Wednesday, March 23, 2005 - 11:10 AM

Modeling Nonlinear Dynamics in a Spark Ignition Engine with a Two-Zone Thermodynamic Model

Brian Kaul, University of Missouri-Rolla, Graduate Student, Rolla, MO 65401, James A. Drallmeier, Mechanical Engineering, Professor, Rolla, MO 65401, Kalyana Chakravarty, Oak Ridge National Laboratory, Research Staff, 2360 Cherahala Blvd, Knoxville, TN 37932, C. Stuart Daw, Distinguished Research Staff, 2360 Cherahala Blvd, Knoxville, TN 37932, and Robert M. Wagner, Senior Research Staff, 2360 Cherahala Blvd, Knoxville, TN 37932.

Cyclic variability in spark ignition engines under very lean operating conditions is modeled using a zero-dimensional two-zone thermodynamic model, coupled with a turbulent flame speed combustion model. The composition and energy of residual gases are feed-forward mechanisms to influence subsequent cycles. The relatively simple zero-dimensional nature of the model allows many cycles to be simulated in a short period of time, so that the nonlinear dynamical nature of the cycle to cycle variations in heat release can be predicted. Consideration of energy effects in this model, in addition to the conservation of mass already included in previous models, allows prediction of this behavior as both equivalence ratio and ignition timing are varied. Results are benchmarked against data acquired on a single-cylinder CFR engine.