Research On Ultrasonic Flow Measurement Technology And Precision Compensation Method

Compared with the traditional flow measurement methods,ultrasonic flow measurement technology has the advantages of almost no pressure loss,no flow blocking parts,non-contact,high precision,wide measurement range and so on.It is widely used in oil transmission,flow tracking,water billing and other fields.The research on ultrasonic flow measurement technology abroad is earlier,and the related products can basically meet the requirements of industrial production,but the price is very expensive.In this field,our country started late,the technology accumulation is insufficient,and the product performance is difficult to meet the market demand.In view of this practical problem,it is of great significance and practical value to carry out in-depth research on ultrasonic flow measurement technology.The specific research contents mainly include the following aspects:First of all,by consulting the relevant literature,the overall design idea of ultrasonic flow measurement system is given,the common ultrasonic flow measurement principle is analyzed theoretically,and the structure principle and installation mode of ultrasonic sensor are analyzed and compared.Finally,the time difference method is selected as the measurement principle,and the time difference method is optimized at the algorithm level to reduce the influence of sound speed on the measurement results.On this basis,combined with the characteristics of ultrasonic echo and the principle of cross-correlation algorithm,using the logic characteristics of FPGA,a semi parallel structure is designed to realize the cross-correlation algorithm,which improves the measurement accuracy of ultrasonic transit time and is verified by application.Secondly,the overall design of the ultrasonic flow measurement system is carried out,and the control core of the flow measurement system is designed by the combination of STM32 MCU and FPGA.Among them,STM32 is responsible for data acquisition and processing,information display and output,its hardware platform constructs the software system of measurement system,FPGA is responsible for logic control and provides drive signal for hardware circuit,the two complement each other.TDC-GP22 high-precision timing chip and cross-correlation algorithm module are combined to complete the upstream and downstream time measurement.Finally,the designed ultrasonic flow measurement system is tested and verified,and the experimental detection system is built.The static flow measurement,ultrasonic sensor installation position offset error,laminar flow velocity region and turbulent flow velocity region flow measurement experiments are carried out respectively.The test data of the prototype and the measurement data of the reference flowmeter are analyzed comprehensively.The experimental results show that the relative error of the prototype is less than 3.68% in laminar region and less than 0.66% in turbulent region.