Simulation Of The Influence Of Pilot Injection And Post Injection On The Combustion And Emissions Of Diesel Engine

The energy and environmental crisis is an increasing attention, emission laws are increasingly stringent, which has higher requirements for emissions control. Experimental results has showed multiple injection is an effective means to reduce emissions, the research is mainly on laboratory works. The paper relied on 1015 diesel engine, simulated pilot and post injection using FIRE to study the influence on combustion and emissions of diesel by them.According to the structural and experimental parameters, investigations conducted a geometric and mesh model to generate the moving-cylinder mesh for combustion calculation models, followed by the traditional SI experiment conditions simulation calculation. The cylinder pressure curves calculated and experimental cylinder pressure curves were compared to verify the calculation and selection of models is reasonable.This investigation conducted pilot injection+main injection simulation to study the influence on combustion and emissions of diesel by PI parameters. Research focused on the influence of cylinder pressure, pressure rise rate, heat release rate, temperature, turbulent kinetic energy,velocity, fuel concentration and temperature field, NO and PM yields,analysis of the influence of NO reduction reasons and the influence of the impact on the reduction of NO of the main spay timing, including the reasons.Then this investigation conducted main injection+post injection simulation to study the influence on combustion and emissions of diesel by the parameters of post injection. Research focused on the influence of the cylinder pressure, the combustion heat release rate, cylinder temperature, velocity, fuel concentration and temperature field in cylinder, NO, and PM yields of the post injection, especially focusing on analysis of the influence of PM generation reasons.Finally, by the results of the pilot and post injection, the optimized pilot injection and post injection program under the same main injection time was adopted. Combine the optimized programs to continue the three-stage injection calculation to study the influence on combustion and emissions of diesel by three-stage injection..By this paper, influence on combustion and emissions of diesel by the pilot and post injection was known, also the reason for NO redution by pilot injection, the reason for PM redution by pilot injection by post injection.In addition, three stage-injection, not only reduceed the NO, also reduced the PM largely, which was comprehensive embodiment of the pilot injection and post injection effects on their own emissions.