（1.Jilin Engineering Normal University，Changchun 130000,China;2.Key Laboratory of Automobile Simulation and Control，Jilin University，Changchun 130025，China;3.FAWVW,Changchun 130000,China）
Based on the common issues of dieselnatural gas dual fuel engine existing in the key technologies and the phenomena of low thermal efficiency and high CH4 emission, the fuel economy improved and the CH4 emission reduced through strengthening the incylinder turbulent flow and improving the mixture combustion in terms of combustion chamber optimization. The numerical simulation platform was established with STAR-CD software and its verification was conducted. Then a new type of combustion chamber was designed to improve the incylinder flow and combustion rate through analyzing the changes of microscopic combustion parameters in the original configuration under the load conditions of 218 N·m at 1 335 r/min. The results show that the new combustion chamber can effectively strengthen the in-cylinder turbulent flow and hence the maximum combustion pressure increases by nearly 25% and the natural gas residual rate decreases from 28.6% to 0.5%. Finally, the optimal combustion quality is determined and the economy and emissions improve.
