Development Of A Low Flow Gas Ultrasound Flowmeter

At present,the main domestic production is still a large flow of gas ultrasonic flowmeters.Because of technical problems,the research on low flow rate is relatively slow.In view of the problem of low measurement accuracy and poor stability of ultrasonic flowmeter,the combination of PID control algorithm and hardware circuit is used to ensure the stability of TDC-GP22.Meanwhile,the time difference processing algorithm is used to reduce the inherent noise of the system.A low flow gas ultrasonic flowmeter is designed,which can measure the minimum flow of 0.016 m~3/h.This article mainly includes the following aspects:1.In the hardware,the STM32F407 single-chip microcomputer is used as the core controller,and the TDC-GP22 is used as the timing chip.At the same time,the excitation circuit and the matching circuit,the amplification and filtering of the ultrasonic signal are designed for the ultrasonic transducer.In the PCB design,the separate layout of the mode power and the digital power reduces the noise brought by the circuit board and enhances the anti-interference ability of the circuit board.2.In the software design,STM32F407 main measurement program,PID control algorithm module,time value measurement program,time difference processing module and flow calculation are mainly designed.Among them,the time difference processing module adopts the combination of sliding average filtering algorithm and arithmetic average filtering algorithm,which can effectively improve the measurement accuracy of the system.3.Initially develop a prototype,perform software and hardware testing of the system in the laboratory,use the sonic nozzle standard device to carry out the air-moving experiment,and correct the prototype through a large number of experimental tests and analysis of experimental data.