EXTENDED LES-PaSR MODEL FOR SIMULATION OF TURBULENT COMBUSTION

In this work, a novel model for Large Eddy Simulations (LES) of high Reynolds moderate Damkohler number turbulent §ames is proposed. The development is motivated by the need for more accurate and versatile LES combustion models for engineering applications such as jet engines. The model is based on the ¦nite rate chemistry approach in which the ¦ltered species equations of a reduced reaction mechanism are solved prior to closure modeling. The modeling of the ¦ltered reaction rate provides the challenge: as most of the chemical activity, and thus also most of the exothermicity occurs on the subgrid scales, this model needs to be based on the properties of ¦ne-scale turbulence and mixing and Arrhenius chemistry. The model developed here makes use of the similarities with the mathematical treatment of multiphase §ows together with the knowledge of ¦ne-scale turbulence and chemistry obtained by Direct Numerical Simulation (DNS) and experiments. In the model developed, equations are proposed for the ¦ne-structure composition and volume fraction that are solved together with the LES equations for the resolved scales. If subgrid convection can be neglected, the proposed model simpli¦es to the Partially Stirred Reactor (PaSR) model. To validate the proposed LES model, comparisons with experimental data and other LES results are made, using other turbulence chemistry interaction models, for a lean premixed blu ̈-body stabilized §ame.