Laser-induced fluorescence measurements and modeling of absolute CH concentrations in strained laminar methane/air diffusion flames

2005 ◽  
Vol 30 (1) ◽  
pp. 455-463 ◽  
Author(s):  
Christophe Gibaud ◽  
Jordan A. Snyder ◽  
Volker Sick ◽  
R. Peter Lindstedt
Keyword(s):  
Diffusion Flames ◽  
Laser Induced Fluorescence ◽  
Fluorescence Measurements ◽  
Air Diffusion

Laser-Induced Fluorescence Measurements in Venturi-Cascaded Propane Gas Jet Flames

1999 ◽  
Author(s):  
Ala R. Qubbaj ◽  
S. R. Gollahalli
Keyword(s):  
Diffusion Flames ◽  
Concentration Field ◽  
Laser Induced Fluorescence ◽  
Pollutant Emissions ◽  
Average Decrease ◽  
Burner Exit ◽  
Fluorescence Measurements ◽  
Air Mixing ◽  
Flame Region ◽  
Lif Spectroscopy

Abstract “Venturi-cascading” technique is a means to control pollutant emissions of diffusion flames by modifying air infusion and fuel-air mixing rates through changing the flow dynamics in the combustion zone with a set of venturis surrounding the flame. A propane jet diffusion flame at a burner-exit Reynolds number of 5100 was examined with a set of venturis of specific sizes and spacing arrangement. The venturi-cascading technique resulted in a decrease of 33% in NO emission index along with a 24% decrease in soot emission from the flame, compared to the baseline condition (same flame without venturis). In order to understand the mechanism behind these results, Laser Induced Fluorescence (LIF) spectroscopy was employed to study the concentration field of the radicals (OH, CH and CN) in the baseline and venturi-cascaded flames. The LIF measurements, in the near-burner region of the venturi-cascaded flame, indicated an average decrease of 18%, 24% and 12% in the concentrations of OH, CH and CN radical, respectively, from their baseline values. However, in the mid-flame region, a 40% average increase in OH, from its baseline value, was observed. In this region, CH or CN radicals were not detected. The OH radical, in the downstream locations, was mostly affected by soot rather than by temperature. In addition, prompt-NO mechanism appeared to play a significant role besides the conventional thermal-NO mechanism.

Laser-Induced Fluorescence Measurements in Venturi-Cascaded Propane Gas Jet Flames

2000 ◽  
Vol 123 (2) ◽  
pp. 158-166
Author(s):  
Ala R. Qubbaj ◽  
S. R. Gollahalli
Keyword(s):  
Diffusion Flames ◽  
Concentration Field ◽  
Laser Induced Fluorescence ◽  
Pollutant Emissions ◽  
Average Decrease ◽  
Burner Exit ◽  
Fluorescence Measurements ◽  
Air Mixing ◽  
Lif Spectroscopy ◽  
Cn Radicals

Venturi-cascading is a technique to control pollutant emissions from diffusion flames by modifying air infusion and fuel-air mixing rates through changing the flow dynamics in the combustion zone with a set of venturis surrounding the flame. A propane jet diffusion flame at a burner-exit Reynolds number of 5100 was examined with a set of venturis of specific sizes and spacing arrangement. The venturi-cascading technique resulted in a decrease of 33 percent in NO emission index along with a 24-percent decrease in soot emission from the flame, compared to the baseline condition (same flame without venturis). In order to understand the mechanism behind these results, laser-induced fluorescence (LIF) spectroscopy was employed to study the concentration field of the radicals (OH, CH, and CN) in the baseline and venturi-cascaded flames. The LIF measurements, in the near-burner region of the venturi-cascaded flame, indicated an average decrease of 18, 24 and 12 percent in the concentrations of OH, CH, and CN radicals, respectively, from their baseline values. However, in the midflame region, a 40-percent average increase in OH from its baseline value was observed. In this region, CH or CN radicals were not detected. The OH radical concentration in the downstream locations was mostly affected by soot rather than by temperature.

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