Numerical Models for Viscoelastic Liquid Atomization Spray

Abstract

Atomization spray of non-Newtonian liquid plays a pivotal role in various engineering applications, especially for the energy utilization. To operate spray systems efficiently and well understand the effects of liquid rheological properties on the whole spray process, a comprehensive model using Euler-Lagrangian approaches was established to simulate the evolution of the atomization spray for viscoelastic liquid. Based on the Oldroyd model, the viscoelastic linear dispersion relation was introduced into the primary atomization; an extended viscoelastic version of Taylor analogy breakup (TAB) model was proposed; and the coalescence criteria was modified by rheological parameters, such as the relaxation time, the retardation time and the zero shear viscosity. The predicted results are validated with experimental data varying air-liquid mass flow ratio (ALR). Then, numerical calculations are conducted to investigate the characteristics of viscoelastic liquid atomization process. Results showed that the evolutionary trend of droplet mean diameter, Weber number and Ohnesorge number of viscoelastic liquids along with axial direction were qualitatively similar to that of Newtonian liquid. However, the mean size of polymer solution increased more gently than that of water at the downstream of the spray, which was beneficial to stable control of the desirable size in the applications. As concerned the effects of liquid physical properties, the surface tension played an important role in the primary atomization, which indicated the benefit of selecting the solvents with lower surface tension for finer atomization effects, while, for the evolution of atomization spray, larger relaxation time and zero shear viscosity increased droplet Sauter mean diameter (SMD) significantly. The zero shear viscosity was effective throughout the jet region, while the effect of relaxation time became weaken at the downstream of the spray field.

Numerical simulation of jet mode in electrospraying of Newtonian and viscoelastic fluids

“…The electrospinning of polyisobutylene-based solutions was investigated theoretically by Carroll and Joo 46 and numerically using the FENE-P model by Zhmayev et al 47 . Additionally, the atomization of polymer solutions was numerically modeled by Qian et al 48 . Li et al 49 used Oldroyd-B and leaky dielectric models to investigate viscoelastic jet axisymmetric and nonaxisymmetric instabilities.…”

Influence of Polyisobutylene Kerosene Additive on Combustion Efficiency in a Liquid Propellant Rocket Engine

“…Owing to the viscoelastic properties of the non-Newtonian PIB kerosene, the cooling film disintegration slowed down and the wavelength of the sheet increased. This resulted in higher travelling distance of the undistorted liquid sheet [3,19].…”

Inhibitory Effects of Convergent Annular Nozzles on the Primary Breakup of Discontinuous Shear-Thickening Suspensions

“…The mechanisms of the primary breakup have gained lots of interest and have been investigated in detail by many researchers. − Through experimental exploration and numerical simulations, the primary breakup process of Newtonian fluids is governed by air–liquid interface instabilities. Many factors affect the performance of primary breakup, such as injection pressure, nozzle geometry, and liquid properties. − To describe the magnitude of surface tension and aerodynamic force, Weber proposed a dimensionless number We = ρ g ( u g – u l ) 2 D l /σ, where ρ g is the air density, u g is the air velocity, u l is the liquid velocity, D l is the exit diameter of the liquid jet, and σ is the surface tension. The viscosity of the working liquid also influences the primary breakup process. , Another important dimensionless number is the ratio of gas-to-liquid momentum flux M = ρ g u g 2 /ρ l u l 2 , proposed by Leroux et al, where ρ l is the density of the liquid jet.…”

“…39−41 Experimental results showed that viscoelasticity influences the evolution and distribution of the drops at the far field. 23,42 Through experimental and simulation studies, it is indicated that the shear-thinning behavior enhances the breakup of the jet. 43−45 According to Ertl and Weigand, 46 the external surface of the jet deforms due to the high-velocity gradient, which leads to a decrease in viscosity and allows it to deform more easily.…”