A Design Of Air Flow Calibration System Based On Wind Tunnle

The wind tunnel air flow testing and calibrating system is designed to test the automobile air flow meter. In our country, the testing system which is used to test air flow meter is imperfect in the related factory. At present, the function of the air flow meter testing system in our country is single, not to say the accuracy. The system can only test air flow meter. If the air flow meter doesn't attain the designated standard, this sensor will be discarded. And the measuring accuracy is not good. So it is necessary to develop a new system which can produce adjustable air flow continuously and have whole function. The system must be stable and easy to use.In this thesis, the merit and shortcoming of the commonly used gas flow calibration facilitys and the present situation of wind tunnel flow measurement is analyzed. And then the technology planning of the project is given. Then the mechanical design, software and hardware of the system are introduced. The result of the experiment is analyzed. Then the process of debugging and antijamming measure is introduced. At last, the whole thesis is summarized.The system is described from two aspects, mechanical design and control system design. Mechanical design is combined by pipeline design, structure layout design of the case, and so on. The control system design is consists of data collection, wind speed control, heating control and communication control, and so on.The system can produce standard air flow.Computer controls the transducer and suction fan.Use pitot and sensors to pickup the signal of temperature, humidity, atmospheric pressure, and so on. At the same time, the air flow meter is also measuring the air flow. After the signal processing circuit, the data is collected by data acquisition and transmitted to computer by RS-485. The computer calculates the density, flow and the speed of the air. And the computer calibrates the air flow meter. Humidity is taken into account. So the system is more accurate. And the system has high temperature measurement function.The air speed of the system can attain 35m/s, and the mass flow can achieve 500kg/h (at the situation of 62mm inner diameter). The system can be stable in 10 seconds after the user input the air flow. The detection precision can achieve±1%. The reliability and stability of the system is good.