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首页> 外文期刊>Combustion and Flame >Mixing time-history effects in Large Eddy Simulation of non-premixed turbulent flames: Flow-Controlled Chemistry Tabulation
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Mixing time-history effects in Large Eddy Simulation of non-premixed turbulent flames: Flow-Controlled Chemistry Tabulation

机译：非预混湍流火焰的大涡模拟中的混合时间历史效应：流控化学表格

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摘要

The time history of mixing is known to play a crucial and non-trivial role in non-premixed turbulent combustion. In a first part, Eulerian balance equations are derived for both a flow residence time and a characteristic time of the mixing which the particles gathered in a fluid element have been subjected to in their flow histories. These equations are analyzed and solved in a Large Eddy Simulation (LES) context for a fuel jet mixing with an oxidizer co-flow. Typical responses of filtered mixture fraction versus flow residence time are highlighted. In a second part, a Flow-Controlled Chemistry Tabulation (FCCT) is devised in which the effects of unresolved fluctuations of thermochemical variables in LES are simulated, combining partially stirred reactors with tabulated chemistry. The reactor evolutions are organized to mimick flow engulfment and micro-mixing, so as to reproduce the observed filtered mixture fraction versus residence time response. This allows for dynamically building subgrid scale joint probability density functions, and thereby the subfilter response of the non-premixed flames, according to four control parameters: the filtered mixture fraction, the progress of reaction, the flow residence time, and a mixing time. Finally, LES of the Cabra et al. [Combust. Flame 143 (2005) 491-506] fuel-jet lifted-flame developing in a vitiated oxidizer environment is performed and results are compared against measurements.
机译：已知混合的时间历史在非预混合湍流燃烧中起着至关重要的作用。在第一部分中，针对流动停留时间和混合的特征时间导出欧拉平衡方程式，聚集在流体元件中的颗粒在其流动历史中已经经历了混合。在大型涡流模拟（LES）上下文中分析和求解了这些方程，用于燃料射流与氧化剂并流混合。突出显示了过滤后的混合物馏分相对于流动停留时间的典型响应。在第二部分中，设计了流控化学制表（FCCT），其中模拟了部分搅拌反应器与制表化学的结合，模拟了LES中未解决的热化学变量波动的影响。组织反应器的演变以模拟流动吞噬和微混合，从而重现观察到的过滤后的混合物馏分与停留时间的关系。这允许根据四个控制参数动态构建亚网格规模联合概率密度函数，从而建立非预混合火焰的子过滤器响应：过滤后的混合物分数，反应进程，流动停留时间和混合时间。最后，卡布拉等人的LES。 [燃烧。火焰143（2005）491-506]进行了在氧化氧化剂环境中产生的燃料喷射燃烧，并将结果与​​测量结果进行了比较。

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