Effect of Spark Condition on Non-Linear Dynamic Characteristics of Natural Gas Engine

In the condition of equivalence ratio α=1 and different spark advance angle (SAA), non-linear dynamic characteristics of combustion process in spark ignition (SI) natural gas engine was studied. The results show that the attractors always have a non-periodic structure within a limited region .When SAA increases indicated mean effective pressure (IMEP) and the scale of attractors increase whereas the coefficients of cyclic variation and the correlation dimension of system decrease. It is observed that the correlation dimension of system is fractal and the largest Lyapunov exponent (LLE) of the system is always greater than zero. Therefore in condition of α = 1, combustion system is of obvious non-linear deterministic nature and the complexity of the system is reduced with the increase of SAA.