Large Eddy Simulation of Partially Premixed Flame with Local Extinction Phenomenon

Abstract

The Sydney partially premixed flame FJ200-5GP-Lr75-103 case with the local extinction phenomenon is studied by large eddy simulation (LES) coupled with the dynamic k equation sub-grid scale model and the dynamic thickened flame (DTF) combustion model. To account for the influence of non-uniform equivalence ratio on the laminar flame speed and thickness, two fitting functions are introduced in the DTF model to automatically adjust these two parameters in the wrinkling functions, according to the local value of mixture fraction in the flow field. The results show that the dynamic k equation model can predict the mixture fraction of the non-uniform premixed gas in the flow field well. In the middle and downstream with more flame extinction, the temperature, the species profiles, and the scatter plot of temperature versus mixture fraction calculated by LES agree well with the experiment data. This demonstrates that the improved DTF model can capture the local extinction phenomenon in partially premixed flame, but for the CO mass fraction, discrepancy between the LES results and experiment data is presented.

Keywords

• local extinction
• partially premixed flame
• thickened flame model
• large eddy simulation (les)