Development Of A Two-channel Gas Ultrasonic Flowmeter Based On TDC-GP21

Gas ultrasonic flowmeter is a process control instrument that uses ultrasonic waves to detect gas flow.It has many advantages that other flowmeters do not have.It is especially suitable for bad work sites such as dirty media and highly corrosive media and requires high measurement accuracy.Measurement site.However,the domestic ultrasonic flow meter research started late,the technology accumulation is lacking,and there is still a large gap with foreign technologies.Therefore,it is urgent to develop a gas flow meter with independent intellectual property rights.Based on the high precision timing chip TDC-GP21 and peak correlation algorithm,and taking into account the low power consumption design requirements,this paper puts forward the method of hardware and software combined with the flowmeter accuracy problem,designs the experimental prototype,and verifies the performance of the experimental prototype through the flow measurement experiment.The main contents of this thesis include:(1)The measurement scheme based on the high precision timing chip TDC-GP21 and peak correlation algorithm is designed.On the basis of the traditional TDC-GP21 timing chip scheme and the traditional cross-correlation measurement scheme,this paper proposes a new measurement scheme based on TDC-GP21 hardware and combined with peak correlation algorithm.The purpose is to solve the problem of large measurement error and high power consumption in traditional methods.(2)Research on peak correlation algorithm based on the signal characteristics of gas ultrasonic flowmeter.Based on the characteristics of gas ultrasonic flowmeter signal,this paper designs the mutual correlation algorithm with peak value as the research object to improve the disadvantages of the traditional mutual correlation algorithm with large computation and poor real-time performance.(3)Gas ultrasonic flowmeter prototype design based on high-precision timing chip TDC-GP21 and peak correlation algorithm.The prototype hardware system adopts modular design.Including the control module with the micro-power consumption machine MSP 430F5418 A as the control core,the transducer driver and switching module,the front matching and receiving switching module,the signal conditioning module,and the timing module and power supply module based on the high-precision timing chip TDC＿GP21.The prototype controls the time of reading timing module through the system software,and uses the data processing method based on peak correlation algorithm to complete the flow calculation.(4)The prototype of the flowmeter is experimentally verified on the flow verification equipment of the negative pressure Sonic nozzle.Firstly,the crossing time of the prototype was verified.The peak cross correlation algorithm and the peak cross correlation algorithm were used to measure the crossing time at different velocity points respectively,and compared with the theoretical crossing time.Then the ultrasonic flowmeter prototype is tested the precision of the whole machine.The gas ultrasonic flowmeter developed in this paper meets the requirements of the national standard.