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Transient process of methane-oxygen diffusion flame-street establishment in a microchannel

Frontiers in Energy 2022年第6期16卷 988-999页

作者： Xin KANG Yu WANG School of Civil Engineering and Architecture Wuhan University of TechnologyWuhan 430070China School of Automotive Engineering Wuhan University of TechnologyWuhan 430070China

“flame-street”is an interesting diffusion flame behavior in which a series of flame-segments is separately distributed along the mixing layer in a narrow *** experimental phenomenon was experimentally and numerically investigated with the focus on the steady-state,thermo-chemical flame structures in previous *** the present paper,the dynamic formation process of a methane-oxygen diffusion flame-street structure was simulated with a reacting flow solver developed based on the open-source framework *** imposing a certain amount of ignition-energy near the channel outlet,a reaction-kernel was formed and ***,three separate flames were consecutively generated from this kernel and propagated within the *** whole process was completed within 15 ms and all the discrete flames were eventually in a ***,different propagation features were observed for the three flame segments:The leading flame experienced a flame shape/type change from a tribrachial structure in its fastpropagating phase to a long,trailing diffusion tail after being anchored to the *** successive flame had a much lower propagation speed,keeping its two wing-like(fuel-lean premixed and fuel-rich premixed)structure while moving toward its stabilization location,which was approximately in the middle of the *** last flame,after the ignition source was turned-off,was immediately convected a bit downstream,and eventually featured a similar two-branch-like structure as the second ***,chemical insights for the premixed and diffusion branches of the leading flame were also provided with the change of significance of some key elementary reactions focused on,in order to attain a detailed profiling of the flame-type *** paper is a first-ever one discussing the transient formation of flame-streets in literature and is believed to be useful for obtaining a comprehensive understanding of this unique flame characte

关键词： micro-combustion flame-street diffusion flame mixing layer flame propagation speed

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The Influence of Fuel-Air Swirl Intensity on flame Structures of Syngas Swirl-Stabilized diffusion flame

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Journal of Thermal Science 2010年第3期19卷 276-283页

作者： Weiwei Shao Yan Xiong Kejin Mu Zhedian Zhang Yue Wang Yunhan Xiao Research Center for Energy and Power Chinese Academy of Sciences Beijing China Key Laboratory of Advanced Energy and Power Chinese Academy of Sciences (Institute of Engineenng Thermophysics) Beijing China P.O. Box 2706 Beijing 100190 China Nanjing TianLing Energy Tech. Co Ltd Jiangsu 210018 China

flame structures of a syngas swirl-stabilized diffusion flame in a model combustor were measured using the OH-PLIF method under different fuel and air swirl *** flame operated under atmospheric pressure with air and a typical low heating-value syngas with a composition of 28.5% CO,22.5% H2 and 49% N2 at a thermal power of 34 *** indicate that increasing the air swirl intensity with the same fuel,swirl intensity flame structures showed little difference except a small reduction of flame length;but also,with the same air swirl intensity,fuel swirl intensity showed great influence on flame shape,length and reaction zone ***,compared with air swirl intensity,fuel swirl intensity appeared a key effect on the flame structure for the model *** OH-PLIF images showed that three distinct typical structures with an obvious difference of reaction zone distribution were found at low swirl intensity,while a much compacter flame structure with a single,stable and uniform reaction zone distribution was found at large fuel-air swirl *** means that larger swirl intensity leads to efficient,stable combustion of the syngas diffusion flame.

关键词： diffusion flame Swirl Intensity flame Structure OH-PLIF

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Three-dimensional temperature reconstruction of diffusion flame from the light-field convolution imaging by the focused plenoptic camera

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Science China(Technological Sciences) 2022年第2期65卷 302-323页

作者： SHI JingWen QI Hong YU ZhiQiang AN XiangYang REN YaTao TAN HePing School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China Key Laboratory of Aerospace Thermophysics Ministry of Industry and Information TechnologyHarbin 150001China

The plenoptic imaging technique provides a promising approach to the non-invasive three-dimensional measurement, especially for the high-temperature combustion diagnosis. We establish a light-field convolution imaging model for diffusion flame in this work, considering the radiation transfer process inside the diffusion flame and the light transfer process inside the focused plenoptic camera together. The radiation transfer process is described by the radiation transfer equation and solved by the generalized source multi-flux method. Wave optics theory is adopted to describe the light transfer process, combining Fresnel diffraction and the phase conversion of the lens. The flame light-field image is obtained by the light-field convolution imaging model and adopted as the measurement signal to reconstruct three-dimensional temperature field. The inverse problem of temperature reconstruction is solved by the least square QR decomposition method. The simulative temperature reconstruction work is conducted, including the inverse analysis, the uncertainty analysis, and the measurement noise influence. All the results show that the proposed measurement method is available to reconstruct three-dimensional temperature with satisfactory accuracy and acceptable uncertainty. Both symmetric and asymmetric distributed temperature fields are investigated, and the reconstructed results prove the validity and universality of the measurement method.

关键词： temperature measurement plenoptic convolution imaging model diffusion flame uncertainty analysis inverse problem

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diffusion flame of a CH4/H2 Jet in a Hot Coflow： Effects of Coflow Oxygen and Temperature

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Chinese Journal of Chemical Engineering 2013年第7期21卷 787-799页

作者：梅振锋王飞飞李鹏飞米建春 State Key Laboratory of Turbulence & Complex Systems Department of Energy & Resources Engineering College of Engineering Peking University Beijing 100871 China

This paper investigates the effects of coflow O2 level and temperature on diffusion flame of a CH4/H2 jet in hot coflow （JHC） from a burner system similar to that of Dally et al. The coflow O2 mass fraction （ Yo2 ） is varied from 3% to 80% and the temperature （Tcof） from 1200 K to 1700 K. The Eddy Dissipation Concept （EDC） model with detailed reaction mechanisms GRI-Mech 3.0 is used for all simulations. To validate the modeling, several JHC flames are predicted under the experimental conditions of Dally et al. [Proc. Combust. Inst., 29 （1）, 1147-1154 （2002）] and the results obtained match well with the measurements. Results demonstrate that, when Yo2 decreased, the diffusion combustion is likely to transform from traditional combustion to MILD （Moderate or Intense Low-oxygen Dilution） combustion mode. When Tcof is higher, the temperature distribution over the whole domain trends to be more uniform. Reducing yo2 or Tcof leads to less production of intermediate species OH and CO. It is worth noting that if Yo2 is high enough （ Yo2 〉80%）, increasing Yo2 does not cause obvious temperature increase.

关键词： jet in hot coflow moderate and intense low-oxygen dilution combustion diffusion flame intermediate specie

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Response of Stretched Cylindrical diffusion flame to Sinusoidal Oscillation of Air Flow Velocity

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Journal of Mechanics Engineering and Automation 2017年第6期7卷 321-326页

作者： Yosuke Suenaga Hideki Yanaoka Mamoru Kikuchi Shun Sasaki Department of Systems Innovation Science Iwate University Morioka 020-8551 Japan Mazda Motor Corporation Hiroshima 730-8670 Japan

An experimental study investigated the characteristics of a stretched cylindrical diffusion flame, with a convex curvature with respect to the air stream, in response to periodic air flow velocity oscillation. The fuel was methane diluted with nitrogen, and the oxidizer air. The oscillation frequency was varied from 5 to 250 Hz. The results are summarized as follows. Though the fluctuation amplitude of the air stream velocity gradient was constant with respect to the frequency, the amplitude of the fuel stream increased. The fluctuation amplitude of the flame radius changed quasi-steadily from 5 to 25 Hz, and decreased with increasing frequency in the frequency range greater than 50 Hz. The flame luminosity did not respond quasi-steadily at 5 Hz, and the oscillation amplitude of flame luminosity was less than that of a steady flame, over the same velocity fluctuation range. The oscillation amplitude of luminosity peaked at 50 Hz, and was greater than that of a steady flame. It is considered that this complex change in flame luminosity with respect to frequency was closely related to the phase difference in the respective time variations in the ratio of flame thickness to radius, the velocity gradients of the air and fuel streams, and the magnitude of these values, with the ratio of flame thickness to radius related to the flame curvature effect, the velocity gradient of the air stream correlated to the flame stretch effect, and the velocity gradient of the fuel stream impacting the fuel transportation.

关键词： Combustion diffusion flame velocity oscillation flame stretch flame curvature

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Effects of Gravity on Numerical Simulation of Soot Formation in a Two-Dimensional Laminar Ethylene-Air diffusion flame

Effects of Gravity on Numerical Simulation of Soot Formation...

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第六届中日微重力科学专题研讨会

作者： Wenjun Kong Weikuo Zhang Xiaoqian Zhang and Fengshan Liu Institute of Engineering Thermophysics CAS Beijing China Inst. for Chemical Process and Environmental Tech. NRC Ottawa Canada Fengshan.

＜正＞Soot is solid byproduct of combustion. It affects contemporary life in many ways. Firstly soot is an important industrial additive to be used in many industrial products. Secondly, respirated soot can cause pulmonary problems and even some types of cancer. Thirdly, the soot particles generated inside combustors enhance the heat transmission and radiation inside the burner. This is an advantage in devices like boilers, but a problem in most engines by causing undesirable radiative heat loads to combustion chambers. In addition to contributing to pollution, soot enhances the emission of other pollutants from flames （e.g., carbon monoxide）, enhances the spread of unwanted fires due to radiant

关键词： Soot Formation diffusion flame Microgravity Numerical Simulations

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Preliminary study on interaction of water mist with diffusion flame of liquid fuels

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Progress in Natural Science:Materials International 2003年第3期 79-82页

作者： LIU Jianghong, LIAO Guangxuan, LI Peide and YAO Bin(State Key Laboratory of Fire Safety Science, University of Science and Technology of China, Hefei 230026, China) State Key Laboratory of Fire Safety Science University of Science and Technology of China Hefei 230026 China

The chemical and physical interaction mechanisms of the water mist with diffusion flame of liquid fuels are *** difference of the thermograms and the thermal field isograms between ethanol flame and kerosene flame with the water mist applica-tion is explained. With the water mist application, the differences between ethanol and kerosene in heat release rate, O2and CO concentra-tions of their combustion products, and the temperature of their srnoke are analyzed. At the same time, the interaction mechanism of thewater mist with diffusion flame is presented and their relationship to the fuel species and to the concentration of water mist is described.

关键词： water mist diffusion flame interaction mechanism.

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Nitrogen Dilution and Extinction Effects for Methane Impinging diffusion flame

Nitrogen Dilution and Extinction Effects for Methane Impingi...

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2012 2nd Internationnall Conference on Mechanical, Industrial, and Manufacturing Engineering

作者： Nadjib Ghiti Abed Alhalim Bentebbiche Ramzi Boulkroune Laboratoire de Mecanique Avancee—LMA URASM-CSC/ANNABA Unite de recherche Appliquee en Siderurgie Metallurgie Centre National de Recherche Scientifique et Technique en Soudage et Controle

In this study we focus an experimental investigation on the effect of the dilution rate on the extinction of a methane diffusion impinging *** infrared thermography camera to show the flame flow structure and to analysis the flow wall interacting behavior,with the variation of the nitrogen added rate to the methane jet flame by 0.2N,0.4N,0.6N,*** temperature fluctuation was shown a turbulent behavior of the flame and the extinction is more dependent on the flame approaching to the impinging wall and with the increase of the dilution rate,more dilution that is short time to extinction limit.

关键词： turbulence dilution diffusion flame impinging methane

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Experimental Study of Electrodes Parameters Effects on Small diffusion Combustion flame

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Journal of Harbin Institute of Technology(New Series) 2015年第3期22卷 107-114页

作者： Tieqiu Huang Qi Chen Limin Yan Yiting Zhang School of Mechanical Electronic and Control EngineeringBeijing Jiaotong University

To study the configuration and conductivity effects on micro-scale methane-air flames by electric field and iron wind,different electric field forces and iron winds are generated by needle,circle and plate electrodes respectively in different electrodes heights under both AC and DC fields though experiments. Experimental results showed that the flame characteristics are affected by needle electrodes mainly through the action of ion wind,by plate type electrodes mainly through the action of electric field force and by annular electrodes through both the electric field force and ion wind at the same time. Under DC field 's effects of all electrodes types,the flame will consequently go down while the voltage reached to a limit value,and it will breakdown under the strong effect of the ion wind by needle electrodes. The results also showed the influence by different electrodes types to the current characteristics,resistance properties and configuration of themicro-scale flames.

关键词： electrodes diffusion flame voltage current characteristic flame resistance

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Numerical Simulation of Turbulent diffusion flames of a Biogas Enriched with Hydrogen

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Fluid Dynamics & Materials Processing 2024年第1期20卷 79-96页

作者： Naima Krarraz Amina Sabeur Khadidja Safer Ahmed Ouadha Laboratoire des Science et Ingénierie Maritimes Facultéde Génie MécaniqueUniversitédes Sciences et de la Technologie d’Oran Mohamed BoudiafOranAlgérie Laboratoire des Carburants Gazeux et de l’Environnement Facultéde Génie MécaniqueUniversitédes Sciences et de la Laboratoire des Carburants Gazeux et de l’Environneme

Any biogas produced by the anaerobic fermentation of organic materials has the advantage of being an environmentally friendly ***,the relatively low calorific value of such gases makes their effective utilization in practical applications relatively *** present study considers the addition of hydrogen as a potential solution to mitigate this *** particular,the properties of turbulent diffusion jet flames and the related pollutant emissions are investigated numerically for different operating *** related numerical simulations are conducted by solving the RANS equations in the frame of the Reynolds Stress Model in combination with the flamelet *** effects are also taken into account and the combustion kinetics are described via the GRI-Mech 3.0 reaction *** considered hydrogen fuel enrichment spans the range from 0%to 50%in terms of *** varies between 1 and 10 *** results show that both hydrogen addition and pressure increase lead to an improvement in terms of mixing quality and have a significant effect on flame temperature and *** also reduce CO_(2) emissions but increase NOx *** NO is shown to be the predominant NO formation mechanism.

关键词： Biogas hydrogen diffusion flame turbulence NO formation route pressure

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