Numerical Analysis of the Particle Dynamics in a Supersonic Gas Stream with a Modified Point-Particle Euler-Lagrange Approach

Numerical simulations of a gas-particle jet through a Laval nozzle are performed using a modified point-particle Euler-Lagrange approach. By excluding the particle-occupied fluid fraction when solving the fluid phase equations and accounting for gas-particle and inter-particle interactions in the mathematical framework, the particle motion behaviors in gas stream and their impact on gas stream structure are studied, and the nonequilibrium dynamics of the two-phase flow are revealed by depicting the particle velocity and temperature evolution in gas stream. The results indicate that the preferential concentration of particles occurs in gas stream, resulting in nonuniform jet structure. The preferential concentration mainly occurs in nozzle divergent section and makes the local flows there lie in dense regime even if a dilute two-phase flow is predetermined. The level of the preferential concentration increases when the powder feeding rate or the particle size increases. Thus, it is necessary to consider the volumetric displacement effect of dispersed phase when modelling such a gas-particle jet system. Based on the impact of powder blowing parameters on particles motion and distribution and oxygen jet structure, the powder feeding rate no more than 2.0 kg/s and the particle size of 50 to 100 mu m are suggested for real industrial operations.