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Show tions of the air ratio on NOx formation. When mixing of fuel and air is not perfect, there is a temporal fluctuation of the air ratio, in addition to a spatial 2 -Samp ling Probe ~nSb nonuniformity of the fuel-air distribution. Semerjian et al. (1978) suggested that in very lean flames, the increased level of NOx emission compared with that of premixed flames can be He-Ne Laser r····-·.. . -·--·-~~~==». . ·---O Light guiding tube attributed to the large statistical ~ Air fluctuations in the local air ratio. Pompei and Heywood tried to Fig.1 Schematic diagram of experimental system. estimate the magnitude of the equivalence fluctuations by measuring the change of 02 concentration in the burner. Semerjian also estimated the magnitude of the fluctuations using the same method. However, this method does not directly measure the fluctuations. In the quantitative estimation of the effect of equivalence fluctuations on NOx formation, more precise estimation of the fluctuations is desired. The objective of this paper is to quantitatively measu re the air ratio fluctuations in the mixture and investigate the relation between the magnitude of the fluctuations and NOx formation. 3.EXPERIMENTAL APPARATUS I. 1 25 • 1111111111 111 111 1111 :! Fig.2 Schematic of multi-port ceramic burner. Figure 1 shows a schematic diagram of the experimental system. The lower part of the combustor functions as a mixer, to which the fuel gas is injected normal to the air flow from the nozzle. The nozzle has 12 holes of diameter 2 mm. The ceramic burner plate is also shown schematically in Figure 2. A ceramic cylinder is mounted above the burner |
