STUDY OF FLAME STABILIZATION IN A SWIRLING COMBUSTOR USING A NEW FLAMELET FORMULATION

ABSTRACT

The dynamics in a swirl-stabilized flame is studied using large eddy simulation (LES). We account for the effect of turbulence on the flame through a model based on a filtered flamelet technique. The model provides a consistent and robust reaction-diffusion expression for simulating the correct propagation of premixed flames. The filtered flamelet formulation has been implemented into a high-order-accurate LES code and used to study the flame stabilization and the combustion dynamics in a gas-turbine combustion chamber. The effects of inlet boundary conditions, in terms of velocity and equivalence ratio radial profiles, have been studied. The flow is found to be very sensitive to small changes in terms of flame shapes and anchoring position. The sensitivity of the results to the subgrid-scale flame thickness has also been investigated. The influence on the flame position is not significant. However, a too-large subgrid-scale flame thickness leads to different flame dynamics.

Keywords:

• large eddy simulation
• premixed combustion
• flamelet
• gas turbine
• swirling flow

Acknowledgments

The authors thank Mr. Dragos Moroianu for his help with some of the data visualizations. The computations were run on LUNARC and HPC2N computing facilities with the SNAC allocation 343-2002-2315-14. This work was financially supported by the Swedish Energy Agency STEM through the TPE program.