Numerical Simulation Of Parameters Of Fuel Injection And Intake Systems Based On No_x And Soot Trade-off

Diesel engines are the most popular power source for commercial vehiclesbecause of their high heat efficiency and clean combustion potential, whereas it isnecessary to address stringent regulatory requirements for further reduction ofemissions. Due to diffusion combustion characteristics of conventional diesel engines,it is critical to obtain a good trade-off relationship between NOxand soot emissions.So we can conclude that reduction of NOxand soot emissions is a hot research topic.Theoretical reference was provided for improving the trade-off relationship betweenNOxand soot emissions by rational matching and optimizing of relevant parameters offuel injection system, intake system and the combustion chamber shape.Numerical simulation was carried out to investigate the effects of parameters offuel injection and intake systems on performance and emissions of a4-cylinder highpressure common rail diesel engine. On one hand, one-dimensional investigation ofeffect of EGR on diesel performance was carried out to provide numerical boundaryconditions for CFD analysis by using GT-POWER. On the other hand, in order toreduce NOxand soot emissions simultaneously, CFD analysis of parameters of fuelinjection and intake systems was conducted by using a modified KIVA-3V code.Results showed that a narrow spray included angle, in combination with retardedsingle injection timings, had a better potential to reduce emissions of a diesel engine.Through optimization of relevant parameters which fuel injection duration wasreduced from15CAD to10CAD and start of injection（SOI）was advanced from0°CA BTDC to6°CA BTDC with40%EGR, perfect combustion characteristics andlow emissions could be achieved. A good trade-off relationship between NOxand sootemissions was obtained with a nozzle tip protrusion（NTP）at1.0mm, and goodengine performance was identically achieved by shortening fuel injection durationwith proper EGR rates.Numerical simulation was carried out to investigate the rational matching ofintake parameter and the combustion chamber shape. Low temperature combustion（LTC）was easily achieved because of low EGR rates with low intake pressures. Theproper intake pressure is2.0bar by contrasting the effect of EGR on combustionefficiency in different intake pressures. And low emissions could be obtained when swirl ratio was about1.0at the speed of3000r/min and50%load（175N m）.