A Fast and Improved Dual-PRT Doppler Technique for Industrial Flow Metering

Ultrasonic velocity profiler (UVP) have their distance range or maximum velocity limited by the Nyquist sampling theorem. Dual-pulse repetition time (PRT) technique employs a nonuniform pulsed ultrasound emission and a set of dealiasing rules to surpass the Nyquist limit. Industrial applications of UVP demand that the ultrasound transducer be positioned with a contact angle with the flow, which increases velocity estimation variance due to transit-time broadening. In this condition, the dual-PRT technique usually presents many outliers in velocity estimation. This letter presents an improved dual-PRT technique that uses an outlier correction algorithm adapted from the Doppler weather radars. The correction algorithm is tested in an industrial horizontal pipe flow for mean flow velocities ranging from 0.8 to 1.4 m/s. The technique proposed can measure velocities up to two times beyond the Nyquist limit and suppresses more than 90% of velocity outliers. Velocity estimation is performed with 128 ultrasound emissions allowing the technique to be applied in real-time applications.