Nonlinear effects of stretch on the flame front propagation
Nonlinear effects of stretch on the flame front propagation
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DOI：
10.1016/j.combustflame.2010.05.013
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发表时间：
2010-10-01
影响因子：
4.4
通讯作者：
Mounaim-Rousselle, C.
中科院分区：
文献类型：
--
作者：
Halter, F.;Tahtouh, T.;Mounaim-Rousselle, C.
在所有的实验配置中，火焰都受到拉伸（曲率和/或应变率）的影响。为了获得与实验配置无关的未拉伸火焰速度，需要对测量的火焰速度进行校正。通常使用火焰速度与拉伸之间的线性关系。然而，这种线性关系是几个假设的结果，这些假设可能是不正确的。本研究旨在评估传统线性方法在层流燃烧速度评估中的误差。实验在一个封闭的容器中进行，在大气压下对两种不同的混合物：甲烷/空气和异辛烷/空气。甲烷和异辛烷的初始温度分别为300 K和400 K。应用了两种方法（线性和非线性），并比较了层流速度和燃烧气体Markstein长度的结果。选择甲烷和异辛烷是因为当当量比增加时，它们的马克斯坦长度呈现相反的演变。以非线性方法为参考，对线性方法引起的误差进行了评价。可以观察到，在甲烷/空气混合物的等效比为1.1之后，在异辛烷/空气混合物的等效比为1之前，使用线性方法开始引起重大误差。在这些关键情况下，提高线性方法准确性的一个解决方案是通过增加使用的初始火焰半径来减少线性方法中使用的点的数量。(C) 2010燃烧研究所。Elsevier Inc.出版。版权所有。
In all experimental configurations, the flames are affected by stretch (curvature and/or strain rate). To obtain the unstretched flame speed, independent of the experimental configuration, the measured flame speed needs to be corrected. Usually, a linear relationship linking the flame speed to stretch is used. However, this linear relation is the result of several assumptions, which may be incorrected. The present study aims at evaluating the error in the laminar burning speed evaluation induced by using the traditional linear methodology. Experiments were performed in a closed vessel at atmospheric pressure for two different mixtures: methane/air and iso-octane/air. The initial temperatures were respectively 300 K and 400 K for methane and iso-octane. Both methodologies (linear and nonlinear) are applied and results in terms of laminar speed and burned gas Markstein length are compared. Methane and iso-octane were chosen because they present opposite evolutions in their Markstein length when the equivalence ratio is increased.The error induced by the linear methodology is evaluated, taking the nonlinear methodology as the reference. It is observed that the use of the linear methodology starts to induce substantial errors after an equivalence ratio of 1.1 for methane/air mixtures and before an equivalence ratio of 1 for iso-octane/air mixtures. One solution to increase the accuracy of the linear methodology for these critical cases consists in reducing the number of points used in the linear methodology by increasing the initial flame radius used. (C) 2010 The Combustion Institute. Published by Elsevier Inc. All rights reserved.