Scaled blade design method and scaled blade

Abstract

The invention provides a scaled blade design method and a scaled blade, and the scaled blade design method comprises the steps: obtaining the flapping rigidity distribution of an original blade, calculating a required similarity criterion number, and calculating the flapping rigidity distribution of the scaled blade according to the flapping rigidity distribution of the original blade and the similarity criterion number; obtaining the aerodynamic shape of the scaled blade based on the geometric scale ratio; calculating to obtain the required cross section size of the support beam based on the aerodynamic configuration of the scaled blade and the distribution of the elastic modulus and the flapping rigidity of the support beam material; the scaled blade is machined through the supporting beam and the skin on the outer side of the supporting beam, and the appearance of the skin is the same as the aerodynamic appearance of the scaled blade. The problem that in the prior art, the design efficiency of scaling blades is low is solved.

Description

Technical Field

[0001] The present invention relates to the field of wind power generation, and in particular to a scaled-down blade design method and a scaled-down blade. Background Art

[0002] A scaled blade refers to a model blade used in wind tunnel tests and model experiments in fields such as energy engineering and aeronautical engineering. It is made by reducing the shape, size and other information of the original-size blade (usually a large blade actually used, such as the wind blade of a wind turbine, the propeller blade of an aircraft, etc.) according to a certain geometric reduction coefficient. The purpose of designing and manufacturing scaled blades is to simulate and study the fluid dynamics, structural dynamics and overall performance of the original-size blade in an actual working environment at a smaller scale in a laboratory or in facilities such as a wind tunnel. Through scaled blades, researchers can obtain data on blades under various working conditions, such as aerodynamic characteristics, vibration characteristics, fatigue characteristics, etc., under controllable experimental conditions, and then analyze and optimize the performance of the blades, reducing the testing cost and time of full-size blades. The key to the design of scaled blades is to ensure that their physical properties are similar to those of the original-size blades, including but not limited to aerodynamic shape, structural stiffness, etc., to ensure that the experimental results can accurately reflect the behavior of the original-size blades.

[0003] At present, there are mainly the following calculation methods in the design of scaled blades: 1. Scale the blades according to the similarity criterion number, use the geometric shape, parameters, materials and processing and manufacturing methods of the original blades, and scale them to obtain scaled blades. This method is simple and convenient, but the weight and size of the blades vary greatly, and the change in blade thickness affects the rigidity of the blades, which in turn affects the blade's flapping stiffness, and the blade's flapping stiffness directly affects the stability of the blade during high overload operation. 2. Obtain the aerodynamic shape of the scaled blade and the cross-sectional dimensions of the support beam through computer simulation, but there is no quantitative method to determine the cross-sectional dimensions of the support beam. It is usually achieved through a repeated process of model trial production, testing, measurement, adjustment, retesting, remeasurement, and readjustment. This method is costly and has a long manufacturing cycle. Summary of the invention

[0004] The main purpose of the present invention is to provide a scaled-down blade design method and a scaled-down blade, so as to solve the problem of low design efficiency of scaled-down blades in the prior art.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a scaled blade design method is provided, comprising obtaining the flapping stiffness distribution of the original blade, calculating the required similarity criterion number, and calculating the flapping stiffness distribution of the scaled blade according to the flapping stiffness distribution of the original blade and the similarity criterion number; obtaining the aerodynamic shape of the scaled blade based on the geometric scale ratio; calculating the required cross-sectional size of the support beam based on the aerodynamic shape of the scaled blade, the elastic modulus of the support beam material and the distribution of the flapping stiffness; and processing the scaled blade using the support beam and the skin on the outside of the support beam, wherein the shape of the skin is the same as the aerodynamic shape of the scaled blade.

[0006] Furthermore, the similarity criterion number N is 1 / (nl^4), and the flapping stiffness EI of the scaled blade is F = flapping stiffness of original blade * N, where nl is the geometric scaling factor.

[0007] Furthermore, the geometric scale ratio is 1 / nl, and the aerodynamic shape of the scaled-down blade is 1 / nl of the aerodynamic shape of the original blade, wherein nl is the geometric scale coefficient.

[0008] Furthermore, the required cross-sectional dimensions of the support beam are calculated, including: obtaining the elastic modulus E of the support beam according to the material of the support beam; calculating the cross-sectional moment of inertia of the support beam: the swing stiffness value is EIF, and the cross-sectional moment of inertia I = EIF / E; calculating the cross-sectional area S of the support beam, the calculation formula is S*h 2 *2=I, where h is the maximum thickness of the cross section of the scaled blade; the width L of the support beam is obtained according to the aerodynamic shape of the scaled blade; the thickness t of the support beam is obtained according to the cross-sectional area S and the width L of the support beam.

[0009] Furthermore, the thickness t of the support beam is calculated as follows: t=S / L.

[0010] Furthermore, calculating the required cross-sectional dimensions of the support beam also includes: along the length direction of the scaled blade, the support beam has multiple cross-sections, and at least some of the cross-sections are of different sizes, and each cross-sectional area S and thickness t is calculated separately.

[0011] Furthermore, after the calculation of the cross-sectional dimensions of the support beam is completed, software is used to simulate the flapping stiffness of each cross section of the scaled blade. When the simulated flapping stiffness exceeds the calculated flapping stiffness of the scaled blade, the thickness and / or width of the support beam is adjusted. The thickness of the support beam is first adjusted so that the simulated flapping stiffness of the scaled blade is equal to the calculated flapping stiffness of the scaled blade. If the adjustment of the thickness of the support beam cannot meet the requirement, the width of the support beam is adjusted.

[0012] Furthermore, the material of the scaled-down blade is high modulus fiber.

[0013] Furthermore, the support beam is arranged in an I-shape, and the support beam comprises multiple layers of high modulus fibers.

[0014] According to another aspect of the present invention, a scaled-down blade is provided. The scaled-down blade adopts the above-mentioned scaled-down blade design method. The scaled-down blade includes a support beam and a skin. The skin is sleeved on the outside of the support beam, and the shape of the skin is the shape of the scaled-down blade.

[0015] By applying the technical solution of the present invention, a support beam is set as a support for the scaled blade, and the cross-sectional size of the support beam is calculated by utilizing the aerodynamic shape of the scaled blade, the elastic modulus of the support beam material and the flapping stiffness distribution of the scaled blade, thereby significantly improving the design efficiency and accuracy of the scaled blade, allowing designers to quickly obtain a more accurate scaled blade through information such as the parameters of the original blade, while reducing performance losses and cost waste caused by design problems, and shortening the cycle of subsequent testing and adjustments of the scaled blade, thereby shortening the manufacturing cycle of the scaled blade, and further improving the design efficiency of the scaled blade. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0017] Figure 1 A flow chart of the scaled blade design method of the present invention is shown. DETAILED DESCRIPTION

[0018] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0019] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs.

[0020] In the present invention, unless otherwise specified, the directional words used, such as "up, down, top, bottom", usually refer to the directions shown in the drawings, or to the components themselves in the vertical, perpendicular or gravity directions; similarly, for ease of understanding and description, "inside and outside" refer to the inside and outside relative to the outline of each component itself, but the above-mentioned directional words are not used to limit the present invention.

[0021] In order to solve the problem of low design efficiency of scaled-down blades in the prior art, the present invention provides a scaled-down blade design method and a scaled-down blade.

[0022] like Figure 1A scaled blade design method is shown, comprising obtaining the flapping stiffness distribution of the original blade, calculating the required similarity criterion number, and calculating the flapping stiffness distribution of the scaled blade based on the flapping stiffness distribution of the original blade and the similarity criterion number; obtaining the aerodynamic shape of the scaled blade based on the geometric scale ratio; calculating the required cross-sectional size of the support beam based on the aerodynamic shape of the scaled blade, the elastic modulus of the support beam material and the distribution of the flapping stiffness; and processing the scaled blade using the support beam and the skin on the outside of the support beam, wherein the shape of the skin is the same as the aerodynamic shape of the scaled blade.

[0023] In this embodiment, a support beam is provided as a support for the scaled blade, and the cross-sectional dimensions of the support beam are calculated by utilizing the aerodynamic shape of the scaled blade, the elastic modulus of the support beam material, and the flapping stiffness distribution of the scaled blade, thereby significantly improving the design efficiency and accuracy of the scaled blade, allowing designers to quickly obtain a more accurate scaled blade through information such as the parameters of the original blade, while reducing performance losses and cost waste caused by design problems, and shortening the cycle of subsequent testing and adjustments of the scaled blade, thereby shortening the manufacturing cycle of the scaled blade, and further improving the design efficiency of the scaled blade.

[0024] It should be noted that, in this embodiment, Figure 1 The scaled blade design steps in are used as an example to illustrate, but in the design process of the scaled blade, the order of the steps is not unique. For example, the aerodynamic shape of the scaled blade can be obtained based on the geometric scale ratio first, and then the flapping stiffness distribution of the scaled blade can be calculated, as long as the cross-sectional size of the support beam can be finally obtained. The cross-section in this embodiment refers to the cross-section perpendicular to the length direction of the blade, and the length direction of the blade refers to the extension direction from the root to the tip of the blade.

[0025] In this embodiment, the similarity criterion number N is 1 / (nl^4), and the flapping stiffness EI of the scaled blade is F= flapping stiffness of the original blade * N, where nl is the geometric scaling coefficient, so that the flapping stiffness distribution of the scaled blade can be accurately calculated using the similarity criterion number. Specifically, the flapping stiffness value of the corresponding position of the scaled blade can be obtained by multiplying the flapping stiffness value of a certain position of the original blade by the similarity criterion number. By obtaining the flapping stiffness values ​​of multiple different positions of the scaled blade, the flapping stiffness distribution of the scaled blade can be obtained. In this way, the consistency of the flapping stiffness between the scaled blade and the original blade can be ensured by the similarity criterion number, which is particularly important for studying the dynamic response of the blade under different wind speed conditions, so that R&D personnel can more accurately predict and control the behavior of the blade under various conditions, thereby designing more stable and efficient wind power generation blades. It should be noted that the geometric scaling coefficient nl is the ratio of the size of the original blade to the size of the scaled blade. Taking the length dimension as an example, nl is the ratio of the length of the original blade to the length of the scaled blade.

[0026] In this embodiment, the geometric scale ratio is 1 / nl, and the aerodynamic shape of the scaled blade is 1 / nl of the aerodynamic shape of the original blade, where nl is the geometric scale factor. In this way, the aerodynamic shape of the scaled blade is obtained through the aerodynamic shape of the original blade, which ensures the similarity of the aerodynamic shape between the scaled blade and the original blade, so as to ensure the similarity of the physical properties between the scaled blade and the original blade, which is conducive to the scaled blade representing the original blade in the laboratory for testing, verification and optimization, so that the scaled blade can reflect the real situation of the original blade, thereby improving the reliability of the test data and avoiding expensive and high-risk experiments directly on the original blade, which has important engineering value.

[0027] In this embodiment, calculating the required cross-sectional dimensions of the support beam includes: obtaining the elastic modulus E of the support beam according to the material of the support beam; calculating the cross-sectional moment of inertia of the support beam: the swing stiffness value is EIF, and the cross-sectional moment of inertia I=EIF / E; calculating the cross-sectional area S of the support beam, and the calculation formula is S*h 2*2=I, where h is the maximum thickness of the cross section of the scaled blade; the width L of the support beam is obtained according to the aerodynamic shape of the scaled blade; the thickness t of the support beam is obtained according to the cross-sectional area S and the width L of the support beam. Specifically, the material of the support beam is first determined. Considering the stiffness requirements of the scaled blade, a material with a higher shear modulus is generally selected. After the material is determined, the elastic modulus of the material can be obtained; then the cross-sectional inertia moment of the support beam can be calculated, and then the maximum thickness of the cross section of the scaled blade is obtained in combination with the aerodynamic shape, and the cross-sectional area of ​​the support beam is calculated; then the width of the support beam is obtained by the width dimension of the corresponding cross section of the original blade (or the width dimension of the beam at the corresponding position of the original blade) and the geometric scale ratio, or directly given according to the aerodynamic shape of the scaled blade, and then the thickness is obtained, thereby obtaining the specific size of the support beam. In this way, this quantitative calculation form simplifies the design process of the scaled blade, while ensuring the structural strength and stiffness of the scaled blade, thereby improving the accuracy of the scaled blade and ensuring the accuracy and reliability of the scaled blade test data. It should be noted that the maximum thickness h of the cross-section of the scaled blade is the maximum thickness of the cross-section of the aerodynamic shape of the scaled blade, and the width L of the support beam refers to the length of the support beam along the chord direction of the scaled blade. Of course, according to the structure of the aerodynamic shape, the support beam is not a regular rectangle, but has a certain curvature along the chord direction of the scaled blade. The width L is the arc length of the support beam; the thickness direction of the support beam is perpendicular to the length direction of the scaled blade and the width direction of the support beam.

[0028] In this embodiment, the thickness t of the support beam is calculated as: t = S / L. After the thickness of the support beam is obtained, the specific size of the support beam is obtained, so that the designer can complete the preliminary design of the scaled blade in a short time, thereby improving the design efficiency of the scaled blade.

[0029] In this embodiment, calculating the required cross-sectional dimensions of the support beam also includes: along the length direction of the scaled blade, there are multiple cross-sections of the support beam, and at least some of the cross-sections are of different sizes, and the cross-sectional area S and thickness t of each are calculated respectively. Considering that the blades of this embodiment, whether scaled blades or original blades, have a certain length, the flapping stiffness of each cross-section in the direction from the root to the tip of the blade is different, and the size and thickness of the cross-section are also different, it is necessary to calculate the cross-sectional area and thickness of each cross-section in the length direction of the scaled blade. In this way, by comprehensively considering the stiffness changes of the scaled blade along the length direction, the mechanical properties of the original blade can be simulated more realistically, so that the mechanical response of the original blade at different positions can be better simulated, thereby improving the accuracy of the scaled blade design, thereby reducing the cycle of subsequent testing and adjustment of the scaled blade, and further improving the design efficiency of the scaled blade.

[0030] In this embodiment, after the calculation of the cross-sectional dimensions of the support beam is completed, the software is used to simulate the flapping stiffness of each cross section of the scaled blade. When the simulated flapping stiffness exceeds the calculated flapping stiffness of the scaled blade, the thickness and / or width of the support beam is adjusted, wherein the thickness of the support beam is first adjusted so that the simulated flapping stiffness of the scaled blade is equal to the calculated flapping stiffness of the scaled blade. If the adjustment of the thickness of the support beam cannot meet the requirement, the width of the support beam is adjusted. That is, after the specific dimensions of the support beam are obtained by calculation, the software simulation is used to verify whether the calculated support beam can approach the performance of the original blade. If the flapping stiffness obtained by the software simulation exceeds the calculated flapping stiffness of the scaled blade, the thickness of the support beam is adjusted first, but the thickness needs to meet the minimum thickness of the support beam material, otherwise the width of the support beam should be adjusted.

[0031] In this embodiment, the material of the scaled-down blade is high modulus fiber. High modulus fiber not only has excellent mechanical properties, but also can significantly reduce the weight of the blade, which has a significant effect on improving the safety and efficiency of the scaled-down blade and reducing the experimental cost. High modulus fiber includes carbon fiber, polyimide fiber, glass fiber, etc. The support beam of this embodiment is made of carbon fiber, and of course other materials can also be used according to actual conditions.

[0032] In this embodiment, the support beam is set to an I-shape. The support beam extends along the length direction of the scaled blade, and the cross-section of the support beam is set to an I-shape, that is, the support beam includes an upper beam, a lower beam, and an intermediate beam, wherein the intermediate beam can be optionally set. This embodiment adopts a method of only setting an upper beam and a lower beam, and both the upper beam and the lower beam are attached to the skin and match the shape of the aerodynamic shape. On the same cross-section of the scaled blade, the width of the upper beam is equal to the width of the lower beam and extends along the chord direction of the scaled blade. The thickness of the upper beam is also equal to the thickness of the lower beam, which is equal to the thickness of the support beam. The upper beam and the lower beam are arranged at both ends of the cross-section thickness direction along the thickness direction of the cross-section, and are located at the maximum thickness of the cross-section. The support beam includes multiple layers of high modulus fiber. Since the support beam includes an upper beam and a lower beam, the support beam includes at least two layers of high modulus fiber to ensure the integrity of the scaled blade.

[0033] The present invention also provides a scaled-down blade, which adopts the above-mentioned scaled-down blade design method. The scaled-down blade includes a support beam and a skin, the skin is sleeved on the outside of the support beam, and the shape of the skin is the shape of the scaled-down blade. In this way, the scaled-down blade can accurately simulate the mechanical and aerodynamic characteristics of the original blade, and also has the advantages of simple structure and low manufacturing cost. By using this scaled-down blade, the cycle of blade design and optimization can be greatly shortened, thereby reducing research and development costs, and providing strong support for blade performance improvement and technological innovation in the fields of wind power generation, aviation, etc. Optionally, foam can be filled between the support beam and the skin to further improve the reliability of the scaled-down blade.

[0034] It should be noted that, the multiple in the above embodiments refers to at least two.

[0035] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0036] 1. Solve the problem of low design efficiency of scaled-down blades in the prior art;

[0037] 2. By setting a support beam as the support of the scaled blade, the cross-sectional size of the support beam is calculated by using the aerodynamic shape of the scaled blade, the elastic modulus of the support beam material and the flapping stiffness distribution of the scaled blade, thereby significantly improving the design efficiency and accuracy of the scaled blade, allowing designers to quickly obtain a more accurate scaled blade through information such as the parameters of the original blade, while reducing performance loss and cost waste caused by design problems;

[0038] 3. It can shorten the cycle of subsequent testing and adjustment of scaled blades, thereby shortening the manufacturing cycle of scaled blades to further improve the design efficiency of scaled blades.

[0039] Obviously, the above-described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0040] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0041] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A scaled blade design method, characterized in that: include: Obtaining the flapping stiffness distribution of the original blade, calculating the required similarity criterion number, and calculating the flapping stiffness distribution of the scaled-down blade according to the flapping stiffness distribution of the original blade and the similarity criterion number; Obtaining an aerodynamic shape of the scaled blade based on a geometric scale ratio; Based on the aerodynamic shape of the scaled blade, the elastic modulus of the support beam material and the distribution of the flapping stiffness, the required cross-sectional dimensions of the support beam are calculated; The scaled-down blade is processed by utilizing the support beam and the outer skin of the support beam, and the outer shape of the skin is the same as the aerodynamic shape of the scaled-down blade.

2. The scaled blade design method according to claim 1, characterized in that: The similarity criterion number N is 1 / (nl^4), and the flapping stiffness EI of the scaled blade is F =The flapping stiffness of the original blade*N, where nl is the geometric scaling factor.

3. The scaled blade design method according to claim 1, characterized in that: The geometric scaling ratio is 1 / nl, and the aerodynamic shape of the scaled-down blade is 1 / nl of the aerodynamic shape of the original blade, wherein nl is the geometric scaling coefficient.

4. The scaled blade design method according to claim 1, characterized in that: The calculation to obtain the required cross-sectional dimensions of the support beam includes: According to the material of the support beam, obtaining the elastic modulus E of the support beam; The cross-sectional moment of inertia of the support beam is calculated: The flapping stiffness value is EI F , the section moment of inertia I=NO F / E; The cross-sectional area S of the support beam is calculated using the formula S*h 2 *2=I, where h is the maximum thickness of the cross section of the scaled blade; Obtaining a width L of the support beam according to the aerodynamic shape of the scaled blade; According to the cross-sectional area S and the width L of the support beam, the thickness t of the support beam is obtained.

5. The scaled blade design method according to claim 4, characterized in that: The calculation formula of the thickness t of the support beam is: t=S / L.

6. The scaled blade design method according to claim 4, characterized in that: The calculation of the required cross-sectional dimensions of the support beam also includes: along the length direction of the scaled blade, the support beam has multiple cross-sections, and at least some of the cross-sections are different in size, and each cross-sectional area S and thickness t is calculated separately.

7. The scaled blade design method according to claim 4, characterized in that: After calculating the cross-sectional dimensions of the support beam, software is used to simulate the flapping stiffness of each cross section of the scaled blade. When the simulated flapping stiffness exceeds the calculated flapping stiffness of the scaled blade, the thickness and / or width of the support beam is adjusted. The thickness of the support beam is first adjusted so that the simulated flapping stiffness of the scaled blade is equal to the calculated flapping stiffness of the scaled blade. If adjusting the thickness of the support beam cannot meet the requirement, the width of the support beam is adjusted.

8. The scaled blade design method according to claim 1, characterized in that: The material of the scaled-down blade is high-modulus fiber.

9. The scaled blade design method according to claim 7, characterized in that: The support beam is configured in an I-shape and includes multiple layers of high modulus fibers.

10. A scaled-down blade, characterized in that: The scaled-down blade design method according to any one of claims 1 to 9 is adopted, wherein the scaled-down blade comprises: Support beams; The skin is sleeved on the outer side of the support beam, and the outer shape of the skin is the outer shape of the scaled blade.

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