The Influence of Pressure on Soot Production and Radiation inTurbulent Kerosine Spray Flames

Abstract

Detailed measurements of mixture fraction, flame temperature, soot volume fraction and spectrally resolved thermal radiation are reported in turbulent kerosine spray flames, burning at elevated temperatures and pressures (up to 13 bar). Flames are supported on an internal mixing, air-assist injector and confined within a cylindrical pressure vessel. Contrasting results, arising from the analysis of data on kerosine spray flames burning at various operating pressures, air-fuel ratios and fuel flow rates, are presented which provide new insight into the influence of operating pressure on soot formation and radiative heat transfer in practically relevant configurations. The experimental results between 1 and 13 bar suggest an underlying pressure dependence of the soot chemistry which is broadly linear. In addition, however, fuel atomisation and injector air-fuel ratio have a pronounced effect on the sooting propensity of the spray flames, which can be stronger than the influence of the operating pressure itself. They have a particularly strong influence on the rates of oxidative attack on soot particles and precursors and on the spectral distribution of thermal radiation between particulate and gaseous emissions. Continuum radiation from clouds of dispersed soot particles in the flame provides the major contribution to the total flame radiation in these comparatively fuel-rich kerosine spray flames with gas band radiation proving of only minor importance. The total radiation intensity from the flame then closely mirrors the trend in soot formation rates with respect to the dependence on operating conditions.

Keywords:

• Soot formation
• spray flames

Additional information

Notes on contributors

B. A. FISCHER

Present address: Combustion Department, Pratt and Whitney Canada, Mississauga, Ontario, Canada.

J. B. MOSS

Corresponding author, e-mail: [email protected]