A Study On Phase Difference Ultrasonic Flowmeter

Ultrasonic flowmeter is applied widely in industrial measurement field for the two advantages, non-contact and installation and maintenance with ease. However, it also has some disadvantages, thus it is necessary to make modification and advance in order that it can work more stable and tried. The intention of this article is phase difference ultrasonic flowmeter. A phase difference flowmeter transmits a long pulse alternately upstream and downstream through a conduit having liquid flowing therin.Flow speed is a function of the total liquid travel time and the difference between the upstream and downstream travel times. The article makes deeply theoretical research on several vital techniques to advance the capability of the whole system. In addition, it supplies methods of concrete cicuits' realizing. Generally, there are four parts as the following:1. Research the measurement theory of time-difference-type ultrasonic flowmeter, derivate the theory formula and show the measurement theory figure of time-difference-type ultrasonic flowmeter. Then discuss the distribution regularity of flow velcocity of piping fluid, especially revision coefficient of flow velcocity distribution according to correlative knowledge in hydromechanics. Eventually propagation character of ultrasonic in fluid is analyzed theoretically, which lays a solid foundation in theory for concrete circuit's realization.2. Discuss some vital techniques and their realization methods of hardwares in the whole system, including the choice of transducer's structure and parameter, the design of signal examination circuit and receive circuit,the design of counter circuit with FPGA, the realization of high precise measurement of the difference between the upstream and downstream travel times.3. In the article,the flow charts of flow velocity calculation software and control software are achived and explained detailedly.4. Analyze and study various factors which influence flow measurement. According to the distribution principle which is to stress main errors, compose all possible errors. In the end, the experience sets and result are achieved.