Nonlinear Dynamics in Cyclic Variations of Combustion Phasing in an HCCI Engine

Temporal dynamics of cyclic variation in a Homogeneous Charge Compression Ignition (HCCI) engine near misfire is analyzed using chaotic theory methods. The analysis of variation of consecutive cycles of CA50 (crank angle of 50% fuel burnt) for an n-heptane fueled engine is performed for a test point near the misfire condition. The return map of the time series of CA50 cycle values reveals the deterministic and random portions of dynamics near misfire occurring in an HCCI engine. A symbol-statistic approach is also used to find the occurrence of possible probabilities of the data points under the same operating conditions. These techniques are then used to predict CA50 one cycle-ahead. Simulated data points in phase space have similar dynamical structure to the experimental measurements.