A direct numerical simulation investigation of ignition at diesel relevant conditions

Abstract

A two-dimensional direct numerical simulation was performed with detailed dimethyl ether chemistry in isotropic turbulence to investigate the ignition behaviour in engine relevant conditions. Dimethyl ether was selected as the fuel because it exhibits two-stage ignition and a negative temperature coefficient of ignition delay times, similar to practical diesel fuels, while having a computationally tractable chemical mechanism. Distinct low and high temperature ignitions are observed which trigger deflagrations that transition to edge-flames, propagating along the stoichiomectric mixture fraction contour. The edge flames have a tetrabrachial (quadruple flame) structure consisting of a main tr..