Application of Flamelet Profiles to Flame Structure in Practical Burners

1999 ◽  
Vol 121 (1) ◽  
pp. 66-72 ◽  
Author(s):  
B. J. Krass ◽  
B. W. Zellmer ◽  
I. K. Puri ◽  
S. Singh
Keyword(s):  
Mixture Fraction ◽  
Flame Structure ◽  
Premixed Flames ◽  
Spatial Location ◽  
Nonpremixed Combustion ◽  
Partially Premixed Flames ◽  
Partially Premixed ◽  
Partial Premixing ◽  
Secondary Air ◽  
Turbulent Nonpremixed

Partial premixing can be induced by design in combustors, occurs inadvertently during turbulent nonpremixed combustion, or arises through inadequate fuel-air mixing. Therefore, it is of interest to investigate the effect of partial premixing in a burner that mimics conditions that might occur under practice. In this investigation, we report on similitude of partially premixed flames encountered in practical complex and multi-dimensional burners with simpler, less complex flames, such as counterflow flamelets. A burner is designed to simulate the more complex multi-dimensional flows that might be encountered in practice, and includes the effects of staging, swirl, and possible quenching by introduction of secondary air. The measurements indicate that the structure of partially premixed flames in complex, practical devices can be analyzed in a manner similar to that of flamelets, even if substantial heat transfer occurs. In particular, the flame structure can be characterized in terms of a modified mixture fraction that differentiates the lean and rich zones, and identifies the spatial location of the flame.

scholarly journals A priori investigation of subgrid correlation of mixture fraction and progress variable in partially premixed flames

2018 ◽  
Vol 22 (5) ◽  
pp. 862-882 ◽  
Author(s):  
Zhi X. Chen ◽  
N. Anh Khoa Doan ◽  
Shaohong Ruan ◽  
Ivan Langella ◽  
N. Swaminathan
Keyword(s):  
Mixture Fraction ◽  
A Priori ◽  
Premixed Flames ◽  
Progress Variable ◽  
Partially Premixed Flames ◽  
Partially Premixed

Aspect Ratio Effects on Partially Premixed Flames From Elliptic Burners in Coflow

2006 ◽  
Author(s):  
P. Hariharan ◽  
C. Periasamy ◽  
S. R. Gollahalli
Keyword(s):  
Flame Structure ◽  
Flame Temperature ◽  
Premixed Flames ◽  
Combustion Products ◽  
Jet Flame ◽  
Aspect Ratios ◽  
Partially Premixed Flames ◽  
Partially Premixed ◽  
Comparison Measurements ◽  
Good Agreement

In this paper, partially premixed flames of propane-hydrogen blends from elliptic burner geometries in coflow environment have been experimentally studied. Two different elliptic burner geometries with aspect ratios (AR) of 3:1 and 4:1 were used. A circular burner with the same discharge area as that of the elliptic burner was employed for comparison. Measurements were taken at stoichiometric and three other equivalence ratios. Global flame characteristics such as visible height, emission indices, and flame radiation were measured. Flame structure data such as transverse profiles of inflame concentrations of combustion products and local flame temperature were also measured at three axial locations in the flame. Results indicate that elliptic burner flames were shorter, more radiating, and produced lower NO and CO emissions than the corresponding circular burner flames. Results from the inflame measurements of NO and CO were in good agreement with the corresponding global data. Further, the 4:1 AR elliptic burners exhibited a twin-jet flame structure at fuel-rich conditions. The twin-flame structure was evident from the inflame measurements of temperature and combustion species. This study suggests that the combination of elliptic burner geometry and coflow reduces NO and CO emissions from combustion systems, which could potentially lead to cleaner environment.

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