Direct numerical simulation and modelling of oxy-fuel combustion processes

Project B3 considers higher levels of details for particle structure and kinetics to provide in-depth analysis of the interactions between solid fuel particles and the fluid flow during ignition and combustion for air and Oxy-Fuel atmospheres under laminar and turbulent conditions. In this project, a point-particle model for reactive solid fuel particles has been developed in an Euler-Lagrange framework using a comprehensive model for devolatilization based on the internal structure of solid fuel particles and detailed gas-phase kinetics, adopting the mechanism that is particularly developed to model coal and biomass combustion within CRC 129.

This project employs high-fidelity direct numerical simulations (DNS) for different configurations to generate benchmark solutions, which are assessed jointly with experimental data from other projects to develop and validate reduced-order models that can be used in predictive large-eddy simulations (LES). Therefore, ignition and combustion processes of single and group particle configurations in laminar and turbulent conditions are simulated. In particular, DNS of ignition and combustion in a turbulent jet is performed to study turbulence/chemistry interactions with a large number of fuel particles to provide sufficient statistics, which is required for reduced-order model development. Solid fuel combustion is also studied in a few simulations of a swirl-stabilized configuration to investigate the impacts of particle/turbulence/chemistry interactions on flame stabilization and further assess the reduced-order models used in LES utilizing a priori and a posteriori analyses. Model development is guided by means of the optimal estimator concept, which is used to gain insights into the interactions of particle combustion, particle dynamics, and molecular and turbulent mixing processes.