Combustion of NH

Ammonia is a promising carbon-free fuel for decarbonizing the energy sectors. However, implementing it in combustion systems is limited by difficulties in maintaining flame stability and controlling nitrogen oxide (NOx) emissions. This study investigates the turbulent non-premixed combustion of NH3-CH4 blend in a coaxial swirl burner under atmospheric pressure, using experimental diagnostics. Two configurations are examined: (i) high swirl number (Sn = 1.4) and (ii) low swirl number (Sn = 0.8). Flame structure and stability was analysed via OH* and NH2* chemiluminescence imaging of four blend cases. Results show that high swirl enhances mixing of fuel and oxidizer resulting in a compact flame anchored to the burner. In contrast, low swirl shows better flame stability, the flame is more diffused toward radial and axial direction. However, it indicates higher NOx emissions.