Combustion in a Cross Flow with Air Jet Nozzles

Abstract

An experimental study was performed on the combustion of a gaseous fuel in a cross inward flow of air through a horizontal array of nozzles. Exhibiting the same aspect of inverse flames, the flame was found to be stabilized with the cross flow configuration near stoichiometric air/fuel ratio over the entire investigated range of velocities. Only with excessive air/fuel ratios, the flame blew out beyond a certain air jet velocity. The role of fluid dynamics in promoting the fuel-air mixing processes was pronounced by imparting swirl to the fuel stream and acoustical excitation to the air jets. It was found that the increase in the swirl strength shortens the flame and reduces CO and UHC species concentrations due to the increased strain rates on the fuel stream boundaries. The acoustical excitation was also found to produce favorable mixing effects by increasing the fuel entrainment into the air jets and stimulating turbulence. Combining both swirl and acoustical excitation improved the combustion efficiency with a saturation limit.

Keywords:

• Air jet
• Combustion
• Cross flow