Experimental Investigation of the Flame Front Propagation Characteristic During Light-round Ignition in an Annular Combustor

Abstract

The light-round process in a transparent annular combustor which comprises 16 swirling injectors injecting lean premixed propane/air mixtures is experimentally investigated. This annular combustor is derived from the ‘MICCA’ combustor, pioneered by EM2C laboratory (Bourgouin et al., Combust. Flame 160(8), 1398, 2013).The annular chamber is formed by two transparent concentric quartz tubes, which provides optical access to high-speed imaging to diagnose the chemiluminescence of flame fronts. Two ignition modes (i.e. two extreme conditions in scheduling fuel delivery and igniter sparking), controlled by ignition procedure are investigated, thus the FFSL (Fuel First, Spark Later) and the SFFL (Spark First, Fuel Later) modes. These two ignition modes exhibit different patterns of injector-to-injector flame propagation during the light-round process. The light-around time and mean circumferential flame propagation speed are obtained for various conditions. The influence of thermal expansion, velocity fluctuation and convection to the light-round process is investigated and compared for two ignition modes.