Power spectral distributions of pseudo-turbulent bubbly flows

An experimental study was carried out to determinate the power spectral density (PSD) of mono-dispersed bubbly flows in a vertical channel using flying hot-film anemometry. To improve bubble detection, optical fibers were installed in close proximity to the anemometer sensing element; in this way, the collisions of bubbles with the probe can be detected and removed from the signal. Measurements were performed with gas fractions up to 6%. The PSD distributions were found to decay with a power of −3, in agreement with previous studies, but for a much wider range of Reynolds and Weber numbers. Our measurements indicate that the power decay does not depend strongly on the nature of hydrodynamic interactions among bubbles.