Thin airfoil family and wind turbine blade

Abstract

The application discloses a thin airfoil family and a wind power blade. The thin airfoil family is based on a geometric shape topology coordination principle, and through deep space coupling of front, middle and rear section characteristics of the full chord profile of the airfoil, flow field reconstruction and energy management are realized, so that the airfoil family with target aerodynamic characteristics is obtained. In the front section of the airfoil, a minimum leading edge radius is adopted to actively induce high-energy turbulent flow, to advance the transition, and to significantly reduce the leading edge roughness sensitivity. In the middle section of the airfoil, a distance of an inverse pressure gradient bias zone of more than 0.58c is forced to be maintained, a long-distance pressure recovery buffer zone is constructed, and the inverse pressure gradient is greatly flattened, so that the boundary layer separation is delayed and the critical stall attack angle is improved. In the rear section of the airfoil, a reverse kick point is arranged to utilize a large trailing edge reverse angle to strengthen the downwash effect, to realize circulation overload, and to ensure that the airfoil still has high design lift and high lift-drag ratio characteristics under high relative thickness.

Description

Technical Field

[0001] This application relates to the field of wind turbine blade technology, and more specifically, to a family of thin airfoils and wind turbine blades. Background Technology

[0002] Airfoils are the core design element of wind turbine blades. Their selection and optimization are the fundamental means to balance the contradictions between blade aerodynamic efficiency, load, structural reliability, and noise. The development and application of high-performance airfoil families has always been the focus of technical research in the wind power industry. 15MW+ ultra-large flexible blades place stringent requirements on power output in low wind speed areas and performance stability in complex environments, and existing general-purpose airfoil families are no longer sufficient to meet these requirements.

[0003] Currently, airfoil design can be improved by only fine-tuning a general airfoil, which has limited effect on lift coefficient and lift-drag ratio; or by increasing lift coefficient, but with low maximum lift-drag ratio and poor aerodynamic adaptability; or by increasing lift-drag ratio, but with lift focused on a moderate level, traditional geometric construction logic, and the lift potential of thick airfoils is limited and lift coefficient must be sacrificed to achieve a smooth stall.

[0004] In summary, the lack of thin airfoil family schemes that can achieve a synergistic improvement in high design lift, high critical angle of attack, and low roughness sensitivity through geometric topology reconstruction has become a technical bottleneck restricting the efficient and low-load design of ultra-large blades. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a thin airfoil family and wind turbine blade to achieve a thin airfoil family solution that synergistically improves high design lift, high critical angle of attack, and low roughness sensitivity.

[0006] To achieve the above objectives, this application provides the following technical solution: In a first aspect, this application provides a family of thin airfoils, including at least two types of thin airfoils, wherein each thin airfoil includes a leading edge, a middle section, and a trailing edge; wherein... Leading edge radius of the airfoil The range is 0.6%c to 1.4%c; The airfoil midsection includes an adverse pressure gradient offset region; The airfoil's trailing section includes a reverse warping feature, which refers to the set of coordinate points where the curvature of the lower surface profile of the airfoil's trailing section reverses and crosses the chord line into the positive value region. Maximum thickness point on the upper surface of the reverse pressure gradient bias region The chordal position of the point of anti-warping amplitude on the lower surface of the airfoil's trailing section Spatial deviation between satisfy: .

[0007] In some embodiments, the leading edge radius Satisfaction: The unit is %c; where, This refers to the relative thickness.

[0008] In some embodiments, the location of the maximum thickness of the airfoil's leading edge satisfy: .

[0009] In some embodiments, the location of the maximum thickness of the airfoil's leading edge The scope is: <0.288c.

[0010] In some embodiments, the location of the maximum thickness of the airfoil's leading edge The range is 0.270c~0.288c.

[0011] In some embodiments, spatial offset Follow Increase and maintain at 0.585°C to 0.600°C.

[0012] In some embodiments, the starting position of the anti-warping feature is located at 0.7c~0.85c.

[0013] In some embodiments, the tangent angle of the line connecting the lower surface anti-warping amplitude point and the trailing edge point is... ,satisfy: .

[0014] In some embodiments, the thin-wing family is in the chordal position The vertical axis coordinate of the upper surface profile curve is ; Thin-winged family in chordal position The vertical axis coordinate of the lower surface profile curve is ; Thin-winged family in chordal position The ordinate of the mid-arc is ;as well as Thin-winged family in chordal position The ordinate of the thickness line is satisfy:

[0015] .

[0016] In some embodiments, the thin airfoil family includes a first thin airfoil, a second thin airfoil, and a third thin airfoil, wherein the relative thickness of the first thin airfoil is 18%, the relative thickness of the second thin airfoil is 21%, and the relative thickness of the third thin airfoil is 25%.

[0017] Secondly, this application provides a wind turbine blade whose airfoil satisfies any of the above-mentioned thin airfoil family.

[0018] As can be seen from the above examples, the thin airfoil family provided in this application is based on the principle of "geometric shape topology synergy". By deeply spatially coupling the characteristics of the front, middle and rear sections of the airfoil's full chordal profile, flow field reconstruction and energy management are achieved, thereby obtaining an airfoil family with the target aerodynamic characteristics. Specifically, in the leading section of the airfoil: using an extremely small leading edge radius can actively induce the transition to occur earlier, obtain high-energy turbulence, and significantly reduce the leading edge roughness sensitivity; in the middle section of the airfoil, a reverse pressure gradient offset distance of more than 0.58c is forcibly maintained to construct a long-distance pressure recovery buffer zone, which greatly smooths out the reverse pressure gradient, thereby delaying boundary layer separation and increasing the critical stall angle of attack; in the rear section of the airfoil, an anti-tilt point is set to enhance the downwash effect by using a large trailing edge anti-tangential angle to achieve circulation heavy load. While effectively offsetting the transition damping, it ensures that the airfoil still has high design lift and high lift-to-drag ratio characteristics under high relative thickness. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0020] Figure 1 A schematic diagram of an airfoil provided in an embodiment of this application; Figure 2 This application provides an airfoil geometry analytical method based on thickness distribution and mid-curvature distribution; Figure 3 The embodiments of this application provide three SN-W1HL thin airfoil geometric profiles; Figure 4 A comparison of the aerodynamic curves of the first thin airfoil and the DU airfoil of the same thickness provided in the embodiments of this application; Figure 5 A comparison of the aerodynamic curves of the second thin airfoil and the DU airfoil of the same thickness provided in the embodiments of this application; Figure 6 A comparison of the aerodynamic curves of the third thin airfoil and the DU airfoil of the same thickness provided in the embodiments of this application; Figure 7 A schematic diagram of the flow field of the first thin airfoil provided in the embodiments of this application; Figure 8 A schematic diagram of the flow field of the second thin airfoil provided in the embodiments of this application; Figure 9 The schematic diagram of the flow field of the third thin airfoil provided in the embodiments of this application. Detailed Implementation

[0021] See Figure 1 and Figure 2 There are various ways to define the geometric characteristic parameters of an airfoil. The definition of the geometric characteristic parameters of the airfoil involved in this application is as follows. The airfoil coordinates are a standardized geometric representation: the length of the characteristic chord is 1 unit, and the fore-end of the airfoil is the origin; the x-coordinate of the trailing edge points on the upper and lower surfaces is 1, and the y-coordinate is symmetrical about the x-axis. Furthermore, from the fore-end to the trailing edge, the airfoil is successively divided into the leading edge, middle edge, and trailing edge. The range of the leading edge is (0, 20%), the range of the middle edge is [20%, 60%], and the range of the trailing edge is (60%, 100%).

[0022] (1) Mid-curve: The curve formed by the midpoints of the vertical coordinates of the upper and lower surfaces of the airfoil profile.

[0023] (2) Leading edge and leading edge radius: The foremost point of the arc in the airfoil is called the leading edge of the airfoil, and the radius of the inscribed circle at the leading edge of the airfoil is called the leading edge radius.

[0024] (3) Trailing edge and trailing edge thickness: The last point of the arc line in the airfoil is called the trailing edge; the distance between the upper and lower contour lines of the airfoil at the trailing edge is called the trailing edge thickness.

[0025] (4) Chord line and chord length: The line connecting the leading edge and trailing edge of the airfoil is called the airfoil chord line, and the length of the chord line is called the airfoil chord length.

[0026] (5) Camber: The maximum vertical distance from the mid-arc line to the chord length is called the airfoil camber, and the ratio of camber to chord length is called relative camber.

[0027] (6) Thickness and thickness distribution: The distance between the upper and lower airfoil surfaces where the airfoil profile line is perpendicular to the chord line is called the airfoil thickness. Conventionally, the relative thickness of an airfoil refers to the maximum relative thickness.

[0028] The chord length is the reference line for the airfoil. Generally, all other airfoil geometric characteristic parameters are relative values ​​obtained with reference to the airfoil chord length. The new geometric characteristic parameters closely related to the innovative realization of this invention are defined as follows: (7) Lower surface anti-warping amplitude: The geometric feature of the lower surface profile of the airfoil undergoing curvature reversal in the latter half and rising axially above the chord is defined as anti-warping; the maximum value of the ordinate of the lower surface profile after entering the positive value region of the coordinate system (above the chord) is defined as anti-warping amplitude.

[0029] (8) Anti-warping amplitude position: the relative position of the chord direction corresponding to the point where the anti-warping of the lower surface of the airfoil reaches the maximum value in the positive direction of the longitudinal axis.

[0030] (9) Tail edge reverse tangent angle The angle between the line connecting the point of maximum anti-warping amplitude on the lower surface of the airfoil and the trailing edge point (coordinate 1, 0) and the chord. This angle characterizes the strong downwash induction capability formed by the rapid contraction towards the trailing edge after the lower surface bulge.

[0031] (10) The spatial distance between the maximum thickness abscissa position of the airfoil (the highest point of the total thickness) and the position of the lower surface anti-warping amplitude (the highest point of the lower surface bulge). This distance defines the physical span of the airfoil transitioning from the structural support zone to the aerodynamic functional reconfiguration zone.

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] See Figure 1 This application provides a family of thin airfoils, including at least two types of thin airfoils, wherein each thin airfoil includes a leading section, a middle section, and a trailing section.

[0034] Among them, the leading edge radius of the airfoil's leading section The range is 0.6%c to 1.4%c; The airfoil midsection includes the reverse pressure gradient offset region; the airfoil trailing section includes the anti-warping feature, which refers to the set of coordinate points where the curvature of the lower surface profile of the airfoil trailing section reverses and crosses the chord line into the positive value region.

[0035] Maximum thickness point on the upper surface of the reverse pressure gradient bias region The chordal position of the point of anti-warping amplitude on the lower surface of the airfoil's trailing section Spatial deviation between satisfy: .

[0036] The thin airfoil family provided in this application is based on the principle of "geometric topological synergy". By deeply spatially coupling the characteristics of the leading, middle and trailing sections of the airfoil's full chordal profile, flow field reconstruction and energy management are achieved, thereby obtaining an airfoil family with the target aerodynamic characteristics. Specifically, in the leading section of the airfoil: using an extremely small leading edge radius can actively induce high-energy turbulence (early transition) and significantly reduce leading edge roughness sensitivity; in the middle section of the airfoil, a reverse pressure gradient offset distance of more than 0.58c is forcibly maintained to construct a long-distance pressure recovery buffer zone, which greatly smooths out the reverse pressure gradient, thereby delaying boundary layer separation and increasing the critical stall angle of attack; in the trailing section of the airfoil, an anti-tilt point is set to enhance the downwash effect with a large trailing edge anti-tangential angle, achieving circulation heavy load. While effectively offsetting transition damping, it ensures that the airfoil still has high design lift and high lift-to-drag ratio characteristics under high relative thickness.

[0037] To ensure consistent performance of this airfoil family across different thicknesses, the leading edge radius... Satisfaction: The unit is %c; where, This refers to the relative thickness.

[0038] Maximum thickness position of the airfoil leading section satisfy: Unit: c. Location of maximum thickness at the leading edge of the airfoil. The scope is: <0.288c. Location of maximum thickness at the leading edge of the airfoil. The range is 0.270c~0.288c.

[0039] Spatial deviation Follow Increase and maintain at 0.585°C to 0.600°C.

[0040] The above formula ensures the logical self-consistency of the airfoil family in terms of geometric evolution, forming an indivisible and synergistic whole.

[0041] By positioning the initial position of the anti-tilt feature at 0.7c~0.85c, lift and lift-to-drag ratio can be improved. Through strong downwash, a flap-like heavy load effect is generated, which increases the lift coefficient, compensates for the pressure drag loss caused by leading-edge transition, and ultimately achieves the goal of high lift-to-drag ratio.

[0042] Specifically, the tangent angle of the line connecting the point of anti-warping amplitude on the lower surface and the point of the trailing edge. ,satisfy: .

[0043] See Figure 1The thin airfoil family includes a first thin airfoil, a second thin airfoil, and a third thin airfoil. The relative thickness of the first thin airfoil is 18%, the relative thickness of the second thin airfoil is 21%, and the relative thickness of the third thin airfoil is 25%. Their detailed characteristic parameters are shown in Table 1. Table 1 Characteristic parameters of three thin airfoils

[0044] Note: The thickest part and the offset of the anti-warping space in the table are... .

[0045] An airfoil's profile curve can be characterized by a series of discrete geometric coordinate points. There are various definitions or analytical methods for airfoil geometry or its corresponding geometric coordinates. One approach is to characterize the airfoil profile curve as a superposition of thickness distribution and mid-curve distribution, such as... Figure 2 As shown. In this application, the mid-curve of the airfoil is defined as the curve formed by the midpoints of the ordinates of the upper and lower surfaces of the airfoil profile on the same abscissa; the thickness distribution line of the airfoil is defined as the distribution of the distance between the upper and lower airfoil surfaces perpendicular to the chord line as a function of the chord length. Thin airfoil families at chord-direction positions... The vertical axis coordinate of the upper surface profile curve is Thin-winged family in chordal position The vertical axis coordinate of the lower surface profile curve is Thin-winged family in chordal position The ordinate of the mid-arc is ; and thin-winged families in the chordal position The ordinate of the thickness line is satisfy:

[0046] .

[0047] It should be noted that the aerodynamic efficiency (lift-drag ratio) - load (lift coefficient) characteristic curves of the first, second, and third thin airfoils are compared with those of a general-purpose airfoil of the same thickness, as shown in the attached figure. Figures 3 to 5As shown in Table 10, the main aerodynamic parameters of the three thin airfoils are compared with the aerodynamic characteristic parameters of the general-purpose DU airfoil. It can be seen that the design lift coefficients of the three airfoils with relative thicknesses of 18%, 21%, and 25% provided in this application are 1.48, 1.43, and 1.50, respectively, which are 76.2%, 28.8%, and 37.6% higher than the DU airfoil of the same thickness; the maximum lift-to-drag ratios are 202.2, 191.0, and 183.5, respectively, which are 23.9%, 13.0%, and 17.8% higher than the DU airfoil of the same thickness; and the critical stall angles of attack are 13°, 13°, and 13°, each 1° higher than the DU airfoil of the same thickness. Regarding the maximum lift coefficient, the three airfoils on clean surfaces have maximum lift coefficients of 1.91, 1.87, and 1.89, respectively, representing increases of 42.5%, 14.7%, and 22.7% compared to the DU airfoil of the same thickness. On rough surfaces, the three airfoils have maximum lift coefficients of 1.86, 1.80, and 1.72, respectively, representing increases of 40.9%, 13.2%, and 17.8% compared to the DU airfoil of the same thickness. Based on the charts, the three SN-W1HL thin airfoil families exhibit characteristics such as high lift-to-drag ratio, high design lift coefficient, high critical stall angle of attack, and high maximum lift, making them particularly suitable for the current design requirements of flexible, slender blades for high aerodynamic efficiency, low load, and high aerodynamic adaptability.

[0048] Table 2 - Comparison of Aerodynamic Characteristic Parameters of Thin Airfoils

[0049] In summary, the thin-wing family of airfoils in this application achieves the following significant beneficial effects through the deep synergy of leading-edge transition induction, mid-section topological offset, and trailing-edge loading compensation: Extremely high design lift coefficient and high efficiency in enhancing work capacity (quantitative analysis): as shown in Table 2 and appendix. Figures 4 to 6 As shown, the thin airfoil family provided in this application achieves design lift coefficients of 1.48, 1.43, and 1.50 respectively when the relative thickness is 18%, 21%, and 25%. Compared with existing technologies (DU airfoils of the same thickness), these represent significant improvements of 76.2%, 28.8%, and 37.6%, respectively. This ensures that the blades possess extremely strong energy capture capabilities in the high-value wind speed range (before rated power), significantly increasing the overall annual power generation (AEP) of the turbine.

[0050] Stall characteristics and safety margin: This application utilizes a "reverse pressure gradient offset zone distance" of 0.58c or more to construct a pressure buffer zone, successfully maintaining the critical stall angle of attack at a high level of 13°, which is more than 1° higher than the prior art.

[0051] Extremely low leading-edge roughness sensitivity: By actively inducing early transition through an extremely small leading-edge radius, the airfoil exhibits exceptional stability under rough operating conditions such as pollution and icing. Data shows that under rough surface conditions, the maximum lift coefficient of the 25% thick airfoil can still reach 1.72, an improvement of 17.8%. This resolves the traditional industry contradiction that "high lift-to-drag ratio equals high sensitivity" for thick airfoils, greatly enhancing the blade's adaptability to complex operating environments.

[0052] See Figures 7 to 9 It can be clearly observed that: the lower leading edge protrusions of the first, second, and third thin airfoils guide the stagnation point downwards, reducing the suction peak; the flow field of the mid-section roof verifies that due to the existence of the 0.58c spatial deviation, a long-distance flat pressure zone is formed on the upper surface, with an extremely low pressure recovery slope; the trailing edge Flap effect: the anti-tilt feature forcibly guides the airflow downwards, forming a significant circulation enhancement zone.

[0053] This application provides a wind turbine blade whose airfoil satisfies any of the above-mentioned thin airfoil families. Since the above-mentioned thin airfoil families have the above-mentioned effects, wind turbine blades whose airfoils satisfy the above-mentioned thin airfoil families also have the corresponding effects, which will not be elaborated here.

[0054] The terms "first" and "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units may include steps or units not listed, but rather not listed.

[0055] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A family of thin-winged structures, characterized in that, It includes at least two thin airfoils, wherein each thin airfoil comprises a leading section, a middle section, and a trailing section; wherein, The leading edge radius of the airfoil's leading section The range is 0.6%c to 1.4%c; The airfoil midsection includes a reverse pressure gradient offset region; The airfoil's trailing section includes a reverse warping feature, which refers to the set of coordinate points where the curvature of the lower surface profile of the airfoil's trailing section reverses and crosses the chord line into the positive value region. The maximum thickness point on the upper surface of the reverse pressure gradient bias region The chordal position of the point of anti-warping amplitude on the lower surface of the airfoil's rear section Spatial deviation between satisfy: 。 2. The thin-wing type family as described in claim 1, characterized in that, The leading edge radius Satisfaction: The unit is %c; where, This refers to the relative thickness.

3. The thin-wing type family as described in claim 2, characterized in that, The maximum thickness position of the leading section of the airfoil satisfy: 。 4. The thin-wing type family as described in claim 3, characterized in that, The maximum thickness position of the leading section of the airfoil The scope is: <0.288c.

5. The thin-wing type family as described in claim 4, characterized in that, The maximum thickness position of the leading section of the airfoil The range is 0.270c~0.288c.

6. The thin-wing type family as described in claim 2, characterized in that, The spatial deviation Follow Increase and maintain at 0.585°C to 0.600°C.

7. The thin-wing type family as described in claim 1, characterized in that, The starting position of the anti-warping feature is located at 0.7c~0.85c.

8. The thin-wing type family as described in claim 7, characterized in that, The tangent angle of the line connecting the lower surface anti-warping amplitude point and the trailing edge point. ,satisfy: .

9. The family of thin-winged airfoils as described in any one of claims 1 to 8, characterized in that, The thin-wing type family in the chord position The vertical axis coordinate of the upper surface profile curve is ; The thin-wing type family in the chord position The vertical axis coordinate of the lower surface profile curve is ; The thin-wing type family in the chord position The ordinate of the mid-arc is ; as well as The thin-wing type family in the chord position The ordinate of the thickness line is satisfy: 。 10. The family of thin-winged airfoils as claimed in any one of claims 1 to 8, characterized in that, The thin airfoil family includes a first thin airfoil, a second thin airfoil, and a third thin airfoil, wherein the relative thickness of the first thin airfoil is 18%, the relative thickness of the second thin airfoil is 21%, and the relative thickness of the third thin airfoil is 25%.

11. A wind turbine blade, characterized in that, The airfoil of the wind turbine blade satisfies the family of thin airfoils as described in any one of claims 1 to 10.

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