DYNAMICS AND LINEAR-STABILITY OF CHARGED JETS IN DIELECTRIC LIQUIDS

The physical system to be considered is a blade-plane configuration in a dielectric liquid. For high electric fields, injection from the bla de takes place with ions of the same polarity. The Coulomb force actin g upon the injected charges originates an electrohydrodynamic (EHD) fl ow, referred in what follows as the charged jet. A laminar solution of this EHD jet is obtained using similarity analysis. If transport of c harged is dominated by convection, i.e., neglecting molecular diffusio n and ion drift, and the electric field is assumed constant, the probl em is mathematically equivalent to the bidimensional thermal plume in the limit of large Prandtl numbers. We examine the stability of this E HD jet using linear theory and the parallel-flow approximations. Neutr al stability curves are computed numerically in terms of a nondimensio nal parameter which is the electrical analogous to the Grashof number. Finally, some experimental observations are presented, followed by a short discussion. The role played by the viscosity correlates reasonab le well with the theoretical analysis.