Modeling Pulsating Combustion Due To Flow-Flame Interactions In Vortex-Stabilized Pre-mixed Flames

Abstract Large amplitude oscillations have been observed in pre-mixed combustion systems, where the flame is stabilized in the recirculation zone behind an obstacle or a sudden expansion (a dump), and have been related to coupling between the combustion dynamics and the acoustics of the system. We have constructed a model, which includes an intake duct connected to a large upstream reservoir at a fixed pressure, a compact combustor with a sudden expansion followed by a sudden contraction (a cavity), and a long exhaust duct connecting the combustor to the atmosphere, to describe a system typical of a pre-mixed dump combustor. The upstream and downstream components are modeled as ID non-reacting flow systems, while the combustor is modeled using a vortex simulation of the 2D Navier-Stokes equations with a low-Mach number, thin flame combustion model. Results indicate that the system dynamics is comprised of the combustor wake-mode, ƒD/U=O(0.l, and several other modes characteristic of the acoustics of the o...

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