Cyclic Variability Analysis of an Engine Fueled With Gasoline/Natural Gas Using Return Maps and Symbol Sequences

The present work investigates the cyclic variability of a single-cylinder spark ignition engine fueled 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 fueled engine. The paper also demonstrates that the identification of deterministic patterns and omitting them through an efficient engine management system brings the engine to a stable state from unstable state. 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.