A co-located particle method for transported PDF simulations of coal flames

摘要

When applying transported PDF methods to the simulations of turbulent pulverized coal flames, two types of particles coexist. One is notional particles for the turbulent gas mixtures, the other one is Lagrangian representation of dispersed coal particles. In a Reynolds-Averaged Simulation, each notional particle for the gas mixture represents an independent realization. Therefore, it may evolve according to a complete different scalar path if the gas mixture contains a coal particle. In this work, a co-located particle method is proposed to resolve the highly-localized multiphase interactions between gas and coal particles, which cannot be resolved easily by a separate representation of gas and solid phases. The coal particles are co-located with a subset of gas notional particles. Each notional particle, regardless containing coal particles or not, represents an independent realization of small mass of the reacting mixture. If the mixture contains coal particles, its evolution is governed by coal combustion interactions. Conversely, if the mixture does not contain any coal particles, it evolves as a conventional particle of the PDF methods. Gaseous mixing occurs among all notional particles in a cell. However, heterogeneous interactions, e.g. multiphase transfer of momentum, heat or mass, are restricted within a notional particle. A sample calculation demonstrates how this arrangement affects particle heat transfer and joint statistics of particle and carrier gas temperatures in a mixing layer.