The polydisperse behaviors of a binary ultralight–heavy mixture particle flow in a swirling axisymmetric chamber were investigated based on a developed second-order-moment gas–particle turbulent model. A binary particle Reynolds stress transport equation to depict the anisotropic interactions between gas-mixture particles and binary ultralight–heavy particles was established to close the governing equations. Hydrodynamic parameters, including particle number density, particle and gas velocities, and fluctuation velocities, Reynolds stress tensors, and their invariants, turbulent kinetic energy, and vortex structure, are numerically simulated. The detailed effects of the density, the diameter of the particle, the Stokes number, and the ultralight particle mass loading ratios on the flow status were studied. It is shown that normal and shear Reynolds stresses and kinetic turbulent energies of mixture particles have been redistributed, particularly, they are very sensitive to the mass loading ratios. Higher particle mass loading ratios enhanced the anisotropic characteristics. The particle number density at central regions of the farthest downstream is approximately three times larger than those of smaller mass loading ratios. Larger Stokes number particles reinforced the axial fluctuations up to 1.2 times that of the light particles, whereas ultralight particles increased tangential fluctuation to 2.5 times for axial ones.

Turbulence modulations by particles of a swirling gas–particle two-phase flow in an axisymmetric chamber are numerically simulated. To fully consider the preferential concentrations and the anisotropic dispersions of particles, a second-order moment model coupling particle–particle collision model was improved. Experimental validation for the proposed model, algorithm, and in-house codes by acceptable match was carried out. The effects of ultralight-expanded graphite and heavy copper particles with a large span of Stokes number on gas velocities and fluctuations, Reynolds shear stresses and tensor invariants, turbulence kinetic energies, and vortice structures are investigated. The results show that turbulent modulation exhibits strong anisotropic characteristics and remains in a close relationship with the flow structure. Modulation disturbances and vortex evolution are enforced by heavy-large particles with higher Stokes numbers. Preferential accumulations of ultralight particles in shear stress regions at lower vortices are weaker than those of heavy particles. For axial turbulence modulations, a heavy particle plays the primary role in the inhibition action because of larger inertia, and a light particle contributes to the enhancement effect due to excellent followability. The instantaneous flow information and coherent turbulent structure are failed to be acquired due to the limitation of the Reynolds time-averaged algorithm.

The dispersion characteristics of ultralight particle (expanded graphite) in swirling mixture particle‐laden coaxial jet combustor was modeled and numerically predicted using developed second‐order moment gas‐particle multifluid turbulent model. An improved gas‐particle and particle‐particle Reynolds stress transport to describe its anisotropic behaviors was proposed. Experimental validation for single‐phase particle flow has been conducted with satisfied agreement. The multifluid hydrodynamic parameters, that is, number density, particle velocity, fluctuation velocity, Reynolds stress correlation of gas‐particle and particle‐particles, and effects of swirling number are investigated. The results found that the ultralight particles exhibited the distinctive anisotropic behaviors, and their unique flow structures were quite different from those of heavier particles. Under the strong swirling flow condition, the anisotropic dispersions were enhanced and concentration at recirculation regions increased. The axial velocities and fluctuations, and the axial‐axial and tangential‐tangential stress correlations of gas‐particles were weakened. The effect of swirling strength on ultralight particle dispersions is more sensitive in comparison with heavier particle.

In the present work, the investigation on strategies to alleviate the cell death in terms of bubble‐liquid two‐phase hydrodynamics in bubble column was performed using the modeling and numerical simulation approaches. A multifluid bubble‐liquid turbulent model based on the second‐order moment algorithm was developed to predict turbulent hydrodynamics. In this model, the anisotropic characteristics of Reynolds stresses and the interactions between bubble and liquid phases are considered by means of the defined bubble‐liquid two‐phase fluctuation velocities correlation. Hydrodynamic parameters such as turbulent energy dissipation rate, the turbulent kinetic energy, the distributions of bubble normal and shear stresses, and the operation conditions of gas entrance velocity and height to diameter of column are accurately simulated. A proposed correlation named turbulent energy production rate is revealed successfully the higher cell death rate at the gas inlet regions that cannot be verified by the rest of the two‐phase hydrodynamics. Superficial gas velocity is the predominant influence on this value distribution as smaller the ratio of height to diameter of bubble column, which reduced by two order of magnitude under decreased by one level of gas velocity. Near inlet region with large height‐to‐diameter ratio, this value is always larger than those of small one.