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首頁> 外文學(xué)位 >A computational fluid dynamics investigation of thermoacoustic instabilities in premixed laminar and turbulent combustion systems.
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A computational fluid dynamics investigation of thermoacoustic instabilities in premixed laminar and turbulent combustion systems.

機譯：預(yù)混層流和湍流燃燒系統(tǒng)中熱聲不穩(wěn)定性的計算流體動力學(xué)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.)
機譯：稀薄的預(yù)混燃燒器已被設(shè)計為降低陸基燃氣輪機中的NOx和其他污染物水平。這些燃燒器通常易受聲學(xué)不穩(wěn)定的影響，這表現(xiàn)為燃燒器中的壓力和熱量釋放振蕩。為了能夠預(yù)測和控制這些不穩(wěn)定性，需要既了解系統(tǒng)的聲學(xué)特性，又了解燃燒過程對入射擾動的頻率分辨響應(yīng)。當(dāng)前，系統(tǒng)級方法被廣泛用于預(yù)測熱聲不穩(wěn)定性。這種方法需要簡單而準(zhǔn)確的模型，這些模型將描述循環(huán)中每個動態(tài)塊的行為。本研究旨在使用計算流體動力學(xué)（CFD）作為開發(fā)層流平面火焰和渦旋穩(wěn)定湍流火焰動力學(xué)降階模型的工具。一種基于有限體積的方法被用來模擬層流和湍流燃燒室中的反應(yīng)流。該研究分為三個部分：-第一部分涉及自激燃燒器的建模（燃燒器的聲學(xué)特性與不穩(wěn)定的熱量釋放相關(guān)聯(lián)）；研究的第二部分旨在研究速度擾動對燃燒器穩(wěn)定的層狀扁平火焰不穩(wěn)定的熱釋放速率的影響。第三部分也是最后一部分涉及層流平焰研究，將其擴展到渦旋穩(wěn)定燃燒室中的湍流反應(yīng)流，并研究由于速度擾動對湍流放熱的影響。選擇了Rijke管燃燒器來研究自激燃燒現(xiàn)象。層狀預(yù)混合甲烷-空氣平面火焰在蜂窩式火焰穩(wěn)定器上穩(wěn)定。將火焰穩(wěn)定劑放置在5英尺垂直管的中心?；鹧嬖诠茏又醒氲奈恢脤?dǎo)致第二聲模的熱聲不穩(wěn)定性。通過CFD模型可以準(zhǔn)確預(yù)測基本熱聲頻率，并且可以合理地匹配振幅（對于Q = 120 cc / s的流量和當(dāng)量比φ= 1.0）。 （摘要由UMI縮短。）

著錄項

  • 作者

    Chatterjee, Prateep.;

  • 作者單位

    Virginia Polytechnic Institute and State University.;

  • 授予單位 Virginia Polytechnic Institute and State University.;
  • 學(xué)科 Engineering Mechanical.
  • 學(xué)位 Ph.D.
  • 年度 2004
  • 頁碼 258 p.
  • 總頁數(shù) 258
  • 原文格式 PDF
  • 正文語種 eng
  • 中圖分類 機械、儀表工業(yè);
  • 關(guān)鍵詞

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