Particle dispersion in turbulent mixing layer at supercritical pressure

Abstract

The heterogeneous structures of particles are generated due to the significant temperature changes when cold particles-dilute jet injects into a supercritical water fluidized bed, which is unfavorable for the reaction of coal particles. We expect to promote the particle dispersion by entrainment mechanism of large-scale vortical structures. The Eulerian-Lagrangian point-source method is used to numerically investigate the dynamics of dilute particles in mixing layer sustained by supercritical water with different temperatures. The effects of density ratio and velocity ratio between two streams are analyzed. In addition to the smaller particle numbers at high-density side, the particle clustering in the vortex core regions is found due to the inhibition of vortical structures by increasing density ratio. With increasing velocity ratio, however, the enhanced vortex stretching promotes the entrainment of particles. As a result, the increase in particle number density at high-density side is up to 26% compared with the constant-property flow. • Study on variable-density effect on dynamics of particle-laden mixing layer. • Enhancement of vortical structure by increasing velocity ratio between two streams. • Particle acceleration decrease with increasing density ratio between two streams. • Improvement of particle dispersion due to the entrainment of vortical structures.