Research Of Flow Measurement Based On Ultrasonic Travel-time-difference Method

As an aspect of energy measurement,flow measurement plays an important role in the field of industry and agriculture.Ultrasonic flowmeter combines acoustical measurement technology with electronic technology and has unique advantages over other flowmeters.The ultrasonic flowmeter with the radial installation of the probe is mainly used in the flow measurement of medium and large pipe diameter.In some important areas,ultrasonic flowmeter is needed for small flow measurement in high precision.High precision measurement for small flow need to design and production flow meter measuring piping,choosing appropriate diameter,the best channel arrangement and high precision of acoustic time difference measuring technology.Based on the ultrasonic propagation characteristics and the basic theory of time difference method of ultrasonic flow measurement,explores the nature of the correction coefficient in the non-ideal flow field,propose to obtain the velocity correction coefficient by simulation and experiment.According to the need of measurement for small flow,design a new structure of flow measuring pipe and installation style of probe,and compared with traditional measurement tube structure,analysis the unique advantages in small flow measurement from theoretical angle.Based on the time difference method of flow measurement,the overall scheme of ultrasonic flow measurement system is designed.On this basis,the ultrasonic detection card and ultrasonic probe are selected,the channel switching control module and the circuit connection diagram of each hardware module is designed.Design and develop flow measurement software based on hardware system.This paper analyzes the sources of error in flow measurement in detail,analysis the nature of the measuring error caused by the uneven distribution of flow field from the theoretical angle,explore the influences of different error factors on the flow rate change rule.According to the different action characteristics of each error factor,a method to reduce the error and improve the precision of measurement system is presented.This paper analyzes the sources of error in flow measurement in detail,analysis the nature of the measuring error caused by the uneven distribution of flow field from the theoretical angle,explore the influences of different error factors on the flow measuring error.According to the different action characteristics of each error factor,a method to reduce the error and improve the precision of measurement system is presented.The basic function of ultrasonic flow meter and the time-difference measurement method were tested.The software and hardware modules of the flow meter have basic functions,and the feasibility of measuring the flow based on the time-difference method is verified.Flow coefficient calibration was carried out through flow calibration test and precision verification test was carried out.