Investigation of auto-ignition in turbulent methanol spray flames using Large Eddy Simulation

Large Eddy Simulation (LES) of a recently developed series of auto-igniting methanol spray flames in a vitiated coflow are presented in the paper. The Eulerian stochastic field method and a reduced chemical mechanism involving 18 reactive species are employed to characterise the turbulent reactive gas phase. A fully coupled Lagrangian particle method is applied to represent the dispersed phase. The gas phase and droplet statistics show good overall agreement with the measurements, confirming that droplet dispersion and evaporation are adequately represented. Comparison of snapshots with images of OH and CH2O from laser induced fluorescence (LIF) highlight, that the employed methodology is also able to capture a range of key features that characterise this complex flame series. This includes the correct lift-off behaviour, the formation of OH that mark the initiation of auto-ignition kernels upstream of the flame base and the presence of "most reactive mixtures" at lean conditions. This agreement with experimental data enables the exploration of mechanisms of auto-ignition in sprays. (C) 2013 The Combustion Institute. Published by Elsevier Inc. All rights reserved.