Fuel mixing effect on the flickering of jet diffusion flames

2010 ◽  
Vol 225 (1) ◽  
pp. 155-162 ◽  
Author(s):  
J Li ◽  
Y Zhang
Keyword(s):  
High Speed ◽  
Diffusion Flames ◽  
Digital Camera ◽  
Reacting Flow ◽  
Buoyant Jet ◽  
Vortical Structures ◽  
Mixed Fuel ◽  
Jet Diffusion Flames ◽  
Key Factor ◽  
Flickering Frequency

An experimental study has been performed for a buoyant jet diffusion flame, which was observed to oscillate at different frequencies spatially. The flame dynamics and structure were visualized by a commercial digital camera and a high-speed camera. Mixed fuel of methane and propane at certain proportion was found to generate very different vortex shedding behaviours. As a result, the flickering frequency of a methane/propane 1:1 mixture can be half of that of typically observed for pure methane or propane flame. The distance between adjacent flame puffs or the size of vortical structures in the reacting flow field, which can be modified by the fuel composition, was identified to be the key factor that affects the flickering frequencies. Repeated tests confirmed that mixed fuel at certain proportions can have a significant effect on the flame flickering frequency through the modification of vortex structure and dynamics.

An Experimental and Computational Study of Swirling Hydrogen Jet Diffusion Flames

1997 ◽  
Vol 119 (2) ◽  
pp. 305-314 ◽  
Author(s):  
M. S. Anand ◽  
F. Takahashi ◽  
M. D. Vangsness ◽  
M. D. Durbin ◽  
W. J. Schmoll
Keyword(s):  
Diffusion Flames ◽  
Computational Study ◽  
Laser Doppler Velocimeter ◽  
Reacting Flow ◽  
Jet Diffusion Flames ◽  
Burner Exit ◽  
Mean And Variance ◽  
Joint Velocity ◽  
Anti Stokes ◽  
Good Agreement

Computations using the joint velocity-scalar probability density function (pdf) method as well as benchmark quality experimental data for swirling and nonswirling hydrogen jet diffusion flames are reported. Previous studies of diffusion flames reported in the literature have been limited to nonswirling flames and have had no detailed velocity data reported in the developing (near-nozzle) region of the flames. The measurements and computations reported herein include velocities (mean and higher moments up to fourth order) and temperature (mean and variance) near the burner exit and downstream locations up to 26.5 jet diameters. The velocities were measured with a three-component laser-Doppler velocimeter (LDV) and the temperature was measured using coherent anti-Stokes Raman spectroscopy (CARS). The joint pdf method offers significant advantages over conventional methods for computing turbulent reacting flow, and the computed results are in good agreement with data. This study serves to present data that can be used for model validation as well as to validate further the joint pdf method.

scholarly journals An Experimental and Computational Study of Swirling Hydrogen Jet Diffusion Flames

1995 ◽  
Author(s):  
M. S. Anand ◽  
F. Takahashi ◽  
M. D. Vangsness ◽  
M. D. Durbin ◽  
W. J. Schmoll
Keyword(s):  
Diffusion Flames ◽  
Computational Study ◽  
Laser Doppler Velocimeter ◽  
Reacting Flow ◽  
Jet Diffusion Flames ◽  
Burner Exit ◽  
Mean And Variance ◽  
Joint Velocity ◽  
Anti Stokes ◽  
Good Agreement

Computations using the joint velocity-scalar probability density function (pdf) method as well as benchmark quality experimental data for swirling and nonswirling hydrogen jet diffusion flames are reported. Previous studies of diffusion flames reported in literature have been limited to nonswirling flames and have had no detailed velocity data reported in the developing (near-nozzle) region of the flames. The measurements and computations reported herein include velocities (mean and higher moments up to fourth order) and temperature (mean and variance) near the burner exit and downstream locations up to 26.5 jet diameters. The velocities were measured with a three-component laser Doppler velocimeter (LDV) and the temperature was measured using coherent anti-Stokes Raman spectroscopy (CARS). The joint pdf method offers significant advantages over conventional methods for computing turbulent reacting flow, and the computed results are in good agreement with data. This study serves to present data that can be used for model validation as well as to further validate the joint pdf method.

High-speed three-dimensional tomography of soot and combustion intermediates in jet diffusion flames

2016 ◽  
Author(s):  
Terrence R. Meyer ◽  
Benjamin R. Halls ◽  
Naibo Jiang ◽  
Daniel J. Thul ◽  
Mikhail N. Slipchenko ◽  
...  
Keyword(s):  
High Speed ◽  
Diffusion Flames ◽  
Three Dimensional ◽  
Jet Diffusion Flames

Flame height and lift-off of turbulent buoyant jet diffusion flames in a reduced pressure atmosphere

Fuel ◽  
2013 ◽  
Vol 109 ◽  
pp. 234-240 ◽  
Author(s):  
Longhua Hu ◽  
Qiang Wang ◽  
Michael Delichatsios ◽  
Fei Tang ◽  
Xiaochun Zhang ◽  
...  
Keyword(s):  
Diffusion Flames ◽  
Flame Height ◽  
Buoyant Jet ◽  
Reduced Pressure ◽  
Jet Diffusion Flames ◽  
Lift Off

scholarly journals A vortex-dynamical scaling theory for flickering buoyant diffusion flames

2018 ◽  
Vol 855 ◽  
pp. 1156-1169 ◽  
Author(s):  
Xi Xia ◽  
Peng Zhang
Keyword(s):  
Diffusion Flames ◽  
Universal Constant ◽  
Scaling Theory ◽  
Experimental Investigations ◽  
Flame Surface ◽  
Dynamical Scaling ◽  
Jet Diffusion Flames ◽  
Toroidal Vortices ◽  
Flickering Frequency ◽  
Buoyant Diffusion Flames

The flickering of buoyant diffusion flames is associated with the periodic shedding of toroidal vortices that are formed under gravity-induced shearing at the flame surface. Numerous experimental investigations have confirmed the scaling,$f\propto D^{-1/2}$, where$f$is the flickering frequency and$D$is the diameter of the fuel inlet. However, the connection between the toroidal vortex dynamics and the scaling has not been clearly understood. By incorporating the finding of Gharibet al.(J. Fluid Mech., vol. 360, 1998, pp. 121–140) that the detachment of a continuously growing vortex ring is inevitable and can be dictated by a universal constant that is essentially a non-dimensional circulation of the vortex, we theoretically established the connection between the periodicity of the toroidal vortices and the flickering of a buoyant diffusion flame with small Froude number. The scaling theory for flickering frequency was validated by the existing experimental data of pool flames and jet diffusion flames.

scholarly journals The Chemiluminescence and Structure Properties of Normal/Inverse Diffusion Flames

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Ting Zhang ◽  
Qinghua Guo ◽  
Xudong Song ◽  
Zhijie Zhou ◽  
Guangsuo Yu
Keyword(s):  
Reaction Zone ◽  
Diffusion Flame ◽  
High Speed ◽  
Diffusion Flames ◽  
Emission Spectrometry ◽  
Initial Reaction ◽  
Jet Diffusion Flames ◽  
Inverse Diffusion Flames ◽  
Inverse Diffusion ◽  
Region Ii

The flame emission spectrometry was applied to detect the distribution of excited radicals in two types CH4/O2 coflow jet diffusion flames (normal and inverse diffusion flames). Combining the image analysis along with the spectrometry, the chemiluminescence and structure characteristics of these diffusion flames were investigated. The results show that the inverse diffusion flame (IDF) with relatively high inlet oxygen velocity is composed of two regions: a bright base and a tower on top of the base, which is quite different from the normal diffusion flame (NDF). The flame is divided into two regions along the flame axis based on maximum OH* position (Region I: initial reaction zone; Region II: further oxidation zone). The degree of the further oxidization taking place in Region II is obvious in accordance with OH* distribution, which is the main difference in reaction zone between fuel-rich condition and fuel-lean condition for NDFs. For IDFs, the change of OH* distribution with increasing equivalence O/C ratio ([O/C]e) in Region II is not conspicuous. More OH* and CH* are generated in IDFs, due to the inner high-speed O2 flow promoting the mixing of fuel and oxygen to a certain extent.

Effects of partial gravity and g-jitter radiation from jet diffusion flames

1997 ◽  
Author(s):  
M. Bahadori ◽  
L. Zhou ◽  
D. Stocker ◽  
M. Bahadori ◽  
L. Zhou ◽  
...  
Keyword(s):  
Diffusion Flames ◽  
Jet Diffusion Flames ◽  
Partial Gravity ◽  
Jitter Radiation
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