Effects of Lewis number on turbulent scalar transport and its modelling in turbulent premixed flames
Effects of Lewis number on turbulent scalar transport and its modelling in turbulent premixed flames
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DOI：
10.1016/j.combustflame.2009.03.010
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发表时间：
2009-07-01
影响因子：
4.4
通讯作者：
Cant, R. S.
中科院分区：
文献类型：
--
作者：
Chakraborty, Nilanjan;Cant, R. S.
采用直接数值模拟（DNS）方法研究了预混火焰中湍流标量通量的行为，着重研究了刘易斯数对湍流标量通量的影响。一个数据库是从DNS的三维自由传播的统计平面湍流预混火焰与简化的化学和一系列的全球刘易斯数从0.34到1.2。在相同的湍流初始条件下，低刘易斯数的火焰表现出反梯度输运，而高刘易斯数的火焰倾向于表现出梯度输运。湍流标量通量的平均传输方程的详细分析和现有的模型的未封闭项的性能进行评估相对于从DNS数据中提取的相应数量。基于这一评估，现有的模型，能够解决非统一刘易斯数石油湍流标量通量传输的影响进行了鉴定，并建议在必要时，新的或修改后的模型。这样，一套完整的封闭模型的标量通量输运方程规定使用的雷诺平均Navier-Stokes模拟。(C)2009燃烧研究所。爱思唯尔公司出版All rights reserved.
The behaviour of the turbulent scalar flux in premixed flames has been studied using Direct Numerical Simulation (DNS) with emphasis on the effects of Lewis number in the context of Reynolds-averaged closure modelling. A database was obtained from DNS of three-dimensional freely propagating statistically planar turbulent premixed flames with simplified chemistry and a range of global Lewis numbers from 0.34 to 1.2. Under the same initial conditions of turbulence, flames with low Lewis numbers are found to exhibit counter-gradient transport, whereas flames with higher Lewis numbers tend to exhibit gradient transport. The Reynolds-averaged transport equation for the turbulent scalar flux is analysed in detail and the performance of existing models for the unclosed terms is assessed with respect to corresponding quantities extracted from DNS data. Based on this assessment, existing models which are able to address the effects of non-Unity Lewis number oil turbulent scalar flux transport are identified, and new or modified models are suggested wherever necessary. In this way, a complete set of closure models for the scalar flux transport equation is prescribed for use in Reynolds-Averaged Navier-Stokes Simulations. (C) 2009 The Combustion Institute. Published by Elsevier Inc. All rights reserved.