2017 Volume 43 Issue 1 Pages 1-15
The cylindrical-wall revolving mixer (CRM) is a high velocity revolution mixer used in industry to produce emulsions with uniform droplet size. However, fundamental verification data and the mechanism by which this mixer imparts size uniformity have not been clarified. In this study, we compared the droplet size distributions of emulsions produced by a CRM and a general rotor-stator mixer. We also conducted an impulse response experiment and analyzed mixer flow using flow visualizations and computational fluid dynamics (CFD) simulations. The preparation results showed that the CRM produces more uniform emulsions than the general rotor-stator mixer operated with a clearance of 0.5–2.0 mm between the rotor and stator. The impulse response results showed that the holding time distribution of processing liquid is approximately the same for the CRM and the general rotor-stator mixer. The flow visualization results near the clearance showed a uniform steady flow state in the CRM but a turbulent flow state with unsteady flow in the general rotor-stator mixer. The CFD simulations indicated that the CRM had a significant supply of the processing liquid in the high velocity gradient region, and that the velocity gradient tended to be uniformly even. These results suggested that the flow state near the clearance and the velocity gradient are important factors for generating a uniform emulsion.
