A DNS Study of Ignition of a Lean PRF/Air Mixture under RCCI/SCCI Conditions

Abstract

A comparative DNS study of the ignition characteristics of dual-fueled reactivity controlled compression ignition (RCCI) and stratification charge compression ignition (SCCI) is investigated using a 116-species reduced primary reference fuel(PRF) mechanism. It is found that the overall RCCI combustion is greatly enhanced and flexibly controlled, thereby significantly reducing the peak HRR. The negative temperature coefficient has a synergistic effect on advancing the overall combustion and smoothing RCCI/SCCI combustion by inducing more low-speed deflagrations. Compared to SCCI, the overall combustion of RCCI is more advanced in time regardless of T0. However, it is also found that the effects of reactivity and/or equivalence ratio stratifications on reducing the peak are nearly eliminated with T0 in the high temperature regime for both RCCI/SCCI due to the dominant spontaneous ignition mode.