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首页> 外文期刊>Journal of Thermophysics and Heat Transfer >Large-Eddy Simulation of Bluff-Body Flame Using the Equilibrium Combustion Model
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Large-Eddy Simulation of Bluff-Body Flame Using the Equilibrium Combustion Model

机译：基于平衡燃烧模型的钝体火焰大涡模拟

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摘要

Flame stabilization is an important issue in practical applications of combustion systems. The bluff-body configuration is a common technique that stabilizes the flame by producing a strong recirculation zone downstream . of the bluff body. Gas turbines provide a typical application of the bluff-body configuration. In this paper, a computational study of a bluff-body flame has been undertaken using an unstructured large-eddy simulation. The filtered Navier-Stokes equations are closed using a standard Smagorinsky model, and an equilibrium combustion model is employed for the chemistry calculation. All filtered scalar quantities are evaluated using a presumed probability density function based on a beta distribution function. It was found that accurate prediction of velocity profiles are strongly dependent upon the inflow conditions. It was also found that the equilibrium model for chemistry calculation does not capture well the dynamics of the reaction in the recirculation zone, where the diffusion timescales are very small. Based on this observation, a criterion was established for the implementation of the equilibrium model in terms of diffusion and chemical timescales. The diffusion timescales are inversely proportional to the scalar dissipation rate. It was found that the ratio of the diffusion timescale to the chemical timescale must be at least 2 x 102 to obtain accurate results with the equilibrium model.
机译：火焰稳定是燃烧系统实际应用中的重要问题。钝体构造是通过在下游产生强大的再循环区域来稳定火焰的常用技术。虚张声势的身体。燃气轮机提供了钝体构造的典型应用。在本文中，使用非结构化大涡模拟对钝体火焰进行了计算研究。使用标准的Smagorinsky模型关闭滤波后的Navier-Stokes方程，并使用平衡燃烧模型进行化学计算。使用基于beta分布函数的假定概率密度函数评估所有滤波后的标量。已经发现，速度分布的准确预测在很大程度上取决于流入条件。还发现用于化学计算的平衡模型不能很好地捕获扩散时间尺度很小的再循环区中反应的动力学。基于此观察结果，建立了在扩散和化学时间尺度方面实施平衡模型的标准。扩散时间尺度与标量耗散率成反比。已发现，扩散时标与化学时标之比必须至少为2 x 102，才能通过平衡模型获得准确的结果。

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  • 来源
    《Journal of Thermophysics and Heat Transfer》 |2015年第1期|179-189|共11页
  • 作者

    Shafiq R. Qureshi; Waqar A. Khan; Robert Prosser;

  • 作者单位

    National University of Sciences and Technology, Karachi 75350, Pakistan;

    National University of Sciences and Technology, Karachi 75350, Pakistan;

    University of Manchester, Manchester, England M13 9PL, United Kingdom;

  • 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
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