Åkerblom A.; 2022, “The Impact of Reaction Mechanism Complexity in LES Modeling of Liquid Kerosene Combustion”, 33rd Congress. of the Int. Council of the Aeronautical Sciences, 4-9 Sept., Stockholm, Sweden.
Abstract: Large Eddy Simulation (LES) is a powerful tool for studying turbulent combustion, but its computational cost necessitates that any combustion models used in conjunction must be compact as well as accurate. A suitable balance between cost and accuracy may be found in the use of finite-rate pathway-centric reaction mechanisms, but these can vary greatly in cost and accuracy depending on the number of species and reactions involved. In this study, the impact of mechanism complexity is studied so that appropriate mechanisms can be chosen for future LES studies, and to aid in the development of new LES-optimized reaction mechanisms. LES is performed on a generic gas turbine combustor operating at two sets of typical aeroengine conditions. The liquid fuel spray is modeled using Lagrangian particle tracking. Two pathway-centric reaction mechanisms for the kerosene surrogate C12H23 are employed, resulting in four cases. One mechanism is more complex, as well as three times more computationally expensive, than the other. The mechanisms show similar results with regard to large-scale flame dynamics, but major product mass fractions in the emissions differ by ∼4% and <1% at idle and cruise conditions, respectively. The equilibrium OH concentration predicted by the more complex mechanism is ∼2 and ∼8 times greater than that of the simpler mechanism at idle and cruise conditions, respectively. The more complex mechanism predicts more heat release at the inner shear layer, while the simpler mechanism predicts a mostly quenched flame there.
