Effects of oxy jet in cross-flow on the combustion instability and NOx emissions in lean premixed flame

Abstract

Combustion instability and NOx emission are crucial factors for modern gas turbine combustors, which seriously hampers the research and development of advanced combustors. To eliminate combustion instability and NOx emissions simultaneously, effects of the oxy (CO2/O2, N2/O2, Ar/O2, and He/O2) jet in cross-flow on combustion instability and NOx emissions are experimentally studied. In this research, the flow rate and oxygen ratio of the combustor are varied to evaluate the control effectiveness. Results denotes that all the four oxyfuel gas: CO2/O2, N2/O2, Ar/O2, and He/O2, could suppress combustion instability and NOx emissions. The CO2/O2 dilution can achieve a better damping results than the other three cases. There are peak values or lowest points of sound pressure amplitude as the parameter of oxy jet in cross-flow changes. Mode transition appears in both acoustic signal and CH* chemiluminescence of the flame. But the turning point of mode transition is different. Under the CO2/O2 cases, the NOx emission decreases from 22.3 ppm to 15.2 ppm, the damping ratio of NOx is 40.39%. The flame shape and length were changed under different jet in cross-flow dilutions. This research could promote the application of jet in cross-flow methods on combustion instability or pollutant emissions in gas turbines.