Ultrasonic pulse-phase method applied in fluid flow measurements

A novel pulse phase method for ultrasonic flow measurement in pipes under pressure is presented. It belongs to a group of direct time measurement methods. The difference in propagation (transit) time between two ultrasonic beams transmitted in upstream and downstream directions across the fluid flow is measured. With a goal to achieve an accuracy better than 1% each of the transit time intervals is decomposed into two intervals. The first interval, called ´coarse´, points to an integer number of the ultrasonic signal periods during propagation time, and the second one, called ´fine´, points to the rest of its periods. Fluid flow velocity and volume quantity are determined through involving the calibration function. The main metrological characteristics of the realised fluid flowmeter are determined using available working etalons. Experiments have shown that the total error of the flowmeter described herein is within the specified accuracy of 1%.