Fully Resolved Simulation of Char Particle Combustion By Immersed Boundary-Lattice Boltzmann Method

There are many challenges for fully resolved simulation of char particle combustion as it couples many physical and chemical process, such as the momentum, heat and mass transfer in inter-phases and the existed heterogeneous and homogeneous reactions. Limited relevant reports can be found to date, especially for the suspended particles. Immersed boundary-lattice Boltzmann method (IB-LBM) has been widely used for the simulation of cold or hot particle-laden flows. A new improved IB-LBM is developed for fully resolved simulation of char particle combustion. The fluid reactive flow is solved by LBM with multi-distribution function scheme. The boundary Dirichlet and Neumann conditions at the particle surface, such as velocity, temperature, and chemical species concentration, are well enforced by the improved immersed boundary method. The combustion reaction in the domain is described by two semi-global heterogeneous reactions and one homogeneous reaction. in addition, MPI parallel computing strategy is adopted to perform the accelerated and large-scale calculation. A benchmark validation is implemented to find a satisfactory agreement between the present simulation results and experimental data in previous literatures. The method is then used to investigate the combustion property of a single char particle. The effects of the temperature of coming flow, Reynolds number, oxygen concentration and environment of combustion (air and oxygen) on burning rate are detailed analyzed. Furthermore, the combustion of particle group with different number of char particles are simulated. And the effect of flow field disturbance on each chemical component as well as the effect of char particles number and spatial distribution on burning rate are discussed.