CN1260481A - Method and device for automatic detection and control of wind tunnel speed - Google Patents

Abstract

The invention relates to a method and device for automatically detecting and automatically controlling wind speed in a wind tunnel. The method of automatic detection and control is as follows: the airflow in the wind tunnel is led out by the pitot tube, the differential pressure signal is obtained through the differential pressure transmitter and input into the computer, the corresponding wind speed is calculated by the computer, and the values of air pressure, temperature and relative humidity are collected and input The computer calculates the total correction coefficient K value and obtains the actual wind speed value; the computer generates a wind speed fuzzy control rule based on the obtained D/A value and the wind speed value of the measuring point to control the wind tunnel motor speed, so that the wind speed is automatically fixed and stable. The invention has the advantages of high measurement sensitivity, precision and accuracy, easy operation and the like.

Description

Method and device for automatic detection and automatic control of wind speed in wind tunnel

The invention relates to a method and device for automatically detecting and automatically controlling wind speed in a wind tunnel.

即等于实际风速值V。当测量时的环境状态不是上述标准状态时，实际风速则不等于相当风速。为获取非标准状态下的实际风速值，需计算出空气密度修正系数，给于修正。方法是：1、读取当时的大气压力、室温、相对湿度各值，代入空气密度修正系数计算公式得出Kρ；2、将Kρ代入总修正系数计算公式得出K。3、用K乘以相当风速值得出实际风速值。这样，才能获得某一个测试点上的实际风速。二、风洞风速的大小与电机转速成正比。因此需要通过控制电机的转速来实现所需要的差压值。目前由人工通过观测微压计示值改变直流电压或交流频率来完成。但当电压或频率一定时，由于其它各种因素可能引起风速的不稳定，人工跟踪调整的速度又远远跟不上差压的波动，最终取得的测试数据也只能是几个近似值的平均值。由上可知，上述方法存在的缺点是：1、人工读数准确度差；2、测量灵敏度和精度低；3、不能迅速给出被测量的风速值；4、差压在某一值上的波动无法控制。Wind tunnels are usually used for scientific research and value transfer of wind measuring instruments such as aerodynamic experiments and verification of anemometers. Depending on the purpose of the wind tunnel, its size, structure, and shape are also different. At present, the methods and methods for testing the wind speed of various wind tunnels are basically the same: 1. Use the pitot tube (wind speed tube) to lead the differential pressure signal from the wind tunnel into the compensation micromanometer, and then adjust the dial manually to observe the level tip. When it is in the same position, read the height of the water column, that is, the differential pressure value (Pv). Under standard conditions: air pressure P=1013.25hPa; temperature T=15°C; relative humidity U=0%, substituting Pv into the equivalent wind speed calculation formula under standard conditions

That is equal to the actual wind speed value V. When the environmental state at the time of measurement is not the above-mentioned standard state, the actual wind speed is not equal to the equivalent wind speed. In order to obtain the actual wind speed value under non-standard conditions, it is necessary to calculate the air density correction coefficient and give it to the correction. The method is: 1. Read the values of atmospheric pressure, room temperature, and relative humidity at that time, and substitute them into the calculation formula of the air density correction coefficient to obtain Kρ; 2. Substitute Kρ into the calculation formula of the total correction coefficient to obtain K. 3. Multiply K by the corresponding wind speed value to get the actual wind speed value. In this way, the actual wind speed at a certain test point can be obtained. 2. The wind speed in the wind tunnel is directly proportional to the motor speed. Therefore, it is necessary to control the rotational speed of the motor to achieve the required differential pressure value. At present, it is done manually by changing the DC voltage or AC frequency by observing the indication value of the micromanometer. However, when the voltage or frequency is constant, other factors may cause instability of the wind speed, and the speed of manual tracking and adjustment is far behind the fluctuation of the differential pressure. The final test data can only be the average of several approximate values. value. It can be seen from the above that the disadvantages of the above method are: 1. The accuracy of the manual reading is poor; 2. The measurement sensitivity and precision are low; 3. The measured wind speed value cannot be quickly given; 4. The fluctuation of the differential pressure on a certain value Unable to control.

The object of the present invention is to provide a method and device using fuzzy control algorithm, improve the accuracy, accuracy and sensitivity of measurement, improve the measurement speed and fully realize the automatic detection and automatic control of wind tunnel wind speed.

Task of the present invention is achieved in that this automatic detection and the method for automatic control wind tunnel wind speed are: it comprises the following steps:

A. Automatic detection:

(1) The airflow in the wind tunnel is led out by the pitot tube to form the total pressure and static pressure, and at the same time, the total pressure and the static pressure are respectively input to the differential pressure transmitter to obtain the analog signal of the differential pressure signal (Pv);

(2) The analog signal of the differential pressure signal (Pv) is converted into a digital signal by the analog-to-digital converter (A/D) and input into the computer, and the corresponding wind speed value is calculated by the computer;

(3), with air pressure sensor, temperature sensor and relative humidity sensor, the analog signal of the air pressure, temperature and relative humidity value that collects respectively is converted into digital signal by respective analog-to-digital converter (A/D) and enters computer, and air density The correction coefficient formula calculates Kρ, and then calculates the total correction coefficient K value with the pre-stored Pitot tube coefficient ξ;

(4) The total correction coefficient K value is multiplied by the equivalent wind speed value to obtain the actual wind speed value at the measuring point and display it immediately;

B. Automatic control:

(1) When the operation starts, the computer collects the voltage of the differential pressure transmitter when the wind speed is 0m/s and sets it as the starting voltage. At this time, input the type code, meter number and verification program selection code of the anemometer to be checked into the computer;

计算K值；(2) At the same time, the air pressure, temperature and relative humidity in the wind tunnel are collected at any time by the air pressure sensor, temperature sensor and relative humidity sensor, and are input into the computer through the analog-to-digital converter (A/D), and the computer is based on the total correction coefficient formula

Calculate K value;

公式，将计算机所得的对应测点风速的输出值(D/A值)与测点风速值生成风速模糊控制规则存入磁盘中；(3), according to the wind speed

Formula, the output value (D/A value) of corresponding measuring point wind speed that computer gains and measuring point wind speed value generate wind speed fuzzy control rule and store in the disk;

(4) When the change of air density causes the calculated value of the actual wind speed to deviate, the total correction coefficient K value can be corrected at any time through the air density correction coefficient Kρ, and then correct the actual wind speed;

(5) The computer outputs the control command and converts the digital signal into an analog signal through the digital-to-analog converter (D/A) to control the motor speed through the governor. During the delay period, the motor speed is still fine-tuned according to the fuzzy control rule to stabilize the wind speed .

The above method can not only select a single wind speed point for automatic detection and control, but also select multiple wind speed points or continuous automatic detection and control of the whole process. for B.

Input the type codes and verification program selection codes of different types of anemometers to be tested into the computer, and the computer can give different control points, stabilization times, reading delay times and motor speed-up and down-speed times for each type of meter.

The above method is applicable to both straight and loop wind tunnels.

A device for automatic detection and automatic control designed to realize the above method, it includes the following components:

(1) Pitot tube installed in the wind tunnel, which can lead the airflow in the wind tunnel to form the total pressure and static pressure;

(2) A differential pressure transmitter connected to the Pitot tube and capable of simulating the pressure difference into a voltage value;

(3) An analog-to-digital converter (A/D) that converts the analog voltage value of the differential pressure transmitter into a digital signal. The input terminal of the analog-to-digital converter (A/D) is connected to the differential pressure transmitter. The output terminal is connected with the computer;

(4), gather the barometric pressure sensor of air pressure, temperature and relative humidity of wind tunnel room, temperature sensor and relative humidity sensor, they are respectively connected with the input end of respective analog-to-digital converter (A/D), analog-to-digital converter ( The output end of A/D) is connected with computer;

(5) A host computer capable of calculating various wind speed values and processing the verification results of various anemometers and using a fuzzy control algorithm to control the wind speed of the wind tunnel, which is connected with four analog-to-digital converters (A/D) and a digital-to-analog converter Connector (D/A) connection, it is also connected with monitor and printer;

(6), a display that can display various parameters and wind speed values in the wind tunnel:

(7), a printer capable of printing verification and test results;

(8), the digital-to-analog converter (D/A) that converts the control command of the computer into an analog signal, its input end is connected with the computer, and the output end is connected with the motor governor;

(9) The motor governor capable of controlling the speed of the wind tunnel motor, its input end is connected to the output end of the digital-to-analog converter (D/A), and its output end is connected to the wind tunnel motor.

The motor speed controller mentioned above is an AC frequency converter or a DC voltage speed controller.

The above device is suitable for use in two types of wind tunnels, straight or loop.

Because the present invention has adopted above-mentioned technical scheme, therefore compared with background technology, has following advantage:

1. Improve the sensitivity, precision and accuracy of the measurement: due to the use of computers and high-precision differential pressure transmitters, the sensitivity, precision and accuracy of the measurement are improved, the work efficiency is improved, and the staff is reduced. labor intensity;

2. It is easy to operate and realizes the automation of detection and control.

The present invention can be widely used in aerodynamic experiments in aviation manufacturing industry, colleges and universities, bridges, buildings and other fields, and provides a good working environment and reliable detection means for the measurement departments of meteorology, coal mines, anemometer manufacturers and other systems .

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a schematic diagram of the device for automatically detecting and automatically controlling wind speed in a wind tunnel according to the present invention.

As shown in Figure 1, the device of the present invention includes: a Pitot tube 3 installed in the working section of the open-circuit wind tunnel 5, its output end is connected with the input end of the differential pressure transmitter (DR1151 type) 6, and the The air flow is drawn out to form the total pressure and static pressure and input to the differential pressure transmitter 6; the power supply terminal of the differential pressure transmitter 6 is connected to a DC 24V power supply, and its output terminal is connected to the analog-to-digital converter (A/D 9007 type) The input end of 7 is connected, and the output end of analog-to-digital converter (A/D) 7 is connected with computer (386 type) 10, and the differential pressure value of differential pressure transmitter 6 input is converted into digital signal input to computer 10; The output terminals of air pressure sensor (XDY-01 type) 18, temperature sensor 17 and relative humidity sensor 16 (HK8816D type) are connected with the input terminals of analog-to-digital converter (A/D 9007 type) 13, 14 and 15, and analog-to-digital conversion The output terminals of the device (A/D) 13,14,15 are connected with the computer 10, and the computer 10 is also connected with the input terminal of the digital-to-analog converter (D/A 9006 type) 11, and the digital-to-analog converter (D/A) 11 The output end of the inverter is connected with the input end of the frequency converter (FVB040E7S-4EX) 12, and the output end of the frequency converter 12 is connected with the AC motor 1 of the wind tunnel 5, so as to realize the automatic control of the wind tunnel wind speed; the monitor 8 and the printer 9 It is connected with the output port of the computer 10; a fan 2 is installed on the shaft of the AC motor 1. The checked anemometer 4 is also installed in the working section of the wind tunnel 5 . 19 among the figure is record key, is connected with computer 10.

The above-mentioned device is also provided with a traffic light and a sound prompter. During normal operation, the green light is always on. When prompting the reading, the green light is on, the red light is flashing and the audio prompter emits a long intermittent tone. When alarming, the green light is off, the red light flashes quickly, and the audio prompter emits a short sound. When shutting down, the red and green lights are off.

The method of automatically detecting and automatically controlling the wind speed of the wind tunnel using the above-mentioned device (take the verification of the DEM6 three-cup portable wind direction anemometer as an example):

The verification procedure is the whole process, that is: start wind speed, 1.5m/s, 5.0m/s, 10.0m/s, 15.0ms, 20.0m/s, 25.0m/s, 30.0m/s wind speed test.

The verification steps are as follows:

1. First install the pitot tube in the working section of the wind tunnel, and the anemometer to be checked is installed in the working section and on one side of the pitot tube.

2. Power on the computer, differential pressure transmitter, air pressure sensor, temperature sensor, relative humidity sensor, and frequency converter in sequence.

3. The computer enters the verification program setting, and the values of air pressure, temperature and relative humidity are converted into digital signals by the analog-to-digital converter (A/D) and entered into the computer for display.

4. The differential pressure transmitter inputs the zero differential pressure signal of 0m/s wind speed into the computer through the analog-to-digital converter (A/D) and sets it as the starting voltage.

5. Use the mouse to enter the type code of the tested anemometer stored in the computer (the code for the DEM6 type meter is 1) and the verification program selection code B (the code for single point and multi-point is A, and the code for the whole process is B), and use the keyboard Enter the watch number (factory number 83-1948).

中计算出Kρ和K值。6. The computer substitutes the input air pressure, temperature, and relative humidity values into the air density correction coefficient formula $\mathrm{K\ρ}=\sqrt{\frac{1013.25(273.15+t)}{288.15(P-0.378\mathrm{Uew})}}$ and the total correction factor formula

Kρ and K values were calculated in .

公式，将计算机所得的对应测点风速的输出值(D/A值)与测点风速值生成风速模糊控制规则存入磁盘中，作为计算机输出控制指令用。7. According to wind speed

The formula, the output value (D/A value) corresponding to the wind speed of the measuring point obtained by the computer and the wind speed value of the measuring point to generate the wind speed fuzzy control rule are stored in the disk, and used as a computer output control command.

8. Measure the start-up wind speed: Press the "Enter" key and the motor starts to rotate slowly. At this time, the airflow in the wind tunnel is drawn out by the Pitot tube to form the total pressure and static pressure, and at the same time input the positive and negative pressure of the differential pressure transmitter respectively. room to form a differential pressure Pv, and the differential pressure transmitter outputs an analog electrical signal of the differential pressure Pv and converts it into a digital signal through an analog-to-digital converter (A/D) and inputs it into a computer; When rotating, press the record key, at this time the motor runs at a constant speed, the differential pressure transmitter automatically collects the Pv value, and the air pressure sensor, temperature sensor and relative humidity sensor automatically collect the air pressure, temperature and relative humidity values, which are passed through the analog-to-digital converter ( A/D) is input into the computer, and the computer calculates the actual starting wind speed and displays the result.

9. Compare the actual starting wind speed with the national measurement standard value stored in the computer, and stop the verification if it is out of tolerance. If it is qualified, the computer will output the control signal, which will be converted into an analog signal by a digital-to-analog converter (D/A), and the motor will be controlled to increase the speed to the 1.5m/s wind speed verification point.

10. When the D/A value output by the computer is equal to the D/A value corresponding to the wind speed of 1.5m/s, the motor speed will be stabilized. After a one-minute stabilization delay, the audio will sound red and the light will be on to prompt the inspector to read the wind speed indication value (wind speed indication value). During the two-minute delay, the differential pressure transmitter continuously collects the differential pressure Pv value. At the end of the delay, the computer accumulates the collected data to calculate the average value, and then calculates the actual wind speed value at this point and displays it.

11. Key in the wind speed indicated by the tested anemometer at this point.

12. The computer compares and displays the difference between the actual wind speed value and the indicated value of the detected wind speed with the national measurement standard value. If it is out of tolerance, stop the verification; if it is qualified, it will automatically proceed to the next test point of 5.0m/s.

13. When the pre-input verification point program is completed, the computer automatically outputs a signal to the digital-to-analog converter (D/A), which converts the digital signal into a control electrical signal to make the motor speed return to zero. The computer performs parameter regression calculation, prompts to print the result, and prints out the data such as linear error, parameters of each verification point and correction value in a form.

The type code of the anemometer to be checked is shown in the table below: Checked anemometer type Measuring range the code DEM6 portable three-cup wind direction anemometer 1.0～30.0m/s 1 DEM6 portable three-cup wind direction anemometer 1.0～20.0m/s 2 Portable magnetic wind direction anemometer 2.0～30.0m/s 3 Mine anemometer (high speed) 0.8～25.0m/s 4 Mine anemometer (medium speed) 0.5～10.0m/s 5 Mining anemometer (low speed) 0.3～5.0m/s 6 Hot bulb anemometer 0.05～5.0m/s 7 Hot bulb anemometer 0.05～10.0m/s 8 Hot bulb anemometer 0.05～5.0m/s 5.0～30.0m/s 9 (spare format) 10

The above method of automatic detection and automatic control of the wind speed in the wind tunnel can not only perform the whole process verification, but also single-point and multi-point verification. The verification program selection code is: single-point and multi-point verification code is A, and the whole process verification code is b. If multi-point verification is selected, it can be selected at one time. During the verification, the motor runs continuously, and there is no need to select a single point.

Enter different types of anemometer type codes and verification program selection codes into the computer, and the computer can provide different control points for each type of meter (that is, the output value (D/A value) and The wind speed value at the measuring point generates wind speed fuzzy control rules), stabilization time (1-2 minutes), reading delay time (1-2 minutes) and motor speed up and down time (depending on the motor wind speed).

The AC motor in the above embodiments can also be replaced by a DC motor, and a DC voltage governor is required for speed regulation when a DC motor is used.

The method for automatically detecting and automatically controlling the wind speed of the wind tunnel of the above-mentioned device can be used not only in the straight wind tunnel, but also in the loop wind tunnel.

Claims (7)

1, a kind of automatic detection and control the method for wind tunnel speed automatically, it is characterized in that: it comprises the following steps:

A, detection automatically:

(1), the air-flow in the wind-tunnel is drawn, form general pressure and static pressure, simultaneously general pressure and static pressure are inputed to differential pressure transmitter respectively, obtain the simulating signal of differential pressure signal (Pv) by pitot tube;

(2), the simulating signal of differential pressure signal (Pv) converts in the digital signal input computing machine through analog to digital converter (A/D), goes out suitable air speed value by COMPUTER CALCULATION;

(3), the simulating signal of the air pressure that will gather separately with baroceptor, temperature sensor and relative humidity sensor, temperature and relative humidity numerical value converts digital signal to through separately analog to digital converter (A/D) and enters computing machine, calculate K ρ with the atmospheric density correction factors formula, calculate total correction factor K value with the coefficient of Pitot tube ξ that pre-deposits again;

(4), total correction factor K is on duty draws in the actual wind speed value of measuring point and demonstration at once with suitable air speed value;

B, control automatically:

(1), operation beginning, the voltage of differential pressure transmitter and be decided to be point voltage during computer acquisition 0m/s wind speed, import the type code of tested anemometer and table number, calibrating procedure selection code to computing machine this moment;

(2), gather the indoor air pressure of wind-tunnel, temperature and rh value at any time by baroceptor, temperature sensor and relative humidity sensor simultaneously and import in the computing machine the total correction factors formula of computing machine basis through analog to digital converter (A/D)

Calculate the K value;

(3), according to wind speed

Formula generates the wind speed fuzzy control rule with the output valve (D/A value) and the measuring point air speed value of the corresponding measuring point wind speed of computing machine gained and deposits in the disk;

(4), when the variation of atmospheric density causes that the calculated value of actual wind speed has when departing from, total correction factor K value can obtain revising by atmospheric density correction factor K ρ at any time, and then the correction actual wind speed;

(5), be that simulating signal is controlled motor speed through speed regulator by computing machine output steering order and by digital to analog converter (D/A) with digital signal transition, still press fuzzy control rule between time delay and finely tune motor speed, wind speed is stablized.

2, a kind of automatic detection according to claim 1 and control the method for wind tunnel speed automatically, it is characterized in that: it both can select single wind speed point to detect automatically and control, also can select the continuous automatic inspection and the control of a plurality of wind speed points or overall process, its calibrating procedure selects code to be: single-point and multiple spot calibrating are A, and the overall process calibrating is B.

3, a kind of automatic detection according to claim 1 and control the method for wind tunnel speed automatically, it is characterized in that: type code and calibrating procedure to the dissimilar tested anemometer of computing machine input are selected code, computing machine just can provide the different reference mark of various table, stabilization time, reading delay time and motor ascending, descending speed time.

4, a kind of automatic detection according to claim 1 and control the method for wind tunnel speed automatically, it is characterized in that: this method is applicable to that two kinds of wind-tunnel of forthright or loop use.

5, a kind of for realizing automatic detection that the described method of claim 1 designs and the device of controlling automatically, it is characterized in that: it comprises with lower member:

(1), be installed in the pitot tube in the wind-tunnel, it can be drawn the air-flow in the wind-tunnel and form general pressure and static pressure;

(2), be connected and pressure differential can be modeled to the differential pressure transmitter of magnitude of voltage with pitot tube;

(3), convert the analog voltage of differential pressure transmitter the analog to digital converter (A/D) of digital signal to, the input end of analog to digital converter (A/D) is connected with differential pressure transmitter, and its output terminal is connected with computing machine;

(4), gather baroceptor, temperature sensor and the relative humidity sensor of air pressure, temperature and the relative humidity of wind-tunnel chamber, they are connected with the input end of separately analog to digital converter (A/D) respectively, and the output terminal of analog to digital converter (A/D) is connected with computing machine;

(5), can calculate various air speed value and handle the verification result of all kinds of anemometers and adopt the main frame of FUZZY ALGORITHMS FOR CONTROL control wind tunnel speed, it is connected with a digital to analog converter (D/A) with four analog to digital converters (A/D), and it also is connected with printer with display;

(6), display that can show various parameters and wind tunnel speed numerical value;

(7), the printer that can print calibrating and test result;

(8), convert the steering order of computing machine the digital to analog converter (D/A) of simulating signal to, its input end is connected with computing machine, and output terminal is connected with machine governor;

(9), can control the machine governor of wind-tunnel motor speed, its input end is connected with the output terminal of digital to analog converter (D/A), its output terminal is connected with the wind-tunnel motor.

6, the automatic detection according to claim 5 and the device of control automatically, it is characterized in that: described machine governor is AC converter or DC voltage speed regulator.

7, the automatic detection according to claim 5 and the device of control automatically is characterized in that: this device is applicable to that two kinds of wind-tunnel of forthright or loop use.

Images