LU102732B1

LU102732B1 - Measuring Device and Method for Unsteady Flow Field of Wind Turbine

Info

Publication number: LU102732B1
Application number: LU102732A
Authority: LU
Inventors: Gao Zhiying; Dong Xueqing; Jianwen Wang; Liru Zhang; Mi Zhaoguo; Sun Zhicheng; BAI Yefei
Original assignee: Univ Inner Mongolia Technology
Priority date: 2021-04-02
Filing date: 2021-04-02
Publication date: 2021-10-04

Abstract

The measuring device is composed of a wind tunnel and a wind turbine. Specifically, the air outlet of wind tunnel is set opposite to the wind turbine and the wind tunnel is wired to a frequency converter. A dynamic yaw platform is fixedly connected below the wind turbine and a pedestal is arranged behind the dynamic yaw platform. The upper end face of the pedestal is fixedly connected with a two-dimensional displacement platform, which drives the measuring bench on the two-dimensional displacement platform through a second servo motor. Besides, Flow field measuring tools are arranged on the measuring bench. According to the measuring method, different control signals are transmitted to the frequency converter and the dynamic yaw platform through computers and then the unsteady flow field parameters of the wind turbine are calculated based on the test data from the flow field measuring tool.

Description

Description LU102732 Measuring Device and Method for Unsteady Flow Field of Wind Turbine

TECHNICAL FIELD The invention relates to the measurement and analysis field of flow field around wind turbines, and particularly involves a device and a method for measuring the unsteady flow field of wind turbines.

BACKGROUND The wind turbine draws kinetic energy from the wind. It drives the generator to convert mechanical energy into electrical energy through the rotation of wind blades. Wind turbines operate in the atmospheric boundary layer, accompanied by random changes in wind speed and direction. What’s more, operating conditions of shear wind, yaw wind, turbulent flow and gust all have a significant impact on the aerodynamic characteristics of wind turbine blades. In the actual operation of a wind turbine, the wind speed and direction are unsteady conditions that change with time. As the main load-bearing component of the wind turbine, the blade transmits almost all the force, which causes the blades to vibrate inevitably, and to withstand the effects of alternating stress. As a result, the blade becomes the most easily damaged part of the wind turbine, and the blade fracture phenomenon occurs frequently. Therefore, obtaining the dynamic parameters of the flow field around the rotating blades of wind turbine under unsteady conditions is of great significance to the study of safety, stability and durability of wind turbine blades in the actual operating environment. It has also become an important requirement for the development and growth of wind power enterprises. Wind turbine is generally composed of wind wheel, generator cabin, speed and direction regulating mechanism and tower.

When the wind turbine is running, the rotating wind LU102732 wheel and the dynamic and static coalition of the generator are connected by the rotating shaft.

In the test process of wind turbine under unsteady working conditions, the yaw angle of wind turbine can be simulated and controlled by the dynamic yaw platform.

Besides, the position transducer of dynamic yaw platform can derive the angle signal.

Wind speed is regulated by computer-controlled frequency converter and electromotor system regulation.

However, in the unsteady state of the wind turbine, measuring tools are required to track the measurement area in real time, which indicates that obtaining the dynamic flow field parameters becomes the bottleneck of the wind turbine flow field test under the unsteady working conditions.

In the domestic research on small wind turbines, numerical simulation methods were mainly used in the early stage to study wind turbines under steady conditions.

In recent years, research on wind turbines under unsteady conditions has been gradually carried out.

In 2016, Wang Tongguang and others of Nanjing University of Aeronautics and Astronautics adopted numerical simulation method to study wind turbines under complex working conditions such as dynamic yaw.

Although the domestic use of numerical simulation to study wind turbine yaw has been relatively mature, there are still few studies on the flow field of wind turbines using experimental methods.

Therefore, it can be said that the proposal of this test method is of great significance to the domestic research of wind turbines under unsteady working conditions.

In 2009, Lin Yonggang and others of Zhejiang University invented a device for wind turbine simulation test, which can simulate the output torque of the wind turbine under different working conditions and further detect the relevant components of the wind turbine generator unit. However, the experimental device can not simulate the flow field LU102732 changes of wind turbines under unsteady working conditions, indicating that this method can not satisfy the requirements of current experimental research on wind turbines. In 2010, Jiang Dongxiang and others in Tsinghua University invented an open type multifunctional wind turbine wind tunnel, with a variable-frequency AC wind turbine built in. The test chamber is equipped with wind turbines, as well as test instruments used for the gas-solid coupling vibration test of the wind turbine blades and the performance test of the wind turbine. The device is used to test the performance of the whole machine and study the vibration characteristics of various working conditions. The test device is far from satisfactory to the need of current experimental research on wind turbines, because it is failure to test the flow field changes of wind turbines under unsteady working conditions. In 2017, Northwest University Yang Bin and others proposed a method for simulating the unsteady wind in an atmospheric boundary wind tunnel. This method regulates and controls the wind speed in the wind tunnel by adjusting the frequency value of the frequency converter, and finally realizes the simulation of unsteady changes in wind speed. However, this invention only simulates the unsteady change of natural wind speed and does not simulate the change of natural wind direction. Therefore, it cannot fulfill the needs of current experimental research on wind turbines. At present, wind turbine flow field tests are conducted by means of fixed yaw angle and wind speed, which can not simulate the operation of wind turbine under unsteady working conditions.

SUMMARY

The purpose of the present invention is to solve above problems, and a measuring device LU102732 as well as method for unsteady flow field of wind turbine is designed.

In order to achieve the above purpose, the technical scheme of the present invention is as follows.

A device for measuring the unsteady flow field of a wind turbine includes a wind tunnel and a wind turbine, wherein the air outlet of wind tunnel is set opposite to the wind turbine and the wind tunnel is wired to a frequency converter.

A dynamic yaw platform is fixedly connected below the wind turbine, with built-in first servo motor and angular displacement transducer.

Besides, the first servo motor is connected to the bottom of the wind turbine through a drive shaft.

A pedestal is installed behind the dynamic yaw platform and fixedly connected to the ground.

On the upper end face of the pedestal, a two-dimensional displacement platform is fixedly arranged with the second servo motor and linear displacement transducer built in.

Meanwhile, the two-dimensional displacement platform can drive the measuring bench on the two-dimensional displacement platform through a second servo motor.

Flow field measuring tools are arranged on the measuring bench.

The measuring tools are PIV (particle image velocity) cameras and PIV lasers but are not limited to them.

The front end of the measuring bench is fixedly connected to the PIV camera and the PIV camera is further located below the position between the wind tunnel and the wind turbine; and the top of the measuring bench is fixedly connected to the PIV laser, which is located behind the wind turbine.

The device further comprises an automatic control module which is connected with the two-dimensional displacement platform, the dynamic yaw platform, the frequency converter, the PIV camera and the PIV laser respectively through wiring. LU102732 The automatic control module comprises a computer and a synchronizer. The computer is connected with the second servo motor and linear displacement transducer in the two- dimensional displacement platform, while the first servo motor and angular displacement transducer in the dynamic yaw platform are connected with the computer circuit respectively. Between the computer and PIV laser, a PIV laser power supply is provided. The computer is connected with the PIV camera and PIV laser through the synchronizer, and the computer circuit is connected with that frequency converter. The wind turbine comprises a wind wheel, a nose and a frame. The wind wheel is connected to the front end of the nose and opposite to the wind tunnel outlet, the upper end of the frame is fixedly connected with the nose, and the lower end of the frame is connected with the dynamic yaw platform. The pedestal and the measuring bench both adopt truss structure.

7. The method for measuring the unsteady flow field of a wind turbine is comprised of the following steps. S1. Turn on the wind turbine switch of the wind tunnel. S2. Turn on the power of the PIV laser and control the PIV laser as well as control the shooting of the PIV camera through the computer. S3. Transmit an angle rotation signal to the first servo motor in the dynamic yaw platform through the computer, and after the first servo motor rotates, an angle position signal from the angular displacement transducer is sent to the computer, and then the computer records the angle. S4. The computer calculates the required displacement of the measuring bench on the upper end of the two-dimensional displacement platform according to the angular LU102732 position signal returned by the dynamic yaw platform and transmits the displacement control signal to the second servo motor in the two-dimensional displacement platform.

Then the linear position signal is transmitted to the computer by the linear displacement transducer in the two-dimensional displacement platform.

SS.

The wind speed control signal is transmitted to the frequency converter through the computer, and the frequency converter controls the wind turbine rotation speed of the wind tunnel based on the signal.

S6. Transmit different control signals to the frequency converter, the dynamic yaw platform, and the two-dimensional displacement platform through the computer, and further calculate the unsteady flow field parameters of the wind turbine according to the test data given by the PIV camera and the PIV laser.

Compared with the prior art, the invention has following advantages and positive effect.

The invention simulates the natural wind under unsteady working conditions by using the frequency converter to control the wind speed of the wind tunnel and utilizing the dynamic yaw platform to change the yaw angle of the wind turbine.

Furthermore, it creates the unsteady flow field environment required in the experiment.

And combined with the method of tracking the measurement area with PIV flow field measuring tools loaded on the two-dimensional displacement platform, the flow field parameters of the wind turbine under unsteady working conditions are tested through the PIV flow field measuring method, so that the results have a reliable scientific basis.

In addition, by setting up an automatic control module, the entire experiment can be controlled and recorded by a computer, which further ensures the accuracy of experimental measurement data. LU102732

BRIEF DESCRIPTION OF THE FIGURES In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following will briefly introduce the figures that need to be used in the description of the embodiments or the prior art. Obviously, the figures in the following description only represent some embodiments of the present invention. For those of ordinary skill in the art, other figures can be obtained based on these without creative labour. Figure 1 is a schematic structural diagram of the present invention. Figure 2 is a partial enlarged view of the present invention. Figure 3 is a workflow chart of the present invention.

DESCRIPTION OF THE INVENTION The technical scheme in the embodiments of the present invention will be described clearly and completely with reference to the figures in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary people in the field without making creative work, and any modifications, equivalent substitutions, and improvements, shall be included in the protection scope of the present invention. As shown in fig. 1, fig. 2 and fig. 3, the device for measuring the unsteady flow field of a wind turbine includes a wind tunnel (10) and a wind turbine (5), wherein the air outlet of wind tunnel (10) is set opposite to the wind turbine (5) and the wind tunnel (10) is wired to a frequency converter (6). À dynamic yaw platform (4) is fixedly connected below the wind turbine (5), with built-in first servo motor and angular displacement LU102732 transducer.

Besides, the first servo motor is connected to the bottom of the wind turbine (5) through a drive shaft.

A pedestal (1) is installed behind the dynamic yaw platform (4) and fixedly connected to the ground.

On the upper end face of the pedestal (1), a two- dimensional displacement platform (2) is fixedly arranged with the second servo motor and linear displacement transducer built in.

Meanwhile, the two-dimensional displacement platform (2) can drive the measuring bench (3) on the two-dimensional displacement platform through a second servo motor.

Flow field measuring tools are arranged on the measuring bench.

Taking PIV measuring tools as an example, a PIV camera (9) is fixedly connected to the front end of measuring bench (3) and located below the position between wind tunnel (10) and wind turbine (5). A PIV laser (8) is fixedly connected to the top end of measuring bench (3) and located behind wind turbine (5). The device also comprises an automatic control module (7) which is connected with the two-dimensional displacement platform (2), the dynamic yaw platform (4), the frequency converter (6), the PIV camera (9) and the PIV laser (8) respectively through wiring.

Besides, it should be noted that PIV measuring tools are not limited to PIV cameras and PIV lasers.

The automatic control module (7) comprises a PIV laser power supply (11), a computer (12) and a synchronizer (13). The computer (12) is connected with the second servo motor and linear displacement transducer in the two-dimensional displacement platform (2), while the first servo motor and angular displacement transducer in the dynamic yaw platform (4) are connected with the computer (12) circuit respectively.

The two ends of the PIV laser power supply (11) are connected to the computer (12) and the PIV laser (8),

respectively.

The computer (12) is connected with the PIV camera (9) and PIV laser (8) LU102732 through the synchronizer (13), and the computer (12) circuit is connected with that frequency converter (6). The computer is used for centralized control of all components and measurement data, which increases the measurement accuracy of the entire experiment process.

The wind turbine (5) comprises a wind wheel (51), a nose (52) and a frame (53). The wind wheel (51) is connected to the front end of the nose (52) and opposite to the wind tunnel (10) outlet, the upper end of the frame (53) is fixedly connected with the nose (52), and the lower end of the frame (53) is connected with the first servo motor.

Compared with arranging the yaw device at the nose of the wind turbine, arranging the yaw device at the bottom of the wind turbine reduces the interference to the flow field of the wind turbine and reduces the error of the measurement data.

Both the pedestal (1) and the measuring bench (3) adopt truss structures, which reduces the interference to the wind turbine flow field and ensures the accuracy of experimental data.

A method for measuring the unsteady flow field of a wind turbine comprises the following steps.

S1. Turn on the wind turbine switch of the wind tunnel (10). S2. Turn on the power (11) of the PIV laser and control the PIV laser (8) as well as control the shooting of the PIV camera (9) through the computer (12). PIV laser power supply, PIV laser, and PIV camera together form a PIV system.

S3. Transmit an angle rotation signal to the first servo motor in the dynamic yaw platform (4) through the computer (12), and after the first servo motor rotates, an angle position signal from the angular displacement transducer is sent to the computer (12), and then the LU102732 computer (12) records the angle.

After the computer controls simulation and records the measurement data each time, the computer will send return control signal to the first servo motor, and then the first servo motor will return to the original position after receiving the signal and wait for the next control simulation.

S4. The computer (12) calculates the required displacement of the measuring bench (3) on the upper end of the two-dimensional displacement platform (2) according to the angular position signal returned by the dynamic yaw platform (4) and transmits the displacement control signal to the second servo motor in the two-dimensional displacement platform (2). Then the linear position signal is transmitted to the computer (12) by the linear displacement transducer in the two-dimensional displacement platform (2). The measuring tools are driven by a two-dimensional displacement platform for testing, which effectively solves the problem that the shooting area changes all the time under dynamic yaw conditions.

Moreover, the flow field changes in a relative space of the blade under unsteady conditions can be measured.

SS.

The wind speed control signal is transmitted to the frequency converter (6) through the computer (12), and the frequency converter (6) controls the wind turbine rotation speed of the wind tunnel (10) based on the signal.

In this way, an unsteady incoming wind speed is provided, and the wind wheel (51) obtains kinetic energy to rotate.

Before the measurement, the congruent relationship between the frequency of the converter and the wind speed should be calibrated, as well as the delay time of the wind from the wind tunnel to the wind turbine.

S6. Transmit different control signals to the frequency converter (6) and the dynamic yaw platform (4) through the computer (12), and further calculate the unsteady flow field LU102732 parameters of the wind turbine (5) according to the test data given by the PIV camera (9) and the PIV laser (8). The invention simulates the natural wind under unsteady working conditions and combines the flow field measuring methods such as PIV for testing.

Through the use of dynamic yaw platform combined with wind tunnel frequency conversion control, the wind speed and direction changes of the wind turbine under unsteady conditions are effectively simulated.

In addition, the flow field measuring tools such as PIV loaded on the two-dimensional displacement platform are used to track the measurement area, thereby the flow field parameters of the wind turbine under unsteady working conditions are accurately measured.

Claims

CLAIMS . LU102732

1. A device for measuring the unsteady flow field of a wind turbine, including a wind tunnel and a wind turbine, wherein the air outlet of wind tunnel is set opposite to the wind turbine and the wind tunnel is wired to a frequency converter; a dynamic yaw platform is fixedly connected below the wind turbine, with built-in first servo motor and angular displacement transducer; besides, the first servo motor is connected to the bottom of the wind turbine through a drive shaft; a pedestal is installed behind the dynamic yaw platform and fixedly connected to the ground; on the upper end face of the pedestal, a two-dimensional displacement platform is fixedly arranged with the second servo motor and linear displacement transducer built in; meanwhile, the two-dimensional displacement platform can drive the measuring bench on the two-dimensional displacement platform through a second servo motor; flow field measuring tools are arranged on the measuring bench.

2. The device for measuring the unsteady flow field of a wind turbine as stated in Claim 1, characterized in that the measuring tools are PIV cameras and PIV lasers but are not limited to them; the front end of the measuring bench is fixedly connected to the PIV camera and the PIV camera is further located below the position between the wind tunnel and the wind turbine; and the top of the measuring bench is fixedly connected to the PIV laser, which is located behind the wind turbine.

3. The device for measuring the unsteady flow field of a wind turbine as stated in Claim 2, characterized in that the device further comprises an automatic control module which is connected with the two-dimensional displacement platform, the dynamic yaw platform, the frequency converter, the PIV camera and the PIV laser respectively through wiring.

4. The device for measuring the unsteady flow field of a wind turbine as stated in Claim

3, characterized in that the automatic control module comprises a computer and a LU102732 synchronizer, the computer is connected with the second servo motor and linear displacement transducer in the two-dimensional displacement platform, while the first servo motor and angular displacement transducer in the dynamic yaw platform are connected with the computer circuit respectively; between the computer and PIV laser, a PIV laser power supply is provided; the computer is connected with the PIV camera and PIV laser through the synchronizer, and the computer circuit is connected with that frequency converter.

5. The device for measuring the unsteady flow field of a wind turbine as stated in Claim 3, characterized in that the wind turbine comprises a wind wheel, a nose and a frame; the wind wheel is connected to the front end of the nose and opposite to the wind tunnel outlet, the upper end of the frame is fixedly connected with the nose, and the lower end of the frame is connected with the dynamic yaw platform.

6. The device for measuring the unsteady flow field of a wind turbine as stated in Claim 1, characterized in that the pedestal and the measuring bench both adopt truss structure.

7. A method for measuring the unsteady flow field of a wind turbine by utilizing the device as stated in Claims 1-6, characterized by comprising the following steps; step 1. turn on the wind turbine switch of the wind tunnel; step 2. turn on the power of the PIV laser and control the PIV laser as well as control the shooting of the PIV camera through the computer; step 3. transmit an angle rotation signal to the first servo motor in the dynamic yaw platform through the computer, and after the first servo motor rotates, an angle position signal from the angular displacement transducer is sent to the computer, and then the computer records the angle; LU102732 step 4. the computer calculates the required displacement of the measuring bench on the upper end of the two-dimensional displacement platform according to the angular position signal returned by the dynamic yaw platform and transmits the displacement control signal to the second servo motor in the two-dimensional displacement platform; then the linear position signal is transmitted to the computer by the linear displacement transducer in the two-dimensional displacement platform; step 5. the wind speed control signal is transmitted to the frequency converter through the computer, and the frequency converter controls the wind turbine rotation speed of the wind tunnel based on the signal; step 6. transmit different control signals to the frequency converter, the dynamic yaw platform, and the two-dimensional displacement platform through the computer, and further calculate the unsteady flow field parameters of the wind turbine according to the test data given by the PIV camera and the PIV laser.