Instabilities and soot formation in high-pressure, rich, iso-octane-air explosion flames - 1. Dynamical structure
Instabilities and soot formation in high-pressure, rich, iso-octane-air explosion flames - 1. Dynamical structure
复制标题
DOI：
10.1016/j.combustflame.2007.08.004
复制
发表时间：
2007-12
影响因子：
4.4
通讯作者：
R. Lockett;R. Woolley
中科院分区：
文献类型：
--
作者：
R. Lockett;R. Woolley
在光学可达的利兹燃烧弹中获得了2巴高浓度异辛烷-空气爆炸火焰，并对火焰进行了OH平面激光诱导荧光（PLIF）和瑞利散射（Rayleigh scattering）的同时测量。在相似的混合条件下，从爆炸火焰中获得了单独的阴影高速视频图像。阴影图像，定量瑞利图像，和归一化的OH浓度图像已被提交这些爆炸火焰的选择。归一化的实验平衡OH浓度背后的火焰前锋进行了比较与归一化的计算平衡OH浓度作为当量比的函数。超平衡OH浓度在火焰前面后面的火焰前面的平衡OH浓度的比率揭示了火焰的热扩散不稳定性和电阻的火焰前面丰富的淬火的响应。燃烧气体的温度已被确定从瑞利散射图像在1.4至1.9的范围内，并被发现是在良好的协议与相应的预测绝热火焰温度。在当量比为1.8（C/O = 0.576）时，观察到在与火焰前缘中发生的大波长裂纹相关的深尖点后面发生碳烟形成。异辛烷热解生成烟灰的反应时间尺度估计约为7.5-10 ms。
Simultaneous OH planar laser-induced fluorescence (PLIF) and Rayleigh scattering measurements have been performed on 2-bar rich iso-octane–air explosion flames obtained in the optically accessible Leeds combustion bomb. Separate shadowgraph high-speed video images have been obtained from explosion flames under similar mixture conditions. Shadowgraph images, quantitative Rayleigh images, and normalized OH concentration images have been presented for a selection of these explosion flames. Normalized experimental equilibrium OH concentrations behind the flame fronts have been compared with normalized computed equilibrium OH concentrations as a function of equivalence ratio. The ratio of superequilibrium OH concentration in the flame front to equilibrium OH concentration behind the flame front reveals the response of the flame to the thermal–diffusive instability and the resistance of the flame front to rich quenching. Burned gas temperatures have been determined from the Rayleigh scattering images in the range 1.4⩽ϕ⩽1.9 and are found to be in good agreement with the corresponding predicted adiabatic flame temperatures. Soot formation was observed to occur behind deep cusps associated with large-wavelength cracks occurring in the flame front for equivalence ratio ϕ⩾1.8 (C/O⩾0.576). The reaction time-scale for iso-octane pyrolysis to soot formation has been estimated to be approximately 7.5–10 ms.