This work aims to investigate the application of ultrasound Doppler velocimetry in multiphase flow.The experimental results show that in the homogeneous liquid-solid system

the amplitude of the received echo energy decreases exponentially with measurement depth

and attenuation rate increases with increase of solid holdup monotonously.A model based on the ultrasound reflection and refraction law and scatter characteristics of particles is proposed to predict the relationship between received echo energy and solid holdup.In the gas-liquid system

liquid velocity and bubble rise velocity can be directly obtained from the velocity profile by Dop 2000 when the bubble number is small

while in medium gas velocity range

FFT must be executed to calculate velocity distribution

resulting in a two-peak distribution

which in turn can be used to obtain liquid velocity and bubble velocity by further data processing.