Abstract
A premixed charge compression ignition(PCCI) combustion was simulated by the Large Eddy Simulation in conjunction with a reaction kinetics model. We analyzed the interrelationships between mixture heterogeneity and reaction in a turbulent flow. Several different initial conditions of heterogeneity of an air-fuel or air-fuel-EGR gas mixture were given at the intake valve closing time by a new method, which generated a statistically reasonable turbulent fluctuations in both velocity and fuel mass fraction fields. The auto-ignition and combustion behaviors were analyzed for several different sets of the rms and the length scale of the fluctuations in fuel mass fraction. The analyses show that the equivalence ratio fluctuations with large rms and length scale have considerable effect in attaining moderate combustion in a PCCI engine.
