• Title/Summary/Keyword: Laminar Premixed Flame

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Experimental Study on Effects of Syngas Addition in Flame Propagation and Stability of DME-Air Premixed Flames (디메틸에테르-공기 예혼합화염의 화염전파와 화염안정성에 있어서 합성가스의 첨가효과에 관한 실험적 연구)

  • Song, Wonsik;Park, Jeong;Kwon, Ohboong;Yun, Jinhan;Kee, Sangin
    • Journal of the Korean Society of Combustion
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    • v.17 no.4
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    • pp.44-50
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    • 2012
  • The present study was conducted to investigate the flame instability(evaluated by Markstein length and cellular instability) and laminar burning velocity in a constant volume combustion chamber at room temperature and elevated pressure up to 0.3 MPa to suggest the possibility of utilizing mixtures of syngas added DME-air premixed flames in internal combustion engines. The experimentally measured laminar burning velocities were compared to predictions calculated the PREMIX code with Zhao reaction mechanism. Discussions were made on effects of syngas addition into DME-Air premixed flames through evaluating laminar burning velocity, Markstein length, and cellular instability. Particular concerns are focused on cellular instability caused by hydrodynamic instability and diffusive-thermal instability.

Behaviors of Premixed Flames and Triple Flames with its Concentration Difference in a Slot Burner (슬롯버너에서 농도차이에 따른 예혼합화염과 삼지화염의 거동)

  • Kim, Tae-Kwon;Jang, Jun-Young;Park, Jeong;Jun, Seong-Hwa;Miwa, Kei
    • 한국연소학회:학술대회논문집
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    • 2004.11a
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    • pp.85-90
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    • 2004
  • We have presented characteristics of a transitional behavior from a premixed flame to a triple flame in a lifted flame according to the change of equivalence ratio. The experimental apparatus consisted of a slot burner and a contraction nozzle for a lifted flame. As concentration difference of the both side of slot burner increases, the shape of flame changed from a premixed flame to a triple flame, and the liftoff height is decreased to the minimum value and then increase again. Around this minimum point, it is confirmed a transition regime from premixed flame to triple flame. Consequently, the experimental results of the liftoff height, flame curvature and luminescence intensity showed that the stabilized laminar lifted flame regime is categorized by regimes of premixed flame, triple flame and critical flame. In the visualization experiment of smoke wire, the flow divergence and redirection reappeared in premixed flame as well as triple flame. Thus we cannot express the flame front of lifted flame has a behavior of triple flame with only flow divergence and redirection. To differentiate triple flame and premixed flame, ${\Phi}$ value of partially premixed fraction is employed. The partially premixed fraction ${\Phi}$ was constant in premixed flame. In critical flame small gradient appears over the whole regime. In triple flame, typical diffusion flame shape is obtained as parabolic distribution type due to diffusion flame trailing.

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Characteristics of Premixed Flame Propagations of R134a/Methane in a Constant Volume Combustion Chamber (정적 연소실 내 R134a 및 메탄 예혼합 화염의 전파 특성)

  • Choi, Byung Chul;Park, June Sung
    • 한국연소학회:학술대회논문집
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    • 2014.11a
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    • pp.85-86
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    • 2014
  • The characteristics of the outward-propagating premixed flames of stoichiometric mixtures of R134a/methane/oxygen/nitrogen have been experimentally investigated in a constant volume combustion chamber. Three regimes of the expanding flames were categorized based on the flame behavior.

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Large Eddy Simulation of Turbulent Premixed Flame in Turbulent Channel Flow

  • Ko Sang-Cheol;Park Nam-Seob
    • Journal of Mechanical Science and Technology
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    • v.20 no.8
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    • pp.1240-1247
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    • 2006
  • Large eddy simulation of turbulent premixed flame in turbulent channel flow is studied by using G-equation. A flamelet model for the premixed flame is combined with a dynamic subgrid combustion model for the filtered propagation flame speed. The objective of this work is to investigate the validity of the dynamic subgrid G-equation model to a complex turbulent premixed flame. The effect of model parameters of the dynamic sub grid G-equation on the turbulent flame speed is investigated. In order to consider quenching of laminar flames on the wall, wall-quenching damping function is employed in this calculation. In the present study, a constant density turbulent channel flow is used. The calculation results are evaluated by comparing with the DNS results of Bruneaux et al.

A study of turbulent premixed flame structure in a plane shear layer (평면전단층의 난류예혼합 화염의 구조에 관한 실험적 연구)

  • 이재득;최병륜
    • Journal of Advanced Marine Engineering and Technology
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    • v.13 no.4
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    • pp.33-39
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    • 1989
  • A turbulent premixed flames of layer formed between burned hot gas and unburned mixture were investigated by means of schlieren photograph with fluctuations of temperature and ion current. The combustion intensity between burned hot gas and shear layer was higher than the intensity between unburned mixture and shear layer. A wrinkled laminar flame and flamelet were appeared at downstream to exist and distributed reaction zone was at upstream as a result of analyzed probability density functions of temperature fluctuation. The initial combustion intensity of reaction zone of eddy between burned hot gas and shear layer was higher than that of final, flowing downstream, and vice versa between unburned mixture and shear layer.

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A Study on Mensurement of NO Concentrations in Laminar Non-premixed H2/N2 Flame Using LIF (레이저 유도 형광법(LIF)을 이용한 층류 비예혼합 수소/질소 화염에서의 NO 농도 측정에 관한 연구)

  • Jin, Seong Ho;Kim, Sung Wook;Park, Kyoung Suk;Kim, Gyung Soo
    • Journal of Hydrogen and New Energy
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    • v.13 no.4
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    • pp.279-286
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    • 2002
  • In this study, quantitative nitric oxide concentration distributions are investigated in the laminar non-premixed $H_2/N_2$ flames by laser-induced fluorescence (LIF). The measurements are taken in flames for different $N_2$ dilution ratios varying from 20~80%, and fuel flow rate is fixed as Islpm. The NO A-X (0,0) vibrational band around 226 nm is excited using a XeCl excimer-pumped dye laser. We applied same excitation line used in $CH_4$, premixed flame. Overall, NO concentration was rapidly decreased with Na addition and we could not measure the concentration any longer for $N_2$ dilution above 80%.

Experimental Performance Evaluation of Optical Receiving Probe (광학식 수광 프로브의 실험적 성능평가)

  • Yang, Young-Joon
    • Journal of the Korean Society of Industry Convergence
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    • v.7 no.3
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    • pp.265-271
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    • 2004
  • A light collecting probe named Multi-colored Integrated Receiving Optics (MICRO) is experimentally examined to verify its performance. For these purposes, the time-series signals of MICRO probe is compared with those of electro-static probe and light-guided probe by monitoring, for example. such as OH radical chemiluminescence. CH radical band and droplet Mie scattering In addition, the experiment was conducted by using laminar premixed Bunsen flame, turbulent premixed Bunsen flame and premixed spray flame, respectively. It was confirmed that the performance of MICRO probe was very useful and convenient to obtain the chemiluminescence signals from local regions in turbulent premixed Bunsen flame and premixed spray flame.

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Application of Optical Receiving Probe in Combustion Field (연소장에서의 광학식 수광프로브의 적용)

  • Yang, Young-Joon
    • Journal of Sensor Science and Technology
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    • v.13 no.5
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    • pp.335-341
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    • 2004
  • A light collecting probe named Multi-colored Integrated Receiving Optics (MICRO) is experimentally examined to verify its performance. For these purposes, the time-series signals of MICRO probe is compared with those of electrostatic probe and light-guided probe by monitoring, for example, such as OH radical chemiluminescence, CH radical band and droplet Mie scattering. In addition, the experiment was conducted by using laminar premixed Bunsen flame, turbulent premixed Bunsen flame and premixed spray flame, respectively. It was confirmed that the performance of MICRO probe was very useful and convenient to obtain the chemiluminescence signals from local regions in turbulent premixed Bunsen flame and premixed spray flame.

Effects of Acoustic Excitation on NOx Emission in Partially Premixed LPG/Air Flames (부분적 예혼합 LPG/공기 화염에서 음향자진이 NOx 배출에 미치는 영향)

  • 장준영;박성호;김태권
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.3
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    • pp.77-84
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    • 2002
  • Measurements of NO and NOx emission of laminar partially premixed LPG/air flames with and without acoustic excitation are reported. The NOx emission at the tailpipe of a combustion chamber is determined by chemiluminescent analyser. The NOx measurements are taken in flames with several different center tube equivalance ratio( ø$\sub$o/), and overall equivalace ratio(ø$\sub$o/) for a fixed fuel flowrate. The NOx emission decrease to reach a minimum value at an optimum ø$\sub$c/ 2. Theø$\sub$c/ 2 flame gives a compromise of thermal NO and prompt NO mechanism. In the case of excitation. the visual shape of the flame is changed from laminar flame to turbulent-like flame. With increasing levels of excitation amplitude, an optimum value of the NO and NOx emission exists. A shorter flame caused by the enhanced upstream mixing due to acoustic excitation results in the reduction of NO and NOx emission in the present flames. The reduction of flame length affects the shorter residence time of center tube mixture, and significantly influences the NOx reduction.

Measurement of Laminar Flame Speed of Syngas(H2/CO)/Air Premixed Flame using the Bunsen Burner Method (분젠 버너법을 이용한 합성가스(H2/CO)/공기 예혼합화염의 층류 연소속도 측정)

  • Jeong, Byeonggyu;Lee, Kee-Man
    • 한국연소학회:학술대회논문집
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    • 2012.04a
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    • pp.181-183
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    • 2012
  • Syngas laminar flame speed measurements were carried out at atmospheric pressure and ambient temperature using the Bunsen flame configuration with nozzle burner as a fundamental study on flame stability of syngas. Representative syngas mixture compositions ($H_2:CO$) such as 25:75%, 50:50% and 70:25% and equivalence ratios from 0.5 to 1.4 were investigated. The measured laminar flame speeds were in good agreement with the previous numerical data as well as experimental data available in the literatures over a wide range of equivalence ratio tested. It was reconfirmed that the laminar flame speed gradually increased with the increase in $H_2$ content in a fuel mixture. In particular, the significant increasing rate of flame speed was observed with the increase in equivalence ratio.

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