Numerical Study on the Morphology of a Re-Ignited Laminar Partially Premixed Flame with a Co-Axial Pilot Flame |
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Authors: | WU Zejun KANG Yinhu HE Xiaomin |
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Affiliation: | College of Aerospace Engineering, Chongqing University, Chongqing 400044, China;Jiangsu Province Key Laboratory of Aerospace Power System, Nanjing 210016, China;School of Energy and Power Engineering, Chongqing University, Chongqing 400045, China;Jiangsu Province Key Laboratory of Aerospace Power System, Nanjing 210016, China;College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China |
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Abstract: | 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 CH_2O 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 CH_2O reduced ignition time significantly. The results of this work are helpful for understanding re-ignited PPF more closely. |
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Keywords: | re-ignited flame partially premixed flame flame morphology numerical simulation |
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