Flame balls with thermally sensitive intermediate kinetics
Flame balls with thermally sensitive intermediate kinetics
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DOI：
10.1088/1364-7830/7/1/310
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发表时间：
2003-03
影响因子：
1.3
通讯作者：
J. Dold;R O Weber;R W Thatcher;A. Shah;W. Weber;R. W. Thatcher;Shah
中科院分区：
文献类型：
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作者：
J. Dold;R O Weber;R W Thatcher;A. Shah;W. Weber;R. W. Thatcher;Shah
采用化学动力学模型对球形火焰球进行了研究，该模型涉及非放热自催化反应，描述了化学自由基的链分支生成和放热完成反应，其速率与温度无关。当链式支化反应具有较大的活化温度时，出现支化反应产生自由基并在较薄的火焰界面上消耗燃料的渐近结构，尽管在更分散的尺度上产生热量和消耗自由基。另一个基于燃料分解生成自由基的模型更简单，但不太现实，它提供了完全相同的阶匹配条件。这些可以用反应片上的跳跃条件来表示，这些条件在因变量及其正态梯度中是线性的。利用这些跃变条件，具有线性热损失的反应-扩散模型可以得到在足够小的热损失水平下的多值解析解，即燃料消耗界面的半径或大或小。在数值上，当分支反应的激活温度降低到似乎是碳氢化合物化学的典型值时，同样的性质仍然存在。当燃料的路易斯数足够低时，具有较大半径的部分解分支变得稳定。
Spherical flame balls are studied using a model for the chemical kinetics which involves a non-exothermic autocatalytic reaction, describing the chain-branching generation of a chemical radical and an exothermic completion reaction, the rate of which does not depend on temperature. When the chain-branching reaction has a large activation temperature, an asymptotic structure emerges in which the branching reaction generates radicals and consumes fuel at a thin flame interface, although heat is produced and radicals are consumed on a more distributed scale. Another model, based more simply, but less realistically, on the generation of radicals by decomposition of the fuel, provides exactly the same leading order matching conditions. These can be expressed in terms of jump conditions across a reaction sheet that are linear in the dependent variables and their normal gradients. Using these jump conditions, a reactive–diffusive model with linear heat loss then leads to analytical solutions that are multivalued for small enough levels of heat loss, having either a larger or a smaller radius of the interface where fuel is consumed. The same properties are found, numerically, to persist as the activation temperature of the branching reaction is reduced to values that seem to be typical for hydrocarbon chemistry. Part of the solution branch with larger radius is shown to become stable for low enough values of the Lewis number of the fuel.