Instantaneous velocity field measurement in densely-laden two-phase flows using Ultrasound Imaging Velocimetry

Ultrasound Imaging Velocimetry (UIV, also known as 'echo-PIV') has, since its introduction a decade ago, been regarded as a promising tool to characterize non-transparent flows. Prime application examples are particle-laden flows and (in vivo) blood flow. Virtually all studies so far have been validation/comparison studies in laminar flow. In this contribution, we show that the technique has matured to a state where also unsteady, turbulent flows can be characterized. We do this by performing measurements in a fully-developed (single-phase) turbulent pipe flow at a Reynolds number of 5300. The outcome agrees with literature data. Subsequently, we demonstrate that the technique can measure in the same flow, but now with a moderate volume fraction of particles; such flows are beyond the capabilities of conventional, optical techniques. This opens up a wide range of application areas, such as studies into turbulence modification and sediment transport