Effects of Lewis number on scalar transport in turbulent premixed flames
Effects of Lewis number on scalar transport in turbulent premixed flames
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DOI：
10.1063/1.3097007
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发表时间：
2009-03
影响因子：
4.6
通讯作者：
N. Chakraborty;R. Cant
中科院分区：
文献类型：
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作者：
N. Chakraborty;R. Cant
采用直接数值模拟方法研究了整体刘易斯数对湍流预混火焰中标量输运的影响。在相同的湍流流场初始条件下，当整体刘易斯数明显小于1时，火焰倾向于表现出反梯度输运，而梯度输运的程度随着整体刘易斯数的增加而增加。研究表明，反应物和产物在火焰法向方向上的速度差受到全局刘易斯数的显着影响。火焰法向加速度随刘易斯数的减小而增大，导致火焰传播平均方向上的平均压力梯度的大小增大。这种效应被证明是负责促进低刘易斯数火焰中的反梯度传输。对于具有刘易斯数特征的火焰，火焰面密度的湍流输运倾向于呈现反梯度行为。
The effects of global Lewis number on scalar transport in turbulent premixed flames are studied using direct numerical simulation. Under the same initial conditions of turbulent flow field, it is observed that flames with global Lewis numbers significantly smaller than unity tend to exhibit countergradient transport, whereas the extent of gradient transport is shown to increase with increasing global Lewis numbers. The velocity difference between reactants and products in the flame normal direction is shown to be significantly affected by the global Lewis number. The flame normal acceleration is shown to increase with decreasing Lewis number, leading to an increase in the magnitude of the mean pressure gradient in the mean direction of flame propagation. This effect is shown to be is responsible for promoting countergradient transport in low Lewis number flames. It is also shown that turbulent transport of flame surface density tends to exhibit countergradient behavior for the flames with Lewis number sig...