Regimes of chemical reaction waves initiated by nonuniform initial conditions for detailed chemical reaction models.
Regimes of chemical reaction waves initiated by nonuniform initial conditions for detailed chemical reaction models.
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DOI：
10.1103/physreve.85.056312
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发表时间：
2012-05
期刊：
影响因子：
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通讯作者：
M. Liberman;A. Kiverin;M. F. Ivanov
中科院分区：
文献类型：
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作者：
M. Liberman;A. Kiverin;M. F. Ivanov
用多组分输运模型和详细的化学模型研究了初始温度不均匀引起的化学反应波在气体混合物中的传播规律，气体混合物的化学行为受支链动力学控制。对于化学计量比的氢-氧和氢-空气混合物，根据初始非均匀陡度的不同，确定了在较大的初始压力和温度水平范围内可能的反应波传播区域。反应波传播模式的极限取决于问题的自发波速和特征速度的值。结果表明，一步动力学不能再现实际混合气体着火过程的定量和定性特征，因为诱导时间和放热反应开始时间之间的差异显著影响自发反应波和压力波的着火、演化和耦合，特别是在较低温度下。我们发现，所有由温度梯度引发的区域都发生在比一步模型预测的温度梯度要浅得多的区域。对于较低的初始压力和缓慢反应的混合物，差别非常大。通过这种方式，本文回答了一些在实践中很重要的问题，即点火能量及其分布，以及在燃烧波传播的一种或另一种区域中点火所需的初始不均匀程度。
Regimes of chemical reaction wave propagation initiated by initial temperature nonuniformity in gaseous mixtures, whose chemistry is governed by chain-branching kinetics, are studied using a multispecies transport model and a detailed chemical model. Possible regimes of reaction wave propagation are identified for stoichiometric hydrogen-oxygen and hydrogen-air mixtures in a wide range of initial pressures and temperature levels, depending on the initial non-uniformity steepness. The limits of the regimes of reaction wave propagation depend upon the values of the spontaneous wave speed and the characteristic velocities of the problem. It is shown that one-step kinetics cannot reproduce either quantitative neither qualitative features of the ignition process in real gaseous mixtures because the difference between the induction time and the time when the exothermic reaction begins significantly affects the ignition, evolution, and coupling of the spontaneous reaction wave and the pressure wave, especially at lower temperatures. We show that all the regimes initiated by the temperature gradient occur for much shallower temperature gradients than predicted by a one-step model. The difference is very large for lower initial pressures and for slowly reacting mixtures. In this way the paper provides an answer to questions, important in practice, about the ignition energy, its distribution, and the scale of the initial nonuniformity required for ignition in one or another regime of combustion wave propagation.