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Show LASER ANEMOMETRY Based on the performance function, conditions were selected for in-situ velocity measurements. A two component Phase Doppler Interferometer (Aerometrics model #3100-S) was used for the laser velocity measurements. Two micron nominal diameter aluminum oxide particles were used to "seed" (i.e., trace) the flow. Only the swirl air stream was seeded due to the high volume of swirling air provided for each condition. The placement of the laser anemometry system in relation to the burner is shown in Figure 3. The two component phase Doppler interferometer is generally used for particle sizing and velocity measurements. For natural gas combustion, only the laser anemometry portion of the instrument was required. The two component transmitter is driven by a 4 W Spectra Physics argon ion laser (Model # 2016-04S). The beam is split to provide a blue (488 nm) and green (514.5 nm) beam. Both beams are focused onto a rotation diffraction grating to provide a frequency shift. The beams are focused onto an overlapping probe volume using a 1,000 mm transmitting achromat lens. Some of the scattered light from the probe volume is then collected by a 500 mm (f/4.75) receiver achromat lens and focused onto a 100 J.1m spatial futer. In order to optimize the data collection rate, the receiver was placed as close to the probe volume as possible in a forward scattering collection position. The receiver was mounted on a platform above the transmitting beam height to prevent direct incidence of the transmitting beams into the receiver. The receiver was angled down at approximately 14° to intercept the scattering from the probe volume. RESULTS PERFORMANCE Emissions measurements were taken for all three fuel injectors (1) to establish the stability range for each injector, and (2) to establish the emission performance of each injector. The emissions for each injector were measured over the entire stability map of the burner at small increments of swirl intensity and excess air. As a result, more than fifty (50) measurements were obtained for each injector to obtain a highly resolved stability map. The plots of NOx versus CO are presented for the three injectors in Figure 6. The performance of the c(T-swirl injector reflects typical CO emission degradation as gains in NOx are attained. The radial injector yields markedly improved performance in that reduced NOx is attained with little sacrifice to the emission of CO. The counter-swirl injector displays the best performance of the three with little, if any, CO degradation as NOx is reduced. To quantify this performance, and place the overall operation of the burner into perspective, the performance function, as defined in Equation 3, is calculated from these emission data. The results are shown in Figure 7. 7 |