Nitrogen Diluted Jet Flames in the Presence of Coflowing Air

2011 ◽  
Author(s):  
James D. Kribs ◽  
Tamir S. Hasan ◽  
Kevin M. Lyons
Keyword(s):  
Diffusion Flame ◽  
Axial Position ◽  
Flammability Limit ◽  
Jet Flames ◽  
Flow Rates ◽  
Nitrogen Dilution ◽  
Flame Shape ◽  
Methane Flow

The purpose of this study is to observe methane jet flames under varying levels of nitrogen dilution and coflowing air. The jet flames were examined in order to determine the conditions for which liftoff and blowout occur under conditions that strain the flame. Methane flow rates were varied, corresponding to intermediate lifted positions to blowout. A sequence of images were taken at each level of dilution and coflow, and were used to determine the lowest radial and axial position of the flammability limit. These flammability regions were compared to the lean flammability limit. It was observed that flame shape and liftoff were considerably more influenced by the effects of the coflowing air compared to the presence of the diluents, and that flames under coflow lost the trailing diffusion flame earlier, which has been shown to be a marker for flame blowout.

Nitrogen-Diluted Methane Flames in the Near-and Far-Field

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
James Kribs ◽  
Nancy Moore ◽  
Tamir Hasan ◽  
Kevin Lyons
Keyword(s):  
Reynolds Number ◽  
Natural Gas ◽  
Low Reynolds Number ◽  
Industrial Applications ◽  
Flame Height ◽  
Far Field ◽  
Jet Flames ◽  
Jet Flame ◽  
Lifted Flame ◽  
Nitrogen Dilution

With the increased utilization of multicomponent fuels, such as natural gas and biogas, in industrial applications, there is a need to be able to effectively model and predict the properties of jet flames for mixed fuels. In addition, the interaction of these diluted fuels with outside influences (such as differing levels of coflow air) is a primary consideration. Experiments were performed on methane jet flames under the influence of varying levels of nitrogen dilution, from low Reynolds number lifted regimes to blowout, observing the influence of the nitrogen on lifted flame height and flame chemiluminesence images. These findings were analyzed and compared with existing lifted jet flame relations, such as the flammable region approximation proposed by Tieszen et al., as well as to undiluted flames. The influence of nitrogen dilution was seen to have an effect on the liftoff height of the flame, as well as the blowout velocity of the flame, but was seen to have a less pronounced effect compared with flames with coflowing air.

Diffusion-flame shape in the wake of a falling droplet.

AIAA Journal ◽  
1967 ◽  
Vol 5 (11) ◽  
pp. 1984-1988 ◽  
Author(s):  
FRANCIS E. FENDELL ◽  
EDWARD B. SMITH
Keyword(s):  
Diffusion Flame ◽  
Flame Shape

Experimental Observations of Nitrogen Diluted Ethylene and Methane Jet Flames

2013 ◽  
Author(s):  
Andrew R. Hutchins ◽  
James D. Kribs ◽  
Richard D. Muncey ◽  
William A. Reach ◽  
Kevin M. Lyons
Keyword(s):  
Thermal Diffusivity ◽  
Higher Order ◽  
Flame Stabilization ◽  
Hydrocarbon Fuels ◽  
Jet Flames ◽  
Nitrogen Dilution ◽  
Fuel Mixtures ◽  
And Behavior ◽  
Ethylene Flames

While the liftoff mechanisms of nitrogen-diluted methane jet flames have been well documented, higher order fuels, such as ethylene, have not been studied as extensively with regards to flame stabilization and behavior. Higher order fuels generally burn more intensely, and thus produce much different stabilization patterns than those of simple hydrocarbon fuels, such as methane. The purpose of this study was to observe the effects of nitrogen dilution on ethylene combustion and compare to that witnessed in typical methane jet flames; specifically, the influence on the liftoff height, blowout, and flame chemiluminescence. Liftoff and blowout velocities were compared for various mixtures of ethylene without nitrogen. It was observed that the reason behind the varying stabilization patterns is due to the higher thermal diffusivity of ethylene as well the higher flame speeds that are characterized in the combustion of ethylene. Using a sequence of images from each mixture, the flame liftoff heights were recorded. Due to the strong chemiluminescence of ethylene flames, little fluctuation between liftoff parameters was observed, with respect the velocity; however, there was a significant effect on the liftoff height, with respect to dilution. Blowout for fuel mixtures was much more difficult to achieve due to the higher thermal diffusivity of ethylene, meaning the flame would stabilize at positions much farther downstream than those of simple hydrocarbon fuels.

scholarly journals Nitrogen Dilution and Extinction Effects for Methane Impinging Diffusion Flame

IERI Procedia ◽  
2012 ◽  
Vol 1 ◽  
pp. 39-46 ◽  
Author(s):  
Nadjib Ghiti ◽  
Abed Alhalim Bentebbiche ◽  
Ramzi Boulkroune
Keyword(s):  
Diffusion Flame ◽  
Nitrogen Dilution

scholarly journals The dilution effect on the extinction of wall diffusion flame

2014 ◽  
Vol 35 (4) ◽  
pp. 43-54
Author(s):  
Nadjib Ghiti
Keyword(s):  
Dilution Rate ◽  
Diffusion Flame ◽  
Flame Temperature ◽  
Dilution Effect ◽  
Lateral Wall ◽  
Flame Extinction ◽  
Jet Flame ◽  
Extinction Process ◽  
Nitrogen Dilution ◽  
Flame Response

Abstract The dynamic process of the interaction between a turbulent jet diffusion methane flame and a lateral wall was experimentally studied. The evolution of the flame temperature field with the Nitrogen dilution of the methane jet flame was examined. The interaction between the diffusion flame and the lateral wall was investigated for different distance between the wall and the central axes of the jet flame. The dilution is found to play the central role in the flame extinction process. The flame response as the lateral wall approaches from infinity and the increasing of the dilution rate make the flame extinction more rapid than the flame without dilution, when the nitrogen dilution rate increase the flame temperature decrease.

Effects of Fuel-Side Nitrogen Dilution on Structure and NOx Formation of Turbulent Syngas Non-premixed Jet Flames

2012 ◽  
Vol 26 (6) ◽  
pp. 3304-3315 ◽  
Author(s):  
Jeongwon Lee ◽  
Sangwoon Park ◽  
Yongmo Kim
Keyword(s):  
Jet Flames ◽  
Nox Formation ◽  
Nitrogen Dilution

Flame and Emission Characteristics of a Premixed Swirl-stabilised Burner

2014 ◽  
Vol 71 (2) ◽  
Author(s):  
Chen Wei Kew ◽  
Cheng Tung Chong ◽  
Ng Jo-Han ◽  
Boon Tuan Tee ◽  
Mohamad Nazri Mohd Jaafar
Keyword(s):  
Equivalence Ratio ◽  
Soot Formation ◽  
Atmospheric Condition ◽  
Emission Characteristics ◽  
Flow Rates ◽  
Lean Blowout ◽  
Unburned Hydrocarbons ◽  
Flame Shape ◽  
Flame Imaging ◽  
Swirl Flame

The flame and emission characteristics of a premixed gaseous flame swirl burner are investigated under various equivalence ratio. The swirl flame is established using propane/air mixture at atmospheric condition. Flame imaging was performed to compare the global flame shape and intensity over a range of equivalence ratios and flow rates. Fuel-rich flame shows increased intensity due to the presence of soot formation. The lean blowout test was performed to determine the operating limit of the burner. Emissions of the propane swirl flame were measured at the exit of the burner outlet. Results show that NOx emissions peak at stoichiometric condition, f =1 as compared to the lean- and rich-burning regions. Carbon monoxide (CO) and unburned hydrocarbons (UHC) emissions were found to be low (< 10 ppm) under premixed, continuous swirl burning conditions for the equivalence ratio range of f = 0.7-1.1.

Effect of Nitrogen Dilution on the Lean Blowout Limit and Emissions of Premixed Propane/Air Swirl Flame

2014 ◽  
Vol 71 (2) ◽  
Author(s):  
Cheng Tung Chong ◽  
Chen Wei Kew ◽  
Ng Jo-Han ◽  
Boon Tuan Tee ◽  
Mohamad Nazri Mohd Jaafar
Keyword(s):  
Digital Camera ◽  
Atmospheric Condition ◽  
Nitrogen Addition ◽  
Lean Blowout ◽  
Nitrogen Dilution ◽  
Flame Burner ◽  
Unburned Hydrocarbons ◽  
Flame Shape ◽  
Flame Imaging ◽  
Swirl Flame

The effects of nitrogen dilution on propane/air flame and emissions was investigated using a model gas turbine type swirl flame burner. The burner consists of a six-vane axial swirler and a combustor wall made from quartz tube. Nitrogen was diluted at 5%, 10% and 15% by volume of the total main air flow rate with propane/air mixture at the burner plenum prior to combustion at atmospheric condition. Direct flame imaging was performed using a digital camera to observe the flame shape, intensity and lean blowout phenomenon of premixed nitrogen-diluted propane/air flames. The result shows that nitrogen addition to propane/air flame reduces flame intensity and lean blowout limit, making the nitrogen-diluted flames more susceptible to blowout. Emissions results show that NOx reduce with the increase of nitrogen dilution rate, while the effect on carbon monoxides and unburned hydrocarbons are insignificant.

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