DNS of EGR-type turbulent flame in MILD condition
DNS of EGR-type turbulent flame in MILD condition
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DOI：
10.1016/j.proci.2012.06.041
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Y. Minamoto;T. Dunstan;N. Swaminathan;R. Cant
中科院分区：
文献类型：
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作者：
Y. Minamoto;T. Dunstan;N. Swaminathan;R. Cant
对中、强低氧稀释（MILD）条件下废气再循环（EGR）型湍流燃烧进行了三维直接数值模拟（DNS），研究了火焰结构和火焰相互作用。为了获得足够的egr型初始/入口混合气场，对与湍流相关的部分预混混合气场进行了预处理。化学动力学是用甲烷-空气燃烧的骨架机制建模的。结果表明，在MILD条件下egr型燃烧中，火焰锋面具有较薄的火焰结构，平均反应速率与标量耗散速率之间的直接联系仍然有效。然而，常用的规范小火焰不能完全代表轻度燃烧。在火焰-火焰相互作用过程中，热释放率的增加幅度大于层流火焰最大值，而进度变量的梯度小于层流火焰最大值。还提出了反应速率和标量梯度可以作为火焰相互作用的标志。
Three-dimensional direct numerical simulation (DNS) of exhaust gas recirculation (EGR)-type turbulent combustion operated in moderate and intense low-oxygen dilution (MILD) condition has been carried out to study the flame structure and flame interaction. In order to achieve adequate EGR-type initial/inlet mixture fields, partially premixed mixture fields which are correlated with the turbulence are carefully preprocessed. The chemical kinetics is modelled using a skeletal mechanism for methane–air combustion. The results suggest that the flame fronts have thin flame structure and the direct link between the mean reaction rate and scalar dissipation rate remains valid in the EGR-type combustion with MILD condition. However, the commonly used canonical flamelet is not fully representative for MILD combustion. During the flame–flame interactions, the heat release rate increases higher than the maximum laminar flame value, while the gradient of progress variable becomes smaller than laminar value. It is also proposed that the reaction rate and the scalar gradient can be used as a marker for the flame interaction.