scholarly journals Burning Rates and Surface Characteristics of Hydrogen-Enriched Turbulent Lean Premixed Methane-Air Flames

2009 ◽  
Author(s):  
Hongsheng Guo ◽  
Badri Tayebi ◽  
Cedric Galizzi ◽  
Dany Escudie´
Keyword(s):  
Surface Area ◽  
Burning Velocity ◽  
Flame Structure ◽  
Surface Characteristics ◽  
Flame Surface ◽  
Laminar Burning Velocity ◽  
Hydrogen Addition ◽  
Lean Premixed ◽  
Burning Rates ◽  
Turbulent Burning Velocity

The burning rates and surface characteristics of hydrogen-enriched turbulent lean premixed methane-air flames were experimentally studied by laser tomography visualization method using a V-shaped flame configuration. Turbulent burning velocities were measured and the variation of flame surface characteristics due to hydrogen addition was analyzed. The results show that hydrogen addition causes an increase in turbulent burning velocity for lean CH4-air mixtures when the turbulent level in the unburned mixture is not changed. The increase rate of turbulent burning velocity is higher than that of the corresponding laminar burning velocity, suggesting that the increase in turbulent velocity due to hydrogen addition is caused by not only chemical kinetics effect, but also the variation in flame structure due to turbulence. The further analysis of flame surface characteristics and brush thickness indicate that hydrogen addition slightly decreases local flame surface density, but increases total flame surface area because of the increased flame brush thickness. As a result, turbulent burning velocity is intensified by the increase in total flame surface area and the increased laminar burning velocity, when hydrogen is added.

scholarly journals Reconciling turbulent burning velocity with flame surface area in small-scale turbulence

2018 ◽  
Vol 858 ◽  
Author(s):  
G. V. Nivarti ◽  
R. S. Cant ◽  
S. Hochgreb
Keyword(s):  
Burning Rate ◽  
Surface Area ◽  
Burning Velocity ◽  
Small Scale ◽  
Flame Surface ◽  
Additional Contribution ◽  
Individual Contributions ◽  
Scale Turbulence ◽  
Turbulence Length ◽  
Turbulent Burning Velocity

A discrepancy between the enhancement in overall burning rate and the enhancement in flame surface area measured for high-intensity turbulence is addressed. In order to reconcile the two quantities, an additional contribution from the effective turbulent diffusivity is considered. This contribution is expected to arise in sufficiently intense turbulence from eddies smaller than the flamelet thickness. In the present work, the enhancement in diffusivity arising from these eddies is estimated based on a model energy spectrum; individual contributions from all turbulence length scales smaller the flamelet thickness are integrated over the corresponding portion of the spectrum. It is shown that diffusivity enhancement, estimated in this manner, is able to account for the measured discrepancy between the overall burning rate enhancement and flame surface area enhancement. The factor quantifying this discrepancy is formalized as a closed-form function of the Karlovitz number.

Numerical study on laminar burning velocity and ignition delay time of ammonia flame with hydrogen addition

Energy ◽  
2017 ◽  
Vol 126 ◽  
pp. 796-809 ◽  
Author(s):  
Jun Li ◽  
Hongyu Huang ◽  
Noriyuki Kobayashi ◽  
Chenguang Wang ◽  
Haoran Yuan
Keyword(s):  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Numerical Study ◽  
Burning Velocity ◽  
Laminar Burning Velocity ◽  
Hydrogen Addition

scholarly journals The Effect of Hydrogen Addition on Low-Temperature Combustion of Light Hydrocarbons and Alcohols

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3808
Author(s):  
Fekadu Mosisa Wako ◽  
Gianmaria Pio ◽  
Ernesto Salzano
Keyword(s):  
Experimental Data ◽  
Burning Velocity ◽  
Engine Performance ◽  
Pollutant Emissions ◽  
Low Temperature Combustion ◽  
Laminar Burning Velocity ◽  
Nox Formation ◽  
Hydrogen Addition ◽  
Temperature Combustion ◽  
Fuel Mixtures

Hydrogen is largely considered as an attractive additive fuel for hydrocarbons and alcohol-fueled engines. Nevertheless, a complete understanding of the interactions between blended fuel mechanisms under oxidative conditions at low initial temperature is still lacking. This study is devoted to the numerical investigation of the laminar burning velocity of hydrogen–hydrocarbon and hydrogen–alcohol fuels under several compositions. Estimations were compared with experimental data reported in the current literature. Additionally, the effects of hydrogen addition on engine performance, NOX, and other pollutant emissions of the mentioned fuels have been thermodynamically analyzed. From the study, it has been observed that the laminar burning velocity of the fuel mixtures increased with increasing hydrogen fractions and the peak value shifted to richer conditions. Besides, hydrogen fraction was found to increase the adiabatic flame temperatures eventually favoring the NOX formation for all fuel blends except the acetylene–hydrogen–air mixture where hydrogen showed a reverse effect. Besides, hydrogen is also found to improve the engine performances and helps to surge thermal efficiency, improve the combustion rate, and lessen other pollutant emissions such as CO, CO2, and unburned hydrocarbons. The model predicted well and in good agreement with the experimental data reported in the recent literature.

A two-eddy theory of premixed turbulent flame propagation

1981 ◽  
Vol 301 (1457) ◽  
pp. 1-25 ◽  
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Burning Velocity ◽  
Turbulent Flame ◽  
Experimental Measurements ◽  
Laminar Burning Velocity ◽  
Turbulent Reynolds Number ◽  
Theoretical Predictions ◽  
Premixed Turbulent Flame ◽  
Turbulent Burning Velocity

Available experimental data on the turbulent burning velocity of premixed gases are surveyed. There is discussion of the accuracy of experimental measurements and the means of ascertaining relevant turbulent parameters. Results are presented in the form of the variation of the ratio of turbulent to laminar burning velocities with the ratio of r.m.s. turbulent velocity to laminar burning velocity, for different ranges of turbulent Reynolds number. A two-eddy theory of burning is developed and the theoretical predictions of this approach, as well as those of others, are compared with experimentally measured values.

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