Full coupling between radiatiOn and Combustion for Unsteady Simulation

Abstract

Numerical simulations of turbulent reacting flows including pollutant formation and radiative heat transfers are mandatory for practical applications but require adapted models and large computational resources. Large eddy simulations (LES) where larger turbulent motions of the flow field are explicitly resolved when only the small ones effects are modelled appear as a promising tool for such simulations. In this approach, cold fresh gas zones and hot burnt gas zones, which behave very differently in terms of pollutant formation and radiative heat transfers, are identified at the resolved scale level and subgrid scale contribution, mainly limited to the vicinity of the resolved flame front, may be neglected at a first step. Physical phenomena involved in combustion and radiative heat transfers are also very different. Flow fields are generally described through balance over small volumes (finite volume context). Whereas radiative heat transfers involve long distance interactions. Accordingly, reacting flows and radiative heat transfers codes have a very different structure. The proposed approach takes advantage of an efficient coupling between a LES solver and codes devoted to radiative heat transfers where data exchanges occurs at time intervals controlled by the physical times of each phenomenon.

Taking advantage of the opportunity provided by the DECI program, 3D simulations will be performed. The impact of radiation on the flame dynamics will, then, be accurately investigated. In the same time an estimation of the impact of the radiative model accuracy on the flame behaviour prediction will be proposed. These results will be also helpful for the gas turbine or the furnace burner designers to avoid the apparition of combustion instabilities in their combustion chamber.