Fluid age-based analysis of a lifted turbulent DME jet flame DNS
Fluid age-based analysis of a lifted turbulent DME jet flame DNS
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基于流体年龄的提升湍流 DME 喷射火焰 DNS 分析
DOI：
10.1016/j.proci.2018.06.126
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发表时间：
2019
影响因子：
3.4
通讯作者：
Shin D
中科院分区：
文献类型：
--
作者：
Shin D
利用直接数值模拟数据分析了流体停留时间分布与反应标量分布之间的联系。需要关于反应标量分布的信息，以便对湍流反应流的大涡模拟和湍流平均模拟中出现的反应项进行建模。考虑到二甲醚燃料的多步化学反应，模拟了火焰的抬升。由于自燃和火焰传播，反应进程随停留时间增加。通过求解流体年龄的欧拉输运方程来评估流体停留时间的变化。流体年龄是一个被动标量与空间均匀的源项，这意味着它的时刻和耗散率在湍流中可以使用封闭已经建立了保守标量，如混合分数。与混合物分数相结合，流体年龄用作有用的映射变量，以区分入口附近的较年轻的反应较少的流体与下游的较老的反应较多的流体。局部波动的混合物分数和流体年龄有很强的负相关性，并建立在建立的混合物分数的假定pdf模型，这一功能可以用来构建一个准确的假定pdf模型的联合混合物分数/流体年龄的pdf。它表明，双条件的一阶矩封闭结合所提出的假定模型的联合PDF的混合物分数和流体年龄给出了准确的预测无条件的反应速率-无论是预点火自由基物种产生的低温过程上游的火焰基地，并在火焰前端产生的主要物种。
The link between the distribution of fluid residence time and the distribution of reactive scalars is analysed using Direct Numerical Simulation data. Information about the reactive scalar distribution is needed in order to model the reaction terms that appear in Large Eddy and Reynolds-Averaged simulations of turbulent reacting flows. The lifted flame is simulated taking account of multi-step chemistry for dimethyl-ether fuel. Due to autoignition and flame propagation, the reaction progress increases with residence time. The variation of fluid residence time is evaluated by solving an Eulerian transport equation for the fluid age. The fluid age is a passive scalar with a spatially-uniform source term, meaning that its moments and dissipation rates in turbulent flows can be modelled using closures already established for conserved scalars such as mixture fraction. In combination with the mixture fraction, the fluid age serves as a useful mapping variable to distinguish younger less-reacted fluid near the inlet from older more-reacted fluid downstream. The local fluctuations of mixture fraction and fluid age have strong negative correlation and, building upon established presumed-pdf models for mixture fraction, this feature can be used to construct an accurate presumed-pdf model for the joint mixture fraction/fluid age pdf. It is demonstrated that the double-conditional first-order moment closure combined with the proposed presumed model for the joint pdf of mixture fraction and fluid age gives accurate predictions for unconditional reaction rates – both for pre-ignition radical species produced by low-temperature processes upstream of the flame base, and for major species that are produced at the flame front.
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影响因子：
4
作者：
Wang X;Xiao Z;Gong J;Liu Z;Zhang M;Zhang Z
通讯作者：
Zhang Z
影响因子：
4.4
作者：
Y. Minamoto;Jacqueline H. Chen
通讯作者：
Y. Minamoto;Jacqueline H. Chen
湍流圆形射流中流体停留时间统计的自相似性
影响因子：
3.7
作者：
Shin D
通讯作者：
Shin D
气体通过加热容器时的反应速度以及对流和扩散的影响。
影响因子：
15
作者：
I. Langmuir
通讯作者：
I. Langmuir