Development of an acoustic instrument for bubble size distribution measurement

Measurement of bubble size distribution and void fraction is of vital importance in many multi-phase flow applications. This paper describes an acoustics based device, the ABS Acoustic Bubble Spectrometer (R), which can conduct measurements accurately in near real-time in a cost-effective fashion. By propagating short bursts of sound at different frequencies through bubbly medium, it measures frequency dependent attenuations and phase velocities of the acoustic waves and uses them to obtain the bubble size distribution (number of bubbles per size) by solving an inverse problem. Recent developments, both in hardware and software, as well as their validations are presented, these new advancements enable the ABS to measure void fractions up to 3x10(-3) with bubble sizes ranging from 10 mu m to 3mm.