Flame stability in combusting turbulent jets
- Univ. of Missouri, Rolla
A simplified theoretical model for the stability of turbulent methane/air flames is developed by assuming that the chemical kinetics are much more important than the fluid dynamics near blowout. The model predicts the stability of flames as a function of ambient atmospheric temperature and composition, initial preheat temperature, and percentage of external product gas recirculation. It equates the rate at which the mass is supplied to the flame to the rate at which the mass is chemically reacted in the flame. This is done by using a one-step reaction and a well-stirred reactor (WSR). The model contains a free parameter, which is evaluated by comparing the theoretical predictions to experimental results available in the literature. Flame stability as defined herein is synonymous to blowout. For an ambient atmospheric temperature that is much lower than the adiabatic flame temperature, a flame in air is stable over a much larger range of initial flow rates and equivalence ratios than a flame in an environment composed of combustion products. However, as the ambient atmospheric temperature approaches the adiabatic flame temperature, the model predicts autoignition, and the flame becomes stable over the entire range of initial flow rates and equivalence ratios and becomes independent of the ambient atmospheric composition. The model predicts that external product gas recirculation--introduction of combustion product gases into the initial fuel/air mixture at the initial fuel/air temperature--decreases the flame stability and it also predicts that preheat increases the flame stability.
- OSTI ID:
- 7143598
- Journal Information:
- Combust. Flame; (United States), Journal Name: Combust. Flame; (United States) Vol. 27:1; ISSN CBFMA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
10 SYNTHETIC FUELS
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800 -- Combustion
Pyrolysis
& High-Temperature Chemistry
ACCIDENTS
AIR
ALKANES
BLOWOUTS
BURNERS
CHEMICAL REACTION KINETICS
COMBUSTION INSTABILITY
COMBUSTION KINETICS
CRYOGENIC FLUIDS
EQUATIONS
FLAMES
FLUIDS
GASES
HYDROCARBONS
INSTABILITY
JETS
KINETICS
MATHEMATICAL MODELS
METHANE
ORGANIC COMPOUNDS
PREDICTION EQUATIONS
REACTION KINETICS
STABILITY
TURBULENCE