Effect of non-Newtonian Rheology on Bag Breakup at Different Liquid to Gas Density Ratios

Spray and atomization of non-Newtonian fluids are seen in engineering applications like combustion of jelled propellants, food, pharmaceutical industry, and chemical process industries. The final droplet size distribution of any spray system is determined by the dynamics of secondary droplet breakup. Droplet breakup dynamics have been well studied for Newtonian fluids. However, only limited studies are reported in the open literature on droplet breakup for non-Newtonian fluids. Moreover, experimental studies of droplet breakup at elevated pressures are difficult to perform. Therefore, this work reports droplet breakup of non-Newtonian fluids at different liquid-togas density ratios using a two-phase finite volume CFD solver. A Coupled Level Set VOF solver based on OpenFOAM libraries has been used in this study. Liquid/gas density ratio ranging between 10 − 103 has been studied. Both shear-thinning and shear-thickening fluids are considered and power-law rheology in the form τ = Kγ̇ n is assumed in this work. Fluid with power-law index, n ranging between 0.2 and 1.8 was simulated. The breakup of a single isolated 2D axisymmetric droplet under bag breakup conditions has been studied. Time-resolved droplet deformation, drag force, and breakup time were estimated for the different flow conditions and presented as part of this work. © 2022 Begell House Inc.. All rights reserved