Simulation Study On Combustion And Emission Performance Optimization Of Highly Intensified Diesel Engine

Highly intensified diesel engine has the characteristics of large amount of in-cylinder air and high power output,which play a pivotal role in military and civilian.However,the NO_xemissions of diesel vehicles exceed 80%of the total vehicle emissions.Facing the current situation of energy shortage and environmental deterioration,it is necessary to put forward higher requirements for the further research and development of the power performance and environmental performance of traditional diesel vehicles while transforming new energy vehicles.In recent years,highly intensified diesel engines have adopted a variety of new technologies to improve the airflow characteristics and fuel-air mixing effects,and ensure that the emissions are within the allowable range while increasing the power output.In order to better study the airflow characteristics and fuel-air mixing,this paper is based on“Converge”software to carry out a three-dimensional numerical simulation of the entire working process of a highly intensified diesel engine.The airflow characteristics at the intake valve clearance ring are explained in detail,and the equivalence ratio method and Lorentz curve method are used to analyze the homogeneity of fuel-air mixing.It is of great significance to further explore the improvement of combustion and emissions of highly intensified diesel engine.Based on the analysis method,this paper uses different intake port combinations,different combustion chamber shapes,and different late intake valve closed angles(LIVC)to compare the effects of swirl flow,different squish flow speeds,and different miller degrees on the performance of highly intensified diesel engines.And select optimization measures to improve its dynamic performance and emission performance.The results show that the in-depth study of in-cylinder flow characteristics and fuel-air mixing is an important part to further analyze the internal mechanism of the working process of highly Intensified diesel engine.Reasonable use of swirl flow and squish flow can significantly improve the engine fuel-air mixing and combustion effect of highly intensified diesel engine.With a reasonable miller cycle scheme,it can significantly improve the emission performance while ensuring the improvement of the dynamic performance of the highly intensified diesel engine.