A skeletal mechanism for gasoline surrogates: Development, validation, and CFD application

Abstract

In this study, a skeletal chemical kinetic mechanism for gasoline surrogates is developed from a detailed mechanism by applying several reduction techniques. Directed relation graph (DRG) routines and DRG-aided sensitivity analysis methods are applied with worst-case error tolerances equal to 30% and 40%, respectively. Issues with reaction dead-ends in the oxidation paths are resolved by adding adequate intermediate species and reactions. Sensitivity analyses are conducted to identify the most impactful fuel-dependent reactions to ignition delay, and the specific reaction rates of such reactions are optimized to replicate the ignition behavior of detailed mechanism. The final version of the skeletal mechanism consists of 152 species and 563 reactions including NOx chemistry. Experiments are carried out in Sandia's low-temperature gasoline combustion research engine with an E10 regular-grade gasoline, termed RD5-87, and the results are replicated in 0D simulations with good accuracies using both detailed mechanism and the skeletal mechanism although a slight over-estimation of the low-temperature heat release is observed. Finally, the performance of the skeletal mechanism is also tested in 3D CFD simulation using LES. Simulations are able to predict the pressure evolution and heat release rate, proving that the proposed skeletal mechanism is adequate for simulations.