火炎伸長による消炎限界近傍における乱流非予混合火炎の構造(熱工学,内燃機関,動力など)

概要

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An experimental study was made on the structure of the turbulent counter flow non-premixed flame established in the forward stagnation region of a porous cylinder. Stable-species-concentration profiles were measured in detail for propane flames at atmospheric pressure. These distributions were analyzed to make clear the effects of flame stretch and turbulence intensity on the flame structure. The non-premixed flames are extinguished by flame stretch caused by the flow field. For the turbulent flow, effects of the flow field can be separated into those of the bulk flow and fluctuating flow. Therefore, the flame stretch consists of the bulk flow stretch and turbulent stretch. In the present study, the turbulent stretch was estimated by the inverse of the Kolmogorov time scale. With increasing the flame stretch, thickness of the turbulent flame zone decreased and spatial gradient of the species become steeper. The main reaction generating the intermediate species occurred on the fuel side of the turbulent flame zone. With the strong stretch, leakage of the intermediate species is large compared to the weak stretch. With the strong turbulence, the profiles of the intermediate species are rather flat, whereas the Gaussian distributions are observed for the case of weak turbulence. Based on the mixture fraction, the effects of flame stretch and turbulence intensity cannot be discernible.
社団法人日本機械学会の論文
2002-06-25