| In order to respond to China's policy of gas law,the GDI technology has been favored by researchers.On the basis of an PFI engine,through the CFD ideas to guide the design,we developed a GDI combustion system,and use it study the injection pressure's influence on the engine combustion and emissions.The paper has calibrated the fuel spray model and combustion model which are used in numerical simulation,calculates 6000r/min@WOT condition for the new combustion system to test flow,spray and combustion performance,and explains detailed numerical simulation on cylinder flow,spray and combustion.This article details are as follows:In paper,three inlet port shape are designed,through CAE simulation analysis and port steady flow test rig to get three shapes of inlet port's flow coefficient and tumble ratio,flow coefficient is relatively uniform,tumble ratio is higher.About fuel injection system design,introduced a fuel injector,high-pressure fuel rail,high-pressure pumps and tubing,three injector proposal designed by CAE simulation.The paper designed five piston shape by CFD,and were carried out flow,spray and combustion simulation.To further enhance the level of GDI engine tumble,In this paper,the design of the valve and valve seat two schemes,By comparing the two schemes' simulation of mass flow and tumble ratio.Increase injection pressure can accelerate the speed of the mixed,shorten the combustion duration,reduce soot emissions,enhance the combustion and emission characteristics of the engine.In this paper,2500r/min@10bar for the calculation condition,select the two fuel injection pressure(12.5MPA / 10MPA)to calculated calculations show injection pressure increase stumble ratio,and TKE are increased accordingly,spray droplet diameter and droplet mass decreases.Full load full speed performance verification indicates combustion system conditions,tumble ratio,TKE,the PHI of the spark plug in ignition time,Oil dilution risk of the combustion system requirements are met. |
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