Vertical axis wind power blade airfoil suitable for medium-low wind speed, wind wheel and generator

Abstract

The invention provides a vertical axis wind power blade airfoil suitable for medium and low wind speeds, a wind wheel and a generator. The maximum thickness of the airfoil is 18.37% of the chord length of the airfoil; the maximum thickness position of the airfoil is 31.20% of the chord length of the airfoil; the maximum camber of the airfoil is 2.11% of the chord length of the airfoil; and the maximum camber position of the airfoil profile is 23.20% of the maximum camber position of the airfoil profile. The blade airfoil provided by the invention has higher lift coefficient and lift-drag ratio under the working conditions of larger local attack angle and lower Reynolds number, the aerodynamic performance of a vertical axis wind turbine at medium and low wind speeds can be effectively improved, and the wind energy utilization efficiency of a unit is improved. The requirements of comprehensive smart energy and distributed wind power projects with complex topographic conditions and dense or mutual shielding buildings can be met, and the power generation efficiency of the vertical axis wind turbine under the working conditions of large wind resource change and low average wind speed is improved.

Description

Technical Field

[0001] The present invention relates to the field of wind power generation, and in particular to a vertical-axis wind power blade airfoil, a wind wheel and a generator suitable for medium and low wind speeds. Background Art

[0002] Compared with horizontal axis wind turbines, vertical axis wind turbines have the characteristics of compact structure and strong environmental adaptability, so they are very suitable for use in integrated smart energy and distributed wind power projects. However, due to the limitations of terrain conditions, the wind resources at the installation sites of integrated smart energy or distributed wind power projects are complex and changeable, and the average wind speed is low. At the same time, since the blades of vertical axis wind turbines rotate in the horizontal direction around the main axis of the unit after being acted upon by wind, the local angle of attack of the airfoil is affected by the incoming wind direction and phase angle at the same time, especially 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 design a special airfoil for the vertical axis unit to ensure that the blade airfoil still has a high lift-to-drag ratio under medium and low wind speeds and large angles of attack.

[0003] For example, the patent application with Chinese publication number CN115288927A discloses a lift-type vertical axis wind turbine. The invention sets a local moving surface for the blade of the vertical axis wind turbine to enhance the ability of the boundary layer to resist separation, thereby improving the lift-to-drag ratio of the blade. However, in order to achieve local movement of the blade surface, the blade of the invention is provided with rotating rollers, tubular motors, angle sensors and other devices, which increases the complexity of the blade and is not conducive to reducing daily maintenance costs. The patent application with Chinese publication number CN115306486A discloses a bionic leading edge slat, blade and preparation method imitating 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 axis unit.

[0004] In view of this, the inventor has designed a vertical axis wind turbine blade airfoil, a wind wheel and a generator suitable for medium and low wind speeds, in order to solve the above technical problems. Summary of the invention

[0005] 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 blade airfoils with a high lift-to-drag ratio and a simple structure under medium and low wind speeds and large angles of attack, and to provide a vertical-axis wind turbine blade airfoil, wind wheel and generator suitable for medium and low wind speeds.

[0006] The present invention solves the above technical problems through the following technical solutions:

[0007] The present invention provides a vertical axis wind turbine blade airfoil suitable for medium and low wind speeds, which is suitable for vertical axis wind turbines under medium and low wind speeds. The airfoil has the following characteristics: the maximum thickness of the airfoil is 18.37% of the airfoil chord length; the position of the maximum thickness of the airfoil is 31.20% of the airfoil chord length; the maximum camber of the airfoil is 2.11% of the airfoil chord length; and the position of the maximum camber of the airfoil is 23.20% of the airfoil.

[0008] According to one embodiment of the present invention, when the blade phase angle is 30°, the incoming wind speed is 5 m / s, the local angle of attack is 16°, and the Reynolds number is 1.1×10 5 Under the working condition of , the lift coefficient of the airfoil is 1.27 and the lift-to-drag ratio is 18.51. According to one embodiment of the present invention, the Reynolds number is 1.1×10 5 When , the maximum lift-to-drag ratio of the airfoil is 39.09, and the local angle of attack is 12°.

[0009] According to one embodiment of the present invention, under the condition that the phase angle is 45° and the incoming wind speed is 8 m / s, the corresponding local angle of attack of the airfoil is 17° and the Reynolds number is 2.5×10 5 , the lift coefficient of the airfoil is 1.25, and the lift-to-drag ratio is 15.54. According to one embodiment of the present invention, the Reynolds number is 2.5×10 5 The maximum lift-to-drag ratio of the airfoil is 71.63, and the local angle of attack is 10°.

[0010] According to one embodiment of the present invention, the geometric shapes of the upper and lower surfaces of the airfoil satisfy the following formula:

[0011]

[0012]

[0013] 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 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.

[0014] 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 suitable for medium and low wind speeds as described above.

[0015] The present invention further provides a vertical axis wind turbine, which is characterized in that the vertical axis wind turbine is equipped with the vertical axis wind wheel as described above.

[0016] The positive and progressive effects of the present invention are:

[0017] The present invention is applicable to vertical axis wind turbine blade airfoils, wind rotors and generators at medium and low wind speeds. The blade airfoils provided have a higher lift coefficient and lift-to-drag ratio under conditions of larger local angle of attack and lower Reynolds number, thereby effectively improving the aerodynamic performance of vertical axis wind turbines at medium and low wind speeds and improving the wind energy utilization efficiency of the unit. It can meet the needs of integrated smart energy and distributed wind power projects with complex terrain conditions, dense buildings or mutual shielding, and improve the power generation efficiency of vertical axis wind turbines under conditions of large wind resource changes and low average wind speeds. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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:

[0019] Figure 1 It is a schematic diagram of the airfoil of a vertical-axis wind turbine blade suitable for medium and low wind speeds according to the present invention.

[0020] Figure 2 It is a schematic diagram of parameters of the vertical-axis wind turbine blade airfoil suitable for medium and low wind speeds according to the present invention.

[0021] Figure 3A The invention is suitable for the vertical axis wind turbine blade airfoil of medium and low wind speed at a Reynolds number of 1.1×10 5 Schematic diagram of the relationship between angle of attack and lift coefficient.

[0022] Figure 3B The invention is suitable for the vertical axis wind turbine blade airfoil of medium and low wind speed at a Reynolds number of 1.1×10 5 Schematic diagram of the relationship between angle of attack and lift-to-drag ratio.

[0023] Figure 4A The invention is suitable for the vertical axis wind turbine blade airfoil of low and medium wind speed and the existing airfoil is suitable for the vertical axis wind turbine blade airfoil of low and medium wind speed and the Reynolds number is 2.5×10 5 Schematic diagram of the relationship between angle of attack and lift coefficient.

[0024] Figure 4B The invention is suitable for the vertical axis wind turbine blade airfoil of low and medium wind speed and the existing airfoil is suitable for the vertical axis wind turbine blade airfoil of low and medium wind speed and the Reynolds number is 2.5×10 5Schematic diagram of the relationship between angle of attack and lift-to-drag ratio. DETAILED DESCRIPTION

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] like Figure 1 and Figure 2 As shown, the present invention provides a vertical axis wind turbine blade airfoil suitable for medium and low wind speeds. 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 18.37% of the airfoil chord length; the maximum thickness position of the airfoil is x t It is 31.20% of the chord length of the airfoil; the maximum curvature of the airfoil y c It is 2.11% of the airfoil chord length; the maximum curvature position of the airfoil is x c It is 23.20% of the airfoil.

[0030] The blade airfoil provided by the present invention has a higher lift coefficient and lift-to-drag ratio under conditions of larger local angle of attack and lower Reynolds number, thereby effectively improving the aerodynamic performance of the vertical axis wind turbine under medium and low wind speeds and improving the wind energy utilization efficiency of the unit. The blade airfoil can meet the needs of integrated smart energy and distributed wind power projects with complex terrain conditions, dense buildings or mutual shielding, and improve the power generation efficiency of vertical axis wind turbines under conditions of large wind resource changes and low average wind speeds.

[0031] like Figure 3A and 3B As shown in FIG. 1 , the blade airfoil provided by the present invention has a blade phase angle of 30° and an incoming wind speed of 5 m / s, corresponding to a local angle of attack α of about 16° and a Reynolds number of about 1.1×10 5, the lift coefficient of the airfoil can reach 1.27, and the lift-to-drag ratio is 18.51. At the same Reynolds number, the maximum lift-to-drag ratio of the airfoil can reach 39.09, when the local angle of attack α is 12°, and the corresponding phase angle is about 22°.

[0032] 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 1.1×10 5 , in most cases with the same local angle of attack α, it has a higher lift coefficient and lift-to-drag ratio.

[0033] It can be seen that the airfoil has better aerodynamic performance at lower Reynolds numbers and larger phase angles, and can improve the wind energy utilization efficiency of vertical axis wind turbines under medium and low speed conditions.

[0034] In addition, the airfoil still has excellent aerodynamic performance at higher wind speeds and larger phase angles.

[0035] like Figure 4A and 4B As shown in FIG. 1 , the blade airfoil provided by the present invention has a phase angle of 45° and an incoming wind speed of 8 m / s, corresponding to a local angle of attack α of about 17° and a Reynolds number of about 2.5×10 5 , the lift coefficient can reach 1.25, and the lift-to-drag ratio is 15.54. At the same Reynolds number, the maximum lift-to-drag ratio is 71.63, the local angle of attack α is 10°, and the corresponding phase angle is about 27°.

[0036] 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 , in most cases with the same local angle of attack α, it has a higher lift coefficient and lift-to-drag ratio.

[0037] 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:

[0038] Step S1, determining the airfoil design boundary conditions, and obtaining a reference airfoil under the boundary conditions.

[0039] Step S2: Use a high-order polynomial to fit the reference airfoil to obtain characteristic parameters of the reference airfoil and determine the value range of the characteristic parameters of the target airfoil.

[0040] Step S3: using the Latin supersampling method to generate characteristic parameters of the target airfoil within the value range, and obtaining the target airfoil geometry from the characteristic parameters, thereby obtaining a series of candidate airfoils.

[0041] Step S4, solving and calculating the aerodynamic performance of the candidate airfoils to obtain an airfoil with relatively excellent performance.

[0042] Step S5: Use the characteristic parameters of the airfoil with relatively excellent performance as initial parameters to perform optimization calculation to obtain the desired airfoil.

[0043] 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.

[0044] The relative width of the airfoil is limited to a value range of 10% to 30%, and the initial reference airfoils are designed to have a relative thickness of 30% and a maximum camber of 1.5% and a relative thickness of 10% and a maximum camber of 0.4%.

[0045] 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.

[0046] The formula is as follows:

[0047]

[0048]

[0049] 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.

[0050] 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].

[0051] Therefore, the geometric description of the airfoil shape can be achieved through the above 10 characteristic parameters.

[0052] 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.

[0053]

[0054] 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 is 30°, the incoming wind speed is 5m / s, the local angle of attack is 16°, and the Reynolds number is about 1.1×10 5 Under the design conditions, the optimal airfoil is selected. The characteristic parameters of the optimal airfoil are used as the initial values ​​to perform optimization calculations and obtain the final optimized airfoil.

[0055] The airfoil provided by 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 phase angle, which can effectively improve the wind energy utilization efficiency of the vertical axis unit under conditions where the wind resources are complex and changeable and the average wind speed is low.

[0056] The present invention also provides a vertical axis wind wheel, which is equipped with blades of the vertical axis wind turbine blade airfoil suitable for medium and low wind speeds according to the present invention.

[0057] The invention also provides a vertical axis wind turbine generator, which is equipped with the vertical axis wind wheel of the invention.

[0058] Since the vertical axis wind wheel and vertical axis wind turbine of the present invention are equipped with the blades of the vertical axis wind turbine blade airfoil suitable for medium and low wind speeds of the present invention, and the blade airfoil of the present invention has a higher lift coefficient and lift-to-drag ratio under the conditions of larger local angle of attack and lower Reynolds number, the aerodynamic performance of the vertical axis wind turbine under medium and low wind speeds can be effectively improved, and the wind energy utilization efficiency of the unit can be improved. It can meet the needs of comprehensive smart energy and distributed wind power projects with complex terrain conditions, dense buildings or mutual shielding, and improve the power generation efficiency of vertical axis wind turbines under conditions of large wind resource changes and low average wind speeds.

[0059] 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 suitable for medium and low wind speeds, characterized in that: The maximum thickness of the airfoil is 18.37% of the chord length of the airfoil; the position of the maximum thickness of the airfoil is 31.20% of the chord length of the airfoil; the maximum camber of the airfoil is 2.11% of the chord length of the airfoil; the position of the maximum camber of the airfoil is 23.20% of the airfoil.

2. The vertical axis wind turbine blade airfoil suitable for medium and low wind speeds as claimed in claim 1, characterized in that: When the blade phase angle is 30°, the incoming wind speed is 5 m / s, the local angle of attack is 16°, and the Reynolds number is 1.1×10 5 Under the working condition, the lift coefficient of the airfoil is 1.27 and the lift-to-drag ratio is 18.

51.

3. The vertical axis wind turbine blade airfoil suitable for medium and low wind speeds as claimed in claim 1, characterized in that: The Reynolds number is 1.1×10 5 When , the maximum lift-to-drag ratio of the airfoil is 39.09, and the local angle of attack is 12°.

4. The vertical axis wind turbine blade airfoil suitable for medium and low wind speeds as claimed in claim 1, characterized in that: Under the conditions of a phase angle of 45° and an incoming wind speed of 8 m / s, the corresponding local angle of attack of the airfoil is 17° and the Reynolds number is 2.5×10 5 The lift coefficient of the airfoil is 1.25, and the lift-to-drag ratio is 15.

54.

5. The vertical axis wind turbine blade airfoil suitable for medium and low wind speeds as claimed in claim 4, characterized in that: The Reynolds number is 2.5×10 5 The maximum lift-to-drag ratio of the airfoil is 71.63, and the local angle of attack is 10°.

6. The vertical axis wind turbine blade airfoil suitable for medium and low wind speeds as claimed in 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.

7. A vertical axis wind wheel, characterized in that: The vertical axis wind rotor comprises a blade of a vertical axis wind turbine blade airfoil suitable for medium and low wind speeds as described in any one of claims 1 to 6.

8. A vertical axis wind turbine, characterized in that: The vertical axis wind turbine comprises the vertical axis wind wheel as claimed in claim 7.

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