Direct numerical simulation of ignition front propagation in a constant volume with temperature inhomogeneities: II. Parametric study

The influence of thermal stratification on autoignition at constant volume and high pressure is studied by direct numerical simulation (DNS) with detailed hydrogen/air chemistry. Parametric studies on the effect of the initial amplitude of the temperature fluctuations, the initial length scales of the temperature and velocity fluctuations, and the turbulence intensity are performed. The combustion mode is characterized using the diagnostic measures developed in Part I of this study. Specifically, the ignition front speed and the scalar mixing timescales are used to identify the roles of molecular diffusion and heat conduction in each case. Predictions from a multizone model initialized from the DNS fields are presented and differences are explained using the diagnostic tools developed.