Doubly conditional moment closure modelling for HCCI with temperature inhomogeneities
Doubly conditional moment closure modelling for HCCI with temperature inhomogeneities
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具有温度不均匀性的 HCCI 双条件矩闭合模型
DOI：
10.1016/j.proci.2014.05.035
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
S. Kook
中科院分区：
文献类型：
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作者：
F. Salehi;M. Talei;E. Hawkes;C. Yoo;T. Lucchini;G. D’Errico;S. Kook
提出了一种基于一阶条件矩闭合（CMC）方法的均质压燃（HCCI）燃烧模型。该模型在开源C++计算流体动力学（CFD）代码OpenFOAM中实现。直接数值模拟（DNSs）被用来评估CFD-CMC求解器的性能。在二维（2D）DNS的情况下，点火的贫庚烷/空气混合物的热不均匀性模拟了九种情况下，有两个不同的平均温度和几个不同层次的热分层。从CFD-CMC求解器的结果是在良好的协议与DNS的情况下，表现出一个自发的顺序点火模式的燃烧，而在混合模式的爆燃和自燃存在的情况下，CMC低估的点火延迟。使用DNS数据的进一步调查表明，这种差异主要归因于一阶闭合假设。有条件的波动被认为是更显着的情况下与爆燃。进一步的分析表明，标量耗散涨落是条件涨落的原因。
This paper presents an approach for modelling combustion in homogeneous charge compression ignition (HCCI) conditions based on the first order conditional moment closure (CMC) method. The model is implemented into the open source C++ computational fluid dynamic (CFD) code known as OpenFOAM. Direct numerical simulations (DNSs) are used to evaluate the performance of the CFD-CMC solver. In the two-dimensional (2D) DNS cases, ignition of a leann-heptane/air mixture with thermal inhomogeneities is simulated for nine cases, with two different mean temperatures and several different levels of thermal stratification. Results from the CFD-CMC solver are in excellent agreement with the DNS for cases which exhibit a spontaneous sequential ignition mode of combustion whereas for the cases in which a mixed mode of deflagration and spontaneous ignition exists, the CMC underpredicts the ignition delay. Further investigation using the DNS data demonstrates that this discrepancy is primarily attributed to the first order closure assumption. Conditional fluctuations are found to be more significant in the case with deflagrations. Further analysis of the DNS shows that scalar dissipation fluctuations are the cause of conditional fluctuations.