چكيده به لاتين
Internal combustion engines are one of the most important factors in air pollution and global warming, and despite many advances, they still have a low efficiency. Therefore, increasing efficiency and reducing pollutants is one of the challenges faced by researchers. Diesel engines have higher efficiency compared to gasoline engines due to lack of throttle and higher compression ratio, but the amount of nitrogen oxides and particulates in these motors is high. In order to solve such problems in recent years, a system called the Reactivity controlled compression ignition (RCCI) has been proposed, in which by low reactivity fuel injection at the inlet port, coupled with high reactivity fuel multi-stage spraying, mixture in the cylinder is provided. Since turbulence models have a significant effect on RCCI engine performance and emissions, this study uses the Converge CFD code coupled with two turbulence models called large eddy simulation(LES) and Navier-Stokes Reynolds averaged (RANS) Examines the impact of five parameters of the natural gas mass fraction, the timing of the secondary injection of diesel fuel, the engine speed, the initial temperature and the spray angle of the diesel spray on the combustion and emissions of the RCCI engine. The results showed that LES compared rans has more ability in natural gas auto-ignition and pollutant prediction.
Keywords: Reactivity controlled compression ignition (RCCI), Pollution, Turbulence Models, LES and RANS
