Numerical Study on the Morphology of a Re-Ignited Laminar Partially Premixed Flame with a Co-Axial Pilot Flame
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Re-ignited partially premixed flame (PPF) is a quite extensive flame type in real applications, which is directly relevant to the local and global extinction and re-ignition phenomenon. The authors designed a model burner to establish laminar re-ignited PPFs. Numerical simulations were carried out to reveal the morphology of laminar re-ignited PPF. Based on the distributions of temperature, heat release and radicals, the morphologies of re-ignited flames were explored. W-shaped flames were formed under pilot-lean conditions. Line-shaped and y-shaped flames were formed under pilot-rich conditions. Both w-shaped and y-shaped flames had a triple-flame structure. The re-ignited flames can stand beyond the rich flammability limit. Additionally, OH distributions indicated both pilot flame and re-ignited flame well as it rapidly increased near the flame front. OH concentration did not increase visibly while CH2O concentration mildly increased during the mild re-ignition process in the pre-zone of the re-ignited PPF. According to the results of 0-D simulations using closed homogeneous reactor, both OH and CH2O reduced ignition time significantly. The results of this work are helpful for understanding re-ignited PPF more closely.
Keywordsre-ignited flame partially premixed flame flame morphology numerical simulation
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This work was supported by the Fundamental Research Funds for the Central Universities (No. 106112017CDJXY320001), the open funds of Jiangsu Province Key Laboratory of Aerospace Power System (No. CEPE2018009) and National Natural Science Foundation of China (No. 51706027).
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