Self-induced unstable behaviors of CH4 and H2/CH4 flames in a model combustor with a low-swirl injector

Abstract Laboratory experiments and modeling analysis have been conducted to gain insight on the self-excited unstable flame behaviors of a model gas turbine combustor that utilizes a low-swirl injector (LSI). The combustor consists of a 5.7 cm I.D. LSI firing into 18 cm diameter by 32 cm or 20.3 cm long cylindrical enclosures at atmospheric condition. The experiments involved lean premixed turbulent CH 4 (0.6  ϕ 2 /0.1 CH 4 (0.3  ϕ 4 flame, analysis shows that the roll up vortices from the dump plane are responsible for generating self-excited acoustically coupled flame instability. For the 0.9 H 2 /0.1 CH 4 flame, the GIM analysis suggests a dominance of shedding vortices but is less conclusive due to flame attachment to the LSI rim resulting from the highly reactive H 2 fuel and possible unsteady heat release contributions from bulk flow oscillations.