Fpga-time Ultrasonic Gas Flowmeter-based Research And Experimental Verification

In recent ten years, on the basis of development of high-speed digital signal processor and microprocessor, on the basis of research for new-style probe material and technology, on the basis of research for acoustic channel configuration and flow mechanic, the ultrasonic flow measurement technology has obtained a great advancement, showing its strong technical advantage and becoming an important flow measurement technology. The ultrasonic flow measurement technology has been used in gas flow rate measurement. Gradually, a new kind of gas flow meter is produced, which is ultrasonic gas flow meter. Due to the accuracy, small volume, low cost, no pressure lose, long life-span, easy to fix and operate, the ultrasonic gas flow meter show its excellent advantages.A travel time difference method ultrasonic flowmeter based on field programmable gate array (FPGA) is designed in this thesis. The hardware structure of the system is microcontroller + FPGA. This hardware structure simplified design and developed the stability and reliability of the system. Making use of the programmable characteristic, the rich inner resources and very high work frequency of a FPGA chip, a date signal processes module including a high speed counter is designed. Witch some other measures, high accuracy gas flow measurement has been achieved. Generally, there are four parts as the following:1) Discussed the principles of some ultrasonic flowmeter, especially about the time-difference-type ultrasonic flowmeter; researched the transducer the propagation character of ultrasonic in fluid. Finite element analysis was proceeding with ANSYS. Then the ultrasonic flowmeter was corrected according to the theory of hydromechanics and physics, and calculation formulae of the flow revision coefficient are given under different state.2) Has conducted the research to the hardware electric circuit of the over all system, including the hardware design of the FPGA. Essential function has been focused on, has completed the monolithic integrated circuit hardware electric circuit design, the debugging.3) This article has produced corresponding design drawing of the software, the over all flow chart key partial.4) Test has been proceed, analyzed and studied various factors which influence flow measurement.