LARGE EDDY SIMULATION OF A LEAN GAS TURBINE MODEL COMBUSTOR

Partially premixed flames although common on many technical devices are difficult to model in numerical simulations. In this paper a Large Eddy Simulation of a lean combustor is presented. To account for mixing effects in case of partially premixed combustion, a suitable extension to the well known coherent flame model (CFM) is applied. The turbulent reaction rate of the partially premixed flame is approximated by solving an additional transport equation for the flame surface density which accounts for flame wrinkling effects as well as for the creation and destruction of flame surface due to stretch and strain effects. The variation of stoichiometry in the flame is accounted for by using a suitable presumed PDF methodology. The pdf-model represents finite rate, as well as non-equilibrium chemistry effects in the flame. The model has been validated against experimental data. The results show an overall reasonable agreement with experimental data, both in profile shapes as well as peak values.