Numerical Modeling in Radio Frequency Suspension Plasma Spray of Zirconia Powders

Abstract

A comprehensive model was developed to investigate the suspension spraying for a radio frequency (RF) inductively coupled plasma torch. Firstly, the electromagnetic field is solved with the Maxwell equations and validated by the analytical solutions. Secondly, the plasma field with different power inputs is simulated by solving the governing equations of the fluid flow coupled with the RF heating. Then, the suspension droplets embedded with nano particles are modeled in a Lagrangian manner, considering feeding, collision, heating and evaporation of the suspension droplets, as well as tracking, acceleration, melting and evaporation of the nano or agglomerate particles. The noncontinuum effects and the influence of the evaporation on the heat transfer are considered. This particle model predicts the trajectory, velocity, temperature and size of the in-flight nano-or agglomerate particles. The effects of operating conditions and intial inputs on the particle characteristics are investigated. The statistical distributions of multiple particles' size, velocity, temperature are also discussed for the cases with and without consideration of suspension droplets collision. List of symbolsheat of evaporation (J kg -1 ) m Mass Nu Nusselt number Pr Prandtl number, Pr = m/a Q J Joule heating (W m -3 ) Q conv Convection heat (W m -3 ) Q rad Radiation heat loss (W m -3 ) Q vap Vaporization heat (W m -3 ) R Radius (nm) Sh Sherwood number r Radial coordinate (m) t Time (s) T Particle temperature (K)

Modeling on effervescent atomization: A review

“…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].…”

Modeling of non-Newtonian suspension plasma spraying in an inductively coupled plasma torch

“…Furthermore, as studied by Ref. [16], the effects of droplet collision and coalescent events on the final particle characteristic are not significant under normal operating conditions. Therefore, with temperatures in the order of 10,000 K, the dominant events of the atomized droplets in a RF plasma field are heat and mass transfer.…”

“…(11), f v accounts for the effect of mass transfer due to evaporation [16]: f v approaches one when the evaporation mass rate _ m v is close to zero. f v is smaller than one when _ m v is larger than zero.…”

“…The calibration of the plasma model and the validation of the gird dependency have been established in Ref. [16].…”

“…Recently, Esfarjani and Dolatabadi [15] numerically investigated the two-phase flow inside an effervescent atomizer for the suspension plasma spray. Qian et al [16] numerically studied the evolution of drops in the suspension plasma spray for a radio frequency (RF) torch. However, for suspension plasma spray, the breakup mechanism of nonNewtonian liquid jet has not been reported yet.…”