Evaluation of unsteadiness in effervescent sprays by analysis of droplet arrival statistics - The influence of fluids properties and atomizer internal design

The ideal spray theory of Edwards and Marx was used to investigate the dependence of effervescent spray unsteadiness on fluid properties and atomizer internal design. Results demonstrate that fluid properties and internal design of atomizer directly affect the two-phase flow pattern inside the atomizer which consequently affects the spray unsteadiness of the atomizer. Water sprays are more unsteady when the air to liquid ratio (ALR) increases, whereas, more unsteady is observed for using glycerol/water mixture (high-viscosity Newtonian fluid) or glycerol/water/xanthan (non-Newtonian fluid) mixture as ALR reduces. In addition, sprays using low-viscosity or strong non-Newtonian fluids usually are more unsteady, regardless of ALR. A short mixing chamber results in less unsteady for water but has no effect on spray unsteadiness for high-viscosity or non-Newtonian fluids at ALR of 0.15. Otherwise, the influence of mixing chamber distance on the spray quality is weak at ALR of 0.15. Large diameter of inclined aeration holes shows the low spray unsteadiness and good spray quality for water but causes more unsteady for glycerol/water/xanthan mixture at ALR of 0.15. Furthermore, the diameter of the inclined aeration holes has little influence on spray unsteadiness for glycerol/water mixture. Spray unsteadiness and quality are not affected by the angle of aeration holes for three fluids at ALR of 0.15. (C) 2010 Elsevier Inc. All rights reserved.