High hydrogen content syngas fuel burning in lean premixed spherical flames at elevated pressures: Effects of preferential diffusion
High hydrogen content syngas fuel burning in lean premixed spherical flames at elevated pressures: Effects of preferential diffusion
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DOI：
10.1016/j.ijhydene.2016.07.086
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发表时间：
2016-10-26
影响因子：
7.2
通讯作者：
Thevenin, D.
中科院分区：
文献类型：
--
作者：
Dinesh, K. K. J. Ranga;Shalaby, H.;Thevenin, D.
本研究探讨了优先扩散对高压下高氢含量 (HHC) 湍流贫预混氢-一氧化碳合成气火焰的火焰结构和传播的影响。在三维域中对恒压燃烧室中的扩展球形火焰结构进行了具有详细化学性质的直接数值模拟。为了确定优先扩散对火焰结构和在高压低和高湍流水平下传播的作用，在 4 bar 的压力值下，在初始湍流雷诺数 15 和 150 下进行了模拟。结果表明，由于高压低湍流水平下的强优先扩散效应，热扩散不稳定性极大地影响了贫预混合成气的蜂窝火焰结构。相反，结果表明，热扩散效应是不稳定的，优先扩散被高压下高湍流水平下的湍流混合所淹没。这一发现表明，多孔火焰结构的发展主要由湍流主导，对于在高湍流和高压条件下运行的贫预混合成气火焰来说，热扩散不稳定性的贡献很小或没有贡献。然而，结果表明，在高湍流和高压条件下运行的贫预混合成气火焰的优先扩散仍然影响火焰加速和物质扩散通量。皇冠版权所有 (C) 2016 由 Elsevier Ltd 代表 Hydrogen Energy Publications LLC 出版。版权所有。
This study addresses the effects of preferential diffusion on flame structure and propagation of high hydrogen content (HHC) turbulent lean premixed hydrogen-carbon monoxide syngas flames at elevated pressures. The direct numerical simulations with detailed chemistry were performed in three-dimensional domain for expanding spherical flame configuration in a constant pressure combustion chamber. To identify the role of preferential diffusion on flame structure and propagation under low and high turbulence levels at elevated pressure, simulations were performed at an initial turbulent Reynolds number of 15 and 150 at a pressure value of 4 bar. The results demonstrate that the thermo-diffusive instability greatly influences the lean premixed syngas cellular flame structure due to strong preferential diffusion effects under low turbulence level at elevated pressure. In contrast, the results reveal that the thermo-diffusive effects are destabilising and preferential diffusion is overwhelmed by turbulent mixing under high turbulence level at elevated pressure. This finding suggests that the development of cellular flame structure is dominated by turbulence with little or no contribution from the thermo-diffusive instability for the lean premixed syngas flame which operates under conditions of high turbulence and elevated pressures. However, results demonstrate that the flame acceleration and species diffusive flux are still influenced by the preferential diffusion for the lean premixed syngas flame which operates under conditions of high turbulence and elevated pressures. Crown Copyright (C) 2016 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC. All rights reserved.