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首页> 外文期刊>Combustion and Flame >Unsteady effects of strain rate and curvature on turbulent premixed flames in an inflow-outflow configuration
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Unsteady effects of strain rate and curvature on turbulent premixed flames in an inflow-outflow configuration

机译：流入和流出配置中应变率和曲率对湍流预混火焰的不稳定影响

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摘要

Three-dimensional direct numerical simulation (DNS) studies of premixed turbulent flames have been carried out using an inflow-outflow configuration at moderate Reynolds number (Re) and with single-step Arrhenius chemistry in the thin reaction zones regime. The compressible Navier-Stokes equations are solved together with a transport equation for a reaction progress variable (c). Results are obtained for several quantities of interest, including the gradient magnitude of the progress variable (|▽c|) and the displacement speed (S_d) of each progress variable isosurface. The probability density function (pdf) of displacement speed and the implications of the pdf shape are discussed in terms of the relative magnitude of reaction rate and molecular diffusion effects. The pdf of S_d itself, as well as the pdfs of its different components S_r, S_n, and S_t, in the present three-dimensional simulations is found to be consistent with previous results based on two-dimensional DNS with detailed chemistry. The validity of the assumption (ρS_d)_s ≈ ρ_0S_L is assessed on averaging ρS_d over the isosurfaces of c across the flame brush. The unsteady effects of tangential strain rate (a_T) and curvature (κ_m) on flame propagation are also considered. Curvature and displacement speed are found to be negatively correlated, while the conditional pdf of tangential strain rate and displacement speed at zero curvature locations also shows a negative correlation, again consistent with previous two-dimensional detailed-chemistry DNS.
机译：预混合湍流火焰的三维直接数值模拟（DNS）研究已经在薄反应区方案中采用中等雷诺数（Re）且采用单步Arrhenius化学的流入-流出配置进行。将可压缩的Navier-Stokes方程与反应进度变量（c）的输运方程一起求解。对于几个感兴趣的量，可以获得结果，包括进度变量的梯度幅度（|▽c |）和每个进度变量等值面的位移速度（S_d）。根据反应速率和分子扩散效应的相对大小，讨论了位移速度的概率密度函数（pdf）和pdf形状的含义。在当前的三维模拟中，发现S_d本身的pdf以及其不同组件S_r，S_n和S_t的pdf与基于二维DNS的详细化学方法的先前结果一致。假设（ρS_d）_s≈ρ_0S_L的有效性是根据火焰刷上c的等值面的平均ρS_d来评估的。还考虑了切向应变率（a_T）和曲率（κ_m）对火焰传播的非稳态影响。发现曲率和位移速度是负相关的，而在零曲率位置处的切向应变速率和位移速度的条件pdf也显示出负相关，再次与先前的二维详细化学DNS一致。

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  • 来源
    《Combustion and Flame》 |2004年第2期|p.129-147|共19页
  • 作者

    Nilanjan Chakraborty; Stewart Cant;

  • 作者单位

    CFD Laboratory, Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ, UK;

  • 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 燃料与燃烧;
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