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Show APPROACH Two methods were used to gather the needed infonnation upstream of the quarl exit: laser anemometry and computational fluid dynamic modeling. Experiment Due to the small, confined area where the fuel is injected, measurements in this region, especially with an intrusive probe, is challenging. Optical techniques are preferred so as not to disturb the flow-field; however, optical access is limited in this region. To characterize the velocity field issuing from the burner throat, a special hardware modification was designed by extending the straight section of the burner in order to place the throat exit in a location accessible by the laser. The simulated burner throat is shown in Figure 4. Axial and swirling velocity measurements were taken as close as possible to the exit (approximately 0.125" downstream) over one diameter traverse of the throat exit. The air flow was seeded with 1 micron, aluminum oxide particles to trace the flow; the natural gas flow was not seeded to avoid clogging the small diameter fuel jet injectors. All of the conditions measured were conducted under non-reacting conditions, and data were taken with and without the fuel jets. Previous measurement plane _ - - - - - - - - - - - - - - - - - - - - - - - - - Actual Burner Quarl Simulated Burner Throat Figure 4: Original Quarl and Simulated Throat Quarl Modeling A computational fluid dynamics package [6] was used to calculate the cold flow velocity and species concentration profiles across the burner throat annulus. The simple, 3-dimensional geometry represents a single jet section of the fuel injector-air annulus region. The geometry is shown in Figure 5. 5 |
