Effects of higher wall roughness on dense particle–laden dispersion behaviors

To analyze the effects of higher wall roughness on dense particle–laden dispersion behaviors under reduced gravity environments, a dense gas–particle two-phase second-order-moment turbulent model are developed. In this model, the wall roughness function and the kinetic theory of granular flows are coupled and closed. Anisotropy of gas–solid two-phase stresses and the interaction between gas–particle are fully considered using two-phase Reynolds stress model and the two-phase correlation transport equation. Numerical simulation test is validated by Sommerfeld and Kussin (2003) experiments data with higher wall roughness 8.32 μm. Predicted results showed that the particle concentration distribution, particle fluctuation velocity, particle temperature and particle collision frequency are greatly affected by higher wall roughness, as well as particle Reynolds stress and interactions between gas and particle turbulent flows are redistributed. Under microgravity conditions, particle temperature and collision frequency are greatly less than those of earth and lunar gravity.

Figure Profiles of axial–axial fluctuation velocity correlation of gas and particle. Gas–particle fluctuation velocity correlation is an important term in the SOM two-phase turbulence model, which stands for turbulence interaction between the gas and particle Reynolds stresses. It indicated that turbulence interaction between gas and particle Reynolds stresses comes mainly from the gas and large-scale particle turbulence fluctuation.Figure optionsDownload as PowerPoint slideHighlights
► A dense gas particle two-phase second-order-moment turbulent model are developed.
► The effects of higher wall roughness on particle dispersion are considered.
► Particle Reynolds stress and interactions of two-phase turbulent flows are redistributed.
► Particle temperature and collision frequency under microgravity have smaller value.