Blade airfoil of vertical-axis wind turbine, vertical-axis wind wheel and wind turbine

Abstract

The invention provides a vertical axis wind turbine blade airfoil, a wind wheel and a wind turbine. The airfoil has a high lift-drag ratio at a low wind speed, and the maximum thickness of the airfoil is 13.19% of the chord length of the airfoil; the maximum thickness position of the airfoil is 32.30% of the chord length of the airfoil; the maximum camber of the airfoil is 2.27% of the chord length of the airfoil; and the maximum camber position of the airfoil profile is 58.90% of the maximum camber position of the airfoil profile. The blade airfoil has a high lift coefficient and lift-drag ratio under the low Reynolds number and the large-range local attack angle, and therefore the aerodynamic performance of the small vertical axis wind turbine at the medium-low wind speed can be effectively improved. The wind energy utilization efficiency of the small vertical axis wind driven generator under the low wind speed can be improved, the generating capacity is improved, the generating efficiency of a unit is improved, and the requirements of comprehensive smart energy projects and distributed wind power with ground wind resources greatly affected by the surrounding environment are better met.

Description

Technical Field

[0001] The invention relates to the field of wind power generation, and in particular to a vertical axis wind turbine blade airfoil, a vertical axis wind wheel and a wind turbine. Background Art

[0002] Small vertical axis wind turbines have the characteristics of compact structure, easy maintenance, and strong environmental adaptability, so they are very suitable for integrated smart energy and zero-carbon green power plant projects of distributed wind power generation. Compared with centralized wind power generation, the site selection of integrated smart energy projects is often closer to users. Therefore, they are more restricted by surrounding conditions such as installation height and building shielding, and the wind resource conditions vary greatly, and the annual average wind speed is low.

[0003] At the same time, since the local angle of attack of the vertical axis wind turbine blade airfoil under the action of wind force is the composite angle of the natural incoming wind direction and the blade phase angle. When the incoming wind speed or blade tip speed is relatively small, the local angle of attack will change greatly with the change of the phase angle. Therefore, it is necessary to develop an airfoil suitable for small vertical axis wind turbines to ensure that the wind turbine blades have good aerodynamic performance and improve power generation efficiency under low wind speed and large changes in the angle of attack.

[0004] For example, the Chinese patent application with publication number CN115288927A discloses a lift-type vertical axis wind turbine, which provides a local moving surface for the vertical axis wind turbine blades to enhance the ability of the boundary layer to resist separation, thereby improving the lift-to-drag ratio of the blades. However, in order to achieve local movement of the blade surface, the blades of the invention are provided with rotating rollers, tubular motors, angle sensors and other devices, which increases the complexity of the blades and is not conducive to reducing daily maintenance costs.

[0005] A patent application with Chinese publication number CN115306486A discloses a bionic leading edge slat, a blade and a preparation method that imitate the dolphin head profile, which connects the bionic leading edge slat and the basic blade airfoil to improve the aerodynamic performance of the blade. However, the invention also increases the structural complexity of the blade, which is not conducive to reducing the manufacturing and operation and maintenance costs of the vertical group unit.

[0006] In view of this, the inventor has designed a vertical axis wind turbine blade airfoil, a wind wheel and a wind turbine in order to solve the above technical problems. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the defect in the prior art that there is a lack of wind turbine blades with good aerodynamic performance and simple structure under low wind speeds and large changes in the angle of attack, and to provide a vertical axis wind turbine blade airfoil, a vertical axis wind wheel and a wind turbine.

[0008] The present invention solves the above technical problems through the following technical solutions:

[0009] The invention provides a vertical axis wind turbine blade airfoil, which has a high lift-to-drag ratio at low wind speeds and is characterized in that the maximum thickness of the airfoil is 13.19% of the airfoil chord length; the maximum thickness position of the airfoil is 32.30% of the airfoil chord length; the maximum camber of the airfoil is 2.27% of the airfoil chord length; and the maximum camber position of the airfoil is 58.90% of the airfoil.

[0010] According to one embodiment of the present invention, when the blade phase angle is 15°, the incoming wind speed is 3.5 m / s, the local angle of attack is 8.5°, and the Reynolds number is 0.75×10 5 Under the working condition, the lift coefficient of the airfoil is 1.09, and the lift-to-drag ratio is 31.93. According to one embodiment of the present invention, the Reynolds number is 0.75×10 5 When , the maximum lift-to-drag ratio of the airfoil is 44.94; according to one embodiment of the present invention, within the range of the local angle of attack of 3.5° to 11°, the lift-to-drag ratio is higher than 20.

[0011] According to one embodiment of the present invention, when the incoming wind speed is 8 m / s, the local angle of attack is 5.5°, and the Reynolds number is 1.25×10 5 Under the working condition of , the lift-to-drag ratio of the airfoil is 58.67, and the corresponding phase angle is 12°. According to one embodiment of the present invention, when the Reynolds number is 1.25×10 5 , under the conditions of local attack angle of 1.5°~12.5°, the lift-to-drag ratio is higher than 20.

[0012] According to one embodiment of the present invention, the geometric shapes of the upper and lower surfaces of the airfoil satisfy the following formula:

[0013]

[0014]

[0015] In the formula, x is the horizontal coordinate of the data point, y is u is the relative position of the data point on the upper surface of the airfoil in the coordinate system, a u0 、a u1 、a u2 、a u3 、a u4 is the characteristic parameter of the airfoil upper surface function, y TEu is the trailing edge coordinate of the upper surface of the airfoil; l is the relative position of the data point on the lower surface of the airfoil in the coordinate system, a l0 、a l1 、a l2 、a l3 、a l4is the characteristic parameter of the lower surface function of the airfoil, y TEl is the trailing edge coordinate of the lower surface of the airfoil.

[0016] The present invention further provides a vertical axis wind wheel, which is characterized in that the vertical axis wind wheel is equipped with blades of the vertical axis wind turbine blade airfoil as described above.

[0017] The present invention further provides a vertical axis wind turbine, which is characterized in that the vertical axis wind turbine comprises the vertical axis wind wheel as described above.

[0018] The positive and progressive effects of the present invention are:

[0019] The invention discloses a vertical axis wind turbine blade airfoil, a vertical axis wind rotor, and a wind turbine. The blade airfoil has a high lift coefficient and lift-to-drag ratio at a low Reynolds number and a wide range of local angles of attack, thereby effectively improving the aerodynamic performance of a small vertical axis wind turbine at low and medium wind speeds. The blade airfoil can improve the wind energy utilization efficiency of a small vertical axis wind turbine at low wind speeds, increase the power generation, and improve the power generation efficiency of the unit, thereby better meeting the needs of integrated smart energy projects and distributed wind power where the ground wind resources are greatly affected by the surrounding environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments, in which the same reference numerals always represent the same features, wherein:

[0021] Figure 1 It is a schematic diagram of the airfoil of a blade of a vertical-axis wind turbine according to the present invention.

[0022] Figure 2 It is a schematic diagram of parameters of the airfoil of the vertical axis wind turbine blade of the present invention.

[0023] Figure 3A The vertical axis wind turbine blade airfoil of the present invention and the existing airfoil are compared with each other at a Reynolds number of 0.75×10 5 Schematic diagram of the relationship between angle of attack and lift coefficient.

[0024] Figure 3B The vertical axis wind turbine blade airfoil of the present invention and the existing airfoil are compared with each other at a Reynolds number of 0.75×10 5 Schematic diagram of the relationship between angle of attack and lift-to-drag ratio.

[0025] Figure 4A The vertical axis wind turbine blade airfoil of the present invention and the existing airfoil are compared with each other at a Reynolds number of 1.25×10 5 Schematic diagram of the relationship between angle of attack and lift coefficient.

[0026] Figure 4BThe vertical axis wind turbine blade airfoil of the present invention and the existing airfoil are compared with each other at a Reynolds number of 1.25×10 5 Schematic diagram of the relationship between angle of attack and lift-to-drag ratio. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Reference will now be made in detail to preferred embodiments of the present invention, examples of which are shown in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to represent the same or similar parts.

[0029] Furthermore, although the terms used in the present invention are selected from well-known and commonly used terms, some terms mentioned in the present invention specification may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this document.

[0030] Furthermore, it is required that the present invention be understood not only by the actual terms used but also by the meanings connoted by each term.

[0031] like Figure 1 and Figure 2 As shown, the present invention provides a small vertical axis wind turbine blade airfoil, Figure 2 The dotted line L1 is the chord line of the airfoil, and the dotted line L2 is the mid-camber line of the airfoil; the maximum thickness y of the airfoil t It is 13.19% of the airfoil chord length. The maximum thickness position of the airfoil is x t It is 32.30% of the airfoil chord length. The maximum curvature y of the airfoil c It is 2.27% of the airfoil chord length. The maximum curvature position of the airfoil is x c It is 58.90% of the airfoil.

[0032] The airfoil provided by the present invention has a high lift coefficient and lift-to-drag ratio at a low Reynolds number and a wide range of local angles of attack, thereby effectively improving the aerodynamic performance of a small vertical axis wind turbine at low and medium wind speeds. It can improve the wind energy utilization efficiency of a small vertical axis wind turbine at low wind speeds, increase the power generation, and improve the power generation efficiency of the unit, and better meet the needs of integrated smart energy projects and distributed wind power where the ground wind resources are greatly affected by the surrounding environment.

[0033] like Figure 3A and 3B As shown in FIG. 1 , the blade airfoil provided by the present invention has a blade phase angle of 15° and an incoming wind speed of 3.5 m / s, corresponding to a local angle of attack α of about 8.5° and a Reynolds number of about 0.75×10 5, the lift coefficient of the airfoil can reach 1.09, and the lift-to-drag ratio is 31.93. At the same Reynolds number, the maximum lift-to-drag ratio of the airfoil is 44.94, and the lift-to-drag ratio is higher than 20 in the range of local angle of attack of 3.5° to 11°, and the corresponding phase angle is about 6° to 20°.

[0034] like Figure 3A and 3B As shown, compared with the existing airfoil, the airfoil of the present invention has a better performance at a Reynolds number of 0.75×10 5 , under the same local angle of attack α, it has a significantly higher lift coefficient and lift-to-drag ratio.

[0035] It can be seen that the airfoil has better aerodynamic performance in a lower Reynolds number and a larger phase angle variation range, and can improve the wind energy utilization efficiency of the vertical axis wind turbine under low speed conditions.

[0036] In addition, the airfoil still has excellent aerodynamic performance at higher Reynolds numbers and larger phase angles.

[0037] like Figure 4A and 4B As shown, when the incoming wind speed is 8 m / s, the local angle of attack α is 5.5°, and the Reynolds number is about 1.25×10 5 Under the condition of , the lift-to-drag ratio reaches 58.67, corresponding to a phase angle of about 12°. Under the same Reynolds number, when the local angle of attack α is 1.5° to 12.5°, the lift-to-drag ratio is higher than 20, corresponding to a phase angle of 3 to 26°.

[0038] like Figure 4A and 4B As shown, compared with the existing airfoil, the airfoil of the present invention has a better performance at a Reynolds number of 2.5×10 5 , under the same partial conditions with the same local angle of attack α, it has a significantly higher lift coefficient and lift-to-drag ratio.

[0039] The inventor of the present application designed the blade airfoil used in the present invention by the following method, the steps of which are as follows:

[0040] Step S 1 , determine the airfoil design boundary conditions and obtain the reference airfoil under the boundary conditions.

[0041] Step S 2 , use high-order polynomials to fit the reference airfoil, obtain the characteristic parameters of the reference airfoil, and determine the value range of the characteristic parameters of the target airfoil.

[0042] Step S 3 , use the Latin supersampling method within the value range to generate the characteristic parameters of the target airfoil, and use the characteristic parameters to obtain the target airfoil geometry, thereby obtaining a series of alternative airfoils.

[0043] Step S 4 , solve and calculate the aerodynamic performance of alternative airfoils to obtain the airfoil with better performance.

[0044] Step S 5 , use the characteristic parameters of the airfoil with better performance as the initial parameters, perform optimization calculations, and obtain the desired airfoil.

[0045] The relative thickness of the airfoil directly affects the geometric shape of the airfoil. Generally speaking, airfoils with a relatively small relative thickness and a curvature are more likely to obtain a higher lift-to-drag ratio. However, when the leading edge of a thin airfoil is eroded or contaminated, the power generation efficiency of the wind turbine will be significantly reduced. Therefore, in order to ensure that the airfoil has a low leading edge roughness sensitivity and good structural performance, the relative thickness of the airfoil needs to be restricted during design. The design parameter value range of the airfoil can be preliminarily obtained through the restriction conditions.

[0046] The relative width of the airfoil is limited to a range of 10% to 30%, and the initial reference airfoils are designed to have a relative thickness of 30%, a maximum camber of 1.5% and a relative thickness of 10%, a maximum camber of 0.4%.

[0047] Taking into account the fitting accuracy and calculation amount, a fourth-order polynomial characteristic function is used to describe the geometric shapes of the upper and lower surfaces of the airfoil respectively.

[0048] The formula is as follows:

[0049]

[0050]

[0051] Where x is the horizontal coordinate of the data point, subscripts u and l represent the upper and lower surfaces of the airfoil, respectively, and y u is the relative position of the data point on the upper surface of the airfoil in the coordinate system, a u0 、a u1 、a u2 、a u3 、a u4 is the characteristic parameter of the airfoil upper surface function, y TEu is the trailing edge coordinate of the upper surface of the airfoil; l is the relative position of the data point on the lower surface of the airfoil in the coordinate system, a l0 、a l1 、a l2 、a l3 、a l4 is the characteristic parameter of the lower surface function of the airfoil, y TEl is the trailing edge coordinate of the lower surface of the airfoil.

[0052] Each (x, y) represents a coordinate point on the airfoil profile, and the formula is y = f(x), which means that the coordinate points on the airfoil profile are fitted into a characteristic curve that can be represented by y = f(x). Therefore, when an x ​​is given, the corresponding y value can be obtained through the formula, thereby obtaining a coordinate point on the airfoil. The value range of x is [0,1].

[0053] Therefore, the geometric description of the airfoil shape can be achieved through the above 10 characteristic parameters.

[0054] The least square method is used to fit the geometric shape of the reference airfoil to obtain the upper and lower limits of the airfoil characteristic parameters.

[0055]

[0056] Using the Latin hypercube sampling method, each characteristic parameter is divided into n intervals within its value range. A value is randomly selected from each interval and combined with the characteristic values ​​selected by the same method for the other 9 characteristic parameters to generate a parameter sequence consisting of 10 new characteristic parameters. The new characteristic parameters are brought into the characteristic function and calculated to obtain a new airfoil data point coordinate. Through multiple sampling, a series of alternatives can be obtained. By calculating the aerodynamic characteristics of all the alternative airfoils, the blade phase angle of 15°, the incoming wind speed of 3.5m / s, the local angle of attack of about 8.5°, and the Reynolds number of about 0.75×10 5 The optimal airfoil is obtained under the design condition. The characteristic parameters of the optimal airfoil are used as initial values ​​and added to the genetic algorithm population for optimization calculation. After multiple iterations, the final optimized airfoil is obtained.

[0057] The airfoil provided in the present invention is designed and developed for vertical axis wind turbines used in integrated smart energy and distributed wind power projects, so the maximum thickness y of its geometric shape is determined by t , maximum thickness position x t , maximum curvature y c , maximum curvature position x c Different from the airfoils in the published patents, this airfoil has a larger lift-to-drag ratio at a lower Reynolds number and a larger scent angle, which can effectively improve the wind energy utilization efficiency of the vertical axis unit under the conditions of complex and changeable wind resources and low average wind speed.

[0058] The present invention also provides a vertical axis wind wheel, which is equipped with blades of the vertical axis wind generator blade airfoil of the present invention.

[0059] The present invention also provides a vertical axis wind turbine generator equipped with the vertical axis wind wheel of the present invention.

[0060] Since the vertical axis wind wheel and the vertical axis wind turbine of the present invention are equipped with blades of the vertical axis wind turbine blade airfoil of the present invention, and the blade airfoil of the present invention has a higher lift coefficient and lift-to-drag ratio at a lower Reynolds number and a larger range of local angles of attack, the aerodynamic performance of a small vertical axis wind turbine at medium and low wind speeds can be effectively improved.

[0061] The blade airfoil can improve the wind energy utilization efficiency of a small vertical axis wind turbine under low wind speed, increase power generation, and improve the power generation efficiency of the unit, thereby better meeting the needs of integrated smart energy projects and distributed wind power where local wind resources are greatly affected by the surrounding environment.

[0062] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that these are only examples, and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A vertical axis wind turbine blade airfoil, the airfoil having a high lift-to-drag ratio at low wind speeds, characterized in that: The maximum thickness of the airfoil is 13.19% of the chord length of the airfoil; the position of the maximum thickness of the airfoil is 32.30% of the chord length of the airfoil; the maximum camber of the airfoil is 2.27% of the chord length of the airfoil; and the position of the maximum camber of the airfoil is 58.90% of the airfoil.

2. The vertical axis wind turbine blade airfoil according to claim 1, characterized in that: When the blade phase angle is 15°, the incoming wind speed is 3.5 m / s, the local angle of attack is 8.5°, and the Reynolds number is 0.75×10 5 Under the working condition, the lift coefficient of the airfoil is 1.09 and the lift-to-drag ratio is 31.

93.

3. The vertical axis wind turbine blade airfoil according to claim 1, characterized in that: The Reynolds number is 0.75×10 5 When , the maximum lift-to-drag ratio of the airfoil is 44.

94.

4. The vertical axis wind turbine blade airfoil as claimed in claim 3 has a lift-to-drag ratio higher than 20 within a local angle of attack range of 3.5° to 11°.

5. The vertical axis wind turbine blade airfoil according to claim 1, characterized in that: When the incoming wind speed is 8 m / s, the local angle of attack is 5.5°, and the Reynolds number is 1.25×10 5 Under the working condition, the lift-to-drag ratio of the airfoil is 58.67, and the corresponding phase angle is 12°.

6. The vertical axis wind turbine blade airfoil of claim 1, characterized in that: At a Reynolds number of 1.25×10 5 , under the conditions of local attack angle of 1.5°~12.5°, the lift-to-drag ratio is higher than 20.

7. The vertical axis wind turbine blade airfoil according to claim 1, characterized in that: The geometric shapes of the upper and lower surfaces of the airfoil satisfy the following formula: Where x is the horizontal coordinate of the data point, y is u is the relative position of the data point on the upper surface of the airfoil in the coordinate system, a u0 、a u1 、a u2 、a u3 、a u4 is the characteristic parameter of the airfoil upper surface function, y TEu is the trailing edge coordinate of the upper surface of the airfoil; l is the relative position of the data point on the lower surface of the airfoil in the coordinate system, a l0 、a l1 、a l2 、a l3 、a l4 is the characteristic parameter of the lower surface function of the airfoil, y TEl is the trailing edge coordinate of the lower surface of the airfoil.

8. A vertical axis wind wheel, characterized in that: The vertical axis wind wheel comprises a blade of a vertical axis wind turbine blade airfoil as described in any one of claims 1-8.

9. A vertical axis wind turbine, characterized in that: The vertical axis wind turbine comprises the vertical axis wind wheel as claimed in claim 9.

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