The development and application of a numerical model of an actively control
led combustor are described. The! main objective was to develop a model tha
t could be used as a platform for studying closed-loop control of unstable
combustors. The model uses a heuristic approach and global kinetics to desc
ribe mixing and combustion processes in a one-dimensional gaseous combustor
. initially, the model is used to investigate a combustor's response to ope
n-loop excitation by periodic fuel injection. The numerical model's predict
ion that 1) the pressure oscillation amplitude decreases and 2) the phase s
hift between the fuel injection rate and heat-release oscillations increase
s linearly, as the frequency of fuel injection rate increases, are in good
agreement with experimental data from a gas rocket. Nest, closed-loop contr
ol is studied. The investigated controller determines the characteristics o
f the most unstable mode in real time and damps the instability by modulati
ng the injection rate of a fraction of the injected fuel to excite a second
ary combustion process within the combustor out of phase with respect to th
e most unstable mode of pressure oscillations. Active control examples incl
ude the study of the dependence of the controller's performance on the amou
nt of fuel pulsed.