Investigation of Reduced Kinetics Mechanisms for Accurate LES and Scaling of the Dynamics of Premixed Swirling Oxy-Fuel Combustion

In this paper, we examine the role of reduced chemical kinetics mechanisms in predicting the flow structure using multi-dimensional large-eddy simulations in complex geometries. We investigate the attributes of the kinetics mechanisms required to predict flow structures such as recirculation zones. Premixed methane-oxy combustion is modeled in a swirl-stabilized combustor. Results show that kinetic mechanisms that accurately predict the extinction strain rate of the underlying flames were able to predict the evolution of the flame macrostructure with equivalence ratio and the associated velocity profiles. The recirculation zone length was found to linearly scale with the extinction strain rate, in agreement with previous findings in different fuel-oxidizer mixtures and combustor geometry. The scaling holds regardless of fuel or oxidizer type, Reynold’s number or inlet temperature. Surprisingly the scaling also held well for two different combustor geometries.