Numerical studies of vortex-induced extinction/reignition relevant to the near-field of high-Reynolds number jets

Abstract

This work is motivated by the need to understand physical mechanisms governing near-field phenomena, such as flame lift-off, in high-Reynolds number jet flames. Numerical studies of vortex-induced flame extinction/reignition are performed for conditions representative of the near field of high-Reynolds number ͑ϳ100 000͒ jets under high pressure and temperature conditions. The governing equations for compressible, viscous, and reacting flows are solved along with a single-step irreversible chemical kinetic model for gaseous n-heptane oxidation. Extinction/ reignition phenomena, influenced by unsteady and curvature effects, are observed. Unsteady flamelet/progress variable models are shown to accurately describe the flame response during extinction/reignition observed in the flame-vortex studies. Furthermore, while unsteady effects on extinction/reignition are found to diminish with weaker vortices and relatively strong flames, curvature effects are found to increase with relatively thicker flames. The observed flame-vortex interaction regimes are summarized on an outcome diagram, which is useful to understand the nature of localized flame dynamics in the near field of jet flames.

Modeling flame extinction and reignition in large eddy simulations with fast chemistry

“…These works have successfully identified the primary physical mechanisms for extinction (thermal, aerodynamic, and kinetic quenching) [1–9], while others have made progress toward developing simple formulations to model flame extinction in cases applicable to realistic fire scenarios [10–13]. Additional studies have highlighted the primary features of flame reignition events, which may follow localized extinction in large-scale turbulent flames [14–19]. …”