Pulsating electrohydrodynamic cone-jets: From choked jet to oscillating cone
Pulsating cone-jets occur in a variety of electrostatic spraying and printing systems. This paper reports an experimental study of the pulsation frequency to reconcile two models based on a choked jet and an oscillating cone, respectively. The two regimes are demarcated by the ratio of the supplied flow rate (Q s) to the minimum flow rate (Q m) required for a steady Taylor cone-jet. When Q s ≈ Q m, the electrohydrodynamic flow is choked at the nozzle because the intermittent jet, when on, emits mass at the minimum flow rate; the pulsation frequency in the choked jet regime is proportional to Q s/Q m. When Q s ≈ Q m, the Taylor cone anchored at the nozzle experiences a capillary oscillation analogous to the Rayleigh mode of a free drop; the pulsation frequency in the oscillating cone regime plateaus to the capillary oscillation frequency, which is independent of Q s/Q m. © 2011 Cambridge University Press.
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