Flame propagation along the interface between a gas and a reacting medium

Flame propagation process over the surface of a solid or liquid fuel (or oxidizer) in contact with a gaseous oxidizer (or fuel) is studied. Flame propagation velocity is calculated by assuming that flame reaches a certain location when temperature at the fuel surface at that location reaches an ignition temperature. This assumption is correct when the time consumed for the heating process is large as compared with the time required for vaporization of the fuel, mixing, and combustion of the oxidizer-fuel vapors mixture. Heating of the fuel ahead of the flame is studied by considering radiation and convection heat-transfer mechanisms flame to fuel, and bidimensional heat conduction within the fuel. The problem lies in solving a heat-balance partial-differential equation in the solid or liquid fuel for which heat fluxes from the flame are the fundamental boundary conditions. An analytical solution is obtained by means of a boundary-layer approximation, and general results are given. An experimental and theoretical application of the general study is performed for the case of liquid hydrocarbon fuels burning in ai