Analysis of LES-based combustion models applied to an acetone turbulent spray flame

ABSTRACT

Two different combustion models are analyzed for the prediction of an acetone turbulent diluted spray flame. Simulations are conducted in the Large Eddy Simulation (LES) framework, coupled with the Flamelet Generated Manifold (FGM) chemistry reduction method. To represent the polydispersed spray the Eulerian-Lagrangian specification is applied. Both combustion models consist of the Artificially Thickened Flame (ATF) and the presumed PDF approach. Effects of the evaporative cooling and the presence of droplets into the combustion modeling are accounted for. Results achieved with both models are validated against experimental data. These consist in statistical data of droplets velocities, liquid volumetric flux, a characteristic diameter, and temperature. A general good agreement with experimental data is observed. Analysis of simulations results allow deeper interpretation of additional flame features, for instance the double flame structure. As an outcome, the concept of the burning potential is introduced in this paper to assist the interpretation of the underlying mechanisms to the occurrence of different flame modes.

KEYWORDS:

• Turbulent spray combustion
• thickened flame
• presumed pdf
• flamelet generated manifold
• large eddy simulation

Acknowledgments

We gratefully acknowledge the financial support of the DFG (TRR 150). We also thank the computational resources by Lichtenberg HPC of the TU Darmstadt and Prof. A. Masri to make the experimental data available. The first author specially acknowledges the financial support (scholarship) by the CNPq (Brazil) and DAAD (Germany).

Notes

1. φ_over is based on the mass fraction of fuel vapor and air. The amount of fuel in form of liquid is not accounted for.

2. Simulations have been averaged for 2 FTT.

3. Ascending part of T_g profiles for increasing r/D.

4. It resembles the concept of most reactive mixture fraction proposed by Mastorakos et al. (Mastorakos et al., 1997).

Additional information

Funding

This work was supported by the Deutsche Forschungsgemeinshaft [TRR 150]; the first author specially acknowledges the financial support (scholarship) by the CNPq (Brazil) and DAAD (Germany).