Modeling spray flame under MILD condition with FGM and a new conditional droplet injectin model

Abstract

solver, the Flamelet Generated Manifolds (FGM) model has been implemented, and used to account for the Turbulent-Chemistry Interaction (TCI). We report here a numerical study on the Delft Spray-in-Hot-Colfow (DSHC) flame with this new “sprayFGMFoam” solver. The enthalpy loss effect due to droplet vaporization is considered by employing an additional controlling parameter in the FGM libraries. Analysis of the DSHC experimental data suggests that flash boiling influences the atomization of liquid fuel. This introduces new challenges for modeling the spray atomization process. A conditional injection model is proposed to provide reliable spray boundary conditions for downstream flow and combustion simulation. In this conditional injection model, the droplets have an asymmetric distribution around the spray half angle, in agreement with experimental observations. Also, the possible range of droplet injection angle is conditioned upon the droplet size (mass). Small droplets can be injected to a very wide range of direction, while large droplets move within a small sector centered at the mean spray trajectory. Two cases employing or not the proposed conditional injection model are compared. The results suggest that using the conditional injection model improves the prediction for all the properties examined.