DNS of H2/air combustion in a constant volume enclosure relevant to HCCI engines

Two-dimensional direct numerical simulation (2D-DNS) is used to investigate the effect of turbulence intensity and composition stratification on the ignition of H-2/air mixture in a constant volume enclosure relevant to homogeneous charge compression ignition (HCCI) engines. A comprehensive H-2 chemical kinetic mechanism is adopted, involving 9 species and 21 elementary reactions. Different turbulence levels and composition fluctuations are simulated to investigate their influence on the combustion behavior. The results show that the ignition delay time tends to be prolonged and the heat release rate increased under higher turbulence intensity. Turbulence can affect the reaction zone, e.g., through wrinkling of reaction front. Higher composition stratification can smoothen the heat release rate. It is found that in HCCI engine flame propagation can co-exist with volumetric auto-ignition. (C) 2014 The Authors. Published by Elsevier Ltd.