A wind turbine blade scaling criterion construction and testing method based on mass relationship

Abstract

The invention provides a method for constructing and testing a wind turbine blade scaling criterion based on a mass relationship, and belongs to the technical field of wind turbine blades. The method for constructing and testing a wind turbine blade scaling criterion based on a mass relationship comprises the following steps: obtaining an existing aerodynamic similarity criterion, and obtaining a dimensionless number according to the existing aerodynamic similarity criterion; obtaining a fan blade structure and a fan blade material, and deriving a centroid position formula and a mass distribution relationship of a fan blade cross section; formulating a similarity ratio between a fan blade and a blade scaling according to a blade vibration response test bench and a 3D printing size; obtaining a blade scaling model material according to the derived similarity ratio and the aerodynamic characteristics of the fan blade; constructing a blade scaling model; and a testing method for testing the accuracy of a simulation result, comprising the following steps: performing a blade vibration response test on a blade scaling model using a blade vibration response test bench; and comparing and analyzing the test frequency with the simulation frequency.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind turbine blades, and in particular, relates to a wind turbine blade scaling criterion construction and testing method based on mass relationship. Background Art

[0002] In the field of wind power generation, the design and optimization of wind turbine blades are key to improving wind energy conversion efficiency. With the advancement of technology and the growth of market demand, accurate prediction and verification of blade performance is particularly important. During their service, wind turbine blades not only have to withstand complex aerodynamic loads, but also face the test of vibration, fatigue and extreme climatic conditions. In order to ensure the feasibility and reliability of blade design, wind tunnel tests under laboratory conditions have become an indispensable part. Especially in exploring the aeroelastic stability and vibration characteristics of blades, the production of wind tunnel test models and the setting of similarity criteria directly affect the validity and accuracy of test data.

[0003] The traditional method of making wind turbine blade aeroelastic wind tunnel test models has established a series of similarity criteria based on mature aerodynamic similarity theory. These criteria mainly revolve around fluid dynamics similarity, including but not limited to the determination of wind speed ratio, time ratio and frequency ratio. These parameters ensure the correspondence between the flow field characteristics in the scaled model and the prototype. In addition, in view of the similarity of structural dynamic response, researchers introduced the concepts of density ratio and damping ratio to quantify the degree of matching between the model material and the prototype material in terms of mass and energy dissipation characteristics. Structural motion similarity is achieved through mass ratio and stiffness ratio. These similarity criteria provide a theoretical basis for ensuring that the model can reproduce the vibration mode of the prototype.

[0004] However, the existing technology has a significant limitation when establishing similarity criteria: it fails to fully consider the impact of mass distribution on the aerodynamic and vibration characteristics of the blade. Mass distribution not only determines the center of gravity position of the blade, but also directly affects the dynamic response characteristics of the blade, such as natural frequency, modal shape and vibration attenuation. Ignoring this factor may cause the model to have large deviations when simulating the actual blade vibration behavior, especially when studying the complex problem of the interaction between blade vibration characteristics and mass distribution. The inadequacy of this simplified treatment is particularly prominent. Inaccurate simulation of mass distribution may cause a series of chain reactions. For example, unreasonable mass layout will change the natural vibration frequency of the blade, affect its dynamic response under wind load, and then affect the stability and life of the entire wind turbine system. In addition, the vibration characteristics of the blade are directly related to its noise emission, fatigue life and power output efficiency. Therefore, accurate simulation of mass distribution is of great significance for blade design optimization. Summary of the invention

[0005] In view of this, the present invention provides a method for constructing and testing wind turbine blade scaling criteria based on mass relationship, which solves the problem that the unreasonable mass layout of traditional scaling criteria affects the natural vibration frequency of the blade and its dynamic response under wind load, thereby improving the stability and life of the blade design.

[0006] The present invention is achieved in that:

[0007] The present invention provides a method for constructing and testing a wind turbine blade scaling criterion based on a mass relationship, wherein the construction method is used to construct a blade scaling criterion, and comprises the following steps:

[0008] S10, obtaining an existing aerodynamic similarity criterion, and obtaining the aerodynamic characteristics of the fan blade according to the existing aerodynamic similarity criterion, that is, a dimensionless number;

[0009] S11, acquiring fan blade data, wherein the fan blade data includes a fan blade structure and a fan blade material, and using the fan blade data to derive a centroid position formula and a mass distribution relationship of a fan blade cross section;

[0010] 12. Build a blade vibration response test bench, and formulate a similarity ratio between the fan blade and the blade scale according to the blade vibration response test bench and the 3D printing size;

[0011] S13, obtaining a blade scale model material according to the derived similarity ratio and the aerodynamic characteristics of the fan blade;

[0012] S14, constructing a blade scaled model using the blade scaled model material, the similarity ratio, and the aerodynamic characteristics of the fan blade;

[0013] The test method is used to test the accuracy of the simulation results, and comprises the following steps:

[0014] S20, performing a blade vibration response test on the blade scale model using the blade vibration response test bench;

[0015] S21, compare and analyze the test frequency and simulation frequency.

[0016] The scaling criterion construction method refers to a blade scaling criterion construction method;

[0017] The testing technology specifically refers to making a blade scale model based on the constructed blade scale criterion, and measuring the vibration response characteristics of the model in a blade vibration response test bench.

[0018] On the basis of the above technical solution, the wind turbine blade scaling criterion construction and testing method based on mass relationship of the present invention can also be improved as follows:

[0019] The dimensionless numbers include the Stroud number, the Reynolds number, the Froude number, and the Euler number.

[0020] Furthermore, the dimensionless number is specifically:

[0021] The Storahar numbers of the fan blade and the blade scale model are equal, so as to make the unsteady inertial forces similar;

[0022] The Reynolds numbers of the fan blade and the blade scale model are equal, so as to make the viscous forces similar;

[0023] The Froude numbers of the fan blade and the blade scale model are equal, so as to make the gravity effect of the fluid similar;

[0024] The Euler numbers of the fan blade and the blade scaled model are equal, so as to make the inertial forces similar.

[0025] Furthermore, the similarity ratio includes an existing aerodynamic similarity criterion and a geometric similarity ratio, and the geometric similarity ratio includes a mass distribution relationship and a length similarity ratio.

[0026] The purpose of focusing on mass distribution and center of mass position in the blade scaling criterion is to ensure the similarity of key physical properties when analyzing and comparing different physical phenomena or systems. Mass distribution determines how the mass inside an object is distributed, while the center of mass position represents the geometric center of the object's mass. These two factors have an important influence on the object's motion state, dynamic characteristics, and interactions. By focusing on mass distribution and center of mass position, the similarity criterion can more accurately evaluate the similarities between different phenomena or systems.

[0027] Furthermore, the step S11 specifically includes:

[0028] Divide the fan blade cross section according to the material, and divide the position with the same material into four areas, including the first area, the second area, the third area, and the fourth area along the blade span direction;

[0029] Calculate the centroid positions of the four regions respectively, and calculate the relationship between the centroid positions of the four regions and the centroid position of the cross section of the fan blade;

[0030] According to the relationship between the centroid positions, it is concluded that the third region is close to the centroid position of the fan blade cross section, and the centroid position of each region is related to the shape of the fan blade cross section and has nothing to do with the density.

[0031] The first area corresponds to the leading edge of the fan blade, the second area corresponds to the leading edge shell, the trailing edge shell and the web of the fan blade, the third area corresponds to the main beam of the fan blade, and the fourth area corresponds to the trailing edge of the fan blade.

[0032] Furthermore, the length similarity ratio is specifically a length ratio of the fan blade to the blade scaled model of 200:1.

[0033] Considering the size of the blade vibration response test bench, the length similarity ratio of the blade scaled model was selected as 200:1.

[0034] Furthermore, the blade vibration response test bench includes a blade scaled model, a support, an acceleration sensor, a force sensor, a force hammer, a charge adapter, and a data acquisition instrument. The support is used to fix the blade scaled model. One end of the blade scaled model is fixedly connected to the support, and the other end is provided with the acceleration sensor. The acceleration sensor is electrically connected to the charge adapter. One end of the charge adapter is electrically connected to the force sensor, and the other end is electrically connected to the data acquisition instrument.

[0035] Furthermore, the step S20 specifically includes:

[0036] Step 1, fixing the root of the blade scale model to the support member, and the acceleration sensor is adhesively fixed at five positions in the span direction of the blade scale model;

[0037] Step 2, amplifying the electrical signal in the charge adapter, transferring it to the data acquisition instrument to convert it into a digital signal, and transmitting it to the computer via a USB cable.

[0038] Furthermore, in step 1, five positions of the blade scaled model in the span direction are equidistantly arranged.

[0039] Furthermore, the blade scale model material is made of PLA material.

[0040] The selection of blade scale model material mainly takes into account the structural stiffness required for blade vibration test and the limitation of 3D printing material types, so PLA material is selected. PLA polylactic acid, also known as polylactide, refers to a polyester polymer obtained by polymerization with lactic acid as the main raw material.

[0041] Compared with the prior art, the wind turbine blade scaling criterion construction and testing method based on mass relationship provided by the present invention has the following beneficial effects:

[0042] Innovation of technical principles:

[0043] The core of the present invention lies in its comprehensive similarity criterion system. Traditional wind tunnel model testing often focuses on geometric similarity and matching of fluid dynamic parameters, while the present invention, on this basis, deeply integrates multi-dimensional similarity requirements such as material properties, boundary conditions, working environment, and critically, mass distribution. This means that the model is not only consistent with the prototype in appearance, but also achieves deep similarity in physical properties, including but not limited to the elastic modulus, density, damping characteristics of the material, and the dynamic response of the blade under different working conditions. By comprehensively considering these factors, the production and testing of the model can more accurately map the aeroelastic performance of the prototype blade in a real environment;

[0044] Improve test accuracy and reliability:

[0045] The test method based on the comprehensive similarity criterion significantly improves the accuracy and reliability of the test results. In the past, models that ignored factors such as mass distribution often failed to accurately simulate the vibration response of blades under complex aerodynamic loads. The present invention ensures that the scaled model is highly similar to the prototype blade in key physical properties by accurately controlling the mass distribution and center of mass position. This not only reduces the error caused by model simplification, but also enables the test results to better reflect the actual performance of the blade, providing solid data support for the vibration characteristic analysis, fatigue life prediction and optimal design of the blade;

[0046] Flexible adaptability and wide applicability:

[0047] The test method of the present invention exhibits extremely high flexibility and wide applicability. According to different blade types, usage environments and test objectives, researchers can flexibly select and adjust similarity criteria to customize the model. This flexibility not only enables the method to be effectively applied to various types of wind turbine blades, from onshore to offshore, from small to large, but also promotes the study of blade performance in special environments (such as extreme climatic conditions), greatly broadening its scope of application. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0049] Figure 1 This is a flow chart of the first embodiment of the present invention;

[0050] Figure 2 This is a diagram showing the centroid position of a blade cross section according to the second embodiment of the present invention;

[0051] Figure 3 This is a scaled-down blade structure model diagram of the second embodiment of the present invention;

[0052] Figure 4 This is an example diagram of a blade vibration response test bench according to the second embodiment of the present invention;

[0053] Figure 5 This is a frequency comparison diagram of the test and simulation of the second embodiment of the present invention;

[0054] Figure 6 This is an exemplary diagram of a wind tunnel test device according to a second embodiment of the present invention;

[0055] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0056] 1. Blade scale model; 2. Support; 3. Acceleration sensor; 4. Force sensor; 5. Hammer; 6. Charge adapter; 7. Data acquisition instrument. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0058] Embodiment 1

[0059] like Figure 1 FIG. 1 is a flow chart of a first embodiment of a method for constructing and testing a wind turbine blade scaling criterion based on a mass relationship provided by the present invention. In this embodiment, the construction method is used to construct a blade scaling criterion, and includes the following steps:

[0060] S10, obtaining an existing aerodynamic similarity criterion, and obtaining the aerodynamic characteristics of the fan blade according to the existing aerodynamic similarity criterion, that is, a dimensionless number;

[0061] 11. Obtaining fan blade data, which includes fan blade structure and fan blade material, and using the fan blade data to derive the centroid position formula and mass distribution relationship of the fan blade cross section;

[0062] S12, building a blade vibration response test bench, and formulating a similarity ratio between the fan blade and the blade scale according to the blade vibration response test bench and the 3D printing size;

[0063] S13, obtaining a blade scale model material according to the derived similarity ratio and the aerodynamic characteristics of the fan blade;

[0064] S14, constructing a blade scaled model 1 using the blade scaled model material, similarity ratio and aerodynamic characteristics of the fan blade;

[0065] The test method is used to test the accuracy of the simulation results, including the following steps:

[0066] 20. Perform a blade vibration response test on the blade scale model 1 using a blade vibration response test bench;

[0067] S21, compare and analyze the test frequency and simulation frequency.

[0068] Firstly, based on motion equivalence, a reasonable simplification similarity criterion for the aeroelastic model of wind turbine blades was derived; then, the variational asymptotic equivalent section method was proposed to design a high-precision special-shaped section of the equivalent wind turbine blade model, realizing the aeroelastic model design of the blade aeroelastic model with aerodynamic-stiffness-mass scale mapping; finally, the aeroelastic model frame was obtained by high-precision 3D printing, and the aeroelastic model frame / outerwear was completed by connecting the ribs to splice the full-length model, filling the hollow area with balsa wood chips to polish the outer coat, pasting the counterweight lead sheet on the trailing edge, pasting the rough strips on the leading edge, and filling the gap with sponge.

[0069] Among them, in the above technical solution, the dimensionless numbers include Stroud number, Reynolds number, Froude number and Euler number.

[0070] The aerodynamic characteristics of the blade refer to the performance characteristics of the blade in the gas flow. The Storahar number, Reynolds number, Froude number and Euler number considered in the present invention respectively reflect the vortex, viscosity, inertia and other characteristics in the gas flow process. The details are as follows:

[0071] Strouhal number: The Strouhal number is a dimensionless number that describes periodic phenomena in a fluid, such as vortex shedding. It is defined as the ratio of the frequency of the periodic phenomenon to the velocity and characteristic length of the fluid flow. The Strouhal number can be used to predict the frequency of vortex shedding in a flow, which is very important in engineering applications such as vibration analysis of bridges and building structures.

[0072] Reynolds number: The Reynolds number is a dimensionless number that describes the flow state of a fluid (laminar or turbulent). It is defined as the ratio of the inertial force to the viscous force of the fluid and is usually expressed as the ratio of the fluid velocity, characteristic length, and dynamic viscosity. When the Reynolds number is low, the flow tends to be laminar; when the Reynolds number is high, the flow tends to be turbulent. The Reynolds number is a key parameter for understanding and predicting the flow characteristics of a fluid.

[0073] Froude number: The Froude number is a dimensionless number that describes the ratio of inertial force to gravity in fluid flow. It is usually used to analyze free surface flows, such as surface waves and flood waves. The size of the Froude number can affect the stability and waveform of the flow, and is of great significance to ship design and marine engineering.

[0074] Euler number: The Euler number is a dimensionless number that describes the ratio of pressure energy to kinetic energy in fluid flow. It is also called energy head or total pressure coefficient in some literature. The Euler number can be used to analyze energy conversion and loss in fluid flow and is important for understanding the performance of fluid machinery such as pumps and compressors.

[0075] Furthermore, in the above technical solution, the dimensionless number is specifically:

[0076] The Storahar numbers of the fan blade and the blade scale model 1 are equal to make the unsteady inertial forces similar;

[0077] The Reynolds numbers of the fan blade and the blade scale model 1 are equal to make the viscous forces similar;

[0078] The Froude numbers of the fan blade and the blade scale model 1 are equal to make the gravity effect of the fluid similar;

[0079] The Euler numbers of the fan blade and the blade scale model 1 are equal to make the inertial forces similar.

[0080] Furthermore, in the above technical solution, the similarity ratio includes the existing aerodynamic similarity criterion and the geometric similarity ratio, and the geometric similarity ratio includes the mass distribution relationship and the length similarity ratio.

[0081] Furthermore, in the above technical solution, step S11 specifically includes:

[0082] Divide the fan blade cross section according to the material, and divide the position with the same material into four areas, including the first area, the second area, the third area, and the fourth area along the blade span direction;

[0083] Calculate the centroid positions of the four regions respectively, and calculate the relationship between the centroid positions of the four regions and the centroid position of the cross section of the fan blade;

[0084] According to the relationship between the centroid positions, it is concluded that the third region is close to the centroid position of the fan blade cross section, and the centroid position of each region is related to the shape of the fan blade cross section and has nothing to do with the density.

[0085] Furthermore, in the above technical solution, the length similarity ratio is specifically a length ratio of the fan blade to the blade scaled model 1 of 200:1.

[0086] Furthermore, in the above technical scheme, the blade vibration response test bench includes a blade scaled model 1, a support 2, an acceleration sensor 3, a force sensor 4, a force hammer 5, a charge adapter 6, and a data acquisition instrument 7. The support 2 is used to fix the blade scaled model 1. One end of the blade scaled model 1 is fixedly connected to the support 2, and the other end is provided with the acceleration sensor 3. The acceleration sensor 3 is electrically connected to the charge adapter 6. One end of the charge adapter 6 is electrically connected to the force sensor 4, and the other end is electrically connected to the data acquisition instrument 7.

[0087] Furthermore, in the above technical solution, step S20 specifically includes:

[0088] Step 1, fixing the root of the blade scale model 1 to the support 2, and bonding the acceleration sensor 3 to five positions in the span direction of the blade scale model 1;

[0089] Step 2, amplify the electrical signal in the charge adapter 6, transfer it to the data acquisition instrument 7 to convert it into a digital signal, and transmit it to the computer via a USB cable.

[0090] Furthermore, in the above technical solution, in step 1, five positions of the blade scaled model 1 in the span direction are equidistantly arranged.

[0091] Furthermore, in the above technical solution, the material of the blade scale model is PLA material.

[0092] Embodiment 2

[0093] The present invention provides a second embodiment of a method for constructing and testing a wind turbine blade scaling criterion based on a mass relationship. In this embodiment, when scaling the blades, it is necessary to consider that the Reynolds number is equal to the self-model, Froude number, Stroud number, and Euler number.

[0094] The similarity of fluid motion is as follows: the air in the flow field where the wind turbine blades are located is a low-speed, incompressible, Newtonian viscous flow, and its fluid motion equation is:

[0095] (1)

[0096] In the formula, is the direction of the first principal axis of the coordinate system of the Laplace operator in the generalized expression of the fluid motion equation; is the principal axis direction of the second coordinate system of the Laplace operator in the generalized expression of the fluid motion equation, where is the coordinate system number; In the first rectangular coordinate system The velocity component of the fluid motion in the direction; In the second rectangular coordinate system The velocity component of the fluid motion in the direction; For time; In the rectangular coordinate system Directional fluid external forces; is the air density; for pressure; is the dynamic viscosity of air, , is the kinematic viscosity of air; They are the three principal axes of the rectangular coordinate system;

[0097] Quote Symbol Represents the model Same as real The ratio of ,in is the model variable The value of For actual variables The value of .

[0098] represents the prototype time, represents the prototype geometry, represents the prototype speed, Represents the prototype additional external force, represents the prototype dynamic viscosity, For pressure, represents the prototype density, , , , , and are the ratios of time, geometry, speed, additional external force, dynamic viscosity, and density, and they are all constants. The relationship between the physical quantities of the prototype and the model and the motion equation of the fluid can be expressed as follows:

[0099] , , , , , , ;

[0100] (2)

[0101] Variables with * are model variables, and those without * are prototype variables;

[0102] Specifically, represents the model variable time, represents the prototype speed, Represents the prototype additional external force, represents the prototype dynamic viscosity, represents the prototype density; is the model variable in the direction of the principal axis of the second coordinate system; It has no special meaning and here only represents the second coordinate system of the Laplace operator in the generalized expression of the fluid motion equation; In the second rectangular coordinate system Directional velocity component of the model's fluid motion;

[0103] Multiply all terms in equation (2) by have to:

[0104] (3)

[0105] To ensure the similarity of the fluid motion between the prototype and the model, the ratio of the physical quantities must satisfy:

[0106] (4)

[0107] Therefore, the dimensionless parameters of the similarity criterion of fluid motion in the aeroelastic wind tunnel test of wind turbine blades are:

[0108] ,Right now (5)

[0109] is the Stothraha number. If the Stothraha numbers of two flows are equal, the unsteady inertial forces of the fluids are similar. For periodic unsteady flows, it reflects the similarity of their periodicity.

[0110] ,Right now (6)

[0111] is the Reynolds number; if the Reynolds numbers of the two flows are equal, the viscous forces of the fluids are similar; for turbulent flows with larger Reynolds numbers, inertial forces play a dominant role and viscous forces are relatively small;

[0112] ,Right now (7)

[0113] is the Froude number; if the Froude numbers of the two flows are equal, it means that the gravity effects of the flows are similar, reflecting the effect of gravity on the fluid; if the mass force on the fluid is only gravity, , is the Earth’s gravitational acceleration;

[0114] but:

[0115] ,Right now (8)

[0116] is the Euler number.

[0117] In addition to aerodynamic similarity, some studies need to focus on the impact of mass distribution on the blade on its vibration characteristics. Therefore, the blade similarity criterion constructed in the present invention focuses on the mass ratio and keeps the position of the scaled-down blade's center of mass unchanged relative to the original blade's center of mass.

[0118] In the airfoil structure of the fan blade, the cross section The centroid coordinates of , ) is calculated as follows:

[0119] (9)

[0120] in, is the density at that location. The density of the NREL 15MW blade material is a constant, and the locations with the same material are divided into four regions (Ⅰ, Ⅱ, Ⅲ, Ⅳ), such as Figure 2 The centroid positions of each region are , then each area of ​​the cross section The formula for calculating the centroid coordinates is as follows:

[0121] (10)

[0122] The centroid position of each region is only related to the cross-sectional shape and has nothing to do with density. and the centroid of the cross section The relationship is as follows:

[0123] (11)

[0124] From the above formula, we can see that the center of mass The position is directly related to the quality of each area. The thickness and density of the main beam in area III are the largest, so the center of mass position and Close. Compared with the carbon fiber material of the main beam, the PVC material of the front and rear edge shell and the main beam has a very low density and a large thickness, but has little effect on the center of mass position. The front and rear edge areas are made of GFRP material, which has a higher density but a smaller cross-sectional area and has little effect on the center of mass position. Based on the above analysis, the scaled model of this study retains Figure 2 The main beam-web structure in the red dotted area (i.e., area III) ensures that the center of mass position of each section remains basically unchanged, and the material of the blade scale model is basically unrelated to the center of mass position. The wind turbine blade structure is a cantilever beam fixed at one end, and the high-strength PLA material is selected to ensure that the model has a small deformation after the acceleration sensor is installed. Considering the size of the test bench, the length similarity ratio of the blade scale model is selected as 200:1. The blade structure used for testing in this study is as follows Figure 3As shown in the figure, in addition to the main beam-web model (a), the hollow blade model (b) and solid models (c, d, e) are introduced for comparison. The filling of the solid models (c), (d), and (e) are 15%, 50%, and 85% respectively. The mass of each model is measured with an electronic scale. Figure 3 The five models in the paper are compared with the simulation model results to verify the accuracy of the simulation results and study the simplification method of the scaled model.

[0125] The scaled blade model test device constructed by the similarity principle of the present invention is as follows: Figure 4 , used to test the accuracy of simulation results and study the simplification method of scaled models.

[0126] The specific steps of the test method of the present invention are as follows: fix the root of the blade scale model, adhere and fix the piezoelectric acceleration sensor on the blade, and during the blade vibration process, convert the deformation into an electrical signal based on the piezoelectric effect. Amplify the electrical signal in the charge adapter, transfer it to the data acquisition instrument to convert it into a digital signal, and then transmit it to the computer via a USB cable. In this test, the mass of the acceleration sensor itself will produce a huge error. Here, the acceleration sensor is used as a mass increment and adhered and fixed on the Figure 3 The vibration signal of the acceleration sensor installed at 0.95R in the span direction of model (e) is shown in Figure 2. Figure 4 , the time domain signal is transformed into the frequency domain signal by Fourier transform. The position of the acceleration sensor in the span direction of the model is changed to obtain the frequency domain response signal.

[0127] Construct the simulation model shown in Figure 5 (taking the acceleration sensor installed at 0.95 R of the scaled model (e) as an example), set the standard earth gravity, the blade root as a fixed support, and the acceleration sensor at the tip of the blade is set to a steel material close to a rigid body, and change the density to make it the same as the actual sensor mass. The blade is set to PLA material. The masses of models (a), (b), and (e) are 8.2g, 17.9g, and 111.8g respectively. The difference in mass from the actual scaled model comes from the filling rate of 3D printing, the gap between layers, etc. Figure 5 It can be seen that the trends of the experiment and simulation are basically the same, and the numerical deviation mainly comes from the difference in model quality.

[0128] The scaled blade model constructed based on the above similarity criteria can be used for Figure 6The wind tunnel test shown in the figure shows that the scaled-down blade can be used for aeroelastic coupling flutter research because of the consideration of aerodynamic and structural similarity. The aerodynamic shapes of regions I, II, and IV are retained, and the thickness of each region is reduced as much as possible so that the center of mass of the blade remains near the center of mass of region III. In order to observe the flutter phenomenon of the blade, the blade is printed with TPU material and used in the wind tunnel test. The experiment can observe the flutter morphology and critical flutter speed of the scaled-down blade.

[0129] Specifically, the principle of the present invention is: a method for constructing a scaled-down criterion and a testing technology for studying the relationship between the vibration characteristics and mass of wind turbine blades. The key point of the invention is that it innovatively combines similarity theory with experimental testing technology, providing an efficient and economical solution for the study of blade vibration characteristics in engineering practice. This method constructs a scaled-down model similar to the actual blade, while retaining key vibration characteristics, greatly reducing experimental costs and time. At the same time, by strictly following the similarity criterion, it is ensured that the scaled-down model is highly similar to the actual blade in terms of geometry, material, mass distribution, etc., so as to accurately simulate the vibration behavior of the actual blade. Secondly, the innovation of the testing method is also the key to the invention. By designing a reasonable test plan, simulating the excitation conditions in the actual working environment, and effectively obtaining the vibration response data of the scaled-down model.

Claims

1. A wind turbine blade scaling criterion construction and testing method based on mass relationship, characterized in that: The construction method is used to construct the blade scaling criterion, including the following steps: S10, obtaining an existing aerodynamic similarity criterion, and obtaining the aerodynamic characteristics of the fan blade according to the existing aerodynamic similarity criterion, that is, a dimensionless number; S11, acquiring fan blade data, wherein the fan blade data includes a fan blade structure and a fan blade material, and using the fan blade data to derive a centroid position formula and a mass distribution relationship of a fan blade cross section; S12, building a blade vibration response test bench, and determining a similarity ratio between a fan blade and a blade scaled model according to the blade vibration response test bench and a 3D printing size; S13, obtaining a blade scale model material according to the derived similarity ratio and the aerodynamic characteristics of the fan blade; S14, constructing a blade scaled model (1) using the blade scaled model material, the similarity ratio and the aerodynamic characteristics of the fan blade; The test method is used to test the accuracy of the simulation results, and comprises the following steps: S20, using the blade vibration response test bench to perform a blade vibration response test on the blade scaled model (1); S21, compare and analyze the test frequency and simulation frequency; The step S11 specifically includes: The cross section of the fan blade is divided according to the material, and the position with the same material is divided into four areas, including the first area, the second area, the third area, and the fourth area along the span direction of the blade, wherein the first area corresponds to the leading edge of the fan blade, the second area corresponds to the leading edge shell, the trailing edge shell, and the web of the fan blade, the third area corresponds to the main beam of the fan blade, and the fourth area corresponds to the trailing edge of the fan blade; Calculate the centroid positions of the four regions respectively, and calculate the relationship between the centroid positions of the four regions and the centroid position of the cross section of the fan blade; According to the relationship between the centroid positions, it is concluded that the third region is close to the centroid position of the fan blade cross section, and the centroid position of each region is related to the shape of the fan blade cross section and has nothing to do with the density.

2. A method for constructing and testing wind turbine blade scaling criteria based on mass relationship according to claim 1, characterized in that: The dimensionless numbers include the Stroud number, the Reynolds number, the Froude number, and the Euler number.

3. A method for constructing and testing wind turbine blade scaling criteria based on mass relationship according to claim 2, characterized in that: The dimensionless number is specifically: The Storahar numbers of the fan blade and the blade scaled model (1) are equal, so as to make the unsteady inertial forces similar; The Reynolds numbers of the fan blade and the blade scaled model (1) are equal, so as to make the viscous forces similar; The Froude numbers of the fan blade and the blade scale model (1) are equal, so as to make the gravity effect of the fluid similar; The Euler numbers of the fan blade and the blade scaled model (1) are equal, so as to make the inertial forces similar.

4. A method for constructing and testing wind turbine blade scaling criteria based on mass relationship according to claim 3, characterized in that: The similarity ratio includes the existing aerodynamic similarity criterion and the geometric similarity ratio, and the geometric similarity ratio includes the mass distribution relationship and the length similarity ratio.

5. A method for constructing and testing wind turbine blade scaling criteria based on mass relationship according to claim 4, characterized in that: The length similarity ratio is specifically a length ratio between the fan blade and the blade scaled model (1) of 200:

1.

6. A method for constructing and testing wind turbine blade scaling criteria based on mass relationship according to claim 5, characterized in that: The blade vibration response test bench comprises a blade scale model (1), a support member (2), an acceleration sensor (3), a force sensor (4), a force hammer (5), a charge adapter (6), and a data acquisition instrument (7). The support member (2) is used to fix the blade scale model (1). One end of the blade scale model (1) is fixedly connected to the support member (2), and the other end is provided with the acceleration sensor (3). The acceleration sensor (3) is electrically connected to the charge adapter (6). One end of the charge adapter (6) is electrically connected to the force sensor (4), and the other end is electrically connected to the data acquisition instrument (7).

7. A method for constructing and testing wind turbine blade scaling criteria based on mass relationship according to claim 6, characterized in that: The step S20 specifically includes: Step 1, fixing the root of the blade scale model (1) to the support (2), and the acceleration sensor (3) is adhesively fixed at five positions in the span direction of the blade scale model (1); Step 2, amplifying the electrical signal in the charge adapter (6), transferring it to the data acquisition instrument (7) to convert it into a digital signal, and transmitting it to the computer via a USB cable.

8. A method for constructing and testing wind turbine blade scaling criteria based on mass relationship according to claim 7, characterized in that: In the step 1, the blade scale model (1) is arranged at equidistant positions in the span direction.

9. A method for constructing and testing wind turbine blade scaling criteria based on mass relationship according to claim 8, characterized in that: The blade scale model material is made of PLA material.

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