On the Nature of Cyclic Dispersion in Spark Assisted HCCI Combustion

An optical study of in-cylinder CH2O and OH chemiluminescence in flame-induced reaction front propagation using high speed imaging

“…SI-CI can be divided into two categories [10]. One category is spark-assisted compression ignition (SACI) [2,[4][5][6][7][8][9], where the spark is used to increase the robustness of the ignition control in HCCI although combustion can be realized without the spark. The other category is flame-induced auto-ignition (FIAI) [3,10,12,13], where spark-triggered flame propagation causes auto-ignition without engine knock and misfiring occurs without the spark.…”

“…However, HCCI faces challenges of the difficult combustion control and narrow operating ranges [1]. Spark ignition-compression ignition (SI-CI) is a hybrid combustion and has become a promising mode in gasoline engines with high efficiency [2][3][4][5][6][7][8][9][10][11][12]. SI-CI can be divided into two categories [10].…”

Analysis of cyclic variability in spark-assisted HCCI combustion using a double Wiebe function

“…The recovery from misfire begins when the residual fuel from the misfire suppresses SI combustion and provides a boost for the HCCI combustion in the post-misfire cycle. This pattern of three successive combustion events (overshoot from the optimal SI-HCCI balance, misfire, and then HCCI-driven recovery) appears to form the basis of the characteristic three-cycle sequence identified for this engine earlier [5][6][7]. Our analyses so far suggest that one possible approach for countering this three-cycle instability with feedback would be to monitor the SI-HCCI balance of each cycle in real-time using some technique such as the double Wiebe algorithm described here.…”

“…Details of the experimental engine and data collection procedures have already been published elsewhere [5][6][7] and are thus not repeated here. Briefly, the data used to develop and demonstrate our proposed algorithm were generated using a 0.5-L single-cylinder, research gasoline engine fueled with indolene.…”

“…In previous studies [5][6][7], we have found that careful measurement of the cyclic variations in unstable combustion occurring at intermediate levels of EGR can provide valuable information for understanding and controlling the kinetics and feedback mechanisms affecting the SI-HCCI mode transition. One result of these measurements has been the recognition that at each intermediate EGR level there is at least one combination of SI and HCCI occurring within single cycles that is more stable than either SI or HCCI alone [5].…”