Prediction of an Apparent Flame Length in a Co-Axial Jet Diffusion Flame Combustor.

摘要

This report is comprised of two parts. In Part I a predictive model for an apparent flame length in a co-axial jet diffusion flame combustor is described. According to this model a diffusion flame is considered as thin cylindrical reactive zone composed of chemically active and dead regions. Fuel consumption by surface oxidation is assumed. Mass transport of oxygen to the reactive surface is considered to control the overall combustion process. Overall mass transfer coefficient, evaluated from an empirically developed correlation, is employed to predict total flame length. Comparison of the experimental and predicted data on total flame length shows a reasonable agreement within sixteen percent over the investigated air and fuel flow rate ranges of 1-2kg/s and 5-11kg/hr, respectively. In Part II a scheme to predict an apparent flame length is described for the circumstances when a recirculation region established immediately downstream of a center-body in a co-axial jet combustor is penetrated by a central fuel jet. A turbulent jet flow theory has been coupled with the theory given in Part I of the report.