 0.15C to 0.5C; The axial installation position of the wind turbine blade accessory is as follows: the distance from the end of the wind turbine blade accessory near the circular area of ​​the wind turbine blade to the end of the circular area of ​​the wind turbine blade in the orthographic projection position is K, where K = 0.15R ~ 0.2R; the installation height of the wind turbine blade accessory above the suction surface of the wind turbine blade is as follows: the vertical height of the wind turbine blade accessory from its orthographic projection on the wind turbine blade is h, where h = 0.05C ~ 0.35C; where C is the chord length of the airfoil area or transition area of ​​the wind turbine blade at the orthographic projection position in the middle of the wind turbine blade accessory, and R is the total axial length of the wind turbine blade.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] This invention utilizes a wind turbine blade accessory with a certain curvature for flow control to improve the aerodynamic performance of the wind turbine blade root region and increase the wind turbine's output power. When the incoming flow passes over the wind turbine blade, the accessory changes the direction of fluid flow above the blade's suction surface, forcing the fluid to deflect towards the blade's suction surface. This prevents flow separation on the blade surface, thereby optimizing the aerodynamic performance of the wind turbine blade root region and increasing the wind turbine's power. Attached Figure Description

[0020] Figure 1: A three-dimensional structural schematic diagram of the wind turbine blade accessory and the wind turbine blade of Embodiment 1 of the present invention.

[0021] Figure 2 : A schematic diagram of the cross-sectional structure of the wind turbine blade accessory and the wind turbine blade in Embodiment 1 of the present invention.

[0022] Figure 3 : Streamline cloud diagram of the cross section of a wind turbine blade without wind turbine blade accessories.

[0023] Figure 4 : A cross-sectional streamline cloud diagram of a wind turbine blade using the wind turbine blade accessory of Embodiment 1 of the present invention.

[0024] Figure 5 : A cross-sectional streamline cloud diagram of a wind turbine blade using the wind turbine blade accessory of Embodiment 2 of the present invention.

[0025] Figure 6 : A three-dimensional structural schematic diagram of the wind turbine blade accessory and the wind turbine blade of Embodiment 3 of the present invention.

[0026] Figure 7 : A schematic diagram of the cross-sectional structure of the wind turbine blade accessory and the wind turbine blade in Embodiment 3 of the present invention.

[0027] Figure 8 The wind turbine blade suction surface wall limit streamline diagrams of both the non-adopted and adopted embodiments of the present invention 3 are shown below.

[0028] Figure 9 : A schematic diagram of one embodiment of the support structure of the present invention.

[0029] In the diagram: 1-Wind turbine blade, 2-Wind turbine blade accessory, 3-Suction surface, 4-Leading edge of wind turbine blade accessory, 5-Tail edge of wind turbine blade accessory, 6-Support structure, 7-First buckle, 8-Second buckle. Detailed Implementation

[0030] The present invention will be further described in detail below through embodiments, but it should not be construed as limiting the scope of the subject matter of the present invention to the following embodiments. All technologies implemented based on the above content of the present invention fall within the scope of the present invention.

[0031] The orientations or positional relationships described herein are based on the relationships shown in the accompanying drawings and are only for the purpose of facilitating the description of the present invention and simplifying the description. They are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0032] This invention provides a wind turbine blade accessory for suppressing flow separation. The wind turbine blade accessory 2 is mounted above the suction surface 3 of the airfoil region of the wind turbine blade 1, or above the suction surface 3 of the transition region between the circular region and the airfoil region of the wind turbine blade 1, via a support structure. The wind turbine blade accessory 2 is a curved surface structure with a certain curvature and a smooth outer surface. The shape of its curved surface structure is the same as the shape of the blade surface at the position of the orthographic projection of the wind turbine blade accessory 2 onto the wind turbine blade 1. The orthographic projection is the projection onto the plane perpendicular to the axial direction of the wind turbine blade 1 and the chord direction of the wind turbine blade 1.

[0033] The wind turbine blade accessory 2 is installed above the suction surface 3 near the transition area of ​​the airfoil region of the wind turbine blade 1.

[0034] The wind turbine blade attachment 2 is located above the suction surface 3 at the leading edge, middle or trailing edge of the airfoil area or transition area of ​​the wind turbine blade 1.

[0035] The wind turbine blade accessory 2 is a thin plate shape.

[0036] The leading edge 4 and trailing edge 5 of the wind turbine blade accessory are both rounded ends.

[0037] The wind turbine blade accessory has a rotating shaft in the middle along the axial direction of the wind turbine blade. The wind turbine blade accessory can be fixed after rotating around the rotating shaft within a certain angle range on the support structure. The rotation angle is θ, where θ = -60° to 60°. Preferably, the rotating shaft has a rotation angle θ = -15° to 15°.

[0038] Other notes: The leading edge and trailing edge in this invention can be referred to in conjunction with the accompanying drawings. The leading edge is the direction shown at the arc-shaped section of the wind turbine blade 1, and the trailing edge is the direction shown at the narrowing section of the wind turbine blade 1.

[0039] In this invention, "the orthographic projection of wind turbine blade attachment 2 onto wind turbine blade 1" refers to the projection of wind turbine blade attachment 2 when it is not rotating around the rotation axis.

[0040] The support structure 6 used in this invention can be a conventional structure in the prior art, such as a frame structure, see [link to relevant documentation]. Figure 9 As shown, the connection between the bracket structure 6 and the wind turbine blade accessory 2 and the wind turbine blade 1 can be a fixed connection through conventional fasteners such as nuts or other fixed connection methods such as welding.

[0041] The wind turbine blade attachment can be fixed after rotating around the rotation axis within a certain angle range on the support structure. If a frame structure is adopted, a rotation axis passing through the centerline of the wind turbine blade attachment 2 along the axial direction of the wind turbine blade 1 can be provided on the frame structure, and a first buckle 7 and a second buckle 8 can be provided on the edge of the frame structure. The first buckle 7 is used to fix the wind turbine blade attachment 2 when it is not rotating, and the second buckle 8 is used to fix the wind turbine blade attachment 2 when it is rotated.

[0042] The present invention will be further described in detail below with reference to specific embodiments:

[0043] Example 1

[0044] A wind turbine blade accessory for suppressing flow separation, wherein the chordal length of the wind turbine blade accessory corresponding to the chordal direction of the wind turbine blade is l, l = 0.05C to 0.5C, and the maximum thickness of the wind turbine blade accessory is M, M = 0.005C to 0.2C; the chordal installation position of the wind turbine blade accessory is: the distance d, d = 0 to 0.7C, from the leading edge of the middle part of the wind turbine blade in the orthographic projection position of the wind turbine blade to the leading edge end of the airfoil region or transition region of the wind turbine blade where it is located; the installation height of the wind turbine blade accessory above the suction surface of the wind turbine blade is: the vertical height of the wind turbine blade accessory from its orthographic projection on the wind turbine blade is h, h = 0.01C to 2C; where C is the chord length of the airfoil region or transition region of the wind turbine blade at the orthographic projection position of the middle part of the wind turbine blade accessory.

[0045] In this embodiment, the wind turbine blade accessory is installed above the suction surface of the airfoil region of the wind turbine blade. The airfoil region of the wind turbine blade adopts the model DTU230 airfoil. C is the chord length of the airfoil region or transition region of the wind turbine blade at the corresponding orthographic projection in the middle of the wind turbine blade accessory. C is 1000mm. The spanwise length (i.e., axial length V) of the wind turbine blade accessory 2 is 100mm.

[0046] The chordal length of the wind turbine blade accessory corresponding to the chordal direction of the wind turbine blade is l, l = 200 mm; the maximum thickness of the wind turbine blade accessory is M, M = 50 mm; the distance from the leading edge of the middle part of the wind turbine blade accessory in the orthographic projection position of the wind turbine blade to the leading edge end of the airfoil region or transition region of the wind turbine blade where it is located is d, d = 250 mm; the vertical height of the wind turbine blade accessory from its orthographic projection on the wind turbine blade is h, h = 50 mm.

[0047] The wind turbine blade attachments do not rotate, that is, the rotation angle θ is 0°.

[0048] Computational fluid dynamics was used to perform aerodynamic simulations on a combination of wind turbine blades and blade accessories using the DTU230 airfoil, with an air density of 1.225 kg / m³.3 The temperature is 20℃, and the DDES kW turbulence model is used. The first layer of mesh Y on the surface of the airfoil region of the wind turbine blade is... + Approximately 1, taking a 20° angle of attack as an example, the lift coefficient C is calculated under the condition Re = 3 million. l Drag coefficient C d and the lift-to-drag ratio C l / C d As shown in Table 1:

[0049] Table 1. Results of fluid dynamics measurements in Example 1

[0050]

[0051] according to Figure 3 Velocity contour maps of wind turbine blades without wind turbine blade accessories. Figure 4 The velocity cloud diagram of a wind turbine blade without blade attachments clearly shows that, under an incoming flow angle of 20°, the blade attachments suppress fluid separation on the suction surface of the airfoil region of the wind turbine blade. This results in a 12.9% increase in lift coefficient, a 31.5% decrease in drag coefficient, and a 64.8% increase in lift-to-drag ratio for the combination of the airfoil region and the blade attachments, significantly improving the aerodynamic performance of the airfoil.

[0052] Example 2

[0053] The wind turbine blade attachments and airfoil areas used in this embodiment are the same as in Embodiment 1, except that the wind turbine blade attachments rotate 5° clockwise (viewed from the root of the wind turbine blade to the tail) around the rotation axis.

[0054] Computational fluid dynamics was used to perform aerodynamic simulation calculations on a combination of wind turbine blades and blade accessories using the DTU230 airfoil. The measurement conditions were the same as in Example 1, and the lift coefficient C was calculated. l Drag coefficient C d and the lift-to-drag ratio C l / C d The results were compared with those of Example 1, and are shown in Table 2:

[0055] Table 2. Fluid Dynamics Measurement Results of Example 2

[0056]

[0057]

[0058] according to Figure 5 Velocity contour plots of wind turbine blades and related accessories Figure 3 , Figure 4In comparison, based on Example 1, the lift coefficient and lift-to-drag ratio of the wind turbine blade attachments were improved by 2.9% and 8.5% respectively after being rotated 5° clockwise around the rotation axis o, and the airfoil aerodynamic performance was further improved.

[0059] Example 3

[0060] A wind turbine blade accessory for suppressing flow separation, wherein the chordal length of the wind turbine blade accessory corresponding to the chordal direction of the wind turbine blade is l, l = 0.15C to 0.35C, the axial length of the wind turbine blade accessory corresponding to the axial direction of the wind turbine blade is V, V = 0.1R to 0.2R, and the maximum thickness of the wind turbine blade accessory is M, M = 0.01C to 0.02C; the chordal installation position of the wind turbine blade accessory is: the distance d, d = 0.15C to 0.35C, from the orthographic projection position of the leading edge of the middle part of the wind turbine blade accessory on the wind turbine blade to the leading edge end of the airfoil region or transition region of the wind turbine blade at which it is located. 5C; The axial installation position of the wind turbine blade accessory is as follows: the distance from the end of the wind turbine blade accessory near the circular area of ​​the wind turbine blade to the end of the circular area of ​​the wind turbine blade in the orthographic projection position of the wind turbine blade is K, K = 0.15R ~ 0.2R; The installation height of the wind turbine blade accessory above the suction surface of the wind turbine blade is as follows: the vertical height of the wind turbine blade accessory from its orthographic projection on the wind turbine blade is h, h = 0.05C ~ 0.35C; where C is the chord length of the airfoil area or transition area of ​​the wind turbine blade at the orthographic projection position in the middle of the wind turbine blade accessory, and R is the total axial length of the wind turbine blade.

[0061] In this embodiment, the wind turbine blade accessory is installed above the suction surface of the airfoil region of the wind turbine blade or above the suction surface of the transition region between the circular region and the airfoil region of the wind turbine blade.

[0062] Computational fluid dynamics was used to perform aerodynamic simulation calculations on the combination of the NREL 5MW wind turbine blade and its accessories, with an air density of 1.225 kg / m³. 3 At a temperature of 20℃, the DDES kW turbulence model was used to simulate the flow state on the surface of a wind turbine blade under an incoming wind speed of 11.4 m / s. Figure 8 . Figure 8 The left side shows the suction surface wall limit streamlines of a wind turbine blade without wind turbine blade accessories. Figure 8 The right side shows the limiting streamlines of the suction surface of a wind turbine blade with a wind turbine blade accessory. It can be seen that the flow separation on the blade surface is improved under the influence of the wind turbine blade accessory in Example 3. At a blade radius of 15 meters, the wind turbine blade accessory's effect on suppressing flow separation is more significant, thus leading to an increase in rotor torque.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent substitutions, and improvements made by those skilled in the art to the above embodiments without departing from the scope of the technical solution of the present invention, based on the technical essence of the present invention, shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A wind turbine blade accessory for suppressing flow separation, characterized in that: The wind turbine blade accessory is installed above the suction surface of the airfoil region of the wind turbine blade, or above the suction surface of the transition area between the circular region and the airfoil region of the wind turbine blade, via a bracket structure; the wind turbine blade accessory is a curved surface structure with a certain curvature and a smooth outer surface; Its curved surface structure shape is the same as the blade surface shape at the position of the wind turbine blade attachment in the orthographic projection of the wind turbine blade. The orthographic projection is the projection perpendicular to the plane formed by the axial direction of the wind turbine blade and the chord direction of the wind turbine blade. The wind turbine blade accessory is in the form of a thin plate. The leading and trailing edges of the wind turbine blade accessories are both rounded. The wind turbine blade accessory has a rotating shaft in the middle along the axial direction of the wind turbine blade. The wind turbine blade accessory can be fixed after rotating around the rotating shaft within a certain angle range on the support structure. The rotation angle is θ, where θ = -60°~60°. A rotating shaft is provided on the support structure, passing through the centerline of the wind turbine blade accessory along the axial direction of the wind turbine blade. A first buckle and a second buckle are provided on the edge of the support structure. The first buckle is used to fix the wind turbine blade accessory that is not rotating, and the second buckle is used to fix the wind turbine blade accessory that is rotating. The chord length of the wind turbine blade accessory corresponding to the chord direction of the wind turbine blade is l, l = 0.05C~0.5C, and the maximum thickness of the wind turbine blade accessory is M, M = 0.005C~0.2C. The chord installation position of the wind turbine blade accessory is: the distance d, d = 0~0.7C, from the leading edge of the middle part of the wind turbine blade accessory in the orthographic projection position of the wind turbine blade to the leading edge end of the airfoil area or transition area of ​​the wind turbine blade where it is located. The installation height of the wind turbine blade accessory above the suction surface of the wind turbine blade is: the vertical height of the wind turbine blade accessory from its orthographic projection on the wind turbine blade is h, h = 0.01C~2C; where C is the chord length of the wind turbine blade airfoil area or transition area at the orthographic projection position of the middle part of the wind turbine blade accessory.

2. The wind turbine blade accessory for suppressing flow separation according to claim 1, characterized in that: The wind turbine blade accessory is installed above the suction surface of the airfoil region of the wind turbine blade, near the transition area.

3. The wind turbine blade accessory for suppressing flow separation according to claim 1, characterized in that: The wind turbine blade accessory is located above the suction surface at the leading edge, middle, or trailing edge of the airfoil region or transition region of the wind turbine blade.

4. The wind turbine blade accessory for suppressing flow separation according to claim 1, characterized in that: The rotation angle θ is -15° to 15°.

5. The wind turbine blade accessory for suppressing flow separation according to claim 1, characterized in that: The chordal length of the wind turbine blade accessory corresponding to the chordal direction of the wind turbine blade is l, l = 0.15C~0.35C; the axial length of the wind turbine blade accessory corresponding to the axial direction of the wind turbine blade is V, V = 0.1R~0.2R; the maximum thickness of the wind turbine blade accessory is M, M = 0.01C~0.02C; the chordal installation position of the wind turbine blade accessory is: the distance d, d = 0.15C~0.5C, from the orthographic projection position of the leading edge of the middle part of the wind turbine blade accessory on the wind turbine blade to the leading edge end of the airfoil region or transition region of the wind turbine blade where it is located; the wind... The axial installation position of the wind turbine blade accessory is as follows: the distance from the end of the wind turbine blade accessory near the circular area of ​​the wind turbine blade to the end of the circular area of ​​the wind turbine blade in the orthographic projection position is K, where K = 0.15R~0.2R; the installation height of the wind turbine blade accessory above the suction surface of the wind turbine blade is as follows: the vertical height of the wind turbine blade accessory from its orthographic projection on the wind turbine blade is h, where h = 0.05C~0.35C; where C is the chord length of the airfoil area or transition area of ​​the wind turbine blade at the orthographic projection position in the middle of the wind turbine blade accessory, and R is the total axial length of the wind turbine blade.

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