Heat Release Imaging in Turbulent Premixed Ethylene-Air Flames Near Blow-off
Heat Release Imaging in Turbulent Premixed Ethylene-Air Flames Near Blow-off
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DOI：
10.1007/s10494-016-9720-y
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发表时间：
2016-03
期刊：
影响因子：
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通讯作者：
J. Kariuki;A. Dowlut;R. Balachandran;E. Mastorakos
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文献类型：
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作者：
J. Kariuki;A. Dowlut;R. Balachandran;E. Mastorakos
这项工作的重点是可视化的区域的CH 2 O和热释放（HR）的无限制的湍流预混海崖体稳定的乙烯-空气火焰在接近贫吹关闭的条件下使用同时成像的OH-和CH 2 O-PLIF。HR区域由OH和CH 2 O剖面的产物估计。在接近吹离的条件下，在回流区（RZ）内观察到广泛的CH 2 O区域。观察到RZ内CH 2 O和HR的存在遵循RZ顶部附近的下游火焰部分的碎裂。在非常接近吹离的条件下，RZ内部存在宽区域的OH和CH 2 O，这表明未反应的气体可能夹带到RZ中。将刘易斯数（Le）大于1的贫乙烯-空气火焰的行为与Le约为1的贫甲烷-空气火焰的行为进行比较。对于这两种燃料，定性相似的观察火焰碎片下游，然后建立的CH 2 O和HR内的RZ观察在贫吹离附近的条件。此外，对于乙烯-空气和甲烷-空气火焰，观察到HR调节的火焰前缘曲率的类似趋势，其中观察到HR的大小随着曲率的绝对值而增加。
The focus of this work is to visualise the regions of CH2O and heat release (HR) of an unconfined turbulent premixed bluff body stabilised ethylene-air flame at conditions approaching lean blow-off using simultaneous imaging of OH- and CH2O-PLIF. The HR regions are estimated from the product of the OH and CH2O profiles. At conditions near blow-off, wide regions of CH2O are observed inside the recirculation zone (RZ). The presence of CH2O and HR inside the RZ is observed to follow fragmentation of the downstream flame parts near the top of the RZ. The presence of wide regions void of both OH and CH2O inside the RZ at conditions very close to blow-off indicates the possible entrainment of un-reacted gases into the RZ. The behaviour of the lean ethylene-air flame with Lewis number (Le) greater than 1 is compared to that of a lean methane-air flame withLeof approximately 1. For both fuels, qualitatively similar observations of flame fragmentation downstream followed by build-up of CH2O and HR inside the RZ are observed at conditions near lean blow-off. Also, a similar trend of flame front curvature conditioned on HR was observed for both the ethylene-air and methane-air flames, where the magnitude of HR was observed to increase with the absolute value of curvature.