Numerical analysis of combustion flow & emission characteristics of a jet-stabilized combustor with varying angled coaxial air-fuel injector

The primary challenges in gas turbine or aircraft engine combustion research are to provide clean emissions, low combustor wall temperature, homogeneous exit temperature distribution, and fuel efficiency. In this study, four novel geometrical arrangements of coaxial air–fuel injector at combustor head are investigated for a jet stabilized combustor aiming to improve thermal distribution and reduce pollutant emission. The simulations are conducted for propane-air combustion with an equivalence ratio of 0.46. For each configuration, three air ratios are studied. Realizable k-Ε model with standard wall functions and Eddy Dissipation Model are used for modelling turbulent combustion. Discrete Ordinates (DO) Model is used for thermal radiation. Pollutant NOx is predicted using Zeldovich mechanism and directly calculated from the detailed chemical mechanism. The vortex structure for every case shows little variation. Enlarged angle increases the axial velocity in the central section of the combustor. High temperature zone concentrates in upstream of the stabilizer jets with increasing air ratio. Higher ratio of coaxially injected annular air initiates combustion closer to combustor axis. Uniformity in temperature increases with air ratio but slightly declines with increasing the angle. At 30° angle, the NO emission shows opposite trend with raising air ratio. The combustor with 0° angled coaxial air–fuel injector has the lowest NO and CO concentration of 16.54 ppm and mole fraction =8.06×10-11 respectively at outlet when operated at 0.20 air ratio. Same combustor system arrangement has 48.49% higher temperature uniformity at outlet and 21.2% more homogeneous temperature distribution throughout the combustor at air ratio 0.15 but shows 27.95% more NO emission. © 2024 Elsevier Ltd