Research On Ultrasonic Gas Flowmeter

How to scientifically measure industrial gas has long been a troublesome issue for industry. In the twenty-first century, the ultrasonic gas flowmeter receives wide attention in industry for its advantages:no pressure loss, no resistance, wide measurement range and less affect from the fluid, etc.Starting from the basic research, the thesis undertakes detailed analysis on the ultrasonic measurement. Then the author puts forth an advanced measurement based on the actual circuit debugging. Based on the improved time difference principle, the system can overcome the impact from the temperature and the velocity of sound and increase the precision.Hardware circuit is divided into analog circuits and digital circuits. On the one hand, the analog circuits include the ultrasonic transmitter circuit, switching circuit, ultrasonic receiver circuit, band-pass filter circuit, AGC circuit, limiter circuit, etc. On the other hand the digital circuits include the single-chip control circuit, LCD display circuit, ADC converting circuit, RS-232communication interface, etc. From the perspective of software, the author adopts KeilC language, including initialization module, pulse transmitter module, data acquisition module, velocity and flow calculation module, LCD drive and display module, etc. After completing the jointing of the hardware circuit and the compiling of the software program, this thesis makes a holistic debugging and a specific analysis on the possibility of errors in practice.This thesis has analyzed the variables in the flow measuring formula and concluded the impacts on the accuracy of the system by error method. After that this thesis provides a feasible reference for practical application.