Flamelet LES of swirl-stabilized oxy-fuel flames using directly coupled multi-step solid fuel kinetics

Abstract

In this work, a new Large-Eddy Simulation (LES) based approach coupled to a flamelet description of the gas-phase and seamless detailed solid-fuel kinetics is introduced and applied to a self-sustained oxy-fuel coal combustion chamber. LES enables a detailed description of the turbulent flow field, mixing, and heat transfer. The latter also includes thermal radiation for the particles and solving the radiative transport equation using the weighted sum of gray gases for the gas phase. The flamelet description of the gas phase represents an accurate and computationally efficient way to include turbulence-chemistry interactions taking into account the reaction of the complex gas mixture released from the solid fuel particles. For the first time, these two detailed models are coupled with a recently developed solid-fuel kinetic mechanism, allowing of the entire particle conversion process, i.e., devolatilization and char oxidation, to be seamlessly included in the simulation. After the required coupling strategies are discussed, the holistic model is applied to an oxy-fuel combustion chamber. Firstly, the results are extensively validated by the available measurements. Secondly, comparisons to state-of-the-art simplified solid fuel kinetics are carried out to assess the interaction of detailed solid-fuel kinetics with the other models.