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H2/CO/air premixed and partially premixed flame structure at different pressures based on reaction limit analysis

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Science Bulletin 2018年第19期63卷 1260-1266页

作者： Zaigang Liu Wenjun Kong Jean-Louis Consalvi Wenhu Han Key Laboratory of Light-Duty Gas-Turbine Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100190 China School of Engineering Sciences. University of Chinese Academy of Sciences Beijing 100049 China IUSTI UMR 7343 Aix-Marseille Universite CNRS Marseille 13453 France

Premixed and partially premixed flames (PPFs) of H2/CO/air syngas are studied numerically to investigate the effect of pressure on syngas PPF structure. Chemical characteristics of the syngas flame at different pressures are investigated based on reaction limit analysis using a one-dimensional configuration. The results show that CO affects the syngas reaction limits through both physical effects that consist mainly in dilution and chemical effects that are related to both R23 (CO+OH=CO2+H) and HCO pathway. In particular, the HCO pathway weakens the flame at low pressures due to the chain-terminating effect of R25 (HCO+O2=CO+HO2) and R26 (HCO+H=CO+H2), and enhances the flame at high pressures because of the contribution of R25 to the HO2chain-branching process. These CO chemical characteristics are also observed in the premixed zone of 50%H2+50%CO syngas PPFs whereas only R23 is important in the non-premixed zone.

关键词： Syngas Partially premixed flame Pressure effect Reaction limit flame structure

Experimental Investigation of flame structure and Combustion Limit During Premixed Methane/Air Jet flame and Sidewall Interaction

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Energy Engineering 2021年第1期118卷 37-52页

作者： Ying Chen Jianfeng Pan Qingbo Lu Yu Wang Chenxin Zhang School of Energy and Power Engineering Jiangsu UniversityZhenjiang212013China

The effects of inlet gas parameters and sloping sidewall angle on the flame structure and combustion limit with and without sidewall were experimentally *** height and impact angle were obtained by chemiluminescence intensity analysis of CH****,the combustion characteristics of flame with and without sidewall at different equivalence ratios were explored;then,the influence of Reynolds number and inlet gas temperature on flame structure and combustion limit of v-shaped flame with sidewall were analyzed,and the results with sidewall were compared with those without ***,the variation trend of flame parameters with different sloping sidewall angles was *** experimental results show that the existence of sidewall makes flame shape change from“M-shaped”to“inverted N-shaped”,and conical shape to trapezoidal *** inhibition effect of sidewall on flame stretching downstream is strengthened with the increase in Reynolds number;but as the temperature of the inlet gas increases,the inhibitory effect is obviously *** sloping sidewall angle decreases from 90°to 55°at 5°intervals,flame height and impact angle of v-shaped flame reach the extreme value whenβ=80°.Compared with the case without sidewall,the range of v-shaped flame with sidewall has no obvious trend of broadening or shrinking when inlet gas temperature is increased;however,as sloping sidewall angle decreases,the range of the v-shaped flame shrinks obviously and flammability limit increases significantly.

关键词： Sidewall premixed flame flame-wall interaction flame structure combustion limit

Investigation of flame structure in plasma-assisted turbulent premixed methane-air flame

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Plasma Science and Technology 2018年第2期20卷 1-7页

作者：张华磊何立明于锦禄祁文涛陈高成 Science and Technology on Plasma Dynamics Lab Air Force Engineering University

The mechanism of plasma-assisted combustion at increasing discharge voltage is investigated in detail at two distinctive system schemes（pretreatment of reactants and direct in situ discharge）.OH-planar laser-induced fluorescence（PLIF） technique is used to diagnose the turbulent structure methane-air flame,and the experimental apparatus consists of dump burner,plasma-generating system,gas supply system and OH-PLIF *** have shown that the effect of pretreatment of reactants on flame can be categorized into three regimes：regime I for voltage lower than 6.6 k V;regime II for voltage between 6.6 and 11.1 k V;and regime III for voltage between11.1 and 12.5 k *** regime I,aerodynamic effect and slower oxidation of higher hydrocarbons generated around the inner electrode tip plays a dominate role,while in regime III,the temperature rising effect will probably superimpose on the chemical effect and amplify *** wire-cylinder dielectric barrier discharge reactor with spatially uneven electric field,the amount of radicals and hydrocarbons are decreased monotonically in radial direction which affects the flame *** regard to in situ plasma discharge in flames,the discharge pattern changes from streamer type to glow *** with the case of reactants pretreatment,the flame propagates further in the upstream *** the discharge region,the OH intensity is highest for in situ plasma assisted combustion,indicating that the plasma energy is coupled into flame reaction zone.

关键词： plasma assisted combustion laser-induced fluorescence flame structure turbulentpremixed combustion dump burner

flame structure of a Jet flame with Penetration of Side Micro-jets

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Chinese Journal of Chemical Engineering 2008年第6期16卷 861-866页

作者：曹玉春吴金星米建春周钰 School of Chemical Engineering Zhengzhou University Henan 450001 China College of Engineering Peking University Beijing 100871 China Department of Mechanical Engineering Hong Kong Polytechnic University Hong Kong China

In this paper, an innovative jet lifted flame with side micro-jets has been proposed and its effects on the flame structure have also been investigated. Due to the changes of the initial combustion conditions, mixing and aerodynamics which resulted from the perturbation of the side micro-jets, such a lifted jet flame has different flame structure compared with the common premixed flame. Results demonstrate that use of the micro-jets can control, to a certain extent, the flame structure, including the flame length, lift-off distance and blow-off limit. With the same fuel and air flow rate, the flame length with the side micro-jets will decrease about 5%-40% as the air volume ratio a increases from 58%-76%. Compared with the common diffusion flame, the jet flame with the side micro-jets demonstrates to be easier to be a momentum-dominated flame. The flame length with 2 micro-jets is about 5% less than with 6 micro-jets under the same fuel and air flow rate. With the same a, the fewer number of the controlled jets lead to the flame with relatively shorter length, not easier to be blown off and higher NOx emission. With certain fuel flow rate, the critical air volume ratio is largest for the flame with 3 micro-jets, which is more difficult to be blown off than the cases with 2, 4 or 6 micro-jets.

关键词： jet flame side micro-jets perturbation flame structure

The Influences of Electric Fields on Soot Formation and flame structure of Diffusion flames

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Journal of Thermal Science 1993年第4期2卷 288-293页

作者： Takeyuki Kishi Michikata Kono Department of Aeronautics and Astronautics Faculty of EngineeringUniversity of Tokyo

The influences of DC and AC electric fields,at frequencies up to 1.48 MHz and the maximum strength of about 6 kV/cm,on soot formation and flame structure were investigated using a counterflow type acetylene diffusion *** distributions of flame luminosity,soot volume fraction,flame temperature and OH concentration in flame were measured by non-invasive detection methods. Under the influence of electric fields,the changes in distribution of the soot volume fraction were confirmed. Electric fields of high frequency and high intensity reduced the soot volume fraction,whereas other electric fields increased *** maximum values of flame temperature and OH concentration decreased. In the relationship between the maximum value of the soot volume fraction and the maximum temperature,the maximum soot volume fraction showed both increase and decrease with maximum temperatures depending on the frequencies and intensities of the electric fields,and both of them occurred at temperatures lower than 1900 *** production of the incipient particles seemed to be the dominant process controlling the soot volume fraction due to the electric *** luminosity of a sooting diffusion flame was found to depend on the volume fraction and temperature of the soot particles in the *** for the behavior of the flame in the electric fields,the ionic wind effect was not found to be dominant in the present work,and the result of the previous simulation based on the ionic wind theory was not consistent with the present experimental results.

关键词： flame structure soot formation electric field non-invasive detection OH concentration

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

structure and Combustion Characteristics of Methane/Air Premixed flame under the Action of Wall

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Energy Engineering 2021年第4期118卷 1135-1154页

作者： Feiyang Li Jianfeng Pan Chenxin Zhang Evans K.Quaye Xia Shao School of Energy and Power Engineering Jiangsu UniversityZhenjiang212013China

In order to obtain the combustion characteristics of the CH4/Air premixed flame under the action of the wall interaction,a study on the impact of the jet flame on the wall at different separation distances was carried *** separation distance from the burner outlet to the lower surface of the wall is changed and the flame structure is obtained through *** temperature,velocity and reaction rate are obtained through numerical simulation,and the law of flame characteristics change is obtained through *** results show that as the separation distance increases,the premixing cone inside the flame gradually changes from a horn shape to a complete cone shape and the length of the premixing cone profile ***,the peak temperature and velocity of the mixture in the axial direction gradually increase,and the temperature and velocity in the radial direction first increase and then *** temperature gradient and velocity reach the maximum when the separation distance is 11 *** peaks of reactants(CH_(4))net reaction rate intermediate products(CO)and products(CO_(2),H_(2)O)on the axis and the axial distance corresponding to the peaks increase *** chemical reaction rate near the wall also gradually decreases with the increase of the separation distance.

关键词： flame-wall interaction separation distance flame structure air flow temperature flow velocity reaction rate

A numerical investigation in buoyancy effects on micro jet diffusion flame

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Journal of Central South University 2020年第3期27卷 867-875页

作者： LIU Lei ZHAO Ming CHEN Yi-kun FAN Ai-wu LI Dan China Tabacco Hubei Industrial Limited Liability Company Wuhan 430014China State Key Laboratory of Coal Combustion Huazhong University of Science and TechnologyWuhan 430074China

The buoyancy effect on micro hydrogen jet flames in still air was numerially *** results show that when the jet velocity is relatively large(V≥0.2 m/s),the flame height,width and temperature decrease,whereas the peak OH mass fraction increases significantly under normal gravity(g=9.8 m/s^2).For a very low jet velocity(e.g.,V=0.1 m/s),both the peak OH mass fraction and flame temperature under g=9.8 m/s^2 are lower than the counterparts under g=0 m/s^*** reveals that when V≥0.2 m/s,fuel/air mixing will be promoted and combustion will be intensified due to radial flow caused by the buoyancy ***,the flame temperature will be slightly decreased owing to the large amount of entrainment of cold air into the reaction *** V=0.1 m/s,since the heat release rate is very low,the entrainment of cold air and fuel leakage from the rim of tube exit lead to a significant drop of flame ***,the heat loss rate from fuel to inner tube wall is larger under g=9.8 m/s^2 compared to that under g=0 m/s^***,the buoyancy effect is overall negative at very low jet velocities.

关键词： micro jet diffusion flame buoyancy effect flame structure flame temperature air entrainment preheating effect