Global characteristics for hydrogen-hydrocarbon composite fuel turbulent jet flames

摘要

The global flame characteristics (flame length, pollutant emission, radiative heat loss fraction, and volumetric soot concentration) of hydrogen-hydrocarbon composite fuel turbulent jet diffusion flames are presented. The correlation of flame length and hydrogen concentration in the fuel mixture is shown. It is found that the flame length decreases with the increase of hydrogen concentration in the mixture. The reactivity of fuel mixture increases with the increase of hydrogen concentration, which ultimately shortens the combustion time, and thereby reduces the overall flame length. Convective time scale decreases with the increase of hydrogen content in the mixture. The measured and predicted flame lengths show a similar trend, however, the predicted values are 1.4 times higher than the measured values. Axial soot concentration decreases with the increase of hydrogen content in the fuel mixture because of lower carbon input and higher soot oxidation due to higher OH concentration. The CO emsission index decreases with the increase of hydrogen concentration in the mixture. On the other hand, NO and NO{sub}x emission indices increase because of the higher flame temperature at higher hydrogen concentration in the mixture.