Numerical investigation of mixture preparation for AI combustion in a two-stroke engine
- Cultural & Communication Publisher
- Publication Type:
- Conference Proceeding
- APAC 2009 - Proceedings of 15th Asia Pacific Automotive Engineering Conference, 2009
- Issue Date:
Computational Fluid Dynamics (CFD) offers an alternative technique to understand the in-cylinder gas behaviour of an internal combustion engine. In our experimental investigations, auto-ignition (AI) was achieved in a small two-stroke engine by internal exhaust gas recirculation (EGR) using an exhaust port valve to trap the burnt gas. A CFD model was developed, aiming to study the temperature and the distribution of the trapped burned gas prior to AI. The engine to be modelled was a 160cc single-cylinder piston ported two-stroke engine equipped with a butterfly valve in the exhaust pipe. The CFD model was developed using a commercial code. The turbulence model was RNG k-e. Experimental data were used to define the initial and boundary conditions. The model simulates the gas exchange process from the exhaust port opening to the point before the ignition. It was verified by comparing the numerical result of cylinder pressure with the experimental one. Then the verified numerical model was used to perform numerical simulations of the gas exchange process at various engine operating conditions. The effect of the exhaust port restriction, the intake valve opening and the engine speed on the temperature and the distribution of trapped burnt gas in cylinder were analysed. The simulation results suggested that the exhaust valve restriction had a stronger effect than the intake valve did. The numerical results for investigating the effect of the engine speed helped understand the AI operation region investigated in the experiments.
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