Influence of Combustion Chamber on Natural Gas Engine Performance and Optimization

AVL Fire numerical simulation software was used to make the optimal design of combustion chamber on a natural gas engine. Based on the analysis of combustion chamber configuration, two optimized combustion chambers were obtained. Based on the analysis of heat release rate, turbulent kinetic energy and velocity fields, it is found that reducing the combustion bowl diameter is conducive to enhance the tumble and swirl flow motion, thus accelerates the combustion process due to the increase of the turbulent kinetic energy and gas velocity. However, the small convex platform in the optimized scheme I increases the energy dissipation of intake gas, leading to a lower turbulent kinetic energy at ignition timing, and there was no improvement in the flame development duration, while the rapid combustion duration has been speeded up under the effect of squish flow. Bench test work shows that the optimized chamber II decreases by 2.9% in brake specific gas consumption and an average of 18.3℃ reduction of exhaust temperature. Furthermore, the optimizing calibration results show that brake specific gas consumption of the optimized scheme II has improved by 1.5% than the original combustion chamber in the case of same nitrogen oxides emissions.