Analysis of Small Scale Turbulence-Combustion Interaction for LES Modeling

Abstract

The purpose of this work is to analyze and model the interaction between turbulence and combustion in LES modeling, particularly focusing on small scales, and to increase subgrid phenomenon modeling accuracy in order to perform more precise numerical simulations of turbulent reacting o ws. The Crocco-Vazsonyi equation has been used as the starting point of this analysis because it links uid-dynamic properties of the o w to the thermodynamic ones. A kinetic energy transport equation specialized for small scales of turbulence has been obtained and a kinetic energy source term was isolated. This term expresses the turbulence-combustion interaction at the \ne scales of the LES simulation and takes into account the uid-dynamic properties together with the thermodynamic eects due to chemical reactions. Moreover momentum and species source terms were derived to complete the description of small scale phenomena. This source term model has been proven to be consistent with combustion physics by analyzing source term distributions for both a 2D non-reactive and a 3D reactive o w. A coaxial burner investigated at Sydney University was used as test case. Kinetic energy, momentum and species source terms represent the base for a LES subgrid modeling approach completely independent of classical Eddy Viscosity models.