Ignition of fuel issuing from a porous cylinder located adjacent to a heated wall: a numerical study

This work deals with the numerical simulation on an unstructured mesh of the ignition and burning in an oxidizing atmosphere. of a fuel droplet heated on one side. This is relevant for studying the ignition of droplets in a spray when they are crossing a flame zone stabilized in it. The droplet here is replaced by a porous cylinder, and the flame by a hot solid wall. The reaction is assumed to be described by a single step, A + vB --> P. The cell-centred finite volume scheme considered here uses a generalized Roe's approximate Riemann solver with the monotonic upwind scheme for conservative laws (MUSCL) technique for the convective part and Green-Gauss type interpolation for the viscous part. The thinness of the reaction zone is taken into account by using,an adaptive refinement-unrefinement procedure. It has been found that the process of droplet ignition takes place by means of a propagation of a triple flame around the 'droplet' when the chemical reaction is sufficiently fast with respect to the molecular heat and mass diffusion process.