CFD(computational fluid dynamics) simulation using a commercial package (Fluent-ANSYS)
on industrial rotary kilns using annulus-type burners and methane gas was carried out to examine
the characteristics of the flame length and flow visualization. New influencing design and operating
parameters—primary air swirl number, primary air inlet annulus diameter, and secondary air
temperature—were investigated and discussed. The influence of these parameters on axial temperature
distribution, axialmeanmixture fractions, velocity vectors,mixture fractions, and temperature contours
were investigated. The current numerical findings were compared with existing experimental results
to validate the simulation approach. The results showed that the primary air swirl number had a
remarkable influence on the flame length at a lower primary air inlet annulus diameter ratio of 2.3.
Moreover, the flame length increased by 20% and 6% with increasing the swirl number from zero to
one for primary air inlet annulus diameter ratios of 2.3 and 5, respectively, and it also increased by 19%
with increasing primary air inlet annulus diameter ratio from 2.3 to 5.