Large-Eddy Simulation of Turbulent Combustion

In recent years, Large Eddy Simulation (LES) has been successfully applied to non-premixed and premixed turbulent combustion problems [1, 2, 3]. In most technical combustion applications, the pure non-premixed or premixed combustion models are no longer valid, since partially premixed combustion has to be taken into account. An example is the stabilization region of a lifted non-premixed flame. To overcome this problem, a Combined Conserved Scalar/Level-Set Flamelet model has been proposed [4, 5], which allows for the computation of reactive flows, where both premixed and non-premixed combustion occurs. In this formulation, the G-equation method is used to describe partially premixed flame propagation and to distinguish between burned and unburned regions. The reacting gases in the post-flame region are described by a laminar diffusion flamelet approach. The principal roadmap for the further development and validation of these models is to develop and validate the appropriate methods for the pure premixed and non-premixed combustion situations, and combine the resulting models for a more general formulation. Much of this work has been done in the past. We have developed unsteady flamelet models for LES of non-premixed turbulent combustion [1, 2], and a level-set method for LES of premixed turbulent combustion [3]. These models have been validated with premixed and non-premixed turbulent jet flame experiments. Preliminary simulations with a Combined Conserved Scalar/Level-Set Flamelet Model have already been performed [6, 5]. Results from these simulations are shown in Figs. 1 and 2. Recently, we have developed a new consistent formu-