Statistical behavior of turbulent kinetic energy transport in boundary layer flashback of hydrogen-rich premixed combustion
Statistical behavior of turbulent kinetic energy transport in boundary layer flashback of hydrogen-rich premixed combustion
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DOI：
10.1103/physrevfluids.4.103201
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发表时间：
2019-10
影响因子：
2.7
通讯作者：
U. Ahmed;A. Pillai;N. Chakraborty;R. Kurose
中科院分区：
文献类型：
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作者：
U. Ahmed;A. Pillai;N. Chakraborty;R. Kurose
本分析考虑了直接数值 (DNS) 数据库，用于在完全发展的湍流通道流中当量比为 1.5 的预混合氢气-空气火焰的边界层闪回。通道流的非反应部分代表基于摩擦速度的雷诺数Reτ = 120。采用具有9种化学物质和20个反应的骨架化学机制来表示氢气-空气燃烧。在这项工作中，流动配置以及湍流和火焰特性与 Gruber 等人的相似。 [J。流体机械，709 516-542（2012）]。为了与 Gruber 等人的早期工作进行比较，研究了边界层闪回的火焰结构和湍流之间的相互作用。 [J。流体机械，709 516-542（2012）]。分析了壁面剪应力、湍流动能及其耗散的统计数据，以探讨火焰对通道流动形态中底层湍流的影响。此外，还研究了通道中给定平面上湍流动能传输方程中各项的预算。研究发现，火焰传播到完全发展的湍流边界层的上游部分在火焰上游的一些区域中引入了流动反转，并且这些区域导致负壁面剪切应力。对湍流动能传输预算的 DNS 数据的询问表明，上述局部流动反转区域对湍流动能产生、压力膨胀和压力传输项具有显着影响。已经发现，火焰传播到上游反应物中会导致一些弱的局部压缩性效应，如湍流动能传递方程中压力相关项的变化所证明的那样。这些结果表明，在壁面回火火焰的情况下，压力膨胀和压力引起的湍流传输是湍流动能方程中的两个主要项。 * umair.ahmed@newcastle.ac.uk
A Direct Numerical (DNS) database for boundary layer flashback of a premixed hydrogen-air flame with an equivalence ratio of 1.5 in a fully developed turbulent channel flow has been considered for this analysis. The non-reacting part of the channel flow is representative of the friction velocity based Reynolds number Reτ = 120. A skeletal chemical mechanism with 9 chemical species and 20 reaction is employed for representing hydrogen-air combustion. In this work the flow configuration and the turbulence and flame characteristics are similar to those of Gruber et al. [J. Fluid Mech, 709 516-542 (2012)]. The interaction between the flame structure and the turbulent flow has been investigated for boundary layer flashback for a comparison with the earlier work of Gruber et al. [J. Fluid Mech, 709 516-542 (2012)]. The statistics of wall shear stress, turbulent kinetic energy and its dissipation have been analysed to probe the influence of the flame on the underlying turbulence in the channel flow configuration. Furthermore, the budgets for the individual terms in the turbulent kinetic energy transport equation have also been investigated at a given plane in the channel. It is found that the propagation of the flame into the upstream part of the fully developed turbulent boundary layer introduces a flow reversal in some regions upstream of the flame and these regions lead to negative wall shear stress. Interrogation of the DNS data for the budgets of the turbulent kinetic energy transport has revealed that the aforementioned local flow reversal regions have significant influences on the turbulent kinetic energy production, pressure dilatation and pressure transport terms. It has been found that the flame propagation into the upstream reactants leads to some weak local compressibility effects as demonstrated by the changes in the pressure related terms in the turbulent kinetic energy transport equation. These results indicate that the pressure dilatation and turbulent transport due to pressure are the two dominant terms in the turbulent kinetic energy equation in the case of wall bounded flashback flames. ∗ umair.ahmed@newcastle.ac.uk