Multiscale analysis of head-on quenching premixed turbulent flames
Multiscale analysis of head-on quenching premixed turbulent flames
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DOI：
10.1063/1.5047061
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发表时间：
2018-10-01
影响因子：
4.6
通讯作者：
Swaminathan, Nedunchezhian
中科院分区：
文献类型：
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作者：
Ahmed, Umair;Nguyen Anh Khoa Doan;Swaminathan, Nedunchezhian
利用火焰-壁面相互作用（FWI）的三维直接数值模拟数据，对壁面湍流预混火焰进行了多尺度分析。所选择的配置代表湍流统计平面化学计量的甲烷-空气火焰的等温惰性壁迎面淬火。不同的湍流强度和化学机制进行了分析。一个带通滤波技术被用来分析不同尺寸的湍流涡旋的影响和与之相关的涡量和应变率场的统计。据发现，火焰的存在并不改变涡流拉伸的湍流时，火焰远离壁的机制，但在FWI的情况下，涡流拉伸的机制被改变，由于减少非局部应变的贡献，和小尺度的湍流开始有助于火焰应变过程。结果表明，当火焰远离壁面时，小尺度涡对切向应变率没有贡献，而当火焰靠近壁面时，小尺度涡对切向应变率的贡献增大。它也被发现，化学机制的选择并不影响FWI涉及的基本流体力学过程。出版社：AIP Publishing
Multiscale analysis of wall-bounded turbulent premixed flames is performed using three-dimensional direct numerical simulation data of flame-wall interaction (FWI). The chosen configuration represents head-on quenching of a turbulent statistically planar stoichiometric methane-air flame by an isothermal inert wall. Different turbulence intensities and chemical mechanisms have been analyzed. A bandpass filtering technique is utilised to analyze the influence of turbulent eddies of varying size and the statistics of vorticity and strain rate fields associated with them. It is found that the presence of the flame does not alter the mechanism of vortex stretching in turbulent flows when the flame is away from the wall, but in the case of FWI, the mechanism of vortex stretching is altered due to a reduction in the contribution from non-local strain, and the small scales of turbulence start to contribute to the flame straining process. The results indicate that small scale eddies do not contribute to the tangential strain rate when the flames are away from the walls, whereas the contribution from the small scales to the tangential strain rate increases when the flame is in the vicinity of the wall. It is also found that the choice of chemical mechanism does not influence the underlying fluid mechanical processes involved in FWI. Published by AIP Publishing.