EFFECT OF INNER FLAME EQUIVALENCE RATIO ON THE LEAN CO-AXIAL PREMIXED WITH NONPREMIXED FLAMES.

Faculty of Engineering, Al-Azhar University, Cairo, Egypt

The premixed flames have the advantage of homogeneous air fuel ratio overall the

combustion space, through which it is possible to control its emissions according to rich or

lean conditions. The nonpremixed flames can produce a range of local compositions spanning

a wide range of stoiechiometries i.e. within the combustion space; there may be regions that

are quite rich, while others may be quite lean. This aspect of nonpremixed combustion adds

considerable complexity to the problem of pollutant formation in such systems. Unfortunately

the stability limits of the premixed flames are extremely narrow. Therefore, the use of lean

premixed flames is quite handicapped.

The present work aims mainly to increase the usage of lean premixed flames by adding, in its

core, a nonpremixed flame. This will help to widen the stability limit of premixed flame as

well as reduce the usage of full energy produced by nonpremixed systems. The results show

that by adding the spray of nonpremixed flame to the premixed flame, the produced flame

mean temperatures are reduced, also the flame stability is increased and its emissions are

reduced.