Lean premixed combustion
is one of the most effective methods to
constrain pollutant emissions for modern industrial gas turbines.
An experimental study was performed on its propagation speed and internal
structure at engine-relevant temperatures. A Bunsen burner was employed
for the measurement with an optical schlieren system. The results
show that the increase of preheating temperature dramatically accelerates
the propagation of methane flames. The numerical results predicted
by
GRI-Mech 3.0, FFCM-1, and USC Mech II were also compared. The GRI-Mech
3.0 seems to overestimate the laminar flame speed at high operating
conditions, while FFCM-1 underestimates the laminar flame speed compared
to the present experimental data. The prediction by FFCM-1 shows good
agreement with the overall existing data. The USC Mech II seems to
overestimate the laminar flame speed at fuel-lean conditions while
shows good agreement with present experimental measurements at stoichiometric
conditions when the inlet temperature increases. It is also indicated
that the flame is thinned at high-temperature conditions and the importance
of CO production to the propagation speed increases. Finally, based
on the experimental data, an empirical correlation of the laminar
flame speed was developed in the range of T
u = 300–800 K and ϕ = 0.7–1.0, the maximum deviation
of which was less than 8%. The results of this study may contribute
to the optimization of advanced gas turbine combustors.