Large Eddy Simulation of a H₂/N₂ Lifted Flame in a Vitiated Co-Flow

Abstract

A lifted turbulent H₂/N₂ flame in a vitiated co-flow is studied using Large Eddy Simulation together with a closure based on perfectly stirred reactors. A part of the closure, chemical look-up tables, are generated to close the filtered temperature equations and to compute local radical concentrations throughout the computational domain. The approach has been used to simulate a lifted turbulent flame. The results have been found to be insensitive to the combustion model employed and to the grid resolution. However, the results are very sensitive to the temperature of the co-flow stream and this result is well in line with previous findings. The numerical predictions were further compared to detailed experimental data obtained by Cabra et al. (2002). The agreement between the two sets of data is very good, indicating that the present approach predicts successfully the combustion process including the OH mass fractions. Finally, the LES data were used to study the flame dynamics and stabilization mechanisms.

Keywords:

• Large eddy simulation
• Lift-off
• Non-premixed flames
• Proper orthogonal decomposition
• Turbulent combustion

This work was supported financially by the Swedish Energy Authority (STEM) and the Swedish Research Council (VR). The computations were run on HPC2N and LUNARC facilities within the allocation program SNAC. The routine used to generate the time dependent inflow boundary condition was kindly provided by Markus Klein (TU-Darmstadt).