variavel0=<b>FERNANDO FACHINI FILHO</b> - fachini@cptec.inpe.br INPE
<b>Abstract.</b> The analysis addresses the extinction problem of diffusion flames in which two fuels are consumed simultaneously. A single step finite rate reaction is considered for each fuel. The extinction problem is described by the large activation energy asymptotics, assuming that the ratio of the activation energies for the two reactions is order unity. Thus, the two chemical reactions take place inside the same zone in the flow field. The present model is characterized by two new parameters. The first parameter, D, is the ratio of the Damkh¨oler numbers of the second and first reactions. It measures the reactivity of the second reaction in terms of the first reaction reactivity. The second parameter, AE, is the ratio of the activation energy of the second reaction to the activation energy of the first reaction. It specifies the thermal sensitivity of the second reaction in terms of the thermal sensitivity of the first reaction. For equal reactivities (D = 1) and equal thermal sensitivities (AE = 1) the classical results (Liñán, 1974) are recovered. The results obtained show a flammability limit for bicomponent fuel diffusion flames.
<b>Keywords.</b> large activation energy asymptotics, extinction, diffusion flame, internal flame structure, bicomponent fuel.