Experimental Investigation of Ignition,Combustion and Stability Characteristics of a Coaxial Sudden Expansion Burner.

摘要

This report describes studies performed on mixing,ignition,flame stability limits and combustion of liquid injected hydrocarbon fuels in a coaxial dump burner. The effects of flow conditions,injection distance,inlet geometry,fuel type and piloting were investigated. It was found that ignition limits differ from lean blowout limits,and that stable flames could be sustained over much wider range than the homogeneous gaseous mixtures. Results also indicate that ignition and flame stability mechanisms are controlled by the vapor phase fuel concentration level in the addy zone similar to spray mixtures,and not the global fuel/air ratio as in the case of homogeneous gaseous mixtures. Fuel injection distance has a profound effect on ignition but not on blowout limits. The observations indicate that increasing inlet velocity,air temperature or relatively low energy piloting improves,even significantly,both the recirculation zone and the overall combustion performance. RJ-5,although more difficult to ignite,exhibits higher heat release rates than JP-4. (Modified author abstract)