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DOI码：10.1016/j.combustflame.2022.112240

发表刊物：Combustion and Flame

摘要：The difference in the mixing timescale among species, i.e., differential mixing, is a combined result due to the difference in molecular diffusivity and the difference in reaction-induced scalar gradient. Being a key component for micro-mixing, incorporating differential mixing is a desirable feature for a transported probability density function (TPDF) simulation. Nevertheless, the lack of understanding of differential mixing hinders its model development. This paper intends to address that whether there exist critical species for differential mixing, such that considering only the differential mixing of these species can reproduce the prediction with the full differential mixing of all species. To achieve so, TPDF simulations have been performed for a temporally evolving, non-premixed ethylene DNS flame, with the DNS-extracted mean velocity, turbulent diffusivity and species mixing timescales to enable a clean assessment on the critical species for differential mixing. An algorithm based on active subspace (AS) method is proposed to identify the critical species. It is found that the identified 10 critical species are neither the ones having the highest mixing frequency nor the ones causing the largest temperature change. The TPDF simulation with the differential mixing of the 10 critical species can well reproduce the mean and conditional mean quantities of the reference simulation with the full differential mixing of all species, illustrating the effectiveness of the AS method. Compared to the crude single-species trial method, the AS method better identifies the critical species as it accounts for the coupling nature of the chemical reaction system. By analyzing the reaction pathway in 1D opposed jet flames, it is found that the critical species all involve in the controlling reactions for the overall combustion process, thus providing a physical interpretation for the identified critical species. The effects of quantity of interest and micro-mixing model on critical species are also analyzed.

论文类型：期刊论文

论文编号：112240

卷号：224

页面范围：112240

是否译文：否

发表时间：2022-06-03

收录刊物：SCI

合写作者：Su Xingyu,Hawkes E.R.,Ren Zhuyin

通讯作者：Zhou Hua