The Design Of Dual Channel Ultrasonic Doppler Flowmeter Based On DSP

In industrial production,it is usually necessary to measure the flow of water or sewage to monitor the process of production and perform production operations.The fluid in industrial pipelines is usually a two-phase flow containing abundant suspended particles or bubbles.Among the measuring instruments for the flow of two-phase fluid in the pipeline,the ultrasonic Doppler flowmeter can measure the two-phase fluid with high accuracy and high measurement speed.The non-contact characteristic of the measured medium has attracted widespread attention.However,according to the current research level of ultrasonic Doppler flowmeter,further research and performance enhancement are still needed.The error problem caused by the uneven flow velocity distribution of the two-phase fluid in the pipeline has still not been fully studied and resolved.Therefore,this article proposes a method of regional flow rate measurement for the uneven distribution of the flow velocity of the two-phase fluid in the pipeline and proposes a two-channel flow measurement method to reduce the measurement error caused by it.In this thesis,a two-channel ultrasonic Doppler flow measurement method is designed,combined with the Doppler principle and the flow velocity distribution law of the pipeline fluid,a mathematical model for flow calculation is built.The hardware structure of the system is based on TMS320F2812 as the core,supplemented by ultrasonic signal transmission driving power,ultrasonic signal receiving,processing circuit,and remote communication modules,which realize the functions of ultrasonic transmission,reception,filtering,mixing,etc.The software design of the system is based on digital signal processing.The fast Fourier transform algorithm is used to analyze the power spectrum of the Doppler signal in the frequency domain and the digital filtering technology is used to carefully process the data to obtain a more accurate signal frequency offset value.In this thesis,it also uses Multisim and Matlab to simulate and debug the system hardware and software system.And it builds a flow measurement experiment platform to experiment with the designed flowmeter.The result proves that the subject designed achieves the requirement that the measurement error of the fluid flowmeter is less than2%,which improves the measurement precision of the ultrasonic doppler flowmeter.