%0 Journal Article
%T Viscous Potential Flow Analysis of Electroaerodynamic Instability of a Liquid Sheet Sprayed with an Air Stream
%A Mukesh Kumar Awasthi
%A Vineet K. Srivastava
%A M. Tamsir
%J Modelling and Simulation in Engineering
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/528723
%X The instability of a thin sheet of viscous and dielectric liquid moving in the same direction as an air stream in the presence of a uniform horizontal electric field has been carried out using viscous potential flow theory. It is observed that aerodynamic-enhanced instability occurs if the Weber number is much less than a critical value related to the ratio of the air and liquid stream velocities, viscosity ratio of two fluids, the electric field, and the dielectric constant values. Liquid viscosity has stabilizing effect in the stability analysis, while air viscosity has destabilizing effect. 1. Introduction The past decade has witnessed a rapid advancement in the study of instability of a liquid sheet because of its importance in several scientific and technological processes. Application of plane liquid sheets is an interesting phenomenon, which can be seen in power generation and propulsion systems [1], chemical and pharmaceutical processes [2], surface curtain coatings, and in the adhesive industry [3]. A host of efforts have been devoted to study the behavior of a thin liquid sheet sprayed with an air stream. The instability and breakup process of a thin inviscid liquid sheet in a stationary gaseous medium have been investigated by Squire [4] and Hagerty and Shea [5]. Their results show that the surface tension resists the development of instability in a liquid sheet. Fraser [6] has defined four modes of disintegration of a liquid sheet, namely, rim, wavy sheet, perforated sheet, and air impact. In rim, the disintegration takes place due to the contraction of the liquid sheet edges under the effect of surface tension. In wavy sheet, the disintegration occurs due to any small protuberance on the sheet which is subjected to two opposing forces: surface tension force, which draws the liquid back to the original undisturbed shape, and aerodynamic force, which pulls the liquid outward. If the aerodynamic force exceeds to the surface tension force, then any small disturbance present in the sheet will grow rapidly, causing sheet instability. In perforated sheet disintegration, disturbances on the sheet puncture it when the sheet becomes thin enough, and the resulting holes expand regularly by surface tension until they coalesce, forming threads. In air impact disintegration, the disruption of the liquid is very near to that of a twin-fluid nozzle, where two streams of air and liquid are caused to impinge together. Squire [4] has studied the disintegration according to the wavy sheet mode. Dombrowski and Johns [7] extended the above analysis including the
%U http://www.hindawi.com/journals/mse/2013/528723/