DNS Investigation on Autoignition and Flame Propagation in HCCI Combustion

Abstract

2-dimensional direct numerical simulation (DNS) of autoignition and flame propagation of turbulent premixed mixture has been conducted to investigate the turbulent combustion mechanism in homogeneous charge compression ignition (HCCI) engines. CH4-air mixtures with spatial inhomogeneity of temperature and equivalence ratio are investigated by considering a detailed kinetic mechanism. Since the combustion process depends on local characteristics of the mixture, an identification method of ignition or flame propagation is proposed based on behaviors of elementary reactions related to OH radical. The proposed identification method shows that the area fraction of the flame propagation region increases drastically with the increase of initial temperature fluctuations.

Keywords

• autoignition
• flame propagation
• hcci engine
• dns
• turbulent premixed combustion.