Drop forming regimes in viscous co-flowing liquid-liquid-systems with equal density

Abstract

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.Drop formation at orifices and capillaries is applied in different industrial applications. The transition from dripping to the laminar jetting regimes must be known. In the non-viscous case the transition point is characterized by a transitional Weber number We = 2. For the viscous case particularly considered here, another characteristic number is maybe more suitable. Experiments are performed with viscous liquids for both phases with equal density to obtain the characteristic parameter for the transition. Droplet diameter, break up length and distance of droplets which refers to the break up wavelength in the jetting regime are analysed. In the laminar jetting regime different kinds of drop formation could be observed and the influence of the volumetric flow rate ratio to the jet diameter and relaxation length is reported as well.