A Study On Influence Law Of Fuel Injection Parameters On Emission Performance Of A Common Rail Diesel Engine

In recent years, with the more and more serious air pollution, especially the haze weather becoming a primary problem of air pollution in our country, reducing diesel harmful emissions is necessary. The diesel engine fuel injection parameters have significant influence on mixture formation and combustion in cylinder. The emission performance of diesel engine could be improved through the analysis of the influence of fuel injection parameters acting on the combustion process in cylinder.A common rail diesel engine is taken as an object in this paper and the research is divided into two parts. The first part is simulation calculation. Establishing a simulation model of combustion chamber based on the software of FIRE and completing the meshing division, and setting up calculation model. Then numerical simulation of combustion process in cylinder is calculated. Combustion process is reflected by the air-fuel equivalent ratio、temperature and pressure changes in cylinder. The influence of fuel injection advance angle, injection pressure and injection hole diameters acting on the combustion process in cylinder, the diesel engine performance and emissions form of the injection parameters is mainly analyzed.The research results show that: Fuel injection advance angle, injection pressure and injection hole diameter has an important influence on the combustion process in cylinder. Advance injection angle may appropriately increase the combustion ignition delay period, increase the mixture mixing time, improve combustion, increase the maximum pressure and temperature in cylinder, increase the NOX emission, reduce Soot emissions, and appropriate fuel injection advance angle can improve the performance and fuel economy of diesel engine. High-pressure jet and small diameter nozzle can narrow refined oil droplets, promote the evaporation of the fuel, speed up the air and the mixture of oil mist, optimize combustion, increase the pressure and temperature in cylinder and improve the power and emission performance of diesel engine.Pilot injection test is carried on a test bench in the second part. Two parameters, injection quantity and main spray-pre injection interval, are analyzed and optimization scheme is put forward. Experimental results show that the small amount of pre spray and larger angle of fuel injection interval can reduce NOX emissions effectively understand the guarantees of Soot and fuel economy not getting worse.