Computational Modeling of Turbulent Ethanol Spray Flames in a Hot Diluted Coflow using OpenFOAM

The objective of this MSc study, is to develop and validate computational models for the properties of flameless spray combustion. In this process the combustion of fuel is done with air that is highly diluted with combustion products. It is a promising approach to increase efficiency and decrease pollutant emission. Its application in case of liquid fuel (spray combustion) is still in an infant stage compared tot the case of gaseous fuel.

The Delft Spray-in-Hot-Coflow (DSHC) flame, was designed to mimic the flameless oxidation of light oils. Its properties will be computed using a combination of CFD models for turbulence, chemistry and dispersed multiphase flow. The results will be validated by comparison with the available experimental data for ethanol flames. This concerns data on droplet properties (distributions of velocity and diameter), gas phase properties (velocity and temperature) as function of fuel jet and coflow properties [1,2].

In a previous MSc graduation project an ethanol flame in hot coflow was computed using Reynolds Averaged Navier-Stokes (RANS) turbulence models, in combination with steady flamelet model (SF) or Flamelet Generated Manifold (FGM) with assumed shape probability density function (PDF) method and standard Eulerian-Lagrangian methods to represent the spray in a turbulent flow. The results were reported in Ref. [3]. Among the recommendations for future work were: a) using more accurate versions of the FGM-method (choice of progress variable, choice of flamelets for creating the manifold) and b) using Large Eddy Simulation (LES) instead of RANS.

In this MSc project the study of the spray in hot-diluted coflow has been continued, taking into account the recommendations of the previous work. In order to be able to implement new models easily, use has been made of the open source code OpenFOAM and the accompanying module for spray combustion SprayFOAM. As in the previous study, it has been tested whether the new model can reproduce the trends observed in the experiments.

The results have been reported in the MSc thesis by Tariq:

Computational Modeling of Turbulent Ethanol Spray Flames in a Hot Diluted Coflow using OpenFOAM

[1] Hugo Correia Rodrigues, Mark J. Tummers, Eric H. van Veen, Dirk J.E.M. Roekaerts

Spray flame structure in conventional and hot-diluted combustion regime, Combustion and Flame, 2014,

[2] H. Correia Rodrigues, M.J. Tummers, E.H. van Veen, D.J.E.M. Roekaerts, Effects of coflow temperature and composition on ethanol spray flames in hot-diluted coflow, Int. J. Heat Fluid Flow, 51 (2015) pp. 309-323.

[3] S.H. Jamali, Computational Modeling of Turbulent Ethanol Spray Flames in Hot Diluted Coflow , MSc Thesis, Delft University of Technology, 2014