A method for liquid velocity measurement by using two interdigital transducers

A technique using a liquid delay line oscillator is presented for measuring the liquid velocity. The key element of the delay line oscillator is two interdigital transducers operating at a liquid-solid interface, which are used for the radiation or the detection of the longitudinal wave in the liquid. The oscillation frequency of the device changes with the liquid velocity. The validity of the operation principle is verified experimentally for the water velocity change.