1. The increase of the primary air greatly suppresses the concentration of soot in the annular
region of the ¯ame. This subsequently reduces the energy transfer to the ¯ame axis.
2. The maximum soot concentration lies inside the maximum ¯ame temperature in both types
of ¯ame, but the distances between these positions are larger in the double ¯ames than those
in the diusion ¯ames.
3. In diusion ¯ames, the increase in fuel ¯ow rate increases the amount of soot present in the
exhaust of the combustion chamber, thus increasing radiation losses. This, in turn, causes a
lower exhaust temperature.
4. In all tested diusion ¯ames, the rates of soot formation and maximum soot concentration
are similar at the ¯ame axis.
5. The increase in primary air by 10% of the stoichiometric air requirement of the fuel causes
a 70% reduction in maximum soot concentration.
6. The time required to initiate soot formation at the ¯ame axis becomes longer as the primary
air is increased.
7. In double ¯ames, the rate of temperature increase is higher than that in diusion ¯ames.