Large-eddy simulation of ethanol spray combustion using a SOM combustion model and its experimental validation

In this paper, large-eddy simulation of ethanol spray-air combustion was made by using an Eulerian-Lagrangian approach, a sub-grid-scale kinetic energy stress model, and a filtered finite-rate combustion model with a sub-grid scale reaction rate, called second-order moment (SOM) combustion model, proposed by our research group. The simulation accounts for the sub-grid turbulence-spray-combustion interactions and the coupling between the temperature fluctuations and species concentrations fluctuations. The simulation results are validated in detail by experiments. It is found that the LES-SOM statistical results are in better agreement with the experimental results than those obtained by LES accounting for only the filtered finite-reaction rate (LES-FA) neglecting the SGS reaction rate, and are in much better agreement than those obtained by RANS modeling using the most complex PDF equation combustion model with detailed chemistry. The instantaneous LES results show the earlier production of the coherent structures in the two-phase jet combustion than that in the single-phase jet combustion. The instantaneous temperature map indicates the existence of small flame islands, expressing the droplet-group combustion, which is not observed in single-phase jet combustion.