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A computational fluid dynamics investigation of thermoacoustic instabilities in premixed laminar and turbulent combustion systems.

机译：预混层流和湍流燃烧系统中热声不稳定性的计算流体动力学研究。

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摘要

Lean premixed combustors have been designed to lower NOx and other pollutant levels in land based gas turbines. These combustors are often susceptible to thereto-acoustic instabilities, which manifest as pressure and heat release oscillations in the combustor. To be able to predict and control these instabilities, it is required that both the acoustics of the system, and a frequency-resolved response of the combustion process to incoming perturbations be understood.; Currently, a system-level approach is being used widely to predict the thermoacoustic instabilities. This approach requires simple, yet accurate models which would describe the behavior of each dynamic block within the loop. The present study is directed toward using computational fluid dynamics (CFD) as a tool in developing reduced order models for the dynamics of laminar flat flames and swirl stabilized turbulent flames. A finite-volume based approach is being used to simulate reacting flows in both laminar and turbulent combustors. The study has been divided into three parts---the first part involves the modeling of a self-excited combustor (the acoustics of the combustor are coupled with the unsteady heat release); the second part of the research aims to study the effect of velocity perturbations on the unsteady heat release rate from a burner stabilized laminar flat flame; the third and final part of work involves an extension of the laminar flat flame study to turbulent reacting flows in a swirl stabilized combustor, and study the effects on the turbulent heat release due to the velocity perturbations.; A Rijke tube combustor was selected to study self-excited combustion phenomenon. A laminar premixed methane-air flat flame was stabilized on a honeycomb flame-stabilizer. The flame stabilizer was placed at the center of the 5 ft vertical tube. The position of the flame at the center of the tube leads to a thermoacoustic instability of the 2nd acoustic mode. The fundamental thermoacoustic frequency was predicted accurately by the CFD model and the amplitude was reasonably matched (for a flow rate of Q = 120 cc/s and equivalence ratio &phis; = 1.0). (Abstract shortened by UMI.)
机译：稀薄的预混燃烧器已被设计为降低陆基燃气轮机中的NOx和其他污染物水平。这些燃烧器通常易受声学不稳定的影响，这表现为燃烧器中的压力和热量释放振荡。为了能够预测和控制这些不稳定性，需要既了解系统的声学特性，又了解燃烧过程对入射扰动的频率分辨响应。当前，系统级方法被广泛用于预测热声不稳定性。这种方法需要简单而准确的模型，这些模型将描述循环中每个动态块的行为。本研究旨在使用计算流体动力学（CFD）作为开发层流平面火焰和涡旋稳定湍流火焰动力学降阶模型的工具。一种基于有限体积的方法被用来模拟层流和湍流燃烧室中的反应流。该研究分为三个部分：-第一部分涉及自激燃烧器的建模（燃烧器的声学特性与不稳定的热量释放相关联）；研究的第二部分旨在研究速度扰动对燃烧器稳定的层状扁平火焰不稳定的热释放速率的影响。第三部分也是最后一部分涉及层流平焰研究，将其扩展到涡旋稳定燃烧室中的湍流反应流，并研究由于速度扰动对湍流放热的影响。选择了Rijke管燃烧器来研究自激燃烧现象。层状预混合甲烷-空气平面火焰在蜂窝式火焰稳定器上稳定。将火焰稳定剂放置在5英尺垂直管的中心。火焰在管子中央的位置导致第二声模的热声不稳定性。通过CFD模型可以准确预测基本热声频率，并且可以合理地匹配振幅（对于Q = 120 cc / s的流量和当量比φ= 1.0）。 （摘要由UMI缩短。）

著录项

  • 作者

    Chatterjee, Prateep.;

  • 作者单位

    Virginia Polytechnic Institute and State University.;

  • 授予单位 Virginia Polytechnic Institute and State University.;
  • 学科 Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2004
  • 页码 258 p.
  • 总页数 258
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;
  • 关键词

  • 入库时间 2022-08-17 11:44:21

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