Transient radial spray from electrified viscous jets

An applied radial electric field can influence the instability and breakup behavior of a liquid jet. Particularly, when the electric field is sufficiently strong, a multi-cone-jet structure can be formed: a number of Taylor cones arise transiently at the equator of the most deformed droplet in the jet; from the tip of each cone, a fine secondary jet is emitted, which quickly breaks up into micrometer-sized progeny droplets. This tip streaming phenomenon is experimentally investigated for finitely conducting, viscous liquid jets in the present work. Different regimes are distinguished in the Be (the electric Bond number)-We (the Weber number) plane and also in the Be-We-Oh (the Ohnesorge number) space. The results show that both viscosity and inertia have a suppression effect on the formation of a multi-cone-jet structure. Moreover, the number of secondary jets can be greatly reduced by increasing viscosity or inertia. Increasing electrical conductivity leads to intense spray of secondary jets. In addition, some interesting phenomena like the coalescence of secondary jets and the coexistence of axisymmetric and non-axisymmetric instability are observed.