• Title/Summary/Keyword: 예혼합

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NO Formation in Partially Premixed Counterflow Flames;Comparison of Computed and PLIF Results (부분예혼합 대향류 화염에서의 NO 생성특징;수치해석 및 PLIF 결과 비교)

  • Lee, Woong-Jae;Lee, Won-Nam;Cha, Min-Suk;Song, Young-Hoon
    • 한국연소학회:학술대회논문집
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    • 2000.05a
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    • pp.57-66
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    • 2000
  • OH radical and NO distributions have been measured in methane/air partially premixed counterflow flames(${\alpha}$=1.0, 0.8, 0.6) using PLIF technique. The results are discussed and compared with the numerical analysis results obtained under the same flame conditions. Measured OH and NO LIF signals agree with the computed concentration distributions. Both numerical and experimental results indicate that the structural change in a flame alters the NO formation characteristics of a partially premixed counterflow flame. The nitrogen dilution also changes flame structure, temperature and OH radical distributions and results in the decreased NO concentrations in a flame. The levels of decrease in NO concentrations, however, depends on the premixedness(${\alpha}$) of a flame. The larger change in the flame structure and NO concentrations have been observed in a premixed flame($\alpha$=1.0), which implies that the premixedness is likely to be a factor in the dilution effect on NO formation of a flame.

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On the extinction of partially premixed diffusion system and the near- stoichiometric structure of premixed flames (부분 예혼합-확산계의 소화특성 및 예혼합 화염의 Near-Stoichiometry 구조에 관한 연구)

  • 김종수;정석호
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.1
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    • pp.72-80
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    • 1988
  • Partially premixed diffusion system is analyzed using the matched asymptotic expansion technique adopting counterflow with supplying fuel and oxidizer from one side and fuel only from the other as a model problem. Results show that single-stage extinction always occurs as stretch increases, and the partially premixed diffusion flame can hardly exist. Depending on the initial mixture concentrations, either premixed or diffusion flame extinction leads to complete extinction of the system, and the diffusion flame can change its character to premixed flame such that two premixed flames can exist in the partially premixed-diffusion system.

A Study on Measurement of Premixed Spray Flame using Cross-correlation PIV (상호상관 PIV를 이용한 예혼합 분무화염의 계측에 관한 연구)

  • Yang Young-Joon;Kim Bong-Hwan
    • Journal of Energy Engineering
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    • v.14 no.4 s.44
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    • pp.259-267
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    • 2005
  • In an attempt to elucidate combustion mechanism or premixed spray flame in detail, both the enlarged photographing, which was performed for spray cross-sectional images of premixed spray flame, and the cross-correlation PIV, which was performed for consecutive time-series images to obtain instantaneous two dimensional flow field, were applied. This study indicated that CW laser as well as pulse laser could be applied for PIV. Furthermore, the results of cross-correlation PIV, which was self-made PIV program, was shown in good agreement with those of PDA. Therefore, it was verified that cross-correlation PIV using CW laser in this study could be effectively used for observing structure of premixed spray flame.

Structure of Premixed Turbulent Flames Stabilized by a Cylinderical Flame Holder (원주 보염기에 의해 안정화된 난류 예혼합 화염의 구조)

  • ;香月正司;水谷幸天
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.9 no.4
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    • pp.497-508
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    • 1985
  • 본 논문에서는 일양한 예혼합 기류중에 놓여진 원주 후류의 고온 순환류에 의 해 보지되는 난류 예혼합 화염을 대상으로 해서 유동의 가시화 및 온도와 이온전류의 변동의 측정에 의해서 화염의 구조를 조사한 결과, 원주 보염기 후류의 재순환 영역부 근에 형성된 전단층에 있어서는 코히렌트(Coherent)구조의 화염이 되고 하류부에서는 불규칙한 3차원 와(渦)에 지배되는 전파성 화염이 형성 되었다. 온도변동에 대한 쌍 봉성의 확율밀도분포와 이온전류변동에 대한 3개의 피이크의 확율밀도분포는 엷은 반 응면을 사이에 두고 미연혼합기괴와 기연가스괴가 서로 접하는 주름 상층류화염 또는 층류화염편의 구조에 대응하며, 코히렌트 와(渦)에 지배되는 화염에 있어서는 거시적 혼합은 코히렌트 와의 거동에 지배되나 그 구조는 주름상층류 화염과 일부 강한 전단 력을 받는 부분에는 분산 반응영역의 구조임이 밝혀졌다.

카오스 이론과 유체혼합 - 3차원 혼합의 적용예를 중심으로 -

  • 황욱렬;권태헌
    • Journal of the KSME
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    • v.42 no.4
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    • pp.42-45
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    • 2002
  • 이 글에서는 카오스의 이론적인 관점에서 성공적이라 할 수 있는 3차원 유동의 적용 예 중에서 산업적으로 관심의 대상이 될 수 있는 파이프 유동에서의 혼합증진, 혼합탱크 내의 혼합증진, 단축압출기에서의 혼합증진, 그리고 마이크로 채널 유동에서의 혼합증진 등 네 가지 유동에 대해 소개하도록 한다.

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A Chemical Reactor Modeling for Prediction of NO Formation of Methane-Air Lean Premixed Combustion in Jet Stirred Reactor (제트 혼합 반응기 내 희박 예혼합 메탄-공기 연소의 NO 생성 예측을 위한 화학 반응기 모델링)

  • Lee, Bo-Rahm;Park, Jung-Kyu;Lee, Do-Yong;Lee, Min-Chul;Park, Won-Shik
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.4
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    • pp.365-373
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    • 2010
  • A chemical reactor model (CRM) was developed for a jet stirred reactor (JSR) to predict the emission of exhaust such as NOx. In this study, a two-PSR model was chosen as the chemical reactor model for the JSR. The predictions of NO formation in lean premixed methane-air combustion in the JSR were carried out by using CHEMKIN and GRI 3.0 methane-air combustion mechanism which include the four NO formation mechanisms. The calculated results were compared with Rutar's experimental data for the validation of the model. The effects of important parameters on NO formation and the contributions of the four NO pathways were investigated. In the flame region, the major pathway is the prompt mechanism, and in the post flame region, the major pathway is the Zelodovich mechanism. Under the lean premixed condition, the N2O mechanism is the important pathway in both flame and postflame regions.

A Numerical Study on Mixing of Fuel/Air Mixture and NOx Emission in a Gas Turbine Burner with a Vortex Generator (와류 발생기를 장착한 가스터빈 연소기에서 연료/공기 혼합 및 NOx 배출 특성에 관한 수치적 연구)

  • Kim, Gu;Lee, Young Duk;Sohn, Chae Hoon
    • Journal of the Korean Society of Combustion
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    • v.18 no.3
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    • pp.68-74
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    • 2013
  • 가스터빈용 희박 예혼합 연소기 내부에 와류 발생기(vortex generator)를 장착하여 그에 따른 연료/공기혼합 및 NOx 배출 특성 변화를 조사하였다. 이를 위해 수치해석적 방법을 채택하여 연소기내 유동특성, 연료/공기 혼합도, 배기가스(NOx), 화염형상을 분석하였다. 와류 발생기를 장착한 경우, 연소기 내부에서 와류 발생기에 의한 나사산 형상으로 인해 와류가 형성되며 이는 연소기 전면부까지 유지되었다. 또한 연소기 내부 면적 차로 인해 압력섭동이 발생하였다. 이와 더불어 연소기 전면부 기준 상류지역의 연료와 공기의 혼합도가 증가됨으로서 연료 과농지역이 감소하게 되며 이로 인해 전반적인 NOx 발생량의 감소 효과를 볼 수 있었다. 화염 형상의 변화로부터 와류 발생기의 영향으로 선회수는 다소 감소할 것으로 예상되며, 이는 와류 발생기로 인한 유속의 반복적 증감에 의한 결과라고 판단된다.

Large Eddy Simulation of Turbulent Premixed Combustion Flow around Bluff Body based on the G-equation with Dynamic sub-grid model (Dynamic Sub-grid 모델을 이용한 G 방정식에 의한 보염기 주위의 난류 예혼합 연소에 관한 대 와동 모사)

  • Park, Nam-Seob;Ko, Sang-Cheol
    • Journal of Advanced Marine Engineering and Technology
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    • v.34 no.8
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    • pp.1084-1093
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    • 2010
  • Large eddy simulation of turbulent premixed flame stabilized by the bluff body is performed by using sub-grid scale combustion model based on the G-equation describing the flame front propagation. The basic idea of LES modeling is to evaluate the filtered-front speed, which should be enhanced in the grid scale by the scale fluctuations. The dynamic subgrid scale models newly introduced into the G-equation are validated by the premixed combustion flow behind the triangle flame holder. The calculated results can predict the velocity and temperature of the combustion flow in good agreement with the experiment data.

Introduction to Flame Transfer Function in Lean Premixed Gas Turbine Combustor (희박 예혼합 가스터빈 연소기에서의 화염 전달 함수 소개)

  • Kim, Dae-Sik
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.9
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    • pp.975-979
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    • 2011
  • Lean premixed gas turbine combustors were successful in meeting current NOx emission regulations. However, these combustors have been found to be susceptible to combustion instability. In this study, general mechanisms for combustion dynamics and instabilities in lean premixed gas turbine combustors are introduced. In addition, the flame transfer functions in the combustor are experimentally determined. The inputs to the flame transfer function are the imposed velocity fluctuations of the mixture. The key results of the measurements are reviewed.