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 torsional rigidity distribution of an original blade, calculating a required similarity criterion number, and calculating the torsional rigidity distribution of the scaled blade according to the torsional 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 and the distribution of the elastic modulus and the torsional rigidity of the support beam material; the scaling blade is processed by utilizing the supporting beam and the skin on the outer side of the supporting beam and filling a filling material between the supporting beam and the skin, and the appearance of the skin is the same as the aerodynamic appearance of the scaling 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, and then affects the torsional stiffness of the blades, and the torsional stiffness of the blades directly affects the stability of the blades during high overload operation. 2. Obtain the aerodynamic shape of the scaled blades and the cross-sectional dimensions of the support beams through computer simulation, but there is no quantitative method to determine the cross-sectional dimensions of the support beams. 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 torsional stiffness distribution of the original blade, calculating the required similarity criterion number, and calculating the torsional stiffness distribution of the scaled blade according to the torsional 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, the elastic modulus of the support beam material and the distribution of torsional stiffness; and processing the scaled blade by filling a filling material between the support beam and the skin using the support beam and the skin outside the support beam, and 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 torsional stiffness S of the scaled-down blade = the torsional stiffness of the original blade*N, where nl is the geometric scaling coefficient.

[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, calculating the required cross-sectional dimensions of the support beam includes: obtaining the elastic modulus G of the support beam according to the material of the support beam; calculating the cross-sectional dimensions of the support beam, the torsional stiffness value of the scaled blade is S, and the cross-sectional dimension J = S / G; obtaining the outer diameter D of the support beam according to the aerodynamic shape of the scaled blade, the outer diameter D being the maximum thickness of the aerodynamic shape; and obtaining the inner diameter d of the support beam according to the cross-sectional dimension J and the outer diameter D.

[0009] Furthermore, the calculation formula of the inner diameter d is: J = π*(D 4 -d 4 ) / 32.

[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 different in size, and the outer diameter D and inner diameter d of each cross-section are calculated respectively.

[0011] Furthermore, the cross section of the support beam is in a circular ring shape, and the filling material is foam.

[0012] Furthermore, the material of the support beam is at least one of bidirectional cloth and three-phase cloth.

[0013] Furthermore, the support beam is in a truncated cone shape, and the outer diameter of the support beam at each axial position corresponds in proportion to the maximum thickness of the scaled blade at each axial position.

[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, and the scaled-down blade includes: a support beam; a skin, which is sleeved on the outside of the support beam, and the shape of the skin is the shape of the scaled-down blade; and a filling material, which is filled between the support beam and the skin to support the skin.

[0015] By applying the technical solution of the present invention, a support beam is set as a support for the scaled blade, and the 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 torsional 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 to further improve the design efficiency of the scaled blade. In addition, the present embodiment also fills filling material between the support beam and the skin to further improve the reliability 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 torsional stiffness distribution of the original blade, calculating the required similarity criterion number, and calculating the torsional stiffness distribution of the scaled blade based on the torsional 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, the elastic modulus of the support beam material and the distribution of torsional stiffness; and using the support beam and the skin on the outside of the support beam to fill the filling material between the support beam and the skin to process the scaled blade, and the shape of the skin is the same as the aerodynamic shape of the scaled blade.

[0023] In this embodiment, a support beam is set as the support of the scaled blade, and the 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 torsional 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 to further improve the design efficiency of the scaled blade. In addition, this embodiment also fills filling material between the support beam and the skin to further improve the reliability of the scaled blade.

[0024] It should be noted that, in this embodiment, Figure 1 The scaled blade design steps in the embodiment are described as an example. However, 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 torsional 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.

[0025] In this embodiment, the similarity criterion number N is 1 / (nl^4), and the torsional stiffness S of the scaled blade = the torsional stiffness of the original blade * N, wherein nl is the geometric scaling coefficient, so that the torsional stiffness distribution of the scaled blade can be accurately calculated using the similarity criterion number. Specifically, the torsional stiffness value of the corresponding position of the scaled blade can be obtained by multiplying the torsional stiffness value of a certain position of the original blade by the similarity criterion number, and the torsional stiffness distribution of the scaled blade can be obtained by superimposing the torsional stiffness values ​​of multiple different positions of the scaled blade. In this way, through the similarity criterion number, the consistency of the torsional stiffness of the scaled blade and the original blade can be ensured, which is particularly important for studying the dynamic response of the blade under different wind speed conditions, so that the research and development personnel can more accurately predict and control the behavior of the blade under various conditions, thereby designing a more stable and efficient wind power generation blade. 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, for example, nl can be 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, the required cross-sectional dimensions of the support beam are calculated, including: obtaining the elastic modulus G of the support beam according to the material of the support beam; calculating the cross-sectional dimensions of the support beam, the torsional stiffness value of the scaled blade is S, and the cross-sectional dimension J=S / G; obtaining the outer diameter D of the support beam according to the aerodynamic shape of the scaled blade, the outer diameter D is the maximum thickness of the aerodynamic shape; obtaining the inner diameter d of the support beam according to the cross-sectional dimension J and the outer diameter D. Specifically, first determine the material of the support beam, and consider the stiffness requirements of the scaled blade. Generally, a material with a higher shear modulus is selected. After the material is determined, the elastic modulus of the material can be obtained, and then the cross-sectional dimensions of the support beam can be obtained. Combined with the aerodynamic shape, the specific dimensions of the support beam are calculated. 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 thickness direction of the aerodynamic shape is consistent with the thickness direction of the cross section of the blade.

[0028] In this embodiment, the calculation formula of the inner diameter d is: J = π*(D 4 -d 4 ) / 32, thus, a quantifiable formula is used to simplify the calculation process of the inner diameter of the support beam, 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, the calculation of 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 outer diameter D and inner diameter d of each cross-section are calculated respectively. Considering the blades of this embodiment, whether it is a scaled blade or an original blade, the torsional stiffness of each cross-section in the direction from the root to the tip of the blade is different, and the size of the cross-section is also different, so it is necessary to calculate the outer diameter and inner diameter 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. It should be noted that the length direction of the scaled blade refers to the extension direction from the root to the tip of the blade.

[0030] In the present embodiment, the cross section of the support beam is annular, and the filling material is foam. In order to improve the aerodynamic performance of the blade and reduce the weight of the blade, the blade of the electric fan is generally designed to be hollow, and correspondingly, the scaled blade is also set to be hollow. The support beam is the main supporting material for the scaled blade, and its cross section is set to be annular to obtain performance that matches the original blade, thereby improving the design efficiency of the scaled blade. Filling material is set on the outer peripheral side of the support beam to further support the skin of the scaled blade, thereby improving the reliability of the scaled blade. In this way, the annular support beam and foam filling material can not only provide sufficient structural support and maintain its structural stability, but also reduce the weight of the blade, which helps to improve the accuracy and efficiency of the wind blade test, and its lightweight design can significantly reduce energy consumption and testing costs. Of course, according to actual conditions, the filling material can also choose other materials that can achieve the effect of lightweight support.

[0031] In this embodiment, considering that the material of the support beam needs to have a high shear modulus to ensure the rigidity of the scaled blade, the material of the support beam is selected to be at least one of a bidirectional cloth and a three-phase cloth. Both the bidirectional cloth and the three-phase cloth have a high shear modulus and can effectively resist shear deformation, which is conducive to maintaining the torsional rigidity of the scaled blade, so that the performance of the scaled blade is closer to that of the original blade, so as to improve the accuracy and reliability of the scaled blade, thereby improving the design efficiency of the scaled blade. At the same time, both the bidirectional cloth and the three-phase cloth have good processability, which is conducive to shortening the manufacturing time of the scaled blade and reducing production costs.

[0032] In this embodiment, considering that the dimensions of the cross section of the original blade are different at different locations, and the thickness of the original blade gradually decreases from the root to the tip, the support beam of the scaled blade is accordingly set to be truncated cone-shaped. The outer diameter of the support beam at each axial location corresponds in proportion to the maximum thickness of the scaled blade at each axial location, so that the size of the support beam can match the aerodynamic shape change of the scaled blade, thereby improving the accuracy of the scaled blade. It should be noted that the axial direction of the support beam refers to the length direction of the scaled blade, that is, the extension direction from the root to the tip.

[0033] The scaled blade design method of the present embodiment includes: obtaining the torsional stiffness distribution of the original blade; calculating the required similarity criterion number N; calculating the torsional stiffness distribution of the scaled blade according to the torsional stiffness distribution of the original blade and the similarity criterion number N; obtaining the aerodynamic shape of the scaled blade based on the geometric scale ratio; selecting the material of the support beam and obtaining the elastic modulus G of the material; calculating the cross-sectional dimension J of the support beam; obtaining the outer diameter D of the support beam according to the aerodynamic shape; obtaining the inner diameter d of the support beam according to J and D; in this way, the sizes of the inner diameter and outer diameter of the support beam are obtained, and the same calculation method is used for different cross-sections of the support beam to obtain the sizes of each cross-section in the length direction of the scaled blade, thereby obtaining the specific size of the support beam, so that the support beam can be processed according to the specific size of the support beam, and foam is filled between the support beam and the skin to obtain the scaled blade. Of course, the order of the aforementioned steps is not fixed. Designers can flexibly adjust the order of the steps according to actual conditions to improve the design efficiency of the scaled blades. For example, the aerodynamic shape of the scaled blade can be obtained based on the geometric scale ratio, and then the outer diameter of the support beam can be determined, and then the torsional stiffness distribution of the original blade can be obtained without affecting the performance of the scaled blade.

[0034] Based on the aerodynamic shape, the elastic modulus of the support beam material and the distribution of torsional stiffness, the required cross-sectional dimensions of the support beam are calculated.

[0035] This embodiment also provides a scaled-down blade, which adopts the above-mentioned scaled-down blade design method. The scaled-down blade includes: a support beam, a skin and a filling material. 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; the filling material is filled between the support beam and the skin to support the skin. 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 blade design and optimization cycle can be greatly shortened, thereby reducing the R&D cost, and providing strong support for blade performance improvement and technological innovation in the fields of wind power generation, aviation, etc.

[0036] It should be noted that, the multiple in the above embodiments refers to at least two.

[0037] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0038] 1. Solve the problem of low design efficiency of scaled-down blades in the prior art;

[0039] 2. By setting a support beam as the support of the scaled blade, the 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 torsional 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;

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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 torsional stiffness distribution of the original blade, calculating the required similarity criterion number, and calculating the torsional stiffness distribution of the scaled-down blade according to the torsional 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; Calculating the required cross-sectional dimensions of the support beam based on the aerodynamic shape, the elastic modulus of the support beam material and the distribution of the torsional stiffness; The scaled-down blade is processed by utilizing the support beam and the outer skin of the support beam and filling material between the support beam and the skin, 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 torsional stiffness S of the scaled-down blade = the torsional stiffness of the original blade*N, wherein nl is the geometric scaling coefficient.

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 G of the support beam; The cross-sectional dimension of the support beam is obtained by calculation, the torsional stiffness value of the scaled-down blade is S, and the cross-sectional dimension J=S / G; Obtaining an outer diameter D of the support beam according to the aerodynamic shape of the scaled blade, wherein the outer diameter D is the maximum thickness of the aerodynamic shape; According to the cross-sectional dimension J and the outer diameter D, the inner diameter d of the support beam is obtained.

5. The scaled blade design method according to claim 4, characterized in that: The calculation formula of the inner diameter d is: J = π*(D 4 -d 4 ) / 32.

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 of different sizes, and the outer diameter D and inner diameter d of each cross-section are calculated respectively.

7. The scaled blade design method according to claim 1, characterized in that: The cross section of the support beam is in a circular ring shape, and the filling material is foam.

8. The scaled blade design method according to claim 1, characterized in that: The material of the support beam is at least one of bidirectional cloth and three-phase cloth.

9. The scaled blade design method according to claim 1, characterized in that: The support beam is in a truncated cone shape, and the outer diameter of the support beam at each axial position corresponds in proportion to the maximum thickness of the scaled blade at each axial position.

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; A skin, wherein 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; A filling material is filled between the support beam and the skin to support the skin.

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