Penetration, accumulation, and swing characteristics of particle cloud in a turbulent axisymmetric opposed-jet flow

Abstract

The behavior of particle cloud in a high Reynolds number (13500) turbulent opposed-jet flow with a moderate nozzle separation (12 times the nozzle diameter) is investigated by a two-phase large eddy simulation. Euler/Lagrangian approaches are applied to simulate gas and particle phases, respectively. Two-way coupling is considered, and a deterministic hard-sphere collision model is used to deal with the interparticle collision. Three particle Stokes numbers (8, 37, and 180) and three particle volume fractions (2 × 10−5, 1.5 × 10−4, and 4.8 × 10−3) are tested. Particle inertia and interparticle collisions are found to exert a significant effect on particle distribution and velocity characteristics, a strong interaction is observed between particle cloud and gas impingement plane. Particle inertia strengthens the penetration of particles in the opposite stream, thus widening the particle aggregation region and decreasing the peak value of particle concentration. The mixing of rightward- and leftward-moving particles in the particle penetration distance noticeably decreases the particle axial mean velocity and increases the particle axial fluctuation velocity. Furthermore, interparticle collisions suppress the reciprocating penetration of particles in the opposed jets and force the particles to accumulate near the impingement plane. Meanwhile, interparticle collisions increase the particle radial mean and radial fluctuation velocities by energy transfer from the axial direction to the radial direction. The unstable gas impingement plane can drive the swing of particle aggregation region, especially for the small inertia particles and massive interparticle collisions. By contrast, the particle cloud can enhance the stability of gas impingement plane, which significantly reduces the gas velocity fluctuation in the impinging region.