Combustion of Synthetic Jet Fuel: Chemical Kinetic Modeling and Uncertainty Analysis

Abstract

Reaction mechanisms for jet-fuel combustion were built with the aim of providing a better description of the chemistry to reacting flow simulations used to design future aircraft engines. This research effort focused on combustion of Fischer–Tropsch synthetic jet fuel (S-8) in vitiated air at conditions relevant to jet engines, augmentors, and interturbine burners (T=650–1700 K P=1–20 atm, and Φ=0.5–2 in air). The complex S-8 fuel mixture was approximated with a two-component surrogate mixture of n-decane and iso-octane. A wholly new, elementary-step reaction mechanism for the surrogate consisting of 291 species and 6900 reactions was constructed using automatic mechanism generation software. Statistical analyses were conducted to determine reaction rate-constant sensitivity, model prediction uncertainty, and consistency of the model with published ignition delay time data. As a test application, the S-8 reaction model was used to estimate augmentor static stability using a simple Damköhler number analysis that showed increased stability with temperature from 800 to 1400 K and NO concentration from 0 to 1000 ppm (v/v). The ability to quickly generate accurate mechanisms for simple surrogates allows for new synthetic fuels to be quickly modeled and their behavior predicted for an array of experimental conditions and practical applications.