An optical study of in-cylinder CH2O and OH chemiluminescence in flame-induced reaction front propagation using high speed imaging
An optical study of in-cylinder CH2O and OH chemiluminescence in flame-induced reaction front propagation using high speed imaging
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DOI：
10.1016/j.fuel.2014.06.002
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发表时间：
2014-10-15
期刊：
影响因子：
7.4
通讯作者：
Wang, Jianxin
中科院分区：
文献类型：
--
作者：
Ma, Xiao;Wang, Zhi;Wang, Jianxin
火焰诱导自燃（FIAI）是一种很有前途的高效燃烧方式，它是由火花触发火焰传播而引起发动机自燃而不发生爆震。FIAI和SI爆震燃烧有几个相似之处，但前者有利于热效率，后者应避免发动机安全。利用光学发动机对FIAI和SI爆震燃烧过程中的火焰结构、中间产物和压力变化进行了研究，并对CH 2 O和OH化学发光进行了超高速成像。火焰结构一起分析气缸压力和中间物种，以了解它们的动态相互作用。研究结果表明，在FIAI自燃开始从SI火焰前沿的外缘;反应前沿传播的速度约为160米/秒，这是一个以上的订单高于正常火焰传播的速度。反应前沿以亚音速传播。传播制度的变化，从正常的火焰传播的反应前沿传播在约795 K的正庚烷。未燃区的温度和剩余能量是爆震发生的关键因素，也是FIAI与典型爆震的区别。(C)2014爱思唯尔有限公司版权所有。
Flame-induced auto-ignition (FIAI), where spark-triggered flame propagation causes auto-ignition without engine knock, is one of the promising high-efficiency combustion modes. FIAI and SI knocking combustion have several similarities; however, the former is beneficial to thermal efficiency, and the latter should be avoided for engine safety. This study investigates the flame structures, intermediate species and pressure evolution during FIAI and SI knocking combustion using an optical engine with ultra-high speed imaging of CH2O and OH chemiluminescence. The flame structures are analyzed together with cylinder pressure and intermediate species to understand their dynamic interactions. Findings reveal that auto-ignition in FIAI begins from the outer rim of the SI flame front; the reaction front propagates at a speed of approximately 160 m/s, which is more than one order higher than the speed of normal flame propagation. The reaction front propagates in subsonic speed. The propagation regime changes from normal flame propagation to reaction front propagation at approximately 795 K for n-heptane. The temperature of the unburned zone and the remaining energy are the key factors for the occurrence of knocking; they also differentiate FIAI from typical knocking. (C) 2014 Elsevier Ltd. All rights reserved.