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Optimized single-step (OSS) chemistry for auto-ignition of heterogeneous mixtures
Combustion and Flame ( IF 4.4 ) Pub Date : 2021-01-07 , DOI: 10.1016/j.combustflame.2020.12.026
Luis A. Carbajal-Carrasco , Zakaria Bouali , Arnaud Mura

With the objective of recovering the values of ignition delays of reactive heterogeneous mixtures a single-step chemistry model has been developed. The corresponding model extends a recent optimization procedure introduced to describe flame propagation in heterogeneous media featuring composition variations (equivalence ratio and temperature) in the fresh reactants or containing residual burned gases (RBG). It is based on the use of an optimized virtual species and a tabulation of the pre-exponential coefficient of an Arrhenius law. The main results of high activation energy asymptotics (AEA) are first recalled to put in evidence the key parameters and the dependence of the ignition delay on the corresponding quantities. The optimization procedure is then applied to these parameters, namely, the pre-exponential factor K and the activation energy Ea of the associated single-step Arrhenius law. An efficient tabulation method benefiting from both rapid access and low storage is proposed for the composition variable (the mixture fraction, in the present case). Finally, the restitution of both ignition and propagation features is ensured through the consideration of the cross-over temperature. The performance of the resulting model is then assessed through comparisons with data obtained from detailed chemistry computations used as reference in several conditions of increasing complexity.



中文翻译:

优化的单步(OSS)化学物质,可自动点燃异质混合物

为了恢复反应性非均质混合物的点火延迟值,已开发了单步化学模型。相应的模型扩展了最近引入的一种优化程序,该程序用于描述火焰在异质介质中的传播,该介质的特征在于新鲜反应物或包含残留燃烧气体(RBG)的成分变化(当量比和温度)。它基于优化虚拟物种的使用以及阿伦尼乌斯定律的指数前系数列表。首先回顾高活化能渐近线(AEA)的主要结果,以证明关键参数以及点火延迟对相应量的依赖性。然后将优化过程应用于这些参数,即指数前因子ķ 和活化能 Ë一种相关的单步阿累尼乌斯定律。针对成分变量(在当前情况下为混合物分数),提出了一种既受益于快速访问又具有低存储量的高效制表方法。最后,通过考虑交叉温度来确保恢复点火特征和传播特征。然后,通过与从复杂化学计算中获得的数据进行比较,评估结果模型的性能,这些化学计算在增加复杂性的几种情况下用作参考。

更新日期:2021-01-07
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