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Show U (ft/s) 120 ·5 Air Swirl ----... Figure 7: Modeled Axial Velocities at Burner Throat for the Counter-swirl Injector at 5% Excess Air and S'=0.72 Since the modeling results show similar characteristics as the measured axial velocities, the fuel distribution at the burner throat was inspected using modeling as the diagnostic tool. Figure 8 shows the fuel mole fraction at the outer wall of the annulus for all six cases investigated. The high concentration of fuel at the wall indicate cross flow penetration of the jet to the outer wall, which is observed for all cases except the co-swirl injector. The high excess air conditions for the counter-swirl (conditions @) and the radial (condition @) injectors exhibit reduced fuel concentration at the wall. It is interesting to note that the jet from the radial injector is deflected in the same direction as the swirling air flow, causing impingement against the annulus wall in the clockwise, downstream direction. The fuel jet for counter-swirl injector, in contra t, how impingement left of the injection plane, against the air flow direction. The mole fraction of fuel at the burner throat exit plane is shown for all six ca e inve tigated in Figure 9. For the counter-swirl and radial injectors, the fuel jet penetration form a "ring" of fuel along the outer ridge of the annulus, with large pockets of fuel that extend inward for the counterswirl injector at 5% excess air (condition @) and the radial injector at 5% and 15 0/0 exces air (conditions @ and @). Although the counter-swirl injector at 200/0 al 0 shows a fuel ring around the annulus wall, absent are the large, undulating fuel pockets. The co-swirl injector conditions show large, discrete pockets of fuel at the exit, indicating jet coherence at the burner throat. 8 |