Analysis of chaos in the combustion process of premixed natural gas engine

In this paper, the dynamical characteristics of a combustion process in the premixed natural gas engine are studied with the phase space reconstruction method and the 0-1 test method. To express the influence of the system parameters the experiments are carried out under different injection timing conditions. The results express that by reconstructing the phase space, the patterns of combustion process can be clearly investigated. The attractors of in-cylinder pressure, IMEP, Q and θ50 time series exhibit more serious variations when the injection timing is 45-60°CA. The normalized time series is proposed to be used in the coordinates of the 0-1 test. In the results we obtained the characteristic values of the control parameter, K, is close to 0 for a motored engine and 1 for all the cases with different injection timings. Moreover, with increasing of the injection timing, the K value firstly increase and then decrease. The results demonstrate that the combustion process of a premixed natural gas engine under different injection timing conditions is considered to be chaotic. Furthermore, the chaotic behavior is stronger under 45-60°CA injection timing conditions. This coincides with the phase space reconstruction results.