Scaling of Droplet Breakup in High-Pressure Homogenizer Orifices. Part I: Comparison of Velocity Profiles in Scaled Coaxial Orifices

Properties of emulsions such as stability, viscosity or color can be influenced by the droplet size distribution. High-pressure homogenization (HPH) is method choice for with a low to medium target mean diameter less than 1 µm. During HPH, droplets emulsion are exposed shear and extensional stresses, which cause them break up. Ongoing work focused on better understanding mechanisms breakup relevant parameters. Since gap dimensions disruption unit (e.g., flat valve orifice) small (usually below 500 µm) also takes place spatial time scales, resolution limit current measuring systems reached. In addition, high velocities impede resolved measurements. Therefore, five-fold fifty-fold magnified optically accessible coaxial orifice were used in this study while maintaining dimensionless numbers characteristic (Reynolds Weber number, density ratio). Three matching material presented. order verify their similarity, local velocity profiles emerging free jet measured using both microparticle image velocimetry (µ-PIV) particle (PIV) system. Furthermore, influence outlet geometry investigated. Similar relationships found all investigated scales. The areas highest fluctuations identified where turbulent forces. Reynolds number had no normalized fluctuation field. confinement started field if channel smaller 10 times orifice. conclusion, scaling approach offers advantages very fast processes scales detail. presented chances optimization unit. However, results show challenges each scale, come from respective production, measurement technology experimental design. Depending problem investigated, we recommend conducting studies at different