Digital wind tunnel balance with temperature and inertia compensation elements

Abstract

The invention discloses a digital wind tunnel balance with temperature and inertia compensation elements, and belongs to the technical field of wind tunnel balance design. The digital wind tunnel balance comprises a body, a force measuring module, a temperature measuring module and a three-axis acceleration and angular velocity measuring module, so that the surface temperature, the three-axis acceleration and the angular velocity of the balance can be measured on the basis of measuring aerodynamic force and moment; accurate information is provided for temperature compensation for static calibration and inertia compensation for dynamic calibration of the balance, so that the balance load measurement error is reduced.

Description

Technical Field

[0001] The invention relates to a digital wind tunnel balance with temperature and inertia compensation elements, belonging to the technical field of wind tunnel balances. Background Art

[0002] The wind tunnel balance is the core equipment for aerodynamic measurement in wind tunnel experiments. It can accurately measure the forces and moments acting on the model. Its performance indicators directly affect the accuracy of load measurement in wind tunnel experiments. Each balance needs to be calibrated before it is officially put into use. The calibration of the wind tunnel balance is divided into dynamic calibration and static calibration. Static calibration is to obtain the balance formula and establish the relationship between the load and the increment of the balance voltage signal; dynamic calibration focuses on the dynamic characteristics of the balance and establishes the relationship between the inertial acceleration and the increment of the balance voltage signal. The purpose is to reduce the measurement error caused by inertial force. The accuracy of calibration directly affects the accuracy and uncertainty of the balance measurement, as well as the quality of wind tunnel experiment data, and is an important indicator of the wind tunnel balance.

[0003] Normally, there is a fixed correspondence between the voltage signal increment of the balance and the applied load. However, in actual wind tunnel experiments, factors such as the experimental Mach number, experimental air pressure, and experimental duration will affect the heat transfer between the model and the balance and the external flow field, causing significant changes in the temperature distribution of the balance, resulting in steady-state temperature effects and dynamic temperature effects. If effective corrections cannot be made, large experimental errors will be caused, seriously affecting the credibility and availability of experimental data. Dynamic calibration can reduce the impact of the movement and vibration of the model in the wind tunnel experiment on the balance signal. At present, most research institutions use filtering, but filtering will filter out some useful signals.

[0004] When the wind tunnel balance measures the dynamic aerodynamic forces and moments acting on the model, the forces and moments include the inertial forces and moments of the wind tunnel model and the floating part of the balance. The existing static correction methods and dynamic filtering methods cannot accurately eliminate the influence of this part of the inertial load. During the wind tunnel test, the balance temperature and its distribution gradient change, which will cause the balance signal to drift and produce errors. The existing temperature compensation and correction technology cannot effectively solve this problem.

[0005] All of the above factors will have an impact on the calibration of the balance. In recent years, the balance technology of various research institutions has been developing towards high precision and automation, and the accuracy requirements for balance data have become increasingly higher. Therefore, it is of great significance to digitize the balance and apply the balance temperature, three-axis acceleration and angular velocity data to static and dynamic calibration. Summary of the invention

[0006] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, and to propose a digital wind tunnel balance with temperature and inertia compensation elements, which can measure the force and torque acting on the model, the balance temperature, the three-axis acceleration, and the angular velocity. On the premise of accurately measuring the aerodynamic force, the balance temperature, the three-axis acceleration, and the angular velocity data are provided for the balance multi-parameter calibration and the dynamic aerodynamic load measurement.

[0007] The technical solution of the present invention is:

[0008] A digital wind tunnel balance with temperature and inertia compensation elements, comprising a body, a force measurement module, a temperature measurement module and a three-axis acceleration and angular velocity measurement module;

[0009] The main body is a six-component rod-type strain balance;

[0010] The force measuring module is used to convert the aerodynamic force and torque acting on the body into a voltage signal;

[0011] The temperature measurement module includes a microcontroller and a plurality of temperature sensors, each of which is distributed at a different position on the body, measures the surface temperature at the position, and transmits the temperature data to the microcontroller;

[0012] The three-axis acceleration and angular velocity measurement module is used to measure the three-axis acceleration and angular velocity of the body and transmit them to the microcontroller.

[0013] Furthermore, the transient temperature response of the main body is simulated through finite element analysis, and according to the simulation results, a plurality of positions with large temperature differences are selected along the temperature conduction path on the main body as setting points of the temperature measurement module.

[0014] Furthermore, the three-axis acceleration and angular velocity measurement module includes a three-axis accelerometer and a gyroscope, which respectively measure the three-axis acceleration and angular velocity of the body.

[0015] Furthermore, the microcontroller, the three-axis accelerometer and the gyroscope are all arranged on the same circuit board, the circuit board is fixed on the body, and the microcontroller is connected to each temperature sensor through a wire.

[0016] Furthermore, an A / D conversion module is provided on the circuit board to convert analog signals obtained by the temperature sensor, the three-axis accelerometer and the gyroscope into digital signals and transmit them to an external computer.

[0017] Furthermore, the circuit board performs serial communication with an external computer via a serial port to USB device.

[0018] Furthermore, the temperature sensor may be a LM35DZ, DA18B20 or LM335 temperature sensor.

[0019] Furthermore, the microcontroller may be an ATmega8, ATmega8A-AU or ATmega8L-8AU microcontroller.

[0020] Furthermore, the three-axis accelerometer and gyroscope can use the ADIS16501, MPU6800 or MPU9250 chips in the IMU inertial navigation module.

[0021] The advantages of the present invention compared with the prior art are:

[0022] (1) The digital wind tunnel balance designed by the present invention can measure the temperature distribution data of the balance surface, and temperature compensation can be performed on the measurement results of the balance based on this information.

[0023] (2) The digital wind tunnel balance designed by the present invention can measure the three-axis acceleration and angular velocity data of the balance, and inertia compensation can be performed on the measurement results of the balance based on this information.

[0024] (3) The digital wind tunnel balance designed by the present invention can convert the measured analog signal into a digital signal for transmission, has higher anti-interference and transmission efficiency, and is convenient for subsequent data processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0026] Figure 1 This is a schematic diagram of the structure of a digital wind tunnel balance according to an embodiment of the present invention;

[0027] Figure 2 The circuit diagram of the temperature measurement module, the three-axis acceleration and the angular velocity measurement module according to the embodiment of the present invention;

[0028] Figure 3 A transient thermodynamic simulation result diagram using a finite element analysis method according to an embodiment of the present invention;

[0029] Figure 4 Schematic diagram of the installation position of the temperature sensor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0031] The present invention proposes a digital wind tunnel balance with temperature and inertia compensation elements, such as Figure 1 As shown, it includes a main body and a force measuring module, a temperature measuring module, and a three-axis acceleration and angular velocity measuring module installed on the main body.

[0032] The main body is a six-component rod-type strain balance main body structure.

[0033] The force measuring module includes three aerodynamic forces and three aerodynamic torque measuring bridges and auxiliary circuits, which are used to convert the aerodynamic forces and torques acting on the body into voltage signals.

[0034] The temperature measurement module is composed of a temperature sensor and a microcontroller (MCU chip). The temperature sensors are distributed at different locations on the balance body, which can accurately measure the surface temperature at each location and calculate the overall temperature of the balance. The specific layout of each temperature sensor is determined by the finite element analysis method, and the transient temperature response of the balance is simulated and analyzed. According to the analysis results, multiple locations with large temperature differences are selected on the balance for layout. Figure 3 This is the result of transient thermodynamic simulation. In the initial state of the simulation, the temperature at one end of the balance is 50°C and the other end is -10°C. The temperature contour diagram of the temperature distribution of the balance after 100s is simulated in the heat conduction mode.

[0035] The circuit board with the microcontroller is placed in the spare part of the balance and connected to each temperature sensor through wires. The circuit board has an A / D conversion function, which can convert the analog signals obtained by the temperature sensor, the three-axis accelerometer and the gyroscope into digital signals and transmit them to the external computer. In this embodiment, there are 6 temperature sensors, such as Figure 2 As shown, each temperature sensor has 2 positive and negative power lines and 1 signal line, all connected to the microcontroller on the circuit board. The circuit board has 2 positive and negative power lines and 2 positive and negative signal lines connected to the external computer. The installation positions of the 6 temperature sensors are as follows: Figure 4 As shown, they are evenly arranged at 6 positions with large temperature differences along the temperature conduction path, so that they can fully measure the balance temperature. The temperature sensor uses LM35DZ, DA18B20 or LM335 temperature sensor, and the microcontroller uses ATmega8, ATmega8A-AU or ATmega8L-8AU microcontroller.

[0036] The three-axis acceleration and angular velocity measurement module is composed of a three-axis accelerometer and a gyroscope, both of which are arranged on a circuit board to accurately measure the three-axis acceleration and angular velocity of the balance. In this embodiment, the three-axis accelerometer and gyroscope use the ADIS16501, MPU6800 or MPU9250 chip in the IMU inertial navigation module.

[0037] The digital wind tunnel balance simulates and calibrates the temperature change without mechanical load increment to generate the temperature compensation formula, and simulates and calibrates the three-axis linear motion and three-axis angular motion with the model installed to generate the inertia compensation formula.

[0038] When the wind tunnel balance is in use, the temperature sensor, the three-axis accelerometer and the gyroscope can all transmit data to the microcontroller, and the microcontroller communicates with the external computer via the serial port to USB device, and transmits the temperature information, the three-axis acceleration information and the angular velocity information to the external computer. All kinds of information are 10-bit hexadecimal codes, including 1 start bit, 8 data bits and 1 stop bit. Compared with the traditional balance, the present invention can measure the balance temperature, three-axis acceleration and angular velocity data in real time, and then perform temperature compensation on the measurement results of the balance according to the measured temperature data, and perform inertia compensation on the measurement results of the balance according to the three-axis acceleration and angular velocity data, so as to reduce the balance load measurement error, and have higher measurement accuracy. The above-mentioned temperature compensation and inertia compensation can be realized in the microcontroller or the host computer through a data processing program.

[0039] The above-described embodiments are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A digital wind tunnel balance with temperature and inertia compensation elements, characterized in that: It includes a body, a force measurement module, a temperature measurement module and a three-axis acceleration and angular velocity measurement module; The main body is a six-component rod-type strain balance main body structure; The force measuring module is used to convert the aerodynamic force and torque acting on the body into a voltage signal; The temperature measurement module includes a microcontroller and a plurality of temperature sensors, each of which is distributed at a different position on the body, measures the surface temperature at the position, and transmits the temperature data to the microcontroller; The three-axis acceleration and angular velocity measurement module is used to measure the three-axis acceleration and angular velocity of the body and transmit them to the microcontroller.

2. The digital wind tunnel balance with temperature and inertia compensation element according to claim 1, characterized in that: The transient temperature response of the main body is simulated through finite element analysis, and according to the simulation results, multiple positions with large temperature differences are selected along the temperature conduction path on the main body as setting points of the temperature measurement module.

3. The digital wind tunnel balance with temperature and inertia compensation element according to claim 1, characterized in that: The three-axis acceleration and angular velocity measurement module includes a three-axis accelerometer and a gyroscope, which respectively measure the three-axis acceleration and angular velocity of the body.

4. The digital wind tunnel balance with temperature and inertia compensation element according to claim 1, characterized in that: The microcontroller, the three-axis accelerometer and the gyroscope are all arranged on the same circuit board, the circuit board is fixed on the body, and the microcontroller is connected to each temperature sensor through a wire.

5. The digital wind tunnel balance with temperature and inertia compensation element according to claim 4, characterized in that: The circuit board is equipped with an A / D conversion module, which converts the analog signals obtained by the temperature sensor, three-axis accelerometer and gyroscope into digital signals and transmits them to an external computer.

6. The digital wind tunnel balance with temperature and inertia compensation element according to claim 4, characterized in that: The circuit board communicates with the external computer via the serial port to USB device.

7. The digital wind tunnel balance with temperature and inertia compensation element according to claim 1, characterized in that: The force measurement module includes three aerodynamic forces and three aerodynamic torque measurement bridges and auxiliary circuits.

8. The digital wind tunnel balance with temperature and inertia compensation element according to claim 1, characterized in that: The temperature sensor should be LM35DZ, DA18B20 or LM335 temperature sensor.

9. The digital wind tunnel balance with temperature and inertia compensation element according to claim 1, characterized in that: The microcontroller is ATmega8, ATmega8A-AU or ATmega8L-8AU microcontroller.

10. The digital wind tunnel balance with temperature and inertia compensation element according to claim 1, characterized in that: The three-axis accelerometer and gyroscope use the ADIS16501, MPU6800 or MPU9250 chips in the IMU inertial navigation module.

Images