Abstract: The cone-jet in electrohydrodynamic atomization has been widely applied into numerous industrial fields owing to micro-sized drops with narrow distribution and high charge. The electrified jet emits from a single capillary sheathed with quartz tube is visualized versus operating parameters and physical properties, and breakup instabilities are also discussed. The range of operating parameters for a steady cone-jet broadens, as well as the minimum flow rate. Taylor cone angle decreases with an increase in flow rate, while increases as electric potential increasing. The jet breakup length decreases with an increase in flow rate and conductivity, while increases as electric potential increasing. The diffusion angle increases as flow rate increasing, while decrease as electric potential and conductivity increasing. Much clearer whipping instabilities are observed with an increase in “electro-Weber” number and conductivity. The completion in disturbance or/and suppression from axial and radial stresses, drag force dominates the variation. Meanwhile, for a large flow rate, the transition from varicose instabilities to whipping instabilities is found. The whipping instabilities are clearly observed for high conductivity due to much more free ions in liquid. For much higher conductivity, an intermittent electrified jet appears and shows an umbrella plume, and breakup length sharply shortens.

Key words: EHDA, Cone-jet regime, Electrified jet, Conductivity, instability

摘要： The cone-jet in electrohydrodynamic atomization has been widely applied into numerous industrial fields owing to micro-sized drops with narrow distribution and high charge. The electrified jet emits from a single capillary sheathed with quartz tube is visualized versus operating parameters and physical properties, and breakup instabilities are also discussed. The range of operating parameters for a steady cone-jet broadens, as well as the minimum flow rate. Taylor cone angle decreases with an increase in flow rate, while increases as electric potential increasing. The jet breakup length decreases with an increase in flow rate and conductivity, while increases as electric potential increasing. The diffusion angle increases as flow rate increasing, while decrease as electric potential and conductivity increasing. Much clearer whipping instabilities are observed with an increase in “electro-Weber” number and conductivity. The completion in disturbance or/and suppression from axial and radial stresses, drag force dominates the variation. Meanwhile, for a large flow rate, the transition from varicose instabilities to whipping instabilities is found. The whipping instabilities are clearly observed for high conductivity due to much more free ions in liquid. For much higher conductivity, an intermittent electrified jet appears and shows an umbrella plume, and breakup length sharply shortens.

关键词: EHDA, Cone-jet regime, Electrified jet, Conductivity, instability