Abstract
The classical emulsion is made up of drops of one liquid dispersed in a containing liquid. Under certain circumstances, however, some of the containing phase may form drops within the drops of the dispersed liquid, giving rise to a structure known as a doubleโmultiple emulsion. This study was an investigation of the hydrodynamic formation of these structures.
Doubleโmultiple emulsions were produced by using both transient and steady state liquid injection, with a cylindrical jet configuration. Analysis of the spray was by means of highโspeed photography.
The distribution of the large drops and that of the included drops were both found to be represented satisfactorily by a logโnormal probability function. A simplified model based on the use of nozzle parameters satisfactorily correlated percent included area and volume as a function of Reynolds number and Weber number. Large dispersed phase drops contained proportionally many more inclusions than did the smaller sizes.
The mechanism of inclusion formation was found to involve the drawing out of a ligament or sheet from the flowing jet, followed by the recoalescence of the free end of this ligament or sheet with the main jet body, entraining in the process a portion of the containing phase. Thus, the inclusions predate the formation of the drops of the dispersed phase from the jet disruption.