| Budget Amount *help |
¥7,000,000 (Direct Cost: ¥7,000,000)
Fiscal Year 1996: ¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1995: ¥4,700,000 (Direct Cost: ¥4,700,000)
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| Research Abstract |
In this work, methane-air counterflow diffusion flame, counterflow double flame and one-dimensional premixed flame were simulated numerically with detailed chemical kinetics, and the NO formation processes were investigated by drawing quantitative reaction path diagram based on the reaction rates per unit flame area. As a result, it was found that the dominant NO formation mechanism among the thermal mechanism, Fenimore mechanism and HCN recycle route differs with the flame types or conditions such as equivalence ratio or velocity gradient. In addition, the dominant elementary reaction in NO formation was investigated by means of the sensitivity analysis of the emission index of NO,and it was found that the initiation reactions of the respective mechanisms descrived above are generally dominant and the relative importance of them differs with the flame types or conditions. Furthermore, the exisymmetric two-dimensional numarical calculation was also conducted for the coflow diffusion flame, and a good agreement was obtained between the flame structure of any cross section normal to the flame surface of the coflow flame and the structure of the counterflow diffusion flame of the same representative diffusion time.
Experimentally, No concentlation distribution was measured by PLIF method, in order to verify the chemical kinetics used in the calculations. Here, the object was changed from the counterflow flame to the axisymmetric coflow flame, because the beam path in the flame zone of the counterflow flame is so long that the absorption is large, which results in a significant inaccuracy of the measurement. Comparing the fluorescence distribution obtained in the experiment with the NO concentration of the numerical result, a good agreement was obtained around the flame surface and the downstream, while the difference is somewhat large in the fuel side of the flame. The cause of the latter difference must be clarified before verifying each elementary reaction in detail.
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