Research On The Technique Of Measuring Tunnel Wind Speed By Ultrasonic

The tunnels used in roads are more and more in China, the safety operation of these tunnels is very outstanding, and the environmental monitoring and control of the tunnel is an important subject of the tunnels safety operation. Ventilation system is an important guarantee of the safety operation, and the wind velocity is an important basis for adjusting the working state of the ventilation system, so the real-time detection of the wind speed in tunnels is very important. The main subject of this dissertation is research on the ultrasonic real-time detection of wind speed in tunnels, and developing an anemometer that can be used in tunnels. The measuring principle of the ultrasonic wind-speed detection is introduced, and a measuring model is established, and a new method of digital phase detection in±180οis designed in this dissertation. And a measurement system that used CPLD and AVR is designed and verified by experiments.The main contents of the dissertation are as follow:1. This dissertation discussed the technology of wind-speed detection based on the ultrasonic, compared the several methods of wind-speed detection, and the phase difference method is selected. The measuring model of phase difference method is established.2. Detailed analysis the source of detection errors and the method of improving precision by using the measuring model of phase difference method, and optimum designed the mechanical construction system.3. Designed the ultrasonic driver and receiver circuit, and performed experiments.4. Analysis the method to improve the precision of phase detection and the principle of digital phase detection. And creative designed a digital phase drtdctor which can detedt phase difference in±180ο, and realized the discerning direction and the high precision phase detect using the CPLD.5. Designed the circuit of the anemometer system cored as ATMEGA128 and CPLD, compiled the program, and realized the wind-speed measure, the system control and RS232 communication. 6. Made the whole machine of the anemometer, and debugged the system, and verified by experiments.