%0 Journal Article %A Birouk, Madjid %A Gupta, Ashwani K. %D 2001 %I Begell House %N 4 %P 13 %R 10.1615/JFlowVisImageProc.v8.i4.30 %T STRUCTURE OF LEAN PREMIXED SWIRLING FLAMES USING PLIF IMAGING %U https://www.dl.begellhouse.com/journals/52b74bd3689ab10b,5dde117608671286,3f3466f51091e9b1.html %V 8 %X The structure of lean premixed methane-air flames at atmospheric pressure conditions has been studied using a planar laser-induced fluorescence (PLIF) technique. The burner geometry used in this investigation, which simulated a single burner in a typical gas turbine combustor, consists of a central nozzle surrounded by two concentric annuli. Three independently varied parameters—the radial swirl distribution in the outer annulus, the axial momentum in the inner annulus, and the premixed equivalence ratio—were used to investigate the flame structure. The spatially resolved PLIF technique allowed obtaining instantaneous and ensemble-averaged OH images at vertical cross sections of the flame (referenced through the centerline) under different flame conditions. These images provide qualitative information on the flame reaction zone, which is of interest for understanding the complex structure and dynamics of a swirling premixed combustion system. These images also assist in understanding why lean premixed gas turbine combustion systems may experience combustion instability, particularly under leaner conditions. %8 2001-12-01