A CRN-CFD incremental fidelity framework for the design and optimization of ammonia-fueled combustors

This work introduces an incremental-fidelity design framework that streamlines the development of ammonia-fueled combustors. The approach begins by representing the combustor using Chemical Reactor Networks (CRNs), which enable the rapid multi-objective optimization of design parameters — including zone equivalence ratios, dilution levels, and reactor volume allocations — to identify Pareto-optimal configurations that balance NOx emissions and combustion efficiency across lean and rich operating regimes. Selected designs are then advanced to high-fidelity Computational Fluid Dynamics (CFD) simulations to capture detailed flow–reaction interactions and validate CRN predictions. Results confirm two complementary strategies: globally lean configurations, which deliver high efficiency with moderate NOx, and globally rich ones, which suppress NOx to trace levels at some efficiency cost. By progressively increasing model fidelity only where needed, the framework combines the speed of CRNs for broad design-space exploration with the accuracy of CFD for targeted refinement. This strategy can significantly reduce computational costs while providing robust insights into combustion behavior, ultimately accelerating the development of sustainable, low-emission combustor concepts for various fuel compositions and operating conditions.