Modeling heat loss effects in the large eddy simulation of a model gas turbine combustor with premixed flamelet generated manifolds

Abstract

Large eddy simulation results are presented for a model gas turbine combustion chamber, which is operated with a premixed and preheated methane/air mixture. The off-center position of the high axial momentum confined jet burner causes a strong outer recirculation, which stabilizes the flame. Turbulent combustion is modeled by the premixed flamelet generated manifolds (PFGM) technique, which is combined with the artificial thickened flame (ATF) approach. The influence of different heat loss modeling strategies on flame propagation and structure is investigated. Besides the established method of using burner-stabilized flames as basis for the non-adiabatic tabulation, an alternative approach based on freely propagating flames with heat loss inclusion by scaling of the energy equation source term is presented. Different grid resolutions are applied to study the impact of cell size and filter width on the results, the effect of subfilter modeling is also examined. The simulation setup and the modeling approach are validated by comparison of computed statistics against measurements. A good overall agreement between simulation and experiment is observed. However, the length of the flame was slightly under-predicted; it is shown that a simple method for consideration of strain effects on the flame has the potential to improve the predictions here. The effect of heat loss on the combustion process is then characterized further based on probability density functions obtained from the simulation results.