Cycle-by-cycle combustion variations in spark-ignited engines

C.S. Daw Oak Ridge National Laboratory Knoxville TN 37932-6472

C.E.A. Finney University of Tennessee Knoxville TN 37996-2210

M.B. Kennel University of California, San Diego La Jolla CA 92093-0402

F.T. Connolly
Ford Motor Company
Dearborn MI 48121-2053

Under constant nominal operating conditions, internal combustion engines can exhibit substantial variation in combustion efficiency from one cycle to the next. Previous researchers have attempted to explain these variations as resulting from stochastic, linear, or chaotic physical processes. Our investigations indicate that cyclic combustion variations can be explained as the result of interactions between a global low-dimensional nonlinearity and small-scale, high-dimensional processes that perturb the nonlinearity. Using this approach, we have proposed a simple model that accurately simulates experimentally observed patterns in cyclic combustion variations. Our model also explains the apparent discrepancies among previous investigators regarding the basic nature of cyclic variations. Further, it appears that symbolic time series analysis is useful for characterizing the observed model and experimental behavior.

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Daw CS, Finney CEA, Kennel MB, Connolly FT (1997). Cycle-by-cycle combustion variations in spark-ignited engines. Proceedings of the Fourth Experimental Chaos Conference (Boca Raton, Florida USA; 1997 August 06-08) (ISBN 981-02-3743-X): 329-340.

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