Laminar and turbulent flow of unstable liquid‐liquid emulsions

Abstract

AbstractLiquid‐liquid dispersions containing various volume fractions of a petroleum solvent dispersed in water have been studied in laminar and turbulent flow conditions. If one assumes that the dispersion behaves as a single‐phase fluid, measured friction factors may be used to calculate an effective viscosity of the mixture.In laminar flow, viscosities were found to be a function of capillary diameter, possibly due of the formation of a thin film of continous phase adjacent to the capillary wall. The thickness of this film was determined to be of the order of 10 to 25 μ, which is probably of the order of the average size of the droplets.Up to 20% solvent, the relative fluidity (or viscosity) of the dispersions was the same in laminar, vertical turbulent, and horizontal turbulent flow. In the laminar flow case viscosity decreased somewhat with flow rate and became essentially constant at a Reynolds number of about 1,000.In vertical turbulent flow all dispersions behaved as Newtonian fluids, and a single curve (Figure 6) is presented to predict fluidities. The 35 and 50% dispersions in horizontal flow exhibited non‐Newtonian characteristics and had effective fluidities considerably less than the same dispersion in vertical flow but agreed with the horizontal turbulent flow results of Baron, et al. The apparent non‐Newtonian behavior could be due to phase separation in the horizontal tube.Corrected laminar flow fluidities for dispersions with 35 and 50% solvent deviated from the vertical turbulent flow results. Reasons for this are unexplained. In laminar flow also, tube orientation affected the viscosity of the 50% dispersion.