Evaluation of the Lean Blowout Limit of Alternative Fuels in a Gas Turbine Combustor

The University of Sheffield’s Low Carbon Combustion Centre (LCCC) is an allied partner in the National Jet Fuels Combustion Program (NJFCP), which is a US multi-agency program led by the Federal Aviation Administration (FAA). Alternative fuels offer the potential of immediate benefits for the energy crisis and environmental pollution. NJFCP aims to gain better understanding of the effect of alternative jet fuel on engine combustion. Moreover, increasing the AFR (burning leaner) is considered as an effective way to increase the thermodynamic efficiency of a gas turbine. However, it increases the instability of the combustion and the tendency of the flame to blow out. Hence, the performance of LBO (Lean blow off) possesses the major consideration for the candidate fuels evaluation. With the support of NJFCP and LCCC, this paper studies on the relationship between fuel properties and their performance on the soot formation and the chemiluminescence radicals emission (CH* and C2*) at LBO of the six alternative fuels, benchmarked against Jet A-1. Six alternative fuels have been conducted on a Rolls-Royce Tay combustor rig and tested with three conditions. Visual images recorded by a high-speed camera combined with digital flame colour discrimination (DFCD) approach are applied to develop a new model for the alternative fuels evaluation on combustor performance. Results show that, the increase of 兼岌 銚 is one of the most effective ways for soot depression and sufficient burning, even the flame blow out at a higher 剛挑喋潮 (burning richer). In addition, the fuel properties of density, viscosity, aromatics and Cetane No. have negative effects on the soot particles control and efficient burning.