A review for developing two-fluid modeling and LES of turbulent combusting gas-particle flows

Abstract

Present two-fluid models are mainly for dense gas-particle flows and combustion in fluidized beds, where the particle-flow behavior, like the particle stress is determined only by inter-particle collision based on kinetic theory. For gas-particle flows and combustion in pulverized solid-fuel combustors and furnaces, where the particle dispersion is determined by its turbulent fluctuation, the mainly used approach is Lagrangian treatment of the particle phase—trajectory models, which needs large computational effort for giving detailed information of the particle flow field in the three dimensional space. An alternative approach is the two-fluid modeling. However, for taking this approach it is necessary to develop the models of particle turbulence and particle history effect. A k-ε-kp model and a unified second-order moment (USM) two-phase turbulence model were proposed by the present author. Regarding to the particle history effect, a two-fluid-trajectory (TFT) model (a continuum-trajectory model of particle phase) and a full two-fluid (FTF) model were developed by the present author. Both TFT and FTF models have been applied to simulate combusting gas-particle flows. The simulation results are validated by experiments. Besides, a LES of swirling combusting particle flows was also made by the present author to study the interactions among the turbulence, particles and combustion. In this paper, a review is given for developing these models by the present author and his colleagues.