Two-fluid turbulence modeling of swirling gas-particle flows - A review

Swirling gas-particle/droplet flows are commonly encountered in various engineering equipments, such as gas turbine combustors, gas-solid cyclone separators, cyclone combustors, hydro-cyclones and swirl burners/combustors in furnaces. To better understand the flow behavior by using numerical simulation is important for optimization and scaling-up of design, in order to increase the combustion efficiency and separation efficiency, reduce the pressure drop and pollutant formation, and stabilize the flame. Many-year systematic two-fluid modeling studies of swirling gas-particle flows were done by the research group directed by the present author, including Reynolds-averaged Navier-Stokes simulation (RANS modeling) using k-epsilon-k(p), unified second-order moment (USM), Reynolds-stress-PDF (DSM-PDF), SOM-Monte-Carlo, and non-linear k-epsilon-k(p) two-phase turbulence models, proposed by the author and two-fluid large-eddy simulation (LES) using a two-phase sub-grid stress model, proposed by the author. The results give the two-phase time-averaged velocities, two-phase RMS fluctuation velocities, and particle concentration distribution, which indicate the advantage of E-E modeling over the E-L modeling and show the complex recirculation structures in the two-phase axial velocities and the Rankine vortex (solid-body rotation plus potential vortex) structures in the two-phase tangential velocities, the anisotropic two-phase turbulence properties, and the effect of different closure methods on the two-phase flow behavior of swirling gas-particle flows. These results will help to develop highly efficient and low pollutant separators and combustors. This paper gives a brief review of our studies and will help the readers to understand in more detail the specific features of two-fluid modeling of complex turbulent gas-particle flows (C) 2016 Published by Elsevier B.V.