Experimental investigation of turbulent mixing between liquids of disparate viscosity in a co-axial jet mixer*

Industrial chemical processes often involve mixing of reactive fluids of different viscosities. These processes would involve a mixer that should efficiently mix reactants molecularly to prevent unwanted side products that decrease yield. To this end, the current work studies the physics of mixing to optimize mixing efficiency. A facility for study of coannular jet mixing was built that produces turbulent flows with high viscosity disparity between the liquids. To investigate the hydrodynamics of such mixing, highly resolved simultaneous PIV and PLIF data are acquired on confined co-flowing jet mixing configuration with refractive index matched binary mixtures of aqueous glycerol and calcium chloride solutions (viscosity ratio of 5). The PIV and PLIF data are used to extract mean and turbulent velocity and passive scalar statistics, and velocity-concentration cross-correlations from the flow fields, providing a statistical description of turbulent mixing and evolution of this confined coaxial jet flow. The observations in this study in concert with collaborative simulations enable the development of more physical models for turbulent mixing of fluids with disparate viscosities.