POLARITY INVERSION IN ELECTROHYDRODYNAMIC SPRAYING

Abstract

An experimental study of polarity inversion effects in electrohydrodynamic spraying is developed by characterizing the several atomization regimes that can be observed by varying liquid flow rate and applied voltage. n-Heptane, doped with an antistatic additive, is atomized in a classical needle-to-plate system. The study allows for the determination of two-dimensional maps of the stability regimes occurring by varying the controlling parameters. These maps have been obtained by comparison of results of direct visualization, by means of a digital camera, and Particle Dynamics Analyzer (PDA) measurements of droplet size and velocity components. Results show that occurrence of the regimes is not qualitatively influenced by polarity inversion, but in the negative polarity case any modification on spraying modes needs higher variation in applied voltage, and so the regimes are stable in larger voltage ranges.

Keywords:

• atomization
• electrosprays
• spraying regimes