Numerical simulation of reacting flows around a bluff-body flame stabilizer with lattice boltzmann method

A 2-dimensional lattice Boltzmann model for combustion phenomena is presented. Mathematically, the model is composed of a standard lattice Boltzmann distribution function to recover the hydrodynamic model which describe the density and flow velocity and two distribution functions to recover the governing equation of temperature and chemical reaction process. The temperature could be described by solving an advection-diffusion equation with a simpler lattice. The actual combustion processes are very complicated. In this work, we consider the simple combustion processes with the assumption that the reaction process is irreversible and described by an empirical equation. The evolution of chemical process is described by another passive scalar convection-diffusion equation. The chemical energy released in the progress of combustion is dynamically coupled into the system by adding a chemical term to the temperature distribution function. The model is verified and validated via well-known benchmark tests. In this paper, the case of vortex street arising from the flow around the circular cylinder at Re=100,150 and 200, is taken to examine the validation of the numerical simulation. The Strouhal numbers achieved in the numerical simulation match well with the theoretical values. We also simulate a flame at constant pressure to validate the model, the temperature and concentration distributions is consistent with the laminar premixed combustion theory. The objective of the present work is to investigate the effect of Reynolds number on the stability of the flame behind the bluff-body. For the circular cylinder flame stabilizers, the effect of different inlet speeds on flame stability was investigated.