Study On The Influence Of Fuel Injection Characteristic Parameters On Combustion And Emission Of High Pressure Common Rail Diesel Engine Of China Ⅵ Emission Regulation

As an important tool of modern transportation,fuel vehicle promotes social development,but also aggravates energy crisis and air pollution.Among them,the fuel consumption and emission pollution of heavy trucks are particularly serious.As environmental protection regulations become more stringent,super trucks with ultra-low fuel consumption and emissions are the development direction of heavy trucks.The fuel injection characteristic parameters of the fuel supply system determine the fuel spray characteristics of the diesel engine and the combustion characteristics in cylinder,which is the key to realize the ultra-low fuel consumption and emissions.Based on the electronically controlled high-pressure common rail fuel supply system of diesel engine,this paper studies the influence of fuel injection characteristic parameters of fuel supply system on combustion and emission,aiming to provide theoretical support for the development and selection of fuel supply system of super truck heavy-duty diesel engine of China VI emission regulation.The injection characteristic parameters studied in this paper include: K-factor,injector fuel flow rate,nozzle cone angle,rail pressure,injection timing.In this paper,to study the influence of the injector geometric parameters: K-factor,injector fuel flow rate,nozzle cone angle on the combustion and emission characteristics of the diesel engine,a modified high-pressure common rail six cylinder diesel engine is used as the test engine.The combustion,emission,and fuel consumption characteristic of the diesel engine under different combinations of injector geometric parameters is comprehensively compared and the optimal combination of the geometric parameters is selected.The effects of injection control parameters,such as common rail pressure and injection timing,on the combustion and emission performance of diesel engine are studied,and the optimal combination of injection control parameters is determined.By analyzing the influence of fuel injection characteristic parameters on combustion and emission of diesel engine,it is found that: as for K-factor,KS hole(K=1)has better fuel atomization effect and the ignition delay period is shorter,which can reduce NOx and particulate emission at the same time;as for injector fuel flow rate,small fuel flow rate injector is beneficial to fuel atomization,and has the effect of shortening engine ignition delay period and reducing NOx emission;as for nozzle cone angle,it is found that the large nozzle cone angle is beneficial to cylinder combustion,but the excessive nozzle cone angle is likely to lead to smoke and NOx emissions increase,while the small nozzle cone angle has the lowest emission;as for rail pressure,it is found that increasing rail pressure will promote cylinder combustion,resulting in the increase of cylinder pressure and heat release rate,more concentrated heat release,lower smoke and CO emissions of diesel engine,and higher NOx emissions;as for injection timing t is found that with the advance of injection tming,the combustion start point advances,the peak of cylinder pressure increases,the smoke emission decreases,and the NOx emission increases.By comparing the effects of the combination of injector geometric parameters on fuel consumption and emissions of the diesel engine,the optimal injector matching with the combustion chamber is determined,and it is found that: compared with the large flow rate injector,the small flow rate injector has better fuel consumption and emissions performance at low speed;compared with other injector geometric parameters,the nozzle cone angle has a deeper impact on the fuel consumption and emissions of the engine;however,with the increase of engine speed and load,the influence of injector geometric parameters on fuel consumption and emissions decreases.In this paper,the optimal rail pressure and injection timing are determined by comparing the injection control parameters,and it is found that: high rail pressure and late injection are conducive to the organization of rational combustion,reduce engine emissions and fuel consumption.