Soot Formation and Flame Characterization of an Aero-Engine Model Combustor Burning Ethylene at Elevated Pressure

Swirl-stabilized, nonpremixed ethylene/air flames were investigated at pressures up to 5 bar to study the effect of different operating parameters on soot formation and oxidation. Focus of the experiments was the establishment of a database describing well-defined flames, serving for validation of numerical simulation. Good optical access via pressure chamber windows and combustion chamber windows enables application of laser-induced incandescence to derive soot volume fractions after suitable calibration. This results in ensemble averaged, as well as instantaneous soot distributions. Beyond pressure, parameters under study were the equivalence ratio, thermal power, and amount of oxidation air. The latter could be injected radially into the combustor downstream of the main reaction zone through holes in the combustion chamber posts. Combustion air was introduced through a dual swirl injector whose two flow rates were controlled separately. The split of those air flows provided an additional parameter variation. Nominal power of the operating points was approximately 10 kW/bar leading to a maximum power of roughly 50 kW, not including oxidation air.