The Simulation Research On The Influence Factors Of Particulate And NO_x Formation Of A Stratified Lean Burn Gasoline Engine

With the development of the national economy and the progress of the technical civilization,Energy and environmental problems have caused people's attention.GDI engine can achieve its economic goal under partial load thin layered combustion technology.Layered thin combustion in cylinder directly affects the soot and NOx emissions.Therefore,This paper simulates particulate matter formation of soot and NOx of a stratified lean burn GDI engine.In this paper,The author established the mathematical model of the GDI engine by using AVL FIRE software,To make a moving grid,the author meshed the three-dimensional model of the engine and set the calculated initial conditions and boundary conditions.This Paper mainly simulates the soot and NOx formation distribution and development process in a GDI engine under the different conditions of injection duration,the fuel injection quantity,injection timing,injection position,injection angle and other combustion cylinder of different parameters.The results are as follows:1)Soot start to form after the ignition and its mass fraction first increased and then decreased.The position,where soot form,transfer from ignition center to the surrounding gradually with the progresses of combustion.soot generated mainly on the edge of the cylinder wall in the post-combustion period.2)NO start to form after the ignition and its mass fraction first increased and then remained the same.The position,where NO form,transfer from ignition center to the whole cylinder.3)The mass fraction of soot are increasing with injection time of delay and The mass fraction of NO are decreasing with injection time of delay.From two aspects of soot and NO generation,Fuel injection Angle 45°the quantity of the soot and the NO are moderate.When injection duration is too long the soot formation is increasing.too short the NO is increasing.With the increase of the crank angle both the mass fraction of soot and NO are increasing.under certain conditions,when injection position is getting closer and closer to the spark plug,the quantity of the soot will increase but the NO will decrease.