Research On Multichannel Doppler Ultrasonic Sewage Flow Measurement Technology

In recent years,with the rapid development of China's economy,the problem of environmental pollution is becoming more and more serious,especially the problem of water pollution.In order to improve the situation and achieve the sustainable development of water resources,it should evaluate the utilization of water resources and environmental protection levelby the real-time monitoring of sewage discharge.It puts forward new requirements for the sewage flow measurement technology.In this article,a mathematical model is established,based on the theory of ultrasonic Doppler effect.The formula of transmitting and receiving ultrasonic wave is deduced,and the mathematical formula of the flow rate can be obtained by Doppler shift;The mathematical model of multi-channel Doppler ultrasonic flow measurement is improved by the analysis of the velocity distribution and the modificationsof average velocity of the cross section in the pipeline.The scattering attenuation,heat conduction and viscous attenuation characteristics are investigated by the MATLAB numerical simulation.We know that the relationship between ultrasonic attenuation coefficient and the density of the medium,medium viscosity,ultrasonic frequency and medium scattering particle radius.The results show that the ultrasonic scattering attenuation mainly affects the amplitude of the scattered echo signal.The feasibility of Doppler method is verified.It analyzes and calculates the working frequency of the ultrasonic transducer and the position of the sensor.The fast Fourier algorithm of frequency estimation algorithm and interpolation algorithm are introduced.It finishesthe design scheme of multi-channel Doppler ultrasonic flow measurement in this paper.In the aspect of hardware design,the microprocessor system circuit,signal reflection and receiving circuit,channel switching circuit,power supply circuit are completed with DSP;In the aspect of software design,the system monitoring software and functional programming are completed.Finally,the computational complexity of DFT and FFT algorithm is compared.The algorithm is verified by simulation.The frequency resolution is improved by using interpolation algorithms.The FFT algorithm and interpolation algorithm are selected.It is based on that the DSP have the tightly coupled FFT hardware accelerator.It accelerates the data processing efficiency and improves the real-time measurement results.The signal emission,bandpass filter and mixing circuit are simulated and debugged.The system design is content with the requirements of multichannel Doppler sewage flow measurement.