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 (µPIV). 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 30 vol % of droplets in a rectangular orifice channel with the narrowest gap being 200 µm. Emulsion flow was compared to a pure continuous phase and the influence of the dispersed phase was analyzed for each individual step of µPIV image processing. For the presented experimental conditions, one‐ and two‐phase flows exhibited no difference in flow characteristics.