Front-tracking simulation for outward propagation of spherical flames
Journal
45th AIAA Aerospace Sciences Meeting
Journal Volume
7
Pages
4631-4639
Date Issued
2007
Author(s)
Pan, K.-L.
Abstract
We have studied the outward propagation of a spherical flame by means of a fronttracking numerical method. The flame speed is modified by the local curvature, via a Markstein length,? , that somehow groups the complicated physiochemical effects and can be monotonically relevant to the system pressure. The flame is found to accelerate in a unified profile, as a function of the average radius, which is insensitive to initial perturbations after a self-similar regime is reached. The extent of acceleration can be quantified by a growth exponent fitted in a power law, which decreases monotonically from 1.5 when?= 0 to about 1 when?= 0.1. Therefore the diversity of the exponent as reported in the literature can be realized via the variation of? , while other factors may also be involved such as the uncertainty of fitted data. The trend is caused by the degeneration of the hydrodynamic instability as ?is increased, whereby cascading of the cellular structure is suppressed. However, even with a large ? , substantial wrinkling of a flame with multiple scales and consequently self similarity are still possible as long as the spatial dimension is large enough for cells with unstable wavelengths to develop while the acceleration may be small.
Type
conference paper