Cyclic variability analysis of an engine fuelled with gasoline/natural gas using return maps and symbol sequences

Abstract

The present work investigates the cyclic variability of a single cylinder spark ignition (SI) engine fuelled with gasoline/natural gas. Return maps and symbol sequence analysis are used to analyze the cycle dynamics at different engine loads and mixture strength. Cycle dynamics is found to be stochastic in nature at high engine loads with low cyclic variability. The frequency of deterministic patterns with close coupling between consecutive cycles is found to be high at low loads with high cyclic variability. In comparison to gasoline, the deterministic effects are found to be more predominant for natural gas fuelled engine. Designing a predictive controller that makes use of the knowledge of the current event to forecast the status of forthcoming occurrences is possible because to the deterministic information available in cycle dynamics. Under the assumption that the controller is active and has successfully brought the engine within stable limits, the predictable patterns are identified and omitted from the dataset. Engine performance is analyzed both with and without the deterministic pattern. The research provides an estimate of how much better engine performance could be achieved with the knowledge of determinism in the system and the subsequent application of this knowledge for efficient engine control.