Modeling cyclic variability during the transition between spark-ignited combustion and HCCI

Numerous experimental studies of the transition between conventional spark-ignited (SI) propagating-flame combustion and homogeneous charge compression ignition (HCCI) combustion in gasoline engines have demonstrated a high degree of deterministic coupling between successive combustion events. Analysis of this coupling suggests that the transition between SI and HCCI can be described as a sequence of bifurcations in a low-dimensional dynamic map. In this paper we describe methods for utilizing the deterministic relationship between cycles to extract global kinetic information that can be used to discriminate multiple distinct combustion states and develop a more quantitative understanding of the SI-HCCI transition. Our results have specific implications for developing feedback control strategies that utilize spark-assist to expand the operating range of HCCI combustion.