Numerical Simulation of HCCI Engine With Multi-Stage Gasoline Direct Injection Using 3D-CFD With Detailed Chemistry

In this paper, the detailed chemical kinetics was implemented into the three-dimensional CFD code to study the combustion process in HCCI engines. An extended hydrocarbon oxidation reaction mechanism (89 species, 413 reactions) used for high octane fuel was constructed and then used to simulate the chemical process of the ignition, combustion and pollutant formation in HCCI conditions. The three-dimensional CFD / chemistry model (FIRE/CHEMKIN) was validated using the experimental data from a Rapid Compression Machine. The simulation results show good agreements with experiments.

Finally, the improved multi-dimensional CFD code has been employed to simulate the intake, spray, combustion and pollution formation process of the gasoline direct injection HCCI engine with multi-stage injection strategy. The models account for intake flow structure, spray atomization, spray/wall interaction, droplet evaporation and gas phase chemistry in complex multi-dimensional geometries. The calculated results show the periphery of fuel-rich zone formed by the second injection ignited first, then the fuel-rich zone ignited and worked as an initiation to ignite the surrounding lean mixture zone formed by the first injection. The results provide a detailed insight into the processes governing combustion and pollutant formation in the HCCI engine.