Efficient mode conversion transducers for use in ultrasonic flow meters

This paper is concerned with the development of miniature, high efficiency transducers for use in ultrasonic flow meters. The ultrasonic flow meter is an instrument that uses ultrasonic waves to measure flow rate of fluids. In the transmission type of ultrasonic flow meter, two transducers are placed on opposite walls of a pipe through which the fluid is flowing. Acoustic waves generated by one transducer travel through the fluid and reach the other transducer. The time taken by the acoustic wave to travel from one transducer to the other, the transit time, is a function of the flow velocity of the fluid. Thus, by measuring this time, one can determine the fluid velocity and other relevant flow parameters. The transducers can either be placed inside the pipe (wetted transducers) or outside the pipe (clamp-on transducers). The work described here is concerned with transducers placed inside the pipe.