Abstract:
The objective of this thesis was to investigate flame
radiation and smoke emission phenomena in a combustor typical
of those in use in aircraft gas turbine engines. One of the
primary aspects of the investigation was to compare the
performance of airblast atomisers with that of conventional
swirl atomisers under as near identical conditions as possible.
A brief study of combustion chamber processes and carbon
formation and thermal radiation mechanisms was made, with
consideration of such experimental data as exists in the literature.
An airblast atomiser and combustion chamber was developed
to a state whereby testing at rich mixtures at moderate combustion pressures could be performed for short periods. This
enabled a preliminary comparison to be made monitoring the
following parameters:-
(i) Flame total radiation.
(ii) Exhaust smoke level.
(iii) Weak extinction.
Data was collected at three different combustion pressures
for various air-fuel ratios and chamber velocities. The results
showed that the airblast atomiser offers significant advantages
over swirl atomisers with regard to total flame radiation and
exhaust smoke emissions whilst suffering from a poor weak
extinction.
A more detailed analysis was performed for swirl atomisers
using the Schmidt Method to establish flame temperatures and
emissivities. The object of this work was to assess the effects
of droplet size and combustion pressure on flame radiation.
Owing to the poor atomisation quality and fuel distribution
of the airblast atomiser used for the preliminary work, two new
injectors were designed. It was hoped that a detailed analysis
for these injectors could be performed via the Schmidt Method in
order to provide a comparison with the swirl atomisers. Unfortunately, manufacturing was not completed with sufficient time
left for this analysis to be completed.
