Anomalous Rheological Characteristics of a High-Internal-Phase-Ratio Emulsion

摘要

High-internal-phase-ratio emulsions containing 97 to 98 percent liquid fuel as the dispersed phase, are shown to exhibit complex rheological behavior including reversible work hardening and apparent slip-flow anomalies. However, when proper precautions are taken to prevent contamination by demulsified fuel, steady flow in glass and steel tubes is characterized by the Bingham model up to a critical wall shear stress. At higher stresses a discontinuity in the flow curve is observed. Experiments in different diameter tubes are used to establish that the critical stress is associated with the rupture of emulsion droplets and the formation of a thin film of fuel at the wall of the tube. The apparent absence of a yield value and critical stress with PTFE (Polytetrafluoroethylene) tubes indicates that the film of fuel forms when the emulsion contacts a hydrophobic surface. (Author)