Three Dimensional Mapping of Bubbly Flows in Tow Tank

A unique three-dimensional imaging system for the purpose of mapping two-phase bubbly flows with applications in tow tanks is presented. A defocusing optical setup was implemented to generate images with imbedded information on the three-dimensional spatial position of bubbles. A novel approach was used to overcome the overcrowding of bubble images within a single camera, which had previously inhibited the practical application of this technique. A camera system based on the optical and spatial requirements was fabricated and tested. Special software was developed to map the three-dimensional position and to estimate bubble sizes and bubble number density within each captured image. The velocity fields are calculated from volumetric image correlation between each pair of consecutive images. Sample data and calibration results are presented in this paper.