Cavitation Bubbles Measurements: Development of an Image Interferometric Technique for Simultaneous nuclei size and velocity measurements

A deep study focused on cavitation nuclei in particular on their size and velocity has been performed. The scope was getting the higher number of information on this phenomenon whose comprehension seems to be really difficult. To this aim, optical techniques such as PIV and ILIDS, ILIDS being the acronym for Interferometric Laser Imaging Droplet Sizing have been used. This technique uses the same setup of a PIV-2D study, evaluating the size of transparent particles. Until now, its feasibility has been demonstrated especially in sprays of water droplets in air, where an optimal light scattering can be obtained thanks to the values of the relative refractive index and to the spherical shape. The proposed technique would be helpful in research applied to the reduction of greenhouse gas into seawater [7], while in our study we tried to apply it to the air bubbles produced by incipient cavitation in marine propeller wake. Analyzing images respectively at each single frame and in two consecutive ones allows to derive simultaneously bubbles size and velocity.