Particle Shadow Velocimetry (PSV) in bubbly flows

The interaction of gas bubbles and the surrounding liquid in bubbly flows is a complex hydrodynamic phenomenon. Precise measurements of the liquid velocity are mandatory to generate accurate models and CFD-validation data sets. For this purpose, methods for Particle Shadow Velocimetry (PSV) that are using a volume illumination and a small depth of field (DOF) are developed in the presented work. Experiments with an oscillating plume were conducted in a rectangular bubble column to test the PSV methods. The results obtained with a Particle Image Velocimetry (PIV) and a Particle Tracking Velocimetry (PTV) processing procedure agree very well with respect to velocity profiles and turbulence parameters. As discussed in previous work, PSV methods have a much simpler experimental setup and can handle much higher gas fractions. With the present findings, robust PSV algorithms for PIV and PTV in bubbly flows are now available.