Local Multiphase Flow Characterization with Micro Particle Image Velocimetry Using Refractive Index Matching

An accurate flow characterization is crucial for the understanding and optimization of emulsification processes. A method is presented to determine velocity fields of droplet-containing phases flowing through an orifice by micro particle image velocimetry (mu PIV). In order to overcome optical inaccessibility of emulsions, a recipe of a transparent emulsion system was developed using refractive index matching. Velocity fields could successfully be determined for an emulsion containing 30vol% of droplets in a rectangular orifice channel with the narrowest gap being 200 mu m. Emulsion flow was compared to a pure continuous phase and the influence of the dispersed phase was analyzed for each individual step of mu PIV image processing. For the presented experimental conditions, one- and two-phase flows exhibited no difference in flow characteristics.