Acoustic liquid flow rate measuring instrument - uses obliquely positioned transducers fed with same pulse trains to measure transit time

摘要

An instrument for liquid velocity or flow measurement determines the anisotropy of acoustic wave propagation. It has two transducers inserted in opposite sides of a conduit carrying the liquid. The two transducers are aligned along a direction at an angle with the liquid velocity vector and they are facing each other. Each transducer can send toward the other and receive from the other ultrasonic quasi-plane surface waves. The instrument also has means for simultaneous excitation of the transducers by a series of recurring pulses modulating a high frequency carrier. It also has means for measuring the duration of the ultrasonic signal travelling between the two transducers. The difference in duration between two signals, the square of their sum and the ratio between these quantities are used to obtain a measure of velocity and flow.