Test device and method for measuring aerodynamic characteristics of scaled wind turbine blade under rotating condition

Abstract

The application discloses a kind of test device and method for measuring the aerodynamic characteristics of scaled wind turbine blades under rotating conditions, which adopts scaled wind turbine blades, airflow probes, surface pressure holes, six-component balances, rotational speed and torque sensors, and data acquisition and analysis devices. The induced velocity of blade lift circulation needs to be removed from the relative inflow velocity vector measured directly by the airflow probe. Therefore, based on the characteristics of the device, the application proposes a calculation method based on lift circulation correction under non-uniform flow without correction under uniform flow, solving the difficulty of measuring the relative inflow velocity vector at the leading edge of the blade and the aerodynamic force (normal force and tangential force in the airfoil chord line coordinate system) under rotating conditions in the wind tunnel environment. At the same time, the application proposes an aerodynamic characteristic and operating characteristic analysis method based on the data calculation results.

Description

Technical Field

[0001] This invention belongs to the field of wind turbine blade aerodynamics technology, and relates to a method and device for measuring aerodynamic parameters. More specifically, it relates to a test device and method for measuring the aerodynamic characteristics of scaled-down wind turbine blades under rotating conditions, which can effectively solve the technical problem of measuring the aerodynamic characteristics and aerodynamic forces of scaled-down wind turbine blades, including blade aerodynamic angle of attack, in a wind tunnel environment. Background Technology

[0002] Wind turbine blades are the actuating elements of wind turbine rotors, used to capture wind energy. Wind turbines operate in harsh environments, and as crucial energy conversion components, the design and manufacturing of wind turbine blades directly impact the operational efficiency and reliability of the wind turbine. Their aerodynamic performance determines the wind energy utilization efficiency (power coefficient) of the wind turbine. Therefore, research on the dynamic performance and operating characteristics of wind turbine blades can promote optimized blade design and improve the power generation efficiency of wind turbines. Wind turbine blades are formed by stacking airfoils along the blade span with a specific twist angle, chord length, and thickness distribution. The key parameters for evaluating the aerodynamic performance of airfoils are angle of attack and aerodynamic forces.

[0003] Currently, the verification and evaluation of the dynamic aerodynamic characteristics of wind turbine blades during rotation in a wind tunnel environment has not been well resolved. The main reasons are: the complexity of the rotational effect (testing the dynamic aerodynamic characteristics of rotating blades in a wind tunnel requires considering the dynamic effects of the blades, including centrifugal force and Coriolis force. The calculation and simulation of these effects are very complex, requiring high-precision numerical simulation methods and computational resources); the lack of verification in real-world environments (for evaluating the aerodynamic characteristics of wind turbine blades, relying solely on experimental data in a wind tunnel cannot fully represent the conditions under real wind field conditions. Real wind fields include different wind speeds, wind directions, turbulence intensities, and other factors, which have a significant impact on the aerodynamic characteristics of the blades. Therefore, how to combine laboratory data with real wind field data to obtain accurate evaluation results remains a challenge); and limitations of testing equipment (current wind tunnels and testing equipment cannot fully meet the testing requirements for rotating blades, such as the need for higher measurement accuracy and a larger testing range. This also leads to certain limitations in the verification and evaluation of the dynamic aerodynamic characteristics of rotating blades in a wind tunnel environment).

[0004] The induction factor during the rotation of wind turbine blades is an unknown quantity closely related to the operating conditions. The induction factor describes the influence of the vortex generated by the rotating blade on the surrounding airflow. It is highly complex and cannot be directly measured during the experiment. It is mainly limited by the following factors: (1) Complex flow field environment. During the rotation of wind turbine blades, the generated aerodynamic flow field is very complex, including airflows of different directions and sizes, centrifugal force of the rotor blade and Coriolis force, etc. The flow field generated by the combined action of these factors is difficult to predict and measure accurately; (2) Interaction of flow field parameters. The calculation of the induction factor requires consideration of the influence of multiple flow field parameters, such as air density, angular velocity, blade shape, etc. These parameters influence each other, and the influence under different conditions is also different, so it is difficult to accurately separate them; (3) Limitation of testing equipment. Current testing equipment cannot directly measure the induction factor, but can only be estimated by other parameters, such as by measuring aerodynamic torque, blade tip deflection and other parameters. Although this method can obtain approximate data, the accuracy is not high. Because the inducible factor cannot be directly measured during the experiment, the aerodynamic angle of attack of the blade cannot be obtained solely from the incoming wind speed and blade rotation speed. (On the one hand, during the rotation of the wind turbine blade, the vortices generated by the blade affect the surrounding airflow, causing the actual angle of attack to differ from that under static conditions. Since the inducible factor cannot be directly measured, this effect is difficult to accurately account for. On the other hand, the inducible factor varies under different operating conditions; for example, wind speed, wind direction, and blade rotation speed all affect the magnitude of the inducible factor. Therefore, even if the wind speed and blade rotation speed are the same under different operating conditions, the aerodynamic performance of the blade cannot be simply calculated using the equivalent static angle of attack.) Consequently, it is difficult to determine the lift-drag coefficient (the lift-drag coefficient is one of the important parameters describing the aerodynamic performance of the blade; it is the ratio of the lift coefficient to the drag coefficient. There is a non-linear relationship between the lift coefficient and the angle of attack, so it is difficult to determine the lift coefficient without accurately measuring the angle of attack. Simultaneously, the drag coefficient is also related to the angle of attack and increases with increasing angle of attack. Therefore, it is also difficult to determine the drag coefficient without accurately measuring the angle of attack). In summary, the challenge in verifying and evaluating the dynamic aerodynamic characteristics of wind turbine blades during rotation in a wind tunnel environment lies in the lack of effective methods for measuring the angle of attack and aerodynamic forces during the rotation of wind turbine blades. Summary of the Invention

[0005] (I) Purpose of the Invention

[0006] To address the aforementioned technical problems in existing technologies, this invention proposes an experimental method for measuring the aerodynamic angle of attack of a wind turbine blade under rotating conditions. This method is based on the fact that the aerodynamic angle of attack of a wind turbine blade is related to the inflow velocity far in front of the rotor, rotor speed, installation twist angle, and axial and circumferential induction factors. An airflow probe can measure the relative inflow velocity vector, which includes the inflow velocity far in front, axial induced velocity, circumferential induced velocity, rotor speed, and the induced velocity of the blade's own lift circulation at the measured position. Therefore, the effective angle of attack of the airfoil can only be obtained by removing the lift circulation induced velocity from the relative inflow velocity vector measured by the probe. The present invention first proposes an experimental apparatus for measuring the aerodynamic characteristics of scaled-down wind turbine blades under rotating conditions. Secondly, based on this apparatus, it addresses the difficulty of monitoring the aerodynamic and operational characteristics of scaled-down blades under different operating conditions in a wind tunnel environment. By arranging airflow probes on the symmetrical axis of adjacent wind turbine blades, when the wind flow is uniform, the induced velocities of adjacent wind turbine blades on the airflow probes are equal in magnitude and opposite in direction. Therefore, the influence of the lift circulation induced velocity can cancel each other out, and the measured angle of attack does not require correction. When the wind flow is non-uniform, a corresponding angle of attack correction method is also proposed. Using airflow probes and blade surface pressure measurements, multiple aerodynamic characteristic parameters can be further calculated simultaneously. These parameters include, but are not limited to, the angle of attack, lift coefficient, drag coefficient, lift-to-drag ratio, and induction factor of the scaled-down blade. Operational characteristic parameters include, but are not limited to, torque coefficient, thrust coefficient, and power coefficient. This solves the technical problem of measuring the aerodynamic characteristics and aerodynamic forces, including the blade's aerodynamic angle of attack, of scaled-down wind turbine blades in a wind tunnel environment.

[0007] (II) Technical Solution

[0008] The specific technical solution adopted by this invention to achieve its inventive purpose and solve its technical problem is as follows:

[0009] A test apparatus for measuring the aerodynamic characteristics of scaled-down wind turbine blades under rotating conditions, comprising at least a wind tunnel, a scaled-down wind turbine unit installed within the wind tunnel test section and adapted to its dimensions, and a data acquisition and controller, characterized in that...

[0010] The scaled-down wind turbine unit includes at least a foundation fixedly installed on the bottom surface of the wind tunnel test section, a scaled-down tower installed on the foundation and extending along the height direction, a scaled-down nacelle installed at the top of the scaled-down tower, and a scaled-down wind turbine installed at the front end of the scaled-down nacelle.

[0011] The scaled-down wind turbine includes at least a scaled-down hub, several scaled-down wind turbine blades evenly distributed circumferentially on the scaled-down hub, and a fairing fixedly disposed at the front end of the scaled-down hub.

[0012] The outer radial edge of the fairing is provided with a plurality of radially extending airflow probes, and the circumferential position of each airflow probe is located on the axis of symmetry of two adjacent scaled-down wind turbine blades.

[0013] Each scaled-down wind turbine blade has several spaced pressure measurement sections along its span. Each pressure measurement section forms a blade airfoil to be tested. On the pressure and suction surfaces of each blade airfoil to be tested, multiple pressure measurement holes are arranged from the leading edge to the trailing edge, penetrating the blade surface and communicating with the blade cavity. Each scaled-down wind turbine blade has multiple pressure measurement tubes in its blade cavity that correspond one-to-one with the pressure measurement holes on its blade surface.

[0014] A pressure scanning valve is fixedly installed inside the cavity of the scaled-up hub. The ends of the pressure measuring tubes in the inner cavities of each scaled-up wind turbine blade are connected to the pressure scanning valve. The pressure scanning valve measures the surface pressure distribution of the airfoil of the scaled-up wind turbine blade through the pressure measuring tubes and measuring holes connected to it.

[0015] The data acquisition controller is communicatively connected to each of the airflow probes and pressure scanning valves to collect in real time the surface pressure distribution of the airfoil of each scaled-down wind turbine blade and the aerodynamic pressure data of each of the airflow probes.

[0016] In a preferred embodiment of the present invention, at least one load motor is provided inside the scaled-down nacelle. The load motor is connected to the scaled-down hub located outside the scaled-down nacelle via the wind turbine main shaft, and the load motor is communicatively connected to the data acquisition controller.

[0017] In a preferred embodiment of the present invention, the airflow probe includes at least a support base, a variable-length probe rod fixedly mounted on the support base and extending radially, and a probe disposed at the front end of the variable-length probe rod. Each airflow probe is fixedly mounted on the radial outer edge of the fairing via its support base and is uniformly distributed circumferentially. In practice, when selecting airflow probes, compact airflow vector sensors with minimal interference to downstream flow, such as porous airflow probes or multi-component hot-wire anemometers, can be used. In this invention, the measurement and calculation of the relative inflow velocity vector employs an offline pre-calibration method for the airflow probe and an online lookup table fitting method.

[0018] In a further embodiment of the present invention, the airflow probe is a porous airflow probe or a multi-component hot wire wind speed probe. Each scaled-down wind turbine blade has at least two spaced-apart airfoils to be tested in its spanwise direction. The radial extension length of each airflow probe is located near the position of the airfoil to be tested in the spanwise direction, such that the rotation plane of the airflow probe, which rotates synchronously with each scaled-down wind turbine blade, corresponds to the airfoil to be tested on the scaled-down wind turbine blade.

[0019] In the experimental apparatus for measuring the aerodynamic characteristics of scaled-up wind turbine blades under rotating conditions according to the present invention, an airflow probe, pressure measuring holes disposed on the surface of each scaled-up wind turbine blade, and a pressure scanning valve are used to measure the surface pressure distribution and relative inflow velocity vector at the leading edge of each airfoil of the scaled-up wind turbine blade, including the composite velocity value V. p Direction angle α p wait.

[0020] In a preferred embodiment of the present invention, the foundation is a fixed base or a six-degree-of-freedom motion platform set on the bottom surface of the wind tunnel test section. When the fixed base is selected, it is used to provide fixed support for the scaled-down wind turbine to simulate the motion response of a fixed onshore wind turbine. When the six-degree-of-freedom motion platform is selected, it is used to provide six-degree-of-freedom motion support for the scaled-down wind turbine to simulate the six-degree-of-freedom motion response of a floating wind turbine in the ocean.

[0021] In a preferred embodiment of the present invention, the scaled-down tower includes at least a tower body, a yaw motor, and two six-component force sensors. The lower end of the tower body is mounted on the foundation via the yaw motor. The yaw motor and the two six-component force sensors are communicatively connected to the data acquisition controller. One of the six-component force sensors is located in the connection area between the scaled-down nacelle and the upper end of the tower body, and the other six-component force sensor is located in the connection area between the lower end of the tower body and the yaw motor. The two six-component force sensors are used to measure the aerodynamic loads experienced by the scaled-down wind turbine in a wind tunnel environment. The aerodynamic loads include aerodynamic forces in the sway, longitudinal, and helical directions, as well as aerodynamic moments in the sway, longitudinal, and helical directions.

[0022] In a preferred embodiment of the present invention, the inner cavity of the scaled-down hub is further provided with a plurality of pitch motors that are connected to the scaled-down wind turbine blades in a one-to-one transmission manner. Each pitch motor is used to drive the scaled-down wind turbine blades connected to it to achieve pitch adjustment. The wind turbine main shaft is provided with a speed and torque sensor that is communicatively connected to the data acquisition controller.

[0023] In a preferred embodiment of the present invention, the data acquisition controller includes at least a model control module and a data acquisition module, wherein,

[0024] The model control module is communicatively connected to the scaled-down wind turbine and is used to control the operating status of the wind turbine. It includes at least a yaw motor driver that is communicatively connected to the yaw motor and issues control commands, a load motor driver that is communicatively connected to the load motor and issues control commands, and a pitch driver that is communicatively connected to each of the pitch motors and issues control commands.

[0025] The data acquisition module includes at least one speed and torque data acquisition card that is communicatively connected to the speed and torque sensor, one six-component force data acquisition card that is communicatively connected to each of the six-component force sensors, one blade surface pressure data acquisition card that is communicatively connected to the pressure scanning valve, and one incoming flow aerodynamic pressure data acquisition card that is communicatively connected to each of the airflow probes. These cards are used to acquire the load power data of the load motor, the six-component aerodynamic load data of the scaled-down tower, the surface pressure distribution data of each airfoil under test in each of the scaled-down wind turbine blades, and the incoming flow aerodynamic data.

[0026] Another objective of this invention is to provide a test method for measuring the aerodynamic characteristics of a scaled-down wind turbine blade under rotating conditions. This test method, based on the aforementioned test apparatus of this invention, simulates the aerodynamic response of a scaled-down blade model in a wind tunnel, and includes at least four steps: test condition design, initial parameter setting, operation control and synchronous data acquisition, and data analysis. Its key feature is that...

[0027] SS1. Test Condition Design

[0028] Analyze the key parameters affecting the aerodynamic characteristics of the blades according to the specific experimental objectives, and design different experimental conditions based on at least the identified key parameters. These key parameters include at least the aerodynamic angle of attack, turbulence intensity, incoming flow conditions, and lift coefficient C. l Drag coefficient C d ;

[0029] SS2. Initial Parameter Settings

[0030] Preset initial operating parameters, including at least wind tunnel wind speed, scaled-down wind turbine speed, test duration, control time step, and load parameters. Then, start the wind tunnel and scaled-down wind turbine according to the preset operating parameters until the operating state is stable.

[0031] SS3. Data Synchronization Acquisition and Operation Control

[0032] This step, when implemented, includes at least two sub-steps: triggering the data acquisition controller to perform synchronous data acquisition and load regulation based on PID control.

[0033] SS3.1 triggers the data acquisition controller to perform synchronous data acquisition.

[0034] The data acquisition module in the data acquisition controller collects in real time the load power data of the load motor, the surface pressure distribution data of each airfoil under test in each scaled-down wind turbine blade, the incoming aerodynamic data measured by each airflow probe, and the six-component aerodynamic load data measured by each six-component force sensor. The incoming aerodynamic data measured by the airflow probe is the relative inflow velocity vector at the leading edge of the airfoil under test, and the relative inflow velocity vector includes the composite velocity value V. p Direction angle α p Based on the collected surface pressure distribution data of each airfoil to be tested and the chord coordinate system of the airfoil to be tested, the tangential force A and normal force N along the chord of the airfoil are obtained by integration.

[0035] SS3.2 Load Regulation Based on PID Control

[0036] Based on the load power data of the load motor acquired by the data acquisition module in the data acquisition controller, the load motor driver uses PID control to control the load parameters of the load motor in real time. The PID control parameters include proportional control coefficient, integral control coefficient, and derivative control coefficient. The PID scheduling control strategy is implemented using the formula... Determine, where u(t) is the load rate of the target load motor at time t, e(t) is the deviation value calculated at time t, and K p K is the proportional adjustment coefficient. i K is the integral adjustment coefficient. d The differential adjustment coefficient;

[0037] SS4. Data Analysis

[0038] This step mainly includes aerodynamic characteristic analysis and operational characteristic analysis. The aerodynamic characteristic analysis includes at least the angle of attack calculation based on lift circulation correction and the blade lift coefficient C. l and drag coefficient C d The calculation of axial induction factor a and circumferential induction factor b, the operational characteristic analysis includes at least the calculation of thrust coefficient, torque coefficient and power coefficient, and includes at least the following steps:

[0039] SS4.1 Angle of attack calculation based on lift circulation correction

[0040] Since the airflow probes are arranged on the symmetrical axis of adjacent blades, when the wind condition is uniform, the induced velocities of adjacent wind turbine blades on the airflow probes are equal in magnitude and opposite in direction. Therefore, the influence of the lift circulation induced velocity can cancel each other out. The direction angle α in the relative inflow velocity vector at the leading edge of the airfoil of the test blade, measured by the airflow probes, is determined accordingly. p Synthesis speed value V pThis yields the relative inflow angle of attack α0 and the inflow velocity V0, and these two values ​​do not require correction. In this case, α0 = α p V0 = V p ;

[0041] When the wind is non-uniform, the relative inflow angle of attack α0 and the inflow velocity V should be considered based on the lift circulation Γ. p By performing a correction iteration, the corrected and updated relative inflow angle of attack α is obtained. e And the corrected and updated relative inflow velocity value V e At this time, α0 = α e V0 = V e ;

[0042] SS4.2 Blade lift coefficient C l and drag coefficient C d calculate

[0043] First, based on the tangential force A and normal force N along the airfoil chord obtained from substep SS3.1, and the relative inflow angle of attack α0 obtained from substep SS4.1, the lift L and drag D of the airfoil under test are calculated. The calculation formulas are as follows:

[0044] L=N·cosα0-A·sinα0, D=N·sinα0+A·cosα0;

[0045] Secondly, based on the calculated lift L, drag D, and relative inflow velocity V0, the blade lift coefficient C can be calculated. l and drag coefficient C d The calculation formulas are as follows:

[0046]

[0047] Where c is the chord length of the airfoil to be tested, and ρ is the airflow density;

[0048] SS4.3 Calculation of Axial Induction Factor a and Circumferential Induction Factor b

[0049] The updated relative inflow velocity value V obtained from step SS4.1. e Updated direction angle α e Based on the measured incoming wind speed V0 and rotor angular velocity Ω, the axial induction factor a and axial induction factor b are calculated, and their calculation formulas are as follows: and r is the spanwise length of the airfoil of the blade to be tested;

[0050] SS.4.4 Calculation of Operating Characteristic Parameters

[0051] The calculation of operating characteristic parameters in this step includes at least the calculation of thrust coefficient, torque coefficient, and power coefficient, where:

[0052] Based on the axial induction factor a and circumferential induction factor b calculated in step SS.4.4, the thrust coefficient C is calculated. T Its calculation formula is Where T is the magnitude of the thrust on the wind turbine, A is the swept area of ​​the wind turbine, and V0 is the measured incoming wind speed;

[0053] Based on the torque T measured by the speed and torque sensor o The torque coefficient C is calculated. q Its calculation formula is Where R is the radius of the wind turbine;

[0054] Based on the torque T measured by the speed and torque sensor o The power coefficient C is calculated based on the wind turbine speed Ω. P Its calculation formula is Where P is the extracted power of the wind turbine.

[0055] In a preferred embodiment of the present invention, in step SS4.1 above, when the wind condition is a non-uniform inflow, the inflow angle of attack α0 is corrected iteratively based on the lift circulation according to the following sub-steps:

[0056] SS4.1.1 Obtain the tangential force A of the j-th airfoil of the i-th blade under test. ij and normal force N ij And the direction angle α in the relative inflow velocity vector of the i-th blade and the j-th airfoil under test, obtained by measuring with an airflow probe. pij Synthesis speed value V pij ;

[0057] Before correcting the inflow angle of attack α0 based on lift circulation in SS4.1.2, let α0 = α pij ;

[0058] SS4.1.3 Calculate the lift L of the n test airfoils for the i-th blade. i1 L i2 ..., L in The calculation formulas are as follows:

[0059] L i1 =N i1 ·cosα0-A i1 ·sinα0、…、L in =N in ·cosα0-A in sinα0;

[0060] SS4.1.4 Calculate the lift circulation Γ of the n test airfoils for the i-th blade. i1 ,Γ i2 , ..., Γ in and the total lift circulation of the i-th blade The calculation formulas are as follows:

[0061]

[0062] SS4.1.5 Calculate the induced velocity vector of the i-th blade at the airflow probe measurement position. The formula is:

[0063]

[0064] SS4.1.6 calculates the relative inflow velocity vector for the updated airfoil of the i-th blade and the j-th blade under test. The calculation formula is as follows:

[0065] SS4.1.7 Determine whether α0 is equal to α eij Do they satisfy the relation |α0-α eij |>α max If this relationship is satisfied, repeat steps SS4.1.2 to SS4.1.6; if this relationship is not satisfied, obtain the corrected inflow angle of attack α. eij ;

[0066] Where m is the number of blades in the wind turbine, n is the number of airfoils to be tested on each blade of the wind turbine, and α pij α0 is the direction angle of the leading edge of the i-th scaled wind turbine blade and the j-th test blade airfoil relative to the inflow velocity vector, as measured by the airflow probe in step SS3; N is the initial value of the inflow angle of the scaled wind turbine blade section. ij and A ij These represent the tangential force and normal force along the airfoil chord of the i-th scaled wind turbine blade at the j-th cross-section, calculated in step SS3, respectively. ij The lift of the i-th blade and j-th airfoil at the position corresponding to the rotating surface of the variable-length airflow probe is Γ. ij Let V be the lift circulation at the j-th cross-section of the i-th scaled-down wind turbine blade, ρ be the inflow density, and V be the lift circulation at the j-th cross-section. pij R is the resultant velocity value of the j-th section of the i-th blade at the leading edge relative to the inflow velocity vector. l R is the radius of the airflow probe from the center of rotation of the wind turbine. b l is the radius from the blade tip to the center of rotation. b The distance from the leaf base to the leaf tip. Let be the induced velocity vector generated by the linear vortex of the i-th scaled-down wind turbine blade at the airflow probe measurement point. V is the updated relative inflow velocity vector of the i-th blade and the j-th blade under test. eij Let α be the relative inflow velocity value after the airfoil update for the i-th blade and the j-th blade under test. eij Let α be the updated directional angle of the airfoil of the i-th blade and the j-th blade under test. max This is the maximum difference that is set.

[0067] As can be seen from the above scheme, the test device and method for measuring the aerodynamic characteristics of scaled-up wind turbine blades under rotating conditions proposed in this invention measure the relative inflow velocity vector of the blade cross section on the same rotating surface by installing an airflow probe on the hub and rotating synchronously with the scaled-up wind turbine blade. It proposes that no angle of attack correction is required under uniform inflow, and also proposes a method for calculating the angle of attack based on the blade lift circulation correction under non-uniform inflow such as shear inflow. Then, the aerodynamic characteristic parameters and operating characteristic parameters of the blade are calculated, including lift coefficient, drag coefficient, axial induction factor, circumferential induction factor, thrust coefficient, torque coefficient, power coefficient, etc.

[0068] (III) Technical Effects

[0069] Compared with existing technologies, the experimental device and method for measuring the aerodynamic characteristics of scaled-down wind turbine blades under rotating conditions proposed in this invention have significant technical advantages:

[0070] (1) The test device and method for measuring the aerodynamic characteristics of scaled-down wind turbine blades under rotating conditions of the present invention proposes a method and device for measuring the angle of attack and aerodynamic force of scaled-down blades during rotation under uniform and non-uniform inflow by arranging airflow probes on the symmetrical axis of adjacent wind turbine blades, providing an effective test means for the study of the aerodynamic characteristics of rotating blades.

[0071] (2) The test device and method for measuring the aerodynamic characteristics of scaled-down wind turbine blades under rotating conditions of the present invention can simultaneously calculate multiple aerodynamic characteristic parameters using airflow probes and blade surface pressure measurement. The aerodynamic characteristic parameters include, but are not limited to, the angle of attack, lift coefficient, drag coefficient, lift-to-drag ratio, and induction factor of the scaled-down blade. The operating characteristic parameters include, but are not limited to, torque coefficient, thrust coefficient, and power coefficient. Thus, the technical problem of measuring the aerodynamic characteristics and aerodynamic forces of scaled-down wind turbine blades, including the blade aerodynamic angle of attack, in a wind tunnel environment is solved. Attached Figure Description

[0072] Figure 1 A schematic diagram of a wind tunnel test setup for the aerodynamic characteristics of scaled-down wind turbine blades for onshore wind turbines;

[0073] Figure 2 A schematic diagram of a wind tunnel test setup for the aerodynamic characteristics of scaled-down wind turbine blades of a floating wind turbine.

[0074] Figure 3 This is a schematic diagram illustrating the principle of measuring operating parameters of a scaled-down wind turbine blade according to the present invention.

[0075] Figure 4 This is a schematic diagram of the experiment for measuring the aerodynamic characteristics of a scaled-down wind turbine blade under rotating conditions according to the present invention.

[0076] Figure 5 This is a schematic diagram of the data analysis process in this invention;

[0077] Figure 6 This is a schematic diagram of the iterative process for correcting the inflow angle of attack based on lift circulation in this invention;

[0078] The meanings of the labels in the attached figures are as follows:

[0079] 1-Scaled-down wind turbine blade, 2-Two airfoils and pressure measurement holes on the scaled-down blade, 3-Airflow probe, 4-Nacelle, 5-Tower, 6-Fixed foundation, 7-Six-component force sensor, 8-Yaw motor, 9-Six-degree-of-freedom motion platform. Detailed Implementation

[0080] The present invention will now be described in further detail with reference to the accompanying drawings. This description is intended to explain, not limit, the invention and to make its objectives and technical solutions clearer. Throughout the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. The described embodiments are some, but not all, embodiments of the present invention and are intended to explain the invention, not to limit it. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0081] like Figure 1 , 2 As shown, the model test device for measuring the aerodynamic characteristics of a scaled-down wind turbine blade cross-section according to the present invention includes at least a wind tunnel (not shown in the figure), a scaled-down wind turbine set installed in the wind tunnel test section and adapted to its size, and a data acquisition controller (not shown in the figure). The scaled-down wind turbine set includes a scaled-down wind turbine blade 1, a surface pressure measurement point 2, an airflow probe 3, a scaled-down nacelle 4, a scaled-down tower 5, a fixed base 6, a six-component force sensor 7, a yaw motor 8, and a six-degree-of-freedom motion platform 9. The fixed base 6 is fixedly installed on the bottom surface of the wind tunnel test section. The scaled-down tower 5 is installed on the fixed base 6 or the six-degree-of-freedom motion platform 9 and extends along the height direction. The scaled-down nacelle 4 is installed at the top of the scaled-down tower 5, and the scaled-down wind turbine is installed at the front end of the scaled-down nacelle 4.

[0082] The airflow probe 3 can be either a multi-hole airflow probe or a multi-component hot-wire anemometer probe. It is mounted on the hub and rotates synchronously with the blade. The probe's rotation plane corresponds to the airfoil section to be tested on the scaled-down wind turbine blade 1. Multiple surface pressure measurement points 2 are arranged from the leading edge to the trailing edge on both the pressure and suction surfaces of each airfoil. Each surface pressure measurement point 2 is communicatively connected to a pressure scanning valve. These surface pressure measurement points 2 are used to measure the surface pressure distribution of the airfoil under test. This is used to measure the relative inflow velocity vector at the leading edge of the scaled-down wind turbine blade section, including the composite velocity value V. p Direction angle α p The data collection and analysis unit integrates the pressure values ​​collected from each surface pressure measurement point 2 and the chord coordinate system of each airfoil under test to obtain the tangential force and normal force along the airfoil chord, and uses the average value of the tangential force and normal force of each airfoil under test as the tangential force A and normal force N of the airfoil at the installation position of the airflow probe 3.

[0083] The six-component force sensor 7 is installed on the lower end face of the tower 5 and the upper end face of the yaw motor 8. It is used to measure the aerodynamic loads on the scaled-down wind turbine in the wind tunnel environment, including the aerodynamic forces in the three directions of sway, longitudinal sway, and heave, as well as the aerodynamic torques in the three directions of sway, longitudinal sway, and heave.

[0084] The foundation can be either a fixed base 6 or a six-degree-of-freedom motion platform 9. The six-degree-of-freedom motion platform 9 is used to provide six-degree-of-freedom motion support for scaled-down wind turbines, simulating the six-degree-of-freedom motion response of floating wind turbines in the ocean.

[0085] The data acquisition controller includes a model control module and a data acquisition module. The model control module includes a yaw motor driver, a load motor driver, a motor control card, and synchronous measurement and control integrated software, which communicate with the model unit to control the operating status of the model unit. The data acquisition module includes a speed and torque acquisition card, a six-component force sensor acquisition card, and a pressure measurement system, which communicate with the model unit, the six-component sensor 7, and the pressure scanning valve to acquire parameters such as speed and torque, six-component aerodynamic load, and blade surface pressure distribution.

[0086] When conducting experimental research using the device of this invention, it includes at least four steps: test condition design, initial parameter setting, operation control and data synchronous acquisition, and data analysis. Taking the aerodynamic characteristic test research of a floating wind turbine with two blades and two pressure-measuring airfoils on each blade as an example, in which...

[0087] 1. Test Condition Design: To investigate the impact of different incoming flow conditions, different platform movements, and different load rates on the aerodynamic characteristics of the blades and the operating characteristics of the wind turbine, the following test conditions (Table 1) can be designed, but are not limited to:

[0088] Table 1

[0089]

[0090] 2. Initial parameter settings: Taking dynamic test, load, uniform flow (10m / s) and simulated turbulence conditions as examples, set the wind tunnel wind speed to 10m / s, the scaled-down wind turbine speed to 900r / min, the test duration to 10min, and the control time step to 0.1s. Start the wind tunnel and scaled-down wind turbine according to the preset parameters until the operating state is stable.

[0091] 3. Operation control and data synchronous acquisition, including load PID regulation and trigger synchronous acquisition.

[0092] In the PID control load regulation method, the load motor is connected to a data acquisition controller. Based on the acquired load power data, the load parameters are controlled in real time to achieve the target torque. The PID parameters include proportional control coefficient, integral control coefficient, and derivative control coefficient. The PID scheduling strategy is implemented using the formula... Determine the initial proportional adjustment coefficient K. p Set to 20, integral adjustment coefficient K i Set to 0.1, differential adjustment coefficient K d Set it to 0.1, and gradually modify the PID parameters as the experiment progresses to achieve faster convergence.

[0093] The data acquisition controller collects aerodynamic pressure data from the pressure measuring holes 2 and the airflow probe 3 at both cross-sections of the blade in real time, reads the six-component aerodynamic load data from the six-component force sensor 7, and processes and analyzes the data simultaneously. The relative inflow velocity vector at the leading edge of the blade airfoil is measured using the velocity directly measured by the airflow probe 3, which is the relative inflow velocity vector at the leading edge of the blade cross-section, including the composite velocity value V. p Direction angle α p Specifically, the measurement and calculation of the relative inflow velocity vector can be performed using the method of offline pre-calibration of the airflow probe 3 and online table lookup fitting; for the aerodynamic measurement of the blade airfoil, two blade airfoils to be tested are selected on the blade, and multiple pressure measuring holes are arranged from the leading edge to the trailing edge on the pressure surface and suction surface of the blade airfoil to measure the pressure distribution on the blade surface, and the tangential force A and normal force N along the airfoil chord are obtained by integrating according to the chord coordinate system of the blade airfoil to be tested.

[0094] 4. Data analysis, including aerodynamic characteristic analysis and operational characteristic analysis.

[0095] 4.1. Angle of attack calculation based on lift circulation correction: Since the airflow probe is arranged on the axis of symmetry of adjacent blades, when the wind condition is uniform, the induced velocities of adjacent wind turbine blades on the airflow probe are equal in magnitude and opposite in direction. Therefore, the influence of the lift circulation induced velocity can cancel each other out, and the measured angle of attack does not need to be corrected. When the wind condition is non-uniform, the iterative steps for angle of attack correction are as follows:

[0096] 4.1.1 Obtain the tangential forces A1, A′1 and normal forces N1, N′1 of the two airfoils under test for the same blade, as well as the direction angle α in the relative inflow velocity vector obtained by measuring with an airflow probe. p1 Synthesis speed value V p1 V′ p1 ;

[0097] 4.1.2 Before correcting the inflow angle of attack α0 based on the lift circulation, let α0 = α p1 ;

[0098] 4.1.3 Calculate the lift L1 and L′1 of the two airfoils to be tested on the same blade. The calculation formulas are: L1=N1·cosα0-A1·sinα0, L′1=N′1·cosα0-A′1·sinα0;

[0099] 4.1.4 Calculate the lift circulation Γ1 and Γ′1 of the two airfoils under test for the same blade. The calculation formulas are as follows:

[0100] 4.1.5 Calculate the induced velocity vectors of the two blades at the airflow probe measurement positions respectively. The formula is:

[0101]

[0102] 4.1.6 Calculate the corrected and updated relative inflow velocity vector, the formula of which is:

[0103] 4.1.7 Determine whether α0 is equal to α e Do they satisfy the relation |α0-α e |>α max If this relationship is satisfied, repeat steps 4.1.2 to 4.1.6; otherwise, obtain the corrected inflow angle of attack α. e ;

[0104] Where, α piLet α0 be the direction angle of the leading edge of the i-th scaled-down wind turbine blade relative to the inflow velocity vector measured by the airflow probe in step SS3, α0 be the initial value of the inflow angle at the two sections of the scaled-down wind turbine blade, N1, N′1 and A1, A′1 be the tangential force and normal force along the airfoil chord at two different sections of the same scaled-down wind turbine blade calculated in step 3, L1, L′1 be the lift of the blade airfoil at the position corresponding to the rotating surface where the variable-length airflow probe is installed, Γ1, Γ′1 be the lift circulation at the two sections of the first scaled-down wind turbine blade, Γ2, Γ′2 be the lift circulation at the two sections of the second scaled-down wind turbine blade, ρ be the inflow density, and V be the inflow density. p1 V′ p1 R represents the resultant velocity value of the relative inflow velocity vectors at the leading edge of the two blade sections, respectively. l R is the radius of the airflow probe from the center of the wind turbine's rotation. b l is the radius from the blade tip to the center of rotation. b The distance from the leaf base to the leaf tip. The induced velocity vector is generated by the linear vortices of the first and second scaled-down wind turbine blades. For the updated relative inflow velocity vector, V e For the updated relative inflow velocity value, α e For the updated direction angle, α max The maximum difference is set.

[0105] 4.2. Based on the lift L and drag D calculated in step 4.1, and the measured inflow velocity V0, the blade lift coefficient C can be calculated. l and drag coefficient C d The calculation formulas are as follows:

[0106]

[0107] 4.3. Calculate the axial induction factor a and circumferential induction factor b based on the blade velocity momentum theory, and then calculate the updated relative inflow velocity value V obtained in step 4.1. e Updated direction angle α e Based on the measured incoming wind speed V0 and rotor angular velocity Ω, the axial induction factor can be calculated. and axial inducing factor

[0108] 4.4. Calculation of operating characteristic parameters, including the calculation of thrust coefficient, torque coefficient, and power coefficient. Based on the rotor thrust T calculated from the six-component aerodynamic load data acquired in step 3, the thrust coefficient can be calculated. The torque coefficient can be calculated based on the torque To measured by the speed and torque sensor and the wind turbine speed Ω. and power coefficient

[0109] 4.5. Control the load motor to rotate to the next time step according to the preset torque and speed. At the same time, the six-degree-of-freedom platform, six-component balance, speed and torque sensor, airflow probe and other sensors also repeatedly monitor and record data until the preset test time of 10 minutes is reached. The wind turbine gradually stops rotating, the load motor is turned off, the wind tunnel is turned off, the test data is exported, and the time history of the aerodynamic parameters and motion characteristic parameters of the scaled-down wind turbine blade is obtained. The test data is then analyzed.

[0110] The objectives of this invention have been fully and effectively achieved through the above embodiments. All equivalent or simple variations made to the structures, features, and principles described in this patent concept are included within the protection scope of this patent. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the structure of this invention or exceed the scope defined in these claims, all of which should fall within the protection scope of this invention.

Claims

1. A test apparatus for measuring the aerodynamic characteristics of scaled-down wind turbine blades under rotating conditions, comprising at least a wind tunnel, a scaled-down wind turbine set and adapted to its size within the wind tunnel test section, and a data acquisition controller, characterized in that, The scaled-down wind turbine unit includes at least a foundation fixedly installed on the bottom surface of the wind tunnel test section, a scaled-down tower installed on the foundation and extending along the height direction, a scaled-down nacelle installed at the top of the scaled-down tower, and a scaled-down wind turbine installed at the front end of the scaled-down nacelle. The scaled-down wind turbine includes at least a scaled-down hub, several scaled-down wind turbine blades evenly distributed circumferentially on the scaled-down hub, and a fairing fixedly disposed at the front end of the scaled-down hub. The outer radial edge of the fairing is provided with a plurality of radially extending airflow probes, and the circumferential position of each airflow probe is located on the axis of symmetry of two adjacent scaled-down wind turbine blades. Each scaled-down wind turbine blade has several spaced pressure measurement sections along its span. Each pressure measurement section forms a blade airfoil to be tested. On the pressure and suction surfaces of each blade airfoil to be tested, multiple pressure measurement holes are arranged from the leading edge to the trailing edge, penetrating the blade surface and communicating with the blade cavity. Each scaled-down wind turbine blade has multiple pressure measurement tubes in its blade cavity that correspond one-to-one with the pressure measurement holes on its blade surface. A pressure scanning valve is fixedly installed inside the cavity of the scaled-up hub. The ends of the pressure measuring tubes in the inner cavities of each scaled-up wind turbine blade are connected to the pressure scanning valve. The pressure scanning valve measures the surface pressure distribution of the airfoil of the scaled-up wind turbine blade through the pressure measuring tubes and measuring holes connected to it. The data acquisition controller is communicatively connected to each of the airflow probes and pressure scanning valves to collect in real time the surface pressure distribution of the airfoil of each scaled-down wind turbine blade and the aerodynamic pressure data of each of the airflow probes.

2. The test apparatus for measuring the aerodynamic characteristics of scaled-down wind turbine blades under rotating conditions as described in claim 1, characterized in that, The scaled-down nacelle is equipped with at least one load motor. The load motor is connected to the scaled-down hub located outside the scaled-down nacelle via the wind turbine main shaft, and the load motor is communicatively connected to the data acquisition controller.

3. The test apparatus for measuring the aerodynamic characteristics of scaled-down wind turbine blades under rotating conditions as described in claim 2, characterized in that, The airflow probe includes at least a support base, a variable-length probe rod fixedly mounted on the support base and extending radially, and a probe disposed at the front end of the variable-length probe rod. Each of the airflow probes is fixedly mounted on the radial outer edge of the fairing via its support base and is evenly distributed circumferentially.

4. The test apparatus for measuring the aerodynamic characteristics of scaled-down wind turbine blades under rotating conditions as described in claim 3, characterized in that, The airflow probe is a porous airflow probe or a multi-component hot wire wind speed probe. Each scaled-down wind turbine blade has at least two spaced-apart airfoils to be tested in its spanwise direction. The radial extension length of each airflow probe is located near the position of the airfoil to be tested in the spanwise direction, so that the rotation plane of the airflow probe, which rotates synchronously with each scaled-down wind turbine blade, corresponds to the airfoil to be tested on the scaled-down wind turbine blade.

5. The test apparatus for measuring the aerodynamic characteristics of scaled-down wind turbine blades under rotating conditions as described in claim 4, characterized in that, The foundation is a fixed base or a six-degree-of-freedom motion platform set on the bottom surface of the wind tunnel test section. When the fixed base is selected, it is used to provide fixed support for the scaled-down wind turbine to simulate the motion response of a fixed onshore wind turbine. When the six-degree-of-freedom motion platform is selected, it is used to provide six-degree-of-freedom motion support for the scaled-down wind turbine to simulate the six-degree-of-freedom motion response of a floating wind turbine in the ocean.

6. The test apparatus for measuring the aerodynamic characteristics of scaled-down wind turbine blades under rotating conditions as described in claim 5, characterized in that, The scaled-down tower includes at least one tower body, one yaw motor, and two six-component force sensors. The lower end of the tower body is mounted on the foundation via the yaw motor. The yaw motor and the two six-component force sensors are all communicatively connected to the data acquisition controller. One of the six-component force sensors is located in the connection area between the scaled-down nacelle and the upper end of the tower body, and the other six-component force sensor is located in the connection area between the lower end of the tower body and the yaw motor. The two six-component force sensors are used to measure the aerodynamic loads experienced by the scaled-down wind turbine in a wind tunnel environment. The aerodynamic loads include aerodynamic forces in the sway, longitudinal, and helical directions, as well as aerodynamic moments in the sway, longitudinal, and helical directions.

7. The test apparatus for measuring the aerodynamic characteristics of scaled-down wind turbine blades under rotating conditions as described in claim 6, characterized in that, The inner cavity of the scaled-down hub is also equipped with several pitch motors that are connected to the scaled-down wind turbine blades one by one. Each pitch motor is used to drive the scaled-down wind turbine blades connected to it to adjust the pitch. The wind turbine main shaft is equipped with a speed and torque sensor that is connected to the data acquisition controller.

8. The test apparatus for measuring the aerodynamic characteristics of scaled-down wind turbine blades under rotating conditions as described in claim 7, characterized in that, The data acquisition controller includes at least one model control module and one data acquisition module, wherein, The model control module is communicatively connected to the scaled-down wind turbine and is used to control the operating status of the wind turbine. It includes at least a yaw motor driver that is communicatively connected to the yaw motor and issues control commands, a load motor driver that is communicatively connected to the load motor and issues control commands, and a pitch driver that is communicatively connected to each of the pitch motors and issues control commands. The data acquisition module includes at least one speed and torque data acquisition card that is communicatively connected to the speed and torque sensor, one six-component force data acquisition card that is communicatively connected to each of the six-component force sensors, one blade surface pressure data acquisition card that is communicatively connected to the pressure scanning valve, and one incoming flow aerodynamic pressure data acquisition card that is communicatively connected to each of the airflow probes. These cards are used to acquire the load power data of the load motor, the six-component aerodynamic load data of the scaled-down tower, the surface pressure distribution data of each airfoil under test in each of the scaled-down wind turbine blades, and the incoming flow aerodynamic data.

9. A method for measuring the aerodynamic characteristics of scaled-down wind turbine blades under rotating conditions, characterized in that, The aerodynamic response simulation of a scaled-down blade model in a wind tunnel using the test apparatus described in claim 8 specifically includes the following steps: SS1. Test Condition Design Analyze the key parameters affecting the aerodynamic characteristics of the blades according to the specific experimental objectives, and design different experimental conditions based on at least the identified key parameters. These key parameters include at least the aerodynamic angle of attack, turbulence intensity, incoming flow conditions, and lift coefficient C. l Drag coefficient C d ; SS2. Initial Parameter Settings Preset initial operating parameters, including at least wind tunnel wind speed, scaled-down wind turbine speed, test duration, control time step, and load parameters. Then, start the wind tunnel and scaled-down wind turbine according to the preset operating parameters until the operating state is stable. SS3. Data Synchronization Acquisition and Operation Control This step, when implemented, includes at least two sub-steps: triggering the data acquisition controller to perform synchronous data acquisition and load regulation based on PID control. SS3.1 triggers the data acquisition controller to perform synchronous data acquisition. The data acquisition module in the data acquisition controller collects in real time the load power data of the load motor, the surface pressure distribution data of each airfoil under test in each scaled-down wind turbine blade, the incoming aerodynamic data measured by each airflow probe, and the six-component aerodynamic load data measured by each six-component force sensor. The incoming aerodynamic data measured by the airflow probe is the relative inflow velocity vector at the leading edge of the airfoil under test, and the relative inflow velocity vector includes the composite velocity value V. p Direction angle α p Based on the collected surface pressure distribution data of each airfoil to be tested and the chord coordinate system of the airfoil to be tested, the tangential force A and normal force N along the chord of the airfoil are obtained by integration. SS3.2 Load Regulation Based on PID Control Based on the load power data of the load motor acquired by the data acquisition module in the data acquisition controller, the load motor driver uses PID control to control the load parameters of the load motor in real time. The PID control parameters include proportional control coefficient, integral control coefficient, and derivative control coefficient. The PID scheduling control strategy is implemented using the formula... Determine, where u(t) is the load rate of the target load motor at time t, e(t) is the deviation value calculated at time t, and K p K is the proportional adjustment coefficient. i K is the integral adjustment coefficient. d The differential adjustment coefficient; SS4. Data Analysis This step mainly includes aerodynamic characteristic analysis and operational characteristic analysis. The aerodynamic characteristic analysis includes at least the angle of attack calculation based on lift circulation correction and the blade lift coefficient C. l and drag coefficient C d The calculation of axial induction factor a and circumferential induction factor b, the operational characteristic analysis includes at least the calculation of thrust coefficient, torque coefficient and power coefficient, and includes at least the following steps: SS4.1 Angle of attack calculation based on lift circulation correction Since the airflow probes are arranged on the symmetrical axis of adjacent blades, when the wind condition is uniform, the induced velocities of adjacent wind turbine blades on the airflow probes are equal in magnitude and opposite in direction. Therefore, the influence of the lift circulation induced velocity can cancel each other out. The direction angle α in the relative inflow velocity vector at the leading edge of the airfoil of the test blade, measured by the airflow probes, is determined accordingly. p Synthesis speed value V p This yields the relative inflow angle of attack α0 and the inflow velocity V0, and these two values ​​do not require correction. In this case, α0 = α p V0 = V p ; When the wind is non-uniform, the relative inflow angle of attack α0 and the inflow velocity V should be considered based on the lift circulation Γ. p By performing a correction iteration, the corrected and updated relative angle of attack α is obtained. e And the corrected and updated relative inflow velocity value V e At this time, α0 = α e V0 = V e ; SS4.2 Blade lift coefficient C l and drag coefficient C d calculate First, based on the tangential force A and normal force N along the airfoil chord obtained from substep SS3.1, and the relative inflow angle of attack α0 obtained from substep SS4.1, the lift L and drag D of the airfoil under test are calculated. The calculation formulas are as follows: L=N·cosα0-A·sinα0, D=N·sinα0+A·cosα0; Secondly, based on the calculated lift L, drag D, and relative inflow velocity V0, the blade lift coefficient C can be calculated. l and drag coefficient C d The calculation formulas are as follows: Where c is the chord length of the airfoil to be tested, and ρ is the airflow density; SS4.3 Calculation of Axial Induction Factor a and Circumferential Induction Factor b The updated relative inflow velocity value V obtained from step SS4.

1. e Updated direction angle α e Based on the measured incoming wind speed V0 and rotor angular velocity Ω, the axial induction factor a and axial induction factor b are calculated, and their calculation formulas are as follows: and r is the spanwise length of the airfoil of the blade to be tested; SS.4.4 Calculation of Operating Characteristic Parameters The calculation of operating characteristic parameters in this step includes at least the calculation of thrust coefficient, torque coefficient, and power coefficient, where: Based on the axial induction factor a and circumferential induction factor b calculated in step SS.4.4, the thrust coefficient C is calculated. T Its calculation formula is Where T is the magnitude of the thrust on the wind turbine, A is the swept area of ​​the wind turbine, and V0 is the measured incoming wind speed; Based on the torque T measured by the speed and torque sensor o The torque coefficient C is calculated. q Its calculation formula is Where R is the radius of the wind turbine; Based on the torque T measured by the speed and torque sensor o The power coefficient C is calculated based on the wind turbine speed Ω. P Its calculation formula is Where P is the extracted power of the wind turbine.

10. The method for measuring the aerodynamic characteristics of scaled-down wind turbine blades under rotating conditions according to claim 9, characterized in that, In step SS4.1 above, when the wind condition is a non-uniform inflow, the inflow angle of attack α0 is corrected iteratively based on the lift circulation according to the following sub-steps: SS4.1.1 Obtain the tangential force A of the j-th airfoil of the i-th blade under test. ij and normal force N ij And the direction angle α in the relative inflow velocity vector of the i-th blade and the j-th airfoil under test, obtained by measuring with an airflow probe. pij Synthesis speed value V pij ; Before correcting the inflow angle of attack α0 based on lift circulation in SS4.1.2, let α0 = α pij ; SS4.1.3 Calculate the lift L of the n test airfoils for the i-th blade. i1 L i2 ..., L in The calculation formulas are as follows: L i1 =N i1 ·cosα0-A i1 ·sinα0、…、L in =N in ·cosα0-A in ·sinα0; SS4.1.4 Calculate the lift circulation Γ of the n test airfoils for the i-th blade. i1 ,Γ i2 、…、Γ in and the total lift circulation of the i-th blade The calculation formulas are as follows: SS4.1.5 Calculate the induced velocity vector of the i-th blade at the airflow probe measurement position. The formula is: SS4.1.6 calculates the relative inflow velocity vector for the updated airfoil of the i-th blade and the j-th blade under test. The calculation formula is as follows: SS4.1.7 Determine whether α0 is equal to α eij Do they satisfy the relation |α0-α eij |>α max If this relationship is satisfied, repeat steps SS4.1.2 to SS4.1.

6. If this relationship is not satisfied, obtain the inflow angle of attack α of the i-th blade and the j-th blade under test after airfoil correction. eij ; Where m is the number of blades in the wind turbine, n is the number of airfoils to be tested on each blade of the wind turbine, and α pij α0 is the direction angle of the leading edge of the i-th scaled wind turbine blade and the j-th test blade airfoil relative to the inflow velocity vector, as measured by the airflow probe in step SS3; N is the initial value of the inflow angle of the scaled wind turbine blade section. ij and A ij These represent the tangential force and normal force along the airfoil chord of the i-th scaled wind turbine blade at the j-th cross-section, calculated in step SS3, respectively. ij The lift of the i-th blade and j-th airfoil at the position corresponding to the rotating surface of the variable-length airflow probe is Γ. ij Let V be the lift circulation at the j-th cross-section of the i-th scaled-down wind turbine blade, ρ be the inflow density, and V be the lift circulation at the j-th cross-section. pij R is the resultant velocity value of the j-th section of the i-th blade at the leading edge relative to the inflow velocity vector. l R is the radius of the airflow probe from the center of rotation of the wind turbine. b l is the radius from the blade tip to the center of rotation. b The distance from the leaf base to the leaf tip. Let be the induced velocity vector generated by the linear vortex of the i-th scaled-down wind turbine blade at the airflow probe measurement point. V is the updated relative inflow velocity vector of the i-th blade and the j-th blade under test. eij Let α be the relative inflow velocity value after the airfoil update for the i-th blade and the j-th blade under test. eij Let α be the updated directional angle of the airfoil of the i-th blade and the j-th blade under test. max This is the maximum difference that is set.

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