LES Modeling of the DLR Generic Single-Cup Spray Combustor: Comparison of Exploratory Category C Jet Fuels

Abstract The combustion of conventional Jet A, alongside two alternative jet fuels, C1 and C5, is simulated with Large Eddy Simulations (LES) in a generic single-cup spray combustor during idle and cruise conditions. The spray is modeled using Lagrangian particle tracking and the combustion chemistry of each fuel is modeled by skeletal reaction mechanisms. The volatility and atomizability of each fuel directly affect the spray penetration depth, with Jet A having the longest spray and C5 the shortest. All fuels have qualitatively similar flames at idle conditions, but the Jet A flame is relatively lifted at cruise conditions. C1 and C5 have similar flames despite different spray lengths, likely due to the rapid breakup of C1. The fuels produce different emission profiles, which is connected to their respective H/C ratios, equivalence ratios, and aromatics contents. NO x emissions are particularly affected by the mixture fraction in the flame, resulting in high NO x emissions for the compact C1 and C5 flames. Thermoacoustic oscillations are observed in all simulations but are strongest for C1 and C5, which we hypothesize is a result of their high volatility.