Velocity-Induced Flame Blowout Of Lean Premixed Bluff-Body Stabilized Flames

An improved understanding of lean turbulent combustion phenomena is critical for the development of the next generation of aerospace propulsion technology. Systems operating at lean conditions are uniquely susceptible to flame stabilization dynamics which induce frequent and continuous local extinction throughout the combustion region. These blowout events originate from the local fluid dynamics, which induce regions of heightened hydrodynamic strain throughout the flow-field. When in excess of the flame’s tolerance, extinction occurs. Much recent experimental work has demonstrated that repeated local blowout and reignition events of this nature are inevitably indicative of global extinction. Global extinction is a critical obstacle which must be overcome in order to improve lean turbulent combustion technology. This research is focused on understanding the physical mechanisms which drive flame extinction using a recently developed and currently improved physics-based model. The model has been used in previous work to understand the flame extinction mechanisms which dominate turbulent combustion systems operating at the lean limit. In the current work, modifications are made to the same Lagrangian vortex model, which is used to analyze the mode of flame extinction driven by increasing inflow velocity. This is a fundamentally different extinction mechanism, induced primarily by increased strain rate rather than decreased flame strain rate tolerance. Improved understanding of this blowout mechanism will increase overall knowledge of flame stabilization dynamics and extinction in turbulent propulsion systems