Nonlinear oscillations in diffusion flames
Nonlinear oscillations in diffusion flames
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DOI：
10.1016/j.combustflame.2005.08.042
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发表时间：
2006-04-01
影响因子：
4.4
通讯作者：
Law, CK
中科院分区：
文献类型：
--
作者：
Wang, HY;Bechtold, JK;Law, CK
最近的扩散火焰实验已经发现了令人着迷的非线性行为。尤其是在接近灭绝极限的时候。在这项工作中，我们对扩散火焰中的脉动不稳定性进行了系统分析。我们考虑平面扩散火焰的简单几何结构，该平面扩散火焰位于从下方供应的燃料与在上方流束前面扩散的氧化剂之间的界面处的通道中。为了关注脉动不稳定性，假设刘易斯数大于 1。我们采用Cheatham和Matalon的渐近理论，并进行分岔分析，推导出扰动幅度的非线性演化方程。我们的分析预测了三种可能的火焰反应。平面火焰可以是稳定的，使得扰动衰减至零。其次，扰动的幅度最终会在有限时间内变得无界，这表明火焰熄灭。最后，我们的振幅方程具有时间周期（极限循环）解，尽管我们发现这种状态对于燃烧系统的典型参数值无法实现。各种可能的燃烧方式都在参数空间中绘制出来，我们的结果与可用的实验和数值数据一致。 (c) 2005 年燃烧研究所。由爱思唯尔公司出版。保留所有权利。
Recent experiments of diffusion flames have identified fascinating nonlinear behavior. especially near the extinction limit. In this work, we carry out a systematic analysis of pulsating instabilities in diffusion flames. We consider the simple geometric configuration of a planar diffusion flame situated in a channel at the interface between a fuel being supplied from below, and oxidant diffusing in front a stream above. Lewis numbers are assumed greater than unity in order to focus on pulsating instabilities. We employ the asymptotic theory of Cheatham and Matalon, and carry out a bifurcation analysis to derive a nonlinear evolution equation for the amplitude of the perturbation. Our analysis predicts three possible flame responses. The planar flame may be stable, such that perturbations decay to zero. Second, the amplitude of a perturbation can eventually become unbounded in finite time, indicating flame quenching. And finally, our amplitude equation possesses time-periodic (limit cycle) solutions, although we find that this regime cannot be realized for parameter values typical of combustion systems. The various possible burning regimes are mapped out in parameter space, and our results are consistent with available experimental and numerical data. (c) 2005 The Combustion Institute. Published by Elsevier Inc. All rights reserved.