THERMAL NATURE OF CONCENTRATION LIMITS OF COMBUSTION

An explanation is proposed for the concentration limits of slow combustion of gas mixtures due to the diffusional–thermal instability of a fl ame and the leading role of the thermal effect of mixture combustion. Basic to this explanation are the following experimental facts obtained for a wide class of mixtures: the concentration limits of slow combustion of a mixture and of its detonation are closely coinciding and depend strongly on the stoichiometric composition of mixture; there is an approximate symmetry relation between the upper and lower combustion limits. It is shown that the fl ame temperature of gas mixtures depends on their stoichiometric composition and that as their stoichiometric relation deviates from unity, the state of mixture combustion approaches the stability threshold beyond which a stationary fl ame cannot exist.
   
Author:  K. O. Sabdenov and T. M. Baitasov
Keywords:  combustion, fl ame, concentration limit, thermal effect, stoichiometric relation, diffusional–thermal instability
Page:  743