DNS OF IGNITION OF A LEAN HOMOGENEOUS N-HEPTANE/AIR MIXTURE WITH TEMPERATURE INHOMOGENEITIES AT CONSTANT VOLUME

摘要

The effect of thermal stratification on auto-ignition of a lean homogeneous n-heptane/air mixture at constant volume and high pressure is investigated by direct numerical simulation (DNS) with a 58-species reduced n-heptane/air chemistry. The two-dimensional DNS are performed in a fixed volume with turbulence and temperature fluctuations superimposed on the initial scalar and velocity fields. The influence of the initial amplitude and size of the temperature and velocity fluctuations on the multi-stage ignition of lean n-heptane/air mixture is studied. This study provides fundamental insight on how to control ignition timing and to reduce the rate of pressure rise in homogeneous charge compression ignition (HCCI) engines.