Effect of Different Fuels on Combustion Instabilities in an Annular Combustor

Abstract Combustion instability in annular combustors of jet engines is a recurring issue. In this study, the characteristics instabilities for different fuels are investigated by combining maps obtained laboratory-scale combustor equipped with multiple swirling spray injectors (MICCA-spray) and flame describing functions (FDFs) from single sector configuration (SICCA-spray). Two types liquid injected as hollow cone sprays: heptane, which fairly volatile, dodecane, less volatile. Experiments also conducted gaseous propane, perfectly premixed air, serves reference. An map systematically drawn varying global equivalence ratio thermal power. The data indicate that amplitude frequency depend, same operating point, on fuel injection conditions (premixed or spray) type. Overall trends show propane unstable broad domain. Injection induces changes time lag modifies regions. For closer to reference map, whereas dodecane exhibits wider stable attempt made understand these features examining FDF, gives relative fluctuations heat release rate velocity. FDFs measured give access gain phase information can be used determine bands calculate an index guiding interpretation differences three fuels.