Determination of Markstein numbers in counterflow premixed flames
Determination of Markstein numbers in counterflow premixed flames
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DOI：
10.1016/s0010-2180(02)00369-3
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发表时间：
2002-07
影响因子：
4.4
通讯作者：
S. Davis;J. Quinard;G. Searby
中科院分区：
文献类型：
--
作者：
S. Davis;J. Quinard;G. Searby
本文试图解决一个长期存在的问题，关于不同的实验方案测量的马克斯坦数的差异。一个完整的传输系数的逆流火焰的数值模拟，但使用一个虚构的反应混合物具有接近渐近层流火焰分析中假设的属性，被用来显示如何正确地识别燃烧速度和拉伸的拉伸火焰与有限宽度的化学区。我们展示了如何测量的Markstein数的火焰相对于未燃烧和燃烧的气体。这些数字的数值根据内部火焰结构而不同。这种差异的物理根源是显而易见的。我们的数值结果与渐近理论的预测是一致的。我们表明，实验室实验逆流火焰给Markstein数相关的未燃气体，而球形膨胀火焰的实验室实验给Markstein数相关的燃烧气体。渐近理论的有效性范围内，刘易斯数离开团结，也检查。我们推测，所谓的消耗速度的火焰（正常积分的物种消耗率）可能允许测量的刘易斯数依赖部分的Markstein数，即使是现实的火焰与复杂的化学和有效的刘易斯数不接近统一。
This paper attempts to settle a long-standing issue concerning the differences in Markstein numbers measured by different experimental protocols. Numerical simulations of a counterflow flame with full transport coefficients, but using a fictitious reactive mixture having properties close to those assumed in asymptotic laminar flame analysis, are used to show how to correctly identify the burning velocity and stretch of a stretched flame with a finite width chemical zone. We show how to measure the Markstein number of the flame with respect to both the unburned and burned gases. The numerical values of these numbers differ by a quantity that depends on the internal flame structure. The physical origin of this difference is made evident. Our numerical results are in close agreement with the predictions of asymptotic theory. We show that laboratory experiments on counterflow flames give Markstein numbers related to the unburned gas, whereas laboratory experiments on spherical expanding flames give Markstein numbers related to the burned gases. The range of validity of asymptotic theory, for Lewis numbers departing from unity, is also examined. We conjecture that the so-called consumption velocity of a flame (normal integral of the species consumption rate) may allow a measure of the Lewis number dependent part of the Markstein number, even for realistic flames with complex chemistry and an effective Lewis number not close to unity.