Dynamics and Breakup of Pulse Microjets of Polymeric Liquids

The possibilities of controlling the dynamics and breakup of pulsed low-viscosity liquid microjets by means of small amounts of polymeric additives are considered. Significant differences between the breakup of pulse jets of Newtonian and viscoelastic polymeric liquids are recorded by means of high-speed photography. In flight a standard Newtonian fluid jet fragments into many secondary droplets. Depending on the molecular parameters, for a polymeric liquid three variants of the behavior of the jet in flight are possible: (1) the jet tail fragments into several secondary droplets; (2) the entire tail flows into the leading drop without loss and a single drop is formed; (3) the drop ejected from the nozzle returns to the nozzle under the action of elastic internal stresses in the tail. Criteria for the transition from one regime of jet motion to another are proposed.