IGNITION OF A RECTANGULAR SOLID BY AN EXTERNAL HEAT-FLUX

The influence of corners on the ignition of a solid exposed to a surfa ce energy flux is analyzed with large activation energy asymptotics. W e begin with the analysis of the ignition of semi-infinite wedges by a constant heat Aux. Two stages and two spatial zones, reactive and ine rt, are found. The ignition stage can be described by a slowly converg ent asymptotic expansion for the increment in temperature due to the c hemical reaction or, more accurately, by a simplified nonlinear parabo lic equation to be solved numerically. This analysis applies to the ig nition of two-dimensional finite bodies with corners if the external h eat Aux is large enough for the size of the reaction zone to be much s maller than that of the solid. The ignition of bodies with rectangular shape for small heat fluxes, when the reaction zone extends to the wh ole solid, is also analyzed.