EVALUATION OF JP-8 SURROGATE UNDER SPRAY DIESEL CONDITIONS USING DETAILED CHEMICAL KINETIC MODELS

Single-Fuel Concept (SFC) describes the desire to operate diesel engines using JP-8 as the only fuel in the US military due to mostly logistic reasons. However, there is a lack of a fundamental database on the combustion characteristics of JP-8 compared to those studies that have been done for diesel combustion. In this current study, several kinetic models are used to look into flame properties including ignition behavior, fuel properties including evaporation characteristics, and species evolution such as soot precursor, acetylene. Several surrogates for JP-8 fuel including tetradecane, n-dodecane and a mixture of 77 vol-% n-dodecane and 23 vol-% m-xylene are selected in the model using a detailed chemical kinetic mechanism with 330 species and 1957 reactions. Included in the model are growth mechanisms of Polycyclic Aromatic Hydrocarbon (PAH), which are known to be important for soot formation. Studies are performed to describe the fundamental combustion characteristics of JP-8 surrogates under spray diesel conditions. Numerical models used include closed reactor simulation, Two-Stage Lagrangian (TSL) model, and Computational Fluid Dynamics (CFD) simulation. Simulation conditions include temperatures range of 1000-1400 K and injection pressures of 1100 bar, and ambient density of 14.8 kg/m³. Experiment was performed with limited number of runs to compare with the result from simulation. Vapor penetration from CFD simulation currently under predicts the values from experiments.