One of the most prominent example for multiphase flows are bubbles dispersed in water. The interaction of both phases is investigated applying a color-coded dual imaging approach: for flow field imaging in water a green light sheet is used to excite the red fluorescence of the PIV particles seeded to the water, and a blue backlight LED screen is used for shadowgraphy tracking bubble shape, size and velocity. A beam splitter in front of the cameras separates the color-coded information from both phases before detection. The recordings of both channels are synchronized and their fields of view are perfectly matched onto each other applying the image mapping functionality in DaVis.
Our ParticleMaster 3D Shadow systems are based on tomographic shadow imaging. Using multiple shadow projections the tomographic reconstruction module in DaVis calculates the position and shape of particles, bubbles and droplets in 3D space. With time-resolved recordings particle trajectories with velocity and acceleration data are measured.
Time-resolved tomographic shadow imaging was successfully applied in bubbly flows for 3D flow imaging of both phases.