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Numerical simulation of the upward propagation of a flame in a vertical tube filled with a very lean mixture

机译:火焰在稀薄混合物垂直管中向上传播的数值模拟

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摘要

Upward propagation of a premixed flame in a vertical tube filled with a very lean mixture is simulated numerically using a single irreversible Arrhenius reaction model with infinitely high activation energy. In the absence of heat losses and preferential diffusion effects, a curved flame with stationary shape and velocity close to those of an open bubble ascending in the same tube is found for values of the fuel mass fraction above a certain minimum that increases with the radius of the tube, while the numerical computations cease to converge to a stationary solution below this minimum mass fraction. The vortical flow of the gas behind the flame and in its transport region is described for tubes of different radii. It is argued that this flow may become unstable when the fuel mass fraction is decreased, and that this instability, together with the flame stretch due to the strong curvature of the flame tip in narrow tubes, may be responsible for the minimum fuel mass fraction. Radiation losses and a Lewis number of the fuel slightly above unity decrease the final combustion temperature at the flame tip and increase the minimum fuel mass fraction, while a Lewis number slightly below unity has the opposite effect.
机译:使用具有无限高活化能的单个不可逆Arrhenius反应模型,通过数值模拟了预混合火焰在充满非常稀薄混合物的垂直管中的向上传播。在没有热损失和优先扩散效果的情况下,对于燃料质量分数高于一定最小值且随半径增大而增大的弯曲火焰,其固定形状和速度接近同一管中上升的气泡的速度。低于此最小质量分数时,数值计算将不再收敛到固定解。对于不同半径的管子,描述了火焰在火焰后方及其输送区域中的涡流。据认为,当燃料质量分数降低时,该流动可能变得不稳定,并且这种不稳定性以及由于窄管中火焰尖端的强曲率引起的火焰拉伸可能是最小燃料质量分数的原因。燃料的辐射损耗和路易斯值略高于1会降低火焰尖端的最终燃烧温度,并增加最小燃料质量分数,而路易斯值略低于1会产生相反的效果。

著录项

  • 来源
    《Combustion and Flame》 |2011年第5期|p.885-892|共8页
  • 作者

    FJ. Higuera;

  • 作者单位

    E. T. S. Ingenieros Aeronduticos, UPM, Pza. Cardenal Cisneros 3. 28040 Madrid, Spain;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    laminar flames; lean flammability limit; flame aerodynamics;

    机译:层流火焰贫燃极限;火焰空气动力学;
  • 入库时间 2022-08-18 00:12:14

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