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LARGE-EDDY SIMULATION OF PARTIALLY PREMIXED TURBULENT COMBUSTION

Heinz Pitsch
Center for Turbulence Research Stanford University Stanford, CA

Resumo

The development of successful modeling techniques for numerical simulations of technical combustion devices will help in the design of more ecient and more stable conversion of chemical into mechanical energy with lower emissions of harmful pollutants. Because of the intricate and complex coupling of chemistry with small-scale and large-scale fluid flow and mixing processes, combustion is inherently a multi-scale problem. For most of the important combustion regimes, the coupling of molecular mixing and chemistry leads to small-scale features, whose structures depend on the flow regime. These local flame structures need to be modeled adequately and incorporated into a large-scale model. Because of the strong non-linearities of the chemical production rates that can lead to the importance of rare events and because of the the importance of scalar mixing for combustion, it will be shown that large-eddy simulations lead to strongly improved predictions for combustion processes. Here, the focus will be on partially premixed combustion, which is characterized by local flame structures in both the premixed and the non-premixed regime. We highlight and discuss some of the modeling challenges that are important for realistic combustion devices.