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 Roeʹs 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 ‘dropletʹ when the chemical reaction is sufficiently fast with respect to the molecular heat and mass diffusion process.