LES Combustion Model With Stretch and Heat Loss Effects for Prediction of Premix Flame Characteristics and Dynamics

Abstract

The present paper extends an approach to include effects of stretch and heat losses into turbulent combustion models from the RANS framework to the LES framework. This approach has shown the potential to improve the prediction of flame stabilization by considering these combined effects. The model is based on the calculation of the consumption speed of laminar premixed flames influenced by variations in strain and heat loss in asymmetric counterflow configurations. The consumption speed depending on strain and heat loss is introduced into a turbulent combustion model based on a progress variable approach. Large Eddy Simulations of a fully-premixed axial swirl burner with and without the influence of stretch and heat loss effects are carried out and validated against flow field and OH* chemiluminescence measurements for different power ratings and equivalence ratios. Flame dynamics are also investigated by extracting the Flame Transfer Function of the fully-premixed axial swirl burner with System Identification methods. Good agreement on the flow field, flame characteristics and dynamics between experiment and simulation was obtained with the inclusion of stretch and heat loss effects into the combustion model. Results show the importance of including these effects into turbulence combustion models for the design of premix burners for gas turbine combustors.