Effects of pressure and oxygen concentration on a stabilized premixed combustion

摘要

In the context of thermal mechanisms induced by a hot spot at the surface of a fuel material, the objective of this work is to describe the conditions of the development, over a long period, of its self-heating. On a practical point of view, a better understanding of the phenomena involved during the potential transition from a steady flameless combustion process (subcritical regime) to auto-ignition (supercritical regime) should help to prevent fire. An original set-up has been designed to study the behavior of a gasoline vapors/oxygen enriched air premixed combustion stabilized at the surface of a grid. The effects of the ambient pressure and oxygen concentrations on the stabilization of the flameless combustion has been studied. This allows to identify the conditions (fuel consumption, flame temperature, chemical species concentrations, etc.) under which auto-ignition and flaming of the material becomes possible. Using this experimental configuration, the preliminary steps of a heterogeneous combustion of a fuel solid (or liquid) material, or combustion in a porous medium has been investigated. This experiment is supposed to represent the self-heating of a material leading either to complete extinction or to flaming. This situation can be found in industrial, domestic or wild fire scenarios after the deposit of energy on the surface of a fuel material by natural or human actions.