Numerical study of effects of the intermediates and initial conditions on flame propagation in a real homogeneous charge compression ignition engine

The premixed flame speed under a small four stock homogeneous charge compression ignition engine fueled with dimethyl ether was investigated. The effects of intermediate species, initial temperature, initial pressure, exhaust gas re-circulation, and equivalence ratio were studied compared to the baseline condition. Results show that under all conditions, the flame speeds calculated without intermediates are larger than those considered the intermediates. Flame speeds increase with the increase of crank angle. The increasing rate is divided into three regions and the increasing rate is obviously large when low temperature heat release occurs. Initial temperature and pressure only affect the crank angle of flame speed, but have little influence on its value. Equivalence ratio and exhaust gas re-circulation ratio not only distinctly decrease the flame speed but also advance the crank angle of flame speed.