Electrospray cone-jet mode for weakly viscoelastic liquids

Area of Science:

• Fluid Dynamics
• Rheology
• Electrospray Technology

Background:

• Electrospray is a technique for generating fine liquid jets.
• The cone-jet mode is crucial for stable electrospray operation.
• Understanding fluid viscoelasticity's role is key to optimizing electrospray.

Purpose of the Study:

• To investigate the influence of viscoelasticity on the steady cone-jet mode in electrospray.
• To analyze the impact of small stress relaxation times on electrospray stability.
• To quantify the effect of polymeric stresses on the cone-jet mode and stability limits.

Main Methods:

• Theoretical study using numerical integration.
• Leaky-dielectric model combined with the Oldroyd-B constitutive relationship.
• Calculation of base flow and linear stability eigenmodes.

Main Results:

• Viscoelasticity introduces significant differences compared to Newtonian electrospray.
• Polymeric stresses affect both the cone-jet mode and the minimum flow rate stability limit.
• Axial polymeric stress shrinks the liquid meniscus, enhancing stability in the cone-to-jet transition region.

Conclusions:

• Even small stress relaxation times in viscoelastic fluids lead to notable changes in electrospray behavior.
• The intense extensional deformation in the cone-jet region amplifies viscoelastic effects.
• Polymeric stresses offer a stabilizing mechanism for the electrospray cone-jet mode.