Design Of Ultrasonic Liquid Flow Measurement System Based On Time Difference Method

Flow measurement is one of the three test parameters in the field of measurement,which plays an extremely important role in ensuring product quality,improving production efficiency and promoting the development of science and technology.As an important branch of flow measurement,liquid flow measurement plays an important role in petrochemical industry,scientific research and daily life.Compared with other liquid flow measurement technology,ultrasonic fluid flow measurement technology has many advantages such as doesn’t contact with the measured liquid,has high measurement accuracy and wide range of usage scenarios,so it was widely used.The ultrasonic liquid flow measurement technology has been studied in foreign countries for a long time and has made many achievements.Our research on ultrasonic liquid flow measurement was later than foreign countries,and the stability and reliability of products are poor.Based on these problems,we need to study the ultrasonic liquid flow measurement system with low cost,high reliability and high stability.First of all,this dissertation consulted the literature about ultrasonic,understand the characteristics of ultrasonic and compared the common ultrasonic flow measurement principle,choose the time difference method as the measurement principle and optimize the time difference method.The characteristics of various installation modes of ultrasonic transducer are compared,and finally Z-shaped installation mode is selected.The characteristics of several ultrasonic transducers are compared and piezoelectric ceramic ultrasonic transducers are selected for measurement.Secondly,the ultrasonic liquid flow measurement scheme is designed and choose FPGA as the control core.The software system of the measurement system has been designed on the basis of hardware,and the two complement and work together.The propagation time of ultrasonic wave in liquid was measured by MS1022,which is a high precision time measurement chip.Finally,the system is tested on the measuring platform,including system calibration,static environment test and dynamic environment test,and the relevant data of the system and reference flowmeter are compared.The test results show that the measurement error of ultrasonic liquid flow measurement system is less than 2.5% and it has good stability and reliability.