EXPERIMENTAL BREAKUP CHARACTERISTICS OF ROUND LIQUID JETS OF A DILUTE POLYMER SOLUTION INTO QUIESCENT AIR

Experiments are performed on dilute polymer solutions jetting into quiescent air with a jet velocity range of 30–87 m/s. Polymer solutions are those with several hundred ppm concentrations of long-chain polyoxyethylene (millions of molecular weight) dissolved in purified water. The breakup characteristics of the jets were recorded by high-speed photography from four observation windows along the jet direction. The breakup morphologies of dilute polymer solution jets are significantly different from that of Newtonian fluids. Small-scale interfacial disturbances are suppressed, while a twisted liquid column waving with large amplitudes is observed. When the jet velocity exceeds a critical value, liquid films and filaments are peeled off successively from the liquid column. Four different breakup patterns are distinguished. The diameters of the central liquid column and the principal liquid filament are observed to decrease with increasing jet velocity.