Ultrasonic Doppler Technique for Application to Multiphase Flows: A Review

Instantaneous velocity of multiphase flow is an important parameter in scientific and industrial applications such as fluid mechanics modeling and flow measurement and monitoring. Ultrasound Doppler provides the spatial-temporal distribution of multiphase flow velocity in a non-intrusive manner. This technique can be used to uncover the fluid dynamics by measuring the flow structures, detecting the gas–liquid interface position, measuring the multiphase rheology, and providing an online sensing solution for flowrate metering and flow status monitoring. These functions facilitate fluid dynamics investigations and modeling, industrial safety assurance and reliability, production estimation, and process control and optimization. This review focuses on the principle and the state-of-art development of the ultrasonic Doppler technique for measuring gas–liquid two-phase flow, liquid–liquid two-phase flow, and three-phase flow, and provides insights into the advantages, limitations, and future trends of this technique.