Modeling on effervescent atomization: A review

Abstract

The study and modeling process of effervescent atomization are reviewed. The mechanism of droplet events and the treatment of liquid fragmentation process and dispersed particles are systematically presented, which includes the primary atomization of Newtonian and non-Newtonian fluid, instability analysis, turbulence treatment, particle tracking, secondary atomization and droplets collision. The review on the sub-models involved in the simulation of effervescence is followed by a summary of the achievements of modeling. First is the validation of models; then the parametric study is summarized; the third part introduces the fitting formula of droplet mean size and impinging factors, and finally the scope of future study is indicated. effervescent atomization spray, modeling, review PACS: 47.55.Ca, 47.55.df, 47.60.Kz ALR air-to-liquid ratio, by mass C D drag coefficient D noz nozzle diameter, m d d the droplet diameter, m e internal energy, J F force, N g gravity force, N k turbulent kinetic energy per unit mass k bu breakup frequency, s 1 k  wave number m  mass flow rate, kg/s m mass, kg p pressure kg s 2 /m Q heat source, J q heat flux vector r droplet radius, m Re Reynolds number Sr nterface velocity slip ratio SMD Sauter mean diameter, m U rel relative velocity vector, m/s u, v, w velocity, m/s x radial coordinate, m y axial coordinate, m Greek symbols  volume fraction of gas  deformation parameter  dynamic viscosity, kg/ms  density, kg/m 3  surface tension, kg/m 2  thickness sheet, m  growth rate  viscous dissipation rate, J/ms  distance between the center of one drop and U rel , m  drop oscillation frequency, /s  viscous shear stress tensor Subscript cr criteria g gas l liquid

Effects of angular injection, and effervescent atomization on high-velocity suspension flame spray process

“…2c. The motion of the liquid at the exit of the injector creates a gas-core surrounded by the liquid film, and due to the pressure difference gases expand and shatter the liquid film into ligaments and fine droplets [32][33][34]40,[42][43][44]. For the ETI, different spray-half-angles of θ = 4°, 6°, and 8°are selected based on various GLRs of 0.095, 0.190 and 0.285, respectively ( Table 2).…”

“…The experiments using an effervescent atomizer nozzle by Liu et al [32] and numerical work of Qian and Lin [43] are utilized for the validation of present numerical work. The present model and the numerical and experimental work considered here for validation use the effervescent nozzle spraying the water droplets into the atmosphere.…”

“…On emerging from the nozzle, due to the pressure difference, gas bubbles rapidly expand and shatter the liquid into ligaments and fine droplets. This method offers the advantage of smaller drop sizes at low injection pressure and atomizing even high viscosity liquids effectively [32][33][34][40][41][42][43][44]. The droplets size and distribution are dependent on the suspension concentration, viscosity, and surface tension which was extensively analysed by the researchers [33,43,45,46].…”

“…Researchers also presented the numerical modelling of effervescent atomization's internal and external flow regimes [33,41,43,44,46]. Esfarjani and Dolatabadi studied the droplets disintegration and twophase flow structure inside the effervescent atomizer [47] using a broad range of nanoparticles types and concentrations for suspension plasma spray process where no effect on the performance of effervescent atomizer was observed [47].…”

“…Smaller values of GLR would decrease the atomization while the larger orifice diameter would result in larger liquid droplets, and the smaller value of the injection pressure could also affect the atomization process adversely. Hence, for increasing the efficiency of effervescent atomization higher values of GLR and injection pressure with smaller orifice exit diameter should be used [33,43,48]. Furthermore, Fung et al [49] experimentally and numerically studied the spray atomization under low pressures.…”