A Fitting Formula for Predicting Droplet Mean Diameter for Various Liquid in Effervescent Atomization Spray

Abstract

The outflow of the effervescent atomization spray is simulated by a comprehensive numerical model based on the Navier-Stokes equation and the particle tracking method. The droplet mean diameter under different operating conditions and liquid properties were calculated. Based on the extensive computations, a formula relating droplet Sauter mean diameter to the operating conditions and liquid physical parameters were obtained with curve fitting technique. The results calculated from the formulae were compared with the experimental data and a good agreement was obtained. The formulae can be used to predict the droplet mean diameter for various Newtonian liquid in axisymmetric effervescent atomization spray conveniently and effectively.

The 2016 Thermal Spray Roadmap

“…The particles must be accelerated and melted, once freed from their liquid carrier (transport media with higher momentum than that of gas) (Ref 65 An optimal liquid injection, to avoid droplets poorly treated in the jet fringes, requires that drop velocities and diameters can be controlled separately before their injection into the hot stream (Ref 64,66). Unfortunately, this is not the case with the three means actually used for injection into plasma jets: (1) co-axial atomization by the injection of a low-velocity liquid inside a nozzle where it is fragmented by a gas (mostly Ar) expanding inside the nozzle, (2) mechanical injection producing uniformly spaced droplets, whose diameters depend on the liquid velocity, these two parameters being not controlled separately, (3) effervescent atomization, where a small amount of gas is injected into the liquid before the exit orifice to form a bubbly mixture of gas and liquid (Ref 67,68). On emerging, due to the pressure difference, the gas bubbles rapidly expand and shatter the liquid into ligaments and fine droplets.…”

Modeling on effervescent atomization: A review

“…Most modeling work focused on the external two-phase flow out of the effervescent atomizer exit [13,14,16,23,[27][28][29][30][31][32][33][34][35][36]. For gas-liquid two phase flow, there are two approaches to establish the numerical model.…”

“…Without considering secondary atomization, these models could not account for the spray evolution along the downstream of the exit orifice, which is critical to the engineering applications of atomization sprays. Lin and his co-workers [27][28][29][30][31][32][33][34][35][36] proposed a three-dimensional model to predict the droplet mean size and other spray characteristics by describing both primary and secondary atomizations [27][28][29]. They described the breakup mechanisms for both Newtonian fluid and non-Newtonian fluid by different primary atomization models [30,31], discussing the characteristics of impinging spray field in detail and indicated the proper plate distance [32,33].…”

“…They also studied the evolution of droplets mean diameter along the axial distance, the mean size and statistical distribution of atomized droplets at cross sections, as well as calculating and analyzing the change of droplet velocity and to reveal their inner driving force [27][28][29]31]. They worked on the influence of operating conditions and liquid physical properties [31], concluded the factors for achieving good atomization effects [27][28][29][30][31][32][33][34][35][36], quantified the influences of various operating conditions and liquid physical properties on atomization effects and impinging outcomes [34,35], and extended the use of effervescent atomization to suspension plasma spray [30,37].…”

Equal consistency spraying and flow field characteristics of spraying water pipe

“…For effects of liquid properties on the spraying, a fitting formula for predicting droplet mean diameter for various liquids in effervescent atomisation spray has been created and a non-Newtonian suspension plasma spraying in an inductively coupled plasma torch has been modelled. [9,10] Meanwhile, effects of operating conditions on the droplet deposition onto the surface in the atomisation impinging spray with an impinging plate have been studied. [11] Until now, there is little literature on the equal consistency spraying.…”