Utilizing Static Autoignition Measurements to Estimate Intake Air Condition Requirements for Compression Ignition in a Multi-mode Engine – Application of Chemical Kinetic Modeling 2019-01-0955
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 second of a two-part study of correlating ignition delay data under various engine-relevant operating conditions (P,T,φ) to combustion phasing and stability data obtained from a modern SI engine operated in compression ignition mode.
In this second part, the focus is on the use of detailed chemical kinetic models to estimate the ignition behavior towards enabling reduced-order approaches for engine combustion control, parameterized in ACI engine relevant operating conditions. The calculated autoignition behavior for multi-component surrogates of three full boiling range gasoline blends are utilized to provide insight into the impact of chemical composition covering a wide range of ACI relevant operating conditions. Both static and variable volume simulations are considered to quantify the existent role of engine dynamics on controlling combustion phasing compared to constant-volume estimations. Finally, the trends are compared against those of experimental measurements from a RCM and further discussions regarding fidelity requirements for use of chemical kinetic mechanisms as a tool for predicting engine combustion phasing at ACI engine relevant operating conditions are made.
Dongil Kang, Ashish Shah, Toby Rockstroh, Scott Goldsborough