Combustion Characteristics of Axial Fuel Staging Nozzles for Gas Turbine Combustors

Axial fuel staging (AFS) nozzle variants for applying to heavy duty gas turbine combustors were designed and experimentally investigated in this study. Four AFS nozzle variants (elliptic, dual elliptic, airfoil, and low-swirl type) were designed and single AFS nozzle test was conducted at the 1/4-scale combustion test rig with measurement module consists of 25-points emissions and 30-points exit temperatures. Flame structures were observed with OH-Planar Laser Induced Fluorescence (PLIF) and direct photo. When the fuel split was about 120% of the air split, NOx emission was minimum which is about 80% of the reference. Flame penetration was increased with air split and temperature profile pattern factor was found to be the lowest in dual elliptic nozzle. Four dual elliptics nozzles were mounted in the middle of the can combustor to conduct the full-can combustion test. Minimum NOx emissions were found at 10.4% fuel split, which is 120% of air dsplit.