Predicting the Liquid Film Thickness and Droplet-Gas Flow in Effervescent Atomization: Influence of Operating Conditions and Fluid Viscosity

The droplet-gas flow in effervescent atomization was simulated using a comprehensive numerical model. Liquid film thicknesses in the nozzle exit orifice and droplet size distribution at the downstream of spray were calculated. The thickness of liquid film in the nozzle exit orifice increased and approached the droplet size in the primary atomization, as the air-liquid ratio increased. The primary breakup model can accurately predict the Sauter mean diameter in the primary atomization when gas-liquid two-phase flow belongs to the annular flow in the nozzle exit orifice. The viscosity of fluid had minimal influence on the liquid film thickness for spray with fluids, the viscosity of which is significantly greater than that of water. Droplet size initially decreased and then increased along the axial distance because of the secondary atomization and droplet coalescence at the downstream of spray.