A DNS Analysis of the Correlation of Heat Release Rate with Chemiluminescence Emissions in Turbulent Combustion
A DNS Analysis of the Correlation of Heat Release Rate with Chemiluminescence Emissions in Turbulent Combustion
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DOI：
10.1007/978-3-319-47066-5_16
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
Feichi Zhang;T. Zirwes;P. Habisreuther;H. Bockhorn
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文献类型：
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作者：
Feichi Zhang;T. Zirwes;P. Habisreuther;H. Bockhorn
采用混合物平均输运方法，采用18种组分69个基元反应的详细反应机理，对甲烷/空气预混火焰的直接数值模拟（DNS），定量分析了湍流燃烧放热率与化学发光的本质关联。本文首先研究了从贫燃料到富燃料的不同化学计量比下的一维自由传播层流火焰。在那里，发光的OH* 物种的本地生成与燃烧反应释放的热量密切相关，特别是在贫燃料范围内。三维DNS已被应用到计算一个综合传播的火焰前锋受到不同的湍流来流条件。联合概率密度函数的OH* 浓度和热释放速率已产生的DNS结果，显示出较强的散射的相关曲线相比，相应的层流火焰。由于化学发光测量仅沿沿着一个观察方向收集光，因此已经从DNS评估了热释放和OH* 浓度的视线积分值，其中域已经被分解为由固定观察方向和特定区域定义的多个射线。一个准线性关系已被确定为这些积分值，其中的相关性变得更强的火焰受到较低的湍流强度或较大的横截面积的射线。具有1600万有限体积的计算网格已用于湍流火焰的DNS，并且模拟已与来自HLRS的Hazel Hen集群的3，600个处理器核心并行执行。的DNS代码，这是基于开源程序OpenFOAM的扩展性能进行了评估。
The essential correlation of heat release rate and chemiluminescence emission from turbulent combustion is quantitatively analyzed by means of direct numerical simulation (DNS) of premixed methane/air flames, employing a detailed reaction mechanism with 18 species and 69 elementary reactions, and the mixture-averaged transport method. One-dimensional freely propagating laminar flames have first been studied for different stoichiometries varying from fuel-lean to fuel-rich conditions. There, the local generation of the chemiluminescent OH* species correlates strongly with the heat released by the combustion reaction, especially in the fuel-lean range. Three-dimensional DNS have then been applied to calculate a synthetically propagating flame front subjected to different turbulent inflow conditions. Joint probability density functions of OH* concentration and heat release rate have been generated from the DNS results, showing a stronger scattering of the correlation curve compared to the corresponding laminar flame. As the chemiluminescence measurement gathers light only along one viewing direction, the line-of-sight integrated values of heat release and OH* concentration have been evaluated from the DNS, where the domain has been decomposed into a number of rays defined by a fixed viewing direction and a specific area. A quasi-linear relationship has been identified for these integral values, where the correlation becomes stronger for flames subjected to lower turbulence intensities or larger cross-section areas of the rays. A computational grid with 16 million finite volumes has been used for the DNS of the turbulent flames and the simulations have been performed in parallel with 3,600 processor cores from the Hazel Hen cluster of HLRS. Scale-up performance of the DNS code, which is based on the open-source program OpenFOAM, has been evaluated.