In-cylinder CFD Simulation of a New 2.0L Turbo Charged GDI Engine 2011-01-0826

This paper describes the application of CFD tools in the design optimization of intake ports, combustion chamber and injector of SAIC Motor's 2.0L turbo charged direct injection gasoline engine. For a more realistic simulation of spray processes, detailed investigations of mesh dependency, wall impingement models were conducted. The validation of the spray simulation was carried out by comparison between the experimental data and calculation results. To investigate the droplet-wall interactions, a comparison between the results from Bai's model and the instantaneous evaporation model was made.

With the Star-CD code, the in-cylinder air motion, fuel injection and air/fuel mixing in the combustion system with central injector were evaluated, at different engine operation conditions and start of injection timings. Several proposed intake port options, with different tumble levels, were numerically investigated and compared. Evaluation parameters include the tumble ratio, the turbulent kinetic energy at ignition, the SMD, and the air/fuel ratio distribution. The engine test data confirmed that the high tumble intake port design leads to a faster flame burning speed. The derived formulation for burn duration correlation allows a fast assessment of the burn duration with the parameters from the results of in-cylinder CFD analysis with fuel injection.