Numerical study of mean mechanical energy loss in a gas cyclone

Reducing energy loss is one of the goals of optimizing gas cyclones, which can be benefitted from a deep understanding of the energy loss mechanism in gas cyclones. In this study, the gas-solid flow in a gas cyclone was simulated using the combined computational fluid dynamics (CFD) and the discrete element method (DEM). An energy loss model for analyzing the spatial distribution and proportion of the mean mechanical energy loss of the gas cyclone was adopted and validated in terms of the total pressure drop. It is found that the near-wall region generally has high rates for both viscous dissipation and turbulent production, especially the vortex finder, the conical part, and the discharger. The effects of the inlet velocity, the wall roughness, and the particle loading ratio on the energy loss are studied. The findings reveal that increasing the inlet velocity mainly increases the viscous dissipation of the wall and the turbulent production of the core region, resulting in an increase in mechanical energy loss. In contrast to the energy loss mechanism of the pipe, the mechanical energy loss of the gas cyclone decreases slightly with increasing wall roughness, which is mainly caused by the reduction of the viscous dissipation of the wall. By injecting particles, the spatial distribution of the energy loss rate is greatly altered, and the mechanical energy loss is also reduced. Further analysis shows that increasing the particle loading ratio reduces both viscous dissipation and turbulent production.