Large eddy simulation of unsteady flame dynamics in a sidewall quenching configuration

Flame–wall interaction (FWI) strongly affects wall heat transfer, near-wall flame extinction, and pollutant formation in combustion systems, with direct consequences for efficiency and emissions. Predicting and controlling these processes requires a mechanistic understanding of the coupled dynamics between wall-bounded flames and surrounding flow structures, yet this coupling remains insufficiently resolved under unsteady conditions. Using wall-resolved large-eddy simulation (LES) with detailed chemistry, this study identifies a recurrent amplification-transfer-dissipation cycle in turbulent sidewall quenching (SWQ) flames: upstream curvature perturbations, associated with unsteady flow features, accelerate the flame front and propagate toward the wall alongside a weak, co-rotating vortex. Near the wall, curvature growth is constrained and the front deforms into a hook-like shape. Perturbation energy transfers to a counter-rotating vortex, which dissipates it by compressing the flame, driving near-wall recirculation, steepening thermal and species gradients, and promoting localized quenching. Linking this cycle to flame stretch, coherent vortex dynamics, and thermochemical transitions, the work integrates geometric, flow, and chemical perspectives to advance modeling of near-wall extinction in turbulent combustion.

Novelty and significance statement

This study provides the first simulation-based characterization of the repeating amplify-transfer-dissipate cycle of curvature perturbations in turbulent sidewall quenching flames, governed by curvature- and strain-induced stretch under wall confinement. By linking this evolution to vortex dynamics and thermochemical transitions, it unifies geometric, flow, and chemical perspectives for improved near-wall extinction modeling.