LES of Turbulent Premixed CH4/H2/Air Flames With Stretch and Heat Loss for Flame Characteristics and Dynamics

Abstract

This paper presents large eddy simulation (LES) turbulent combustion models for premixed methane/hydrogen/air mixtures which account for stretch, heat loss and Lewis number effects by means of a previously proposed turbulent flame speed expression [1]. In this expression stretch and heat loss effects are introduced by means of strained non-adiabatic laminar consumption speed calculations in fresh-to-burnt counter flow configurations with detailed chemistry, and preferential diffusion of hydrogen is accounted for by calculating an effective Lewis number of the reactants. To validate and analyze the performance of the models, large eddy simulations of fully premixed atmospheric bluff body stabilized methane/hydrogen/air flames are compared against experimental measurements [2, 3]. Heat release distributions and mean flame shapes are compared against OH* chemiluminescence data. Flame dynamics are investigated by extracting flame transfer functions (FTFs) with system identification (SI) methods and comparing them with measured FTFs from experiments.