Computational Fluid Dynamics Laboratory

Localized Extinction/Reignition in Turbulent Diffusion Flame

This work is progressing toward a simulation of Sandia Flame D, E, and F to study the dynamics of localized flame extinction and reignition, for the purposes of developing extinction models for common engineering use. The large eddy simulation (LES) technique is used along with the filtered mass density function (FMDF) scalar closure model which solves for the sub-grid scalar joint PDF, allowing accurate representation of the highly-nonlinear combustion kinetics. A 16-species reduced chemical mechanism is used along with a custom implementation of the in situ adaptive tabulation (ISAT) dynamic lookup table for accelerating chemistry calculations by several orders of magnitude.

Early Results

Below is an animation of an early isothermal mixing simulation using the FMDF closure model. The movie begins by visualizing vortical structures in the flow along with contours of mixture fraction. The camera then zooms into the near-field region to show the sub-grid stochastic particles in a single plane of grid cells through the jet centerline. It is these particles from which the resolved scales are derived.

Stochastic Particles
(MPEG - 24MB)   (AVI - 28MB)   (Animated GIF - 41MB)

Below are some animations of an early reacting simulation of Sandia Flame D. These show the beginning of a simulation, where the initially-laminar flow transitions to turbulence and combustion begins. Mass fraction and volumetric mass production rate are shown for a few select chemical species.

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