Ultrasonic particle velocimetry in multiphase flows

Two-dimensional ultrasonic speckle correlation velocimetry (USV) is a new technique that allows to image moving scattering media, at a high frame-rate. In this paper we apply the. technique to determine two-dimensional particle velocity profiles of multiphase flows. Experiments are realized with suspensions of Sonazoid (medical contrast agent) and Magnetite (Fe₃O₄) in water. All measurements are performed in a vertical pipe with the flow moving downwards. The two-dimensional particle velocity profiles are then compared with a reference liquid volume flow velocity. As expected from theory, the heavier Magnetite particles have slightly higher velocity than the liquid whereas the contrast agent simply follows the liquid motion. The proposed technique can be used in combination with other techniques to measure the mass flow of the solid phase, in solid/liquid multiphase flow. This is generally more interesting than-measuring the bulk mass or volume flow.