Utilizing Static Auto-ignition Measurements to Estimate Intake Air Condition Requirements for Compression Ignition in a Multi-Mode Engine – Engine and RCM experimental study 2019-01-0957
A multi-mode operation strategy, wherein an engine operates compression ignited at low load and spark ignited at high load, is an attractive way of achieving better part-load efficiency in a light duty spark ignition (SI) engine. Given the sensitivity of compression ignition operation to in-cylinder conditions, one of the critical requirements in realizing such strategy in practice, is accurate control of intake charge conditions – pressure (P), temperature (T) and equivalence ratio (φ), in order to achieve stable combustion and enable rapid mode-switches. This article presents the firstof a two part study of correlating ignition delay data under various engine-relevant operating conditions (P,T,φ) obtained from rapid compression machine (RCM), to combustion phasing and stability data obtained from a modern SI engine operated in compression ignition mode. This article specifically focuses on experimental data obtained from the two devices, where in three full boiling range gasoline blends were tested. A modern SI engine is used to establish an ACI operating zone in the in-cylinder P-T space, at two equivalence ratios, while staying within a specified combustion noise threshold. Through establishing a correlation with ignition delay data obtained from the RCM, the feasibility of utilizing trends in the auto-ignition measurements to estimate intake air conditions required for stable compression ignition operation, and thus predictive control, has been discussed.
Ashish Shah, Dongil Kang, Scott Goldsborough, Toby Rockstroh