Dynamic instabilities in spark-ignited combustion engines with high exhaust gas recirculation

Conference · Sat Jan 01 04:00:00 EST 2011

OSTI ID:1023826

Daw, C Stuart ^[1]; FINNEY, Charles E A ^[1]

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1. ORNL

We propose a cycle-resolved dynamic model for combustion instabilities in spark-ignition engines operating with high levels of exhaust gas recirculation (EGR). High EGR is important for increasing fuel efficiency and implementing advanced low-emission combustion modes such as homogenous charge compression ignition (HCCI). We account for the complex combustion response to cycle-to-cycle feedback by utilizing a global probability distribution that describes the pre-spark state of in-cylinder fuel mixing. The proposed model does a good job of simulating combustion instabilities observed in both lean-fueling engine experiments and in experiments where nitrogen dilution is used to simulate some of the combustion inhibition of EGR. When used to simulate high internal EGR operation, the model exhibits a range of global bifurcations and chaos that appear to be very robust. We use the model to show that it should be possible to reduce high EGR combustion instabilities by switching from internal to external EGR. We also explain why it might be helpful to deliberately stratify the fuel in the pre-spark gas mixture. It might be possible to extend the simple approach used in this model to other chemical reaction systems with spatial inhomogeneity.

• Research Organization: Oak Ridge National Laboratory (ORNL); Fuels, Engines and Emissions Research Center
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1023826
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
CHEMICAL REACTIONS
COMBUSTION
COMPRESSION
DILUTION
DISTRIBUTION
EFFICIENCY
ENGINES
FEEDBACK
IGNITION
NITROGEN
PROBABILITY