Abstract
The temporal instability and primary breakup length of a non-Newtonian viscoelastic liquid jet moving in an inviscid gaseous environment were carried out by solving a set of linearized Navier-Stokes equations and employing the linear viscoelastic model, respectively. The dimensionless dispersion equation that governs the instability was derived and solved by a numerical method. The effects of fluid properties on the instability and primary breakup length of viscoelastic liquid jets were carried out. It could be seen that by increasing the growth rate, the instability range and the primary breakup length of the viscoelastic liquid jets could result in an increase in the liquid Weber number and the ratio of gas to liquid density. Moreover, the significant findings are that an increase in the time constant ratio, and also the Ohnesorge number reduced both of the growth rates of disturbances and primary breakup length. Though, increasing the elasticity number resulted in a higher growth rate of disturbances and enhanced the breakup mechanism.
Highlights
When a liquid jet exits from an atomizer, it becomes unstable
The instability and breakup of non-Newtonian viscoelastic liquid jets with axisymmetric disturbances moving in an inviscid gaseous environment was investigated in this article
A dispersion relation for axisymmetric disturbances on a non-Newtonian viscoelastic liquid jet was derived from linearized governing equations and the constitutive equation of the non-Newtonian fluid
Summary
When a liquid jet exits from an atomizer, it becomes unstable. The amplitude of the disturbances on the liquid-gas interface grows and leads to the breakup of the liquid sheet into ligaments and into droplets. The instability and breakup of inviscid liquid sheets of uniform thickness in an inviscid gas environment were analyzed by Squire [9] and Hagerty and Shea [10] Their results showed that the surface tension forces always tend to dampen out any protuberances, and the aerodynamic forces are responsible for the instability of inviscid sheets. Brenn et al [20] investigated the temporal instability behavior of non-Newtonian liquid jets moving in an inviscid gaseous environment for axisymmetrical disturbances, and gained the corresponding dispersion relation between the wave growth rate and the wave number. The objective of the present work was to derive a distribution relation by means of linear stability analysis for non-Newtonian viscoelastic liquid jets under the action of surface tension and aerodynamic forces, as well as to investigate and analyze its predictions of the jet characteristics. The influence of non-dimensional parameters on the stability and primary breakup of the viscoelastic liquid jet will be discussed
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