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首页> 外文期刊>Physics of fluids >Impact of the Lewis number on finger flame acceleration at the early stage of burning in channels and tubes
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Impact of the Lewis number on finger flame acceleration at the early stage of burning in channels and tubes

机译：刘易斯号码对沟道和管燃烧早期手指火焰加速度的影响

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摘要

For premixed combustion in channels and tubes with one end open, when a flame is ignited at the centerline at the closed end of the pipe and it propagates toward the open one, significant flame acceleration occurs at an early stage of the combustion process due to formation of a finger-shaped flame front. This scenario is tagged "finger flame acceleration" (FFA), involving an initially hemispherical flame kernel, which subsequently acquires a finger shape with increasing surface area of the flame front. Previous analytical and computational studies of FFA employed a conventional assumption of equidiffusivity when the thermal-to-mass-diffusivity ratio (the Lewis number) is unity (Le = 1). However, combustion is oftentimes nonequidiffusive (Le not equal 1) in practice such that there has been a need to identify the role of Le in FFA. This demand is addressed in the present work. Specifically, the dynamics and morphology of the Le not equal 1 flames in two-dimensional (2D) channels and cylindrical tubes are scrutinized by means of the computational simulations of the fully compressible reacting flow equations, and the role of Le is identified. Specifically, the Le > 1 flames accelerate slower as compared with the equidiffusive ones. In contrast, the Le < 1 flames acquire stronger distortion of the front, experience the diffusional-thermal combustion instability, and thereby accelerate much faster than the Le = 1 flames. In addition, combustion in a cylindrical configuration shows stronger FFA than that under the same burning conditions in a 2D planar geometry. Published under license by AIP Publishing.
机译：对于在通道和管道，其一端开放，当火焰在在管的封闭端的中心线点燃并朝向打开一个传播预混燃烧，显著火焰加速发生在燃烧过程由于形成的早期阶段的手指状的火焰前锋。这种情况下被标记“指火焰加速”（FFA），涉及一个最初半球形火焰核，随后获取与增加火焰前缘的表面积的手指形状。 FFA的先前分析和计算研究采用equidiffusivity的常规假设当热与质量扩散率比（路易斯数）为1（LE = 1）。然而，燃烧是经常nonequidiffusive（乐不等于1），在实践中，使得一直需要确定FFA乐的作用。这种需求在目前的工作中解决。具体而言，动态和乐的形态不等于1米的火焰在二维（2D）通道和圆筒形管被完全压缩的反应流方程的计算模拟的装置审查，和Le的作用被识别。具体而言，乐> 1个火焰加速与equidiffusive那些相比，更慢。与此相反，勒<1个火焰获取前方的较强的失真，体验扩散热燃烧不稳定性，并由此加速比乐= 1个火焰快得多。另外，在燃烧的圆筒状构型示出了比在2D平面的几何形状相同的燃烧条件下FFA更强。通过AIP发布在许可证下发布。

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  • 来源
    《Physics of fluids》 |2019年第8期|共10页
  • 作者

    Alkhabbaz Mohammed; Abidakun Olatunde; Valiev Damir; Akkerman Vyacheslav;

  • 作者单位

    West Virginia Univ Dept Mech &

    Aerosp Engn Computat Fluid Dynam &

    Appl Multiphys Ctr CAFEE CIGPU Morgantown WV 26506 USA;

    West Virginia Univ Dept Mech &

    Aerosp Engn Computat Fluid Dynam &

    Appl Multiphys Ctr CAFEE CIGPU Morgantown WV 26506 USA;

    Umea Univ Dept Appl Phys &

    Elect S-90187 Umea Sweden;

    West Virginia Univ Dept Mech &

    Aerosp Engn Computat Fluid Dynam &

    Appl Multiphys Ctr CAFEE CIGPU Morgantown WV 26506 USA;

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  • 正文语种 eng
  • 中图分类 流体力学;
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