Development of physical-chemical surrogate models and skeletal mechanism for the spray and combustion simulation of RP-3 kerosene fuels

RP-3 kerosene is a widely used fuel for civil and military transportation in China. Two RP-3 kerosene surrogates (UM1 and UM2) were proposed by genetic algorithm optimization methodology, aiming to simulate viscosity, density, surface tension, cetane number, lower heating value, H/C ratio and molecular weight along with sooting tendency under spray and engine relevant conditions. The RP-3 kerosene surrogates were composed of four components including n-dodecane, 2,2,4,6,6-pentamethylheptane, decalin and n-propylbenzene (UM1, 0.3374/0.3042/0.1954/0.163. UM2, 0.1449/0.3706/0.2059/0.0195/0.2591 by mole fraction). The carbon number of n-dodecane and 2,2,4,6,6-pentamethylheptane was both much closer to that of the real RP-3. Based on the proposed surrogates, a skeletal RP-3 surrogate chemical reaction mechanism was developed by decoupling methodology. The skeletal RP-3 surrogate mechanism was reduced only including 89 species and 225 reactions, which was efficient and reliable in CFD simulation. The surrogate models were validated during spray process under vapor and nonevaporating environment. The skeletal mechanism was verified against the foundational experiments such as ignition delay times, species concentrations and laminar flame speed under wide conditions. The applicability of skeletal mechanism was also well verified with our test data from a real compression-ignition engine.