Combustion and Flame 149 (2007) 191–205 www.elsevier.com/locate/combustflame A study of jet fuel sooting tendency using the threshold sooting index (TSI) model Yi Yang, André L. Boehman ∗ , Robert J. Santoro The Energy Institute, The Pennsylvania State University, University Park, PA 16802, USA Received 13 February 2006; received in revised form 16 October 2006; accepted 6 November 2006 Available online 26 January 2007 Abstract Fuel composition can have a significant effect on soot formation during gas turbine combustion. Consequently, this paper contains a comprehensive review of the relationship between fuel hydrocarbon composition and soot formation in gas turbine combustors. Two levels of correlation are identified. First, lumped fuel composition parameters such as hydrogen content and smoke point, which are conventionally used to represent fuel sooting ten- dency, are correlated with soot formation in practical combustors. Second, detailed fuel hydrocarbon composition is correlated with these lumped parameters. The two-level correlation makes it possible to predict soot formation in practical combustors from basic fuel composition data. Threshold sooting index (TSI), which correlates lin- early with the ratio of fuel molecular weight and smoke point in a diffusion flame, is proposed as a new lumped parameter for sooting tendency correlation. It is found that the TSI model correlates excellently with hydrocar- bon compositions over a wide range of fuel samples. Also, in predicting soot formation in actual combustors, the TSI model produces the best results overall in comparison with other previously reported correlating parameters, including hydrogen content, smoke point, and composite predictors containing more than one parameter.  2006 The Combustion Institute. Published by Elsevier Inc. All rights reserved. Keywords: Jet fuel; Gas turbine combustor; Soot; Fuel composition; Sooting tendency; Hydrogen content; Smoke point 1. Introduction Fuel hydrocarbon composition is one of the most important factors controlling soot formation in gas turbine combustion. Pure hydrocarbons with dissimi- lar molecular structures exhibit dramatically different sooting performance in laboratory burners and gas turbine combustors. However, it is not yet possible to theoretically derive the propensity to form soot for a fuel based on known fuel composition and combus- * Corresponding author. Fax: +1 (814) 863 8892. E-mail address: boehman@ems.psu.edu (A.L. Boehman). tion conditions. This is primarily due to the lack of mechanisms of soot formation and oxidation for in- dividual hydrocarbons, as well as to the complexity resulting from the coupling of the turbulent flow and rapid chemical reaction kinetics. Moreover, gas tur- bine fuels contain hundreds of compounds and their compositions vary from batch to batch, making it im- possible to correlate soot formation to individual hy- drocarbon content. In response to such difficulties, practical investi- gations on the effects of fuel composition on soot formation have largely relied on empirical correla- tions, which can be classified into two categories. One correlates soot formation in actual combustors 0010-2180/$ – see front matter  2006 The Combustion Institute. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.combustflame.2006.11.007