Properties of Nonadiabatic Premixed Combustion Fronts Arising in Single-step Reaction Schemes
Properties of Nonadiabatic Premixed Combustion Fronts Arising in Single-step Reaction Schemes
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单步反应方案中出现的非绝热预混燃烧锋的性质
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
V. Gubernov
中科院分区：
文献类型：
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作者：
J. Sharples;H. Sidhu;V. Gubernov
本文研究了具有牛顿热损失的单步均质预混燃烧反应扩散方程组的行波解。具体来说，我们考虑气体燃料，其中的热扩散率和质量扩散率的比例是1和2之间。行进的燃烧前沿的属性，例如波速度、最高温度、反应前沿后面剩余的燃料量和熄灭条件，是在一系列不同参数值（例如描述燃料放热和速率的参数值）上通过数值推导出来的。热损失。结果表明，要么燃烧锋不存在，或有两个不同的波速度的解决方案。此外，燃烧前与较低的波速度（“慢”分支）被证明是不稳定的扰动，而高速燃烧前（“快”分支）被证明是稳定的或开发的振荡行为时，扰动。这些过渡到不稳定的研究非常详细。我们表明，在某些情况下，存在一个混乱的制度燃烧波传播。从历史上看，早在1950年就在铬镁铝热剂的实验中观察到了预混燃料中火焰传播的脉动状态。然而，没有给出这种现象的解释，它被视为一种不寻常的火焰传播类型。
We consider travelling wave solutions of a reaction-diffusion system corresponding to a single-step homogeneous premixed combustion scheme with Newtonian heat-loss. Specifically, we consider gaseous fuels, for which the ratio of thermal and mass diffusivities is between one and two. Properties of the travelling combustion fronts, such as the wave speed, the maximum temperature, the residual amount of fuel that remains behind the reaction front and extinction conditions are derived numerically over a range of different parameter values, such as those describing fuel exothermicity and rate of heat loss. It is shown that either the combustion front doesn't exist or that there are two solutions with distinct wave speeds. Moreover, the combustion front with the lower wave speed ('slow' branch) is shown to be unstable to perturbations, while the high speed combustion front ('fast' branch) is shown to be either stable or to develop oscillatory behaviour when perturbed. These transitions to instability are investigated in great detail. We show that in some circumstances there exists a chaotic regime of combustion wave propagation. Historically, pulsating regimes of flame propagation in premixed fuels have been observed from as early as 1950 in experiments with chrome-magnesium thermite. However, no explanation of this phenomenon was given and it was treated as an unusual type of flame propagation.