Reconciling turbulent burning velocity with flame surface area in small-scale turbulence
Reconciling turbulent burning velocity with flame surface area in small-scale turbulence
复制标题
小规模湍流中湍流燃烧速度与火焰表面积的协调
DOI：
10.1017/jfm.2018.841
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发表时间：
2018
影响因子：
3.7
通讯作者：
Simone Hochgreb
中科院分区：
文献类型：
--
作者：
G. Nivarti;RS Cant;Simone Hochgreb
在高强度湍流测量的火焰表面积的增强和整体燃烧速率的增强之间的差异被解决。为了调和这两个数量，被认为是一个额外的贡献，从有效的湍流扩散。这种贡献预计将出现在足够强烈的湍流小于小火焰厚度的涡流。在目前的工作中，从这些涡流所产生的扩散率的增强估计模型的能量谱的基础上，从所有的湍流长度尺度较小的小火焰厚度的个人贡献集成在相应的部分频谱。结果表明，扩散增强，以这种方式估计，是能够占整体燃烧速率增强和火焰表面积增强之间的测量差异。量化这种差异的因素被正式作为一个封闭形式的函数的Karlovitz数。
A discrepancy between the enhancement in overall burning rate and the enhancement in flame surface area measured for high-intensity turbulence is addressed. In order to reconcile the two quantities, an additional contribution from the effective turbulent diffusivity is considered. This contribution is expected to arise in sufficiently intense turbulence from eddies smaller than the flamelet thickness. In the present work, the enhancement in diffusivity arising from these eddies is estimated based on a model energy spectrum; individual contributions from all turbulence length scales smaller the flamelet thickness are integrated over the corresponding portion of the spectrum. It is shown that diffusivity enhancement, estimated in this manner, is able to account for the measured discrepancy between the overall burning rate enhancement and flame surface area enhancement. The factor quantifying this discrepancy is formalized as a closed-form function of the Karlovitz number.