Experimental investigation on fuel-staging mode of internally-staged combustor under approach condition

A lean-burn internally-staged combustor was designed and the emission experiments using a single module rectangular combustor were operated under the approach condition of a certain large aero-engine. Three fuel-staging modes including the pilot-fueled only mode, the two stages-fueled together mode and the main-fueled circumferentially-staged in the annular combustor mode were investigated experimentally on combustion efficiency, NO_x and smoke emission. The experimental results indicate that for this designed internally-staged combustor the combustion efficiency is high with the high NO_x emission index (EI) exceeding the target when applying the pilot-fueled only mode. The NO_x EI is rather low when applying the two stages-fueled together mode with the combustion efficiency being difficult to reach the target. The combustion efficiency and NO_x EI are satisfied for the targets simultaneously when applying the main-fueled circumferentially-staged in the annular combustor mode with the proper fuel-staging proportion. The smoke number (SN) is far below the limited index for all the three modes.