Forms of the multijet mode of electrohydrodynamic spraying

Forms of the multijet mode of electrohydrodynamic spraying are discussed in detail and a qualitative model is offered to describe the transition between them. Based on photographs taken in stroboscopic light, the multijet mode can either consist of several fine jets issuing simultaneously from the distinct sites at the circumference of the capillary (continuous multijet mode—known from the literature), or only one short, relatively thick jet ejected sequentially from distinct, stable points at the circumference of the capillary (intermittent multijet mode—not documented in the literature). We propose that the transition between these two forms is related to a critical velocity νc = σ/μc (σ is the surface tension and μc is the liquid viscosity), and the experiments with water, ethanol and ethylene glycol are qualitatively consistent with this approach.