Effect of Viscosity on Dispersion Behavior in Stratified Flow

Abstract

Molten oxides are widely used as refining slag and mold flux in the steelmaking process. In the stationary state, the molten oxide and the molten iron form a layer due to their density difference. However, in the actual operation, they are partially mixed and dispersed as droplets, which can increase the slag-metal reaction area or cause the formation of nonmetallic inclusions. In this study, the dispersion behavior in density stratified flow was investigated by water model experiments. It was suggested that the dispersion behavior of silicone oil was affected by viscosity. As the kinematic viscosity was higher than 100 mm²/s, droplet generation tended to be less likely to occur.

The conventional equations for interface instability and energy balance underestimated the critical velocity of droplet generation when the kinematic viscosity of oil was higher than 100 mm²/s. On the other hand, we were able to reproduce the influence of viscosity in this experiment by applying the empirical formula using the Ohnesorge number. Furthermore, an energy balance formula including the influence of viscosity was newly constructed. We confirmed that the new formula agreed with the experimental results.