Numerical Investigation of NOx Emission Reduction in Non-Premixed Lean Reverse-Flow Combustor in a Micro Gas Turbine Engine

This paper details a NOx emissions characteristics study of a reverse-flow combustor using the steady Reynolds averaged Navier-Stokes (RANS) methodology. The combustor considered in this paper is the SR-30 engine model. The aim of this work is to understand the pollutant formation characteristics within the combustor chamber volume across various combustor zones. Effective ways to counter such high emissions by means of flow dilution were also investigated in the present study. Results indicated that the baseline reverse-low combustor model showed high NOx emission characteristics in the primary and secondary zones due to uneven temperature distribution. The emissions can be reduced effectively with additional dilution holes at the dilution zone of the reverse-flow combustor. The flow split due to the newly designed holes caused the velocity components (axial, radial and tangential), turbulence kinetic energy and the temperature within the primary and secondary zone to reduce significantly. The recovery of flow in the dilution zone with further reduction in temperature reduced the overall NOx emission significantly.